CARE Spring/Summer 2012 newsletter - Engineers Ireland

care 

conservation accreditation 

register for engineers 

newsletter 

NEWS, VIEWS AND INFORMATION 

FOR CONSERVATION ENGINEERS 

IN THIS ISSUE: 

P10 ENGINEERS IRELAND 

Supporting CARE 

P11 DEWSBURY MARKET HALL 

Conservation repairs 

P15 THE HORNIMAN MUSEUM 

Recounts of subsidence caused by heat 

P16 ST WILFRID’S CHURCH 

Repairs to an unusual roof 

P18 FORTHCOMING EVENTS 

Conservation events and competitions 

Spring/Summer 2012

There can be no finer tribute 

to the energy, passion and community 

spirit of the people of Liverpool than the 

completed restoration of the Florence 

Institute in the Dingle area of the city. 

Sited just yards from the River Mersey, 

the impressive grade II Listed building 

was built in 1889 as a tribute to Florence 

Hall, the daughter of former Liverpool 

Mayor Bernard Hall who died tragically at 

the young age of 22. 

For decades the building served the 

people of Liverpool and is Britain’s oldest 

surviving purpose-built boys’ club. The 

Florrie finally closed her doors in 1988 

and subsequently fell into disrepair. 

York and Manchester based building 

restoration contractors William Anelay, 

a firm with 265 years experience was 

charged with the restoration work under 

the auspices of architects Purcell Miller 

Tritton LLP and Project Manager Buro 

Four on behalf of The Florence Institute 

Trust Ltd, set up by local residents in 

2005. 

The £4.8 million programme of works, 

which started in the summer of 2010 

and completed in March 2012, was 

funded by the Heritage Lottery Fund in 

partnership of european, regional and 

local regeneration agencies, including 

the Northwest Regional Development 

Agency, and ERDF. The project has 

converted the former dangerously 

derelict and vandalised landmark into 

a thriving community resource and 

social comprehensive centre, with a well 

balanced community and commercial 

remit. 

William Anelay, has carried the work 

out in two distinct phases, to achieve 

a ‘very good’ BREEAM rating. The first 

four month tranche of activity focused 

on initial enabling works to clear the 

building and make it safe enough for 

the Project Design Team to 

safely gain access and assess 

for necessary repairs and 

alterations with William 

Anelay experts on hand to 

advise on technical issues. 

The second phase of 

works began in earnest early 

in 2011 and included the 

complete repair of external 

brickwork and terracotta to all 

elevations, the construction 

of a new traditional lead and 

slate roof and the recreation 

and reinstatement of 

architectural features such as vents and 

the distinctive copper cupola that sits 

high above the existing entrance. 

Internally the building was restored 

and reordered with extensive repairs to 

floors and walls and the installation of 

new mechanical and electrical services 

throughout. 

Anelay’s Site Manager Gary Shea 

commented: “Arson and vandalism had 

taken its toll on the building and left it 

disused and structurally compromised 

for over two decades. There was a strong 

element of risk given the building’s 

perilous condition. 

“The initial enabling works has paved 

the way for transforming the building 

back into a valuable community resource. 

“The ground floor of the finished 

building comprises of a large 220m² gym 

facility with library, heritage centre café, 

kitchen and toilet facilities as well as a 

number of small business units. 

“On the first floor there is a large 

320m² main hall which will be used for 

functions with a stage lift constructed 

alongside associated bar facilities. 

There’s also a balcony area and steps up 

to the observatory upon which a new 

copper cupola has been restored. 

“Restoring the main hall has been a 

complex operation with five huge roof 

trusses installed to replace the existing, 

heavily damaged beams that had led to 

roof collapse and water ingress. Internal 

birdcage scaffolding allowed these works 

to take place safely with a temporary 

external roof covering installed over the 

winter months. 

Denise Bernard (formerly Devine) 

Chair/Trustee of The Florence Institute 

Trust Ltd said: “For years, the Florrie 

became a blight both visually and 

physically on the landscape for local 

people and after an arson attack left it 

considerably damaged it became clear 

that something had to be done. Some 

people wanted the Florrie to be razed to 

the ground but thankfully the appetite 

was there to save her. 

“By the Spring of 2012 the Florrie will 

once again be playing a pivotal role in 

this vibrant and diverse community,” 

Denise added. 

York 

Tel: 01904 412 624 

Fax: 01904 413 535 

Manchester 

Tel: 0161 223 7462 

Fax: 0161 230 6514 

info@williamanelay.co.uk 

www.williamanelay.co.uk

CARE 

The Conservation Accreditation Register for Engineers 

The Conservation Accreditation Register 

for Engineers (CARE) identifies civil 

and structural engineers skilled in the 

conservation of historic structures 

and sites. Members have followed a 

rigorous approval procedure to confirm 

an appreciation of disciplines and 

interests extending well beyond their 

professional training as engineers. They 

have demonstrated that they are fully 

conversant with conservation philosophy 

and methods applied to heritage 

projects. 

Additionally, CARE has been established to: 

▪ Assist clients in selecting an 

appropriate engineer with proven 

conservation experience 

▪ Encourage education and training 

in conservation engineering 

▪ Promote sympathetic and 

‘best practice’ conservation 

▪ Raise the awareness of conservation 

in the engineering profession 

Those who are registered are listed 

on the CARE website and entitled to 

use the descriptor ‘Conservation 

Accredited Engineer.’ 

Further information, application forms 

and a list of registered members can be 

found at ice.org.uk/care 

THE CARE PANEL 

Chairman 

Jon Avent 

Technical Secretary 

Clive Richardson 

IN THIS ISSUE: 

P04 WELCOME 

Chairs notes 

P05 ACCREDITATION UPDATE 

News from our partners 

P10 ENGINEERS IRELAND 


P11 DEWSBURY MARKET HALL 


P15 THE HORNIMAN MUSEUM 


P16 ST WILFRID’S CHURCH 


P18 FORTHCOMING EVENTS 


Panel Members 

Ian Hume, Terry Girdler, 

Lawrance Hurst, John Ruddy, 

Charles Blackett-Ord, Sarah Fray 

Architect Representatives 

Tony Walker, Bob Chittham, 

Tim Ratcliffe 

RICS Representative 

Amanda Watmore 

Engineers Ireland Representative 

Roseanna O’Leary 

CARE Panel 

Regional Representatives 

Wales, Cadw - Richard Turner 

Northern Ireland, NIEA - Manus Deery 

Scotland, Historic Scotland - David Mitchell 

Institution of Civil Engineers 

Tony Blackmore 

Awards and Registers Executive 

t +44 (0) 20 7665 2102 

f +44 (0) 20 7222 7500 

e registers@ice.org.uk 

ice.org.uk/care 

03 CARE NEWSLETTER Spring/Summer 2012 ICE.ORG.UK

Chair Notes 

Spring/Summer 2012 

CARE Panel Chairman 

Jon Avent 

NEW MEMBERS 

The Panel are pleased to 

welcome our newest members of 

the CARE Register: 

▪ Margaret Cooke 

▪ Bridget Drake-Wilkes 

▪ Jim Kerr 

Over the past year the CARE Panel has 

continued to promote the register with 

the on-going support of the Institution 

of Civil Engineers and the Institution 

of Structural Engineers. With a stated 

objective of promoting accreditation 

within the engineering profession 

the Panel has sought to widen the 

opportunities for engineers working in 

the heritage sector. In response to this 

objective and also following approaches 

from engineers outside of the UK the 

first links have been formalised with 

Engineers Ireland, and their chartered 

engineers are now able to apply to join 

the CARE register and achieve the widely 

recognised accredited status. 

I have been encouraged by the level 

of support given by ICE and IStructE 

together with Engineers Ireland in 

achieving this agreement and look 

forward to welcoming those engineers 

who have already expressed interest 

in submitting applications. The 

significance of this link-up should not 

be underestimated, as it recognises that 

building conservation needs to embrace 

local, national and international 

construction skills and techniques, 

and that having the ability to share 

knowledge and experience across a 

wider spectrum is to everyone’s benefit. 

We only have to look at the on-going 

heritage loss in New Zealand and 

the recent proposals to demolish 

Christchurch Cathedral to recognise the 

specific need for engineers across the 

world with highest possible standards of 

in-depth and wide ranging experience of 

traditional buildings and structures. 

The New Zealand Historic Places Trust 

believes retaining both the cathedral and 

other heritage central city landmarks 

would help Christchurch’s recovery by 

reinstating cultural tourism. Having 

professionals with universally recognised 

experience of heritage structures can 

only assist with ensuring that all options 

are fully explored. With ICE and IStructE 

members practicing across the world 

these would be areas where we can, and 

should, encourage those working in the 

heritage and traditional buildings sectors 

to consider applying to join CARE. 

Options to forge links in a similar manner 

to that formed with Engineer Ireland 

should also be explored and encouraged; 

particularly now the first steps on this 

path have been successfully negotiated. 

Jon Avent 

BSc(Hons) CEng MIStructE IHBC 

Accredited Conservation Engineer 

Chair CARE Panel 

ICE.ORG.UK 

04 CARE NEWSLETTER Spring/Summer 2012

Accreditation Update 

Our partners 

The principal construction professions 

of Architecture, Building Surveying and 

Engineering all have strong accreditation 

schemes that formally assess and 

approve an individual’s experience 

and competency working within the 

field of building conservation. The 

recent issue of the Home Countries 

Protocol on Accreditation is a formal 

acknowledgement of the need and 

benefits offered by recognised schemes 

and a welcome recent progression. 

These accreditation schemes recognised 

by the UK’s principal conservation 

Home Countries Accreditation Prorocol 

Criteria against which 

Accreditation Schemes would be 

considered by the Home Countries: 

Accreditation of individuals rather 

than companies or practices. 

The skills of a practice are only the 

combined skills of its individual members, 

and as individuals move, the skills of the 

practice will vary. 

Eligibility of all suitably qualified and 

experienced professionals to gain 

accreditation. 

Schemes should be open to all members 

of the relevant professional discipline 

Assessment of a verifiable record of 

work carried out. 

Accreditation needs to be a measure 

of experience and competence, so 

assessment cannot be based simply on 

a statement of philosophy or principles. 

organisations and in many instances 

have become a specific requirement for 

working on heritage projects. 

The following pages provide an overview 

of the principal accreditation schemes 

operated for professionally qualified 

individuals working in the heritage sector. 

Whilst the IHBC scheme is different to 

the accreditation schemes operated by 

the principal professions of Architecture, 

Engineering and Surveying, it does provide 

a significant membership and skills base 

which is recognised across a wide range 

of built heritage professionals. 

Assessment by suitably experienced, 

impartial assessors against agreed criteria. 

Peer assessment, together with 

reassessment on a regular basis 

(say every 5 years) to ensure that 

accreditation indicates current 

competence. 

The use of the ICOMOS Guidelines for 

Education and Training in the Conservation 

of Monuments, Ensembles and Sites. 

These are agreed as the basis of 

assessment of candidates’ experience. 

A credible ethical and linked disciplinary 

framework to ensure that standards are 

observed and maintained. 

There needs to be a way in which 

proper account is taken of examples of 

competence falling below the standards 

required by accreditation 

THE CARE REGISTER 

CARE is administered by the 

Institution of Civil Engineers (ICE) 

and the Institution of Structural 

Engineers (IStructE) and has been 

established to identify engineers 

skilled in the conservation of 

historical structures and sites, be 

they buildings, bridges, harbours, 

riverbanks, canals, industrial sites 

or natural landscapes. These 

engineers may either be working 

as lead consultants on projects 

where engineering is dominant or 

as sub-consultants where there 

is structural engineering content. 

They must have an appreciation of 

disciplines and interests extending 

well beyond their professional 

training as engineers and show that 

they understand the philosophy 

and methods applicable to the 

conservation of historic work. 

The Register is intended as a means 

of encouraging engineers to raise 

their awareness and standards 

by pursuing their continuing 

professional development in this 

specialist field. 


RIBA 

The RIBA’s Register of accredited 

conservation architects was launched 

in 2010. It enables those looking to 

commission work on heritage buildings 

to find architects with the specific 

skills and experience they require, 

encompassing all aspects of historic 

building conservation, repair and 

maintenance. 

Recognising the distinctive nature of 

conservation work, and moving away 

from a ‘one size fits all’ approach, the 

Register operates upon three levels of 

membership, which also provide an 

incremental process of accreditation 

for those who are in the early phases 

of establishing their careers in building 

conservation: 

▪ Specialist Conservation Architect 

(SCA): For those working on historic 

buildings of out-standing national 

importance, such as Grade I and II* 

listed buildings or scheduled 

monuments, and with highly 

specialist skills in one or more 

aspects of conservation. 

▪ Conservation Architect (CA): Suitable 

for those working on Grade II listed 

buildings, regionally important 

historic buildings and in sensitive 

historic environments. 

▪ Conservation Registrant (CR): 

For those working on the repair, 

maintenance, alteration and 

refurbishment of heritage buildings, 

e.g. unlisted buildings in Conservation 

Areas, locally important historic 

buildings and the general pre 1919 

building stock. 

The RIBA Conservation Register is 

endorsed by English Heritage and 

Historic Scotland, who recognise the SCA 

level only for grant purposes. 

More information can be found on 

www.architecture.com 

ICE.ORG.UK 


AABC 

The Register of Architects Accredited in 

Building Conservation is an independent 

accreditation body established in 1999 

with the active support of English 

Heritage. The purpose of the Register is 

to protect the historic built environment 

from damaging interventions devised 

by people not skilled in historic building 

conservation and adaptation. It does so 

by publishing, for the benefit of clients, 

a register of architects whose work and 

skills in building conservation have been 

established by careful assessment. 

AABC’s twenty assessment teams 

each comprise two accredited 

conservation architects and one lay 

person knowledgeable in the field and 

usually from a client background. Lay 

involvement in the accreditation process 

ensures the Register’s objectivity and 

client emphasis. Executive architects who 

personally devise and produce contract 

documentation and administer contracts 

make up the majority of the register 

and may use the suffix AABC (Architect 

Accredited in Building Conservation). 

Architects acting in more of an advisory 

or managerial capacity, perhaps leading 

several projects or acting as conservation 

officers but not personally producing 

detailed documentation or carrying out 

contract supervision, 

may apply for accreditation as a 

consultant architect. 

Similarly, specialist architects practising 

as conservators or researchers and 

having only a limited involvement in 

projects may also be accredited as 

a consultant architect. In this case 

registrants may use the suffix CAABC 

(Consultant Architect Accredited in 

Building Conservation). 

There are over 400 architects listed 

on the Register. AABC’s website offers 

detailed guidance on core conservation 

principles, key competences and 

the preparation of applications for 

accreditation. AABC also operates an 

Apprentice scheme which offers a 

structured pro-gramme of mentoring 

and guidance to younger architects 

who wish to become accredited. Since 

the Register was established AABC has 

become a benchmark in historic building 

conservation. Membership has increased 

regularly over the last twelve years and 

continues to grow. 

More information can be found on 

www.aabc-register.co.uk 

07 CARE NEWSLETTER Spring/Summer 2012 

ICE.ORG.UK

RICS 

The RICS Building Conservation 

Accreditation Scheme (BACS) was 

established in 1992 to provide a register 

of individuals knowledgeable in the field 

of conservation of historic buildings 

or sites. Since its introduction the 

scheme has promoted good practice and 

standards and has gone on to become 

recognised and respected throughout 

the industry. 

The aim of the scheme is to provide a 

register of individuals with experience 

and knowledge in the field of 

conservation of historic buildings or sites. 

The scheme has the backing of 

English Heritage who will only select 

professionals form a number of approved 

bodies, RICS being one of these. 

There are currently two routes into 

accreditation depending on educational 

attainment and experience. 

▪ Experienced – Only route for 

applicants with no posts graduate 

academic qualification in Building 

Conservation; or 

▪ 

Academic – For applicants with 

experience and a recognised post 

graduate academic qualification in 

Building Conservation. 

Members of the Building Conservation 

Accreditation Scheme are subject to 

ongoing monitoring by RICS Regulation. 

Accredited members of the Building 

Conservation Accreditation Scheme are 

required to provide details of continued 

involvement in building conservation on 

an annual basis by submitting details of 

their CPD records, and any additional 

documentation that may be required. 

The register of fully accredited members 

is updated regularly and is available 

to the public and other client groups 

through RICS information services and 

the RICS Website. 

More information of the scheme can be 

found on www.rics.org 

ICE.ORG.UK 


IHBC 

Membership of the IHBC differs 

from other accreditation schemes 

as assessment concentrates on 

competence across conservation advice 

and processes. IHBC accreditation 

demands com-petent standards across 

the key stages of conservation: valuing 

and managing heritage, and where 

appropriate changing it for the better 

through intervention (illus). If applicants 

do not demonstrate competence in their 

primary discipline, they cannot satisfy the 

demands of IHBC accreditation. 

Applicants are not expected to be experts 

across each stage of conservation, 

but must demonstrate competence 

outside their specialist area. The 

application process ensures applicants 

consider conservation skills holistically, 

acknowledging what they do not know 

as well as what they do. This satisfies 

the spirit of the 1993 ICOMOS guidelines 

as well as the letter. Also, applicants 

might come from any discipline, but must 

also articulate and verify a high-level 

balance of skills, knowledge and 

experience across conservation, all to 

the satisfaction of an inter-disciplinary 

panel of assessors. 

Unlike other professional bodies, the 

IHBC do not re-accredit members, but 

operate a disciplinary process tied to 

a Code of Conduct, that provides a 

continual monitoring of conservation 

standards in accredited members. 

Like others systems, the IHBC does not 

accredit businesses, but does ‘recognise’ 

them through a quality-assurance 

listing called HESPR. The services these 

businesses provide are tied to the IHBC 

standards through employees who are 

also IHBC accredited members. 

IHBC: www.ohbc.org.uk 

HESPR: www.ihbc.org.uk/hespr/ 

Contact: Sean O’Reilly, 

director@ihbc.org.uk 

The IHBC’s Conservation Cycle 

informs our accreditation as 

applicants must demonstrate 

skills across the cycle from 

valuing and management to, 

where appropriate, intervention. 


Engineers Ireland 


Restoration of Dunboy Castle 

by Cork based conversation 

engineers, Southgate 

Associates 

John Power, Director General 

of Engineers Ireland and 

Sarah Fray, Technical 

Director of Institution of 

Structural Engineers signing 

formal agreement. 

With CARE providing the framework to 

promote engineering standards within 

the heritage sector and with growing 

recognition of the benefits of achieving 

formal accreditation it is a welcome 

and logical step for Engineers Ireland 

to provide its support to the register. 

Following the recent formalising of links 

with the register, Chartered members of 

Engineers Ireland are now eligible to apply 

to join the register by following the same 

application process open to chartered 

members of ICE and IStructE. 

For those unfamiliar with Engineers 

Ireland, the working title for “The 

Institution of Engineers of Ireland” it 

traces its origins back to 1835 when a 

group of leading Irish engineers formed 

a society to promote the civil engineering 

profession and share their experiences. 

In 1844 the organisation became the 

Institution of Civil Engineers of Ireland 

and 33 years later in 1877 became one 

of the first chartered institutions in the 

British Isles. Cumann na nInnealtoiri (The 

Engineers Society) was founded in 1928 

to advance the prospects and status of its 

members. 

In 1969 the Oireachtas (national 

parliament ) passed the Institution 

of Civil Engineers of Ireland (Charter 

Amendment) Act, 1969 and following 

this the Institution of Civil Engineers and 

Cumann na nInnealtóirí merged to form 

the Institution of Engineers of Ireland, 

later rebranded as Engineers Ireland. 

The new institution widened its scope to: 

Cater for all engineering disciplines 

Ensure standards in the profession 

▪ Promote engineering as a career 

▪ Encourage Continuing Professional 

Development for engineers 

▪ Represent the interests of the 

engineering profession in Ireland and 

internationally 

Ireland has a rich and varied built heritage 

spanning many centuries. Throughout the 

country there are many building types and 

structures represented, some of which are 

unique to the country. This built heritage 

takes the form of large estate houses, 

vernacular heritage such as thatched 

cottages, industrial related structures 

such as canals, bridges, mill buildings and 

warehouses with planning authorities 

obliged to have a Record of Protected 

Structures (RPS). Owners and occupiers of 

protected buildings are required to ensure 

that buildings do not become endangered 

through harm, decay or damage. 

Having widely recognised professional 

conservation accreditation standards 

to support this process and provide the 

highest standard of advice is undoubtedly 

a benefit to all concerned. Engineers 

Ireland look forward to developing and 

growing strong links across the heritage 

sector through their support of CARE. 

Further details can be found on Engineers 

Ireland website at 

http://www.engineersireland.ie/care/ 

ICE.ORG.UK 


Dewsbury Market Hall 


Ian Andrew CEng MICE MIStructE, WYG Engineering Limited, August 2011 

The cast-iron and steel framed Dewsbury 

Market Hall, which is owned by Kirklees 

Metropolitan Council and stands in 

Dewsbury Conservation Area, was erected 

in 1903 and 1904 to the design of local 

architect and borough engineer Henry 

Dearden (Associate Member of the ICE), 

by H E Hodgson & Co, Contractors. 

The hall is a single-storey four-bay framed 

building comprising an array of cast-iron 

columns supporting a series of riveted 

steel plate-and-angle perimeter beams, 

and three intermediate lattice girders 

made from steel plates and angles 

spanning east-west at valley positions. 

The roof structure comprises a series of 

45-degree duo-pitched tied-arch trusses 

made from steel plates, rods and angles 

such that they span north-south from the 

perimeter girders on the south and north 

sides and the intermediate lattice girders. 

The four roof bays are hip-ended, and the 

half-trusses for these are supported by the 

east and west perimeter girders. The plan 

shape of the building is approximately an 

equilateral rhombus, the overall lengths 

of each side being just over thirty metres. 

The height to the eaves is approximately 

8.5 metres. 

Lateral stability in the structure is obtained 

through gravity and nominal connections 

via the tapped location bolts between 

the roof structure and the column tops, 

assisted by cantilever action assumed to 

be available from the foundations. 

In practice, this is probably also assisted 

by the timber-framed glazing that exists 

between the undersides of the perimeter 

girders and RSJs above shop-front level. 

During routine re-painting in 2006, 

severe local corrosion was discovered in 

concealed steelwork above a cast-iron 

stanchion in the north-east corner of the 

market hall. Intrusive inspection behind 

the decorative cast-iron box-castings 

above remaining perimeter column 

tops revealed that severe corrosion was 

present at all these locations. The interior 

column tops, which are not concealed by 

decorative castings, were found to be free 

of damaging corrosion. The expansive 

action due to this highly-localised 

corrosion had lifted the perimeter beams 

by up to 25mm, such that many of the 

tapped location bolts fitted through the 

bearing areas had failed in tension. 

At several column tops, the perimeter 

beam webs had failed causing beam 

sections to settle onto the glazed screens 

below. In addition, the bolts that secured 

the ends of the intermediate lattice girders 

to the east- and west perimeter beams 

had failed due to corrosion of the beam 

webs. 

The cause of the corrosion was electrolytic 

action between the dissimilar metals. 

This was promoted by the damp and 

dirty conditions that prevailed behind the 

castings, aggravated because the column 

shafts had also been used to convey 

rainwater to the public drainage system. 

It is thought that the damage had been 

present for a long time. 

PROJECT INFORMATION 

Existing part-section through roof 

Cleaned-up column top revealing 

necked location bolts 

Decorative box-casting removed reveals lattice 

girder end bolts have failed 



Detail of existing part-elevation of column 

top and perimeter beams 

Cutting out corroded steel in 

perimeter beams 

Detail of proposed repair to 

column top using UB 

The design principle for permanent 

repair was to reinstate the function 

of the perimeter beams and to ensure 

their bearings on the tops of the 

columns would be even (by removal of 

eccentricity induced by corrosion). Various 

improvements to prevent further corrosion 

were specified, including application 

of a two-pack epoxy protective paint 

system and introduction of a contactbreaker 

barrier between the new UB 

bearing flanges and the existing column 

tops. This principle allowed a minimal 

intervention route to be followed so that 

as much of the original fabric could be 

retained as possible. 

The worst-affected areas were shored 

immediately to prevent further 

settlement. The presence of Batley 

Beck culvert very close to the east side 

was taken into account in the shoring 

scheme. The shoring, which was 

extended to provide temporary support 

for all perimeter beams, included a 

device to allow the perimeter beam 

ends to be jacked up slightly if desired 

to permit accurate realigning and relevelling 

following implementation 

of permanent repairs. The method of 

implementing these repairs as originally 

designed was to cut out the corroded 

parts of the perimeter beams where 

they pass over each column and replace 

them with short UB sections spliced 

to the remaining beam sections, thus 

reinstating the bearings. This work also 

reinstated horizontal continuity in the 

perimeter beams across the column tops. 

However, at the start of the work on site 

it was decided that the new UB sections 

would be too heavy to install easily. 

Whilst maintaining the design principle, 

the detail was therefore amended using 

folded steel plate and angle sections 

assembled on site. This had a further 

advantage that jacking was not required 

as the components were able to be 

fabricated on site to suit the distorted 

shape of the perimeter beam. The 

disadvantage is that the perimeter beams 

have been left in their distorted positions, 

although this has minimal visual effect. 

The tolerance gaps under the new 

bearings were grouted using a specialist 

cementitious mortar. The grout also 

ensured there will be no direct contact 

between differing metals (mortar is a 

non-conductor and is alkaline), thus 

providing passive protection against 

future electrolytic action. The boxcasting 

pieces, which had been cut up 

to allow them to be removed for access, 

were bolted to the structure and the cut 

edges cold-stitched back together, thus 

completing the repair work. 

Certain other minimally-intrusive repairs 

and alterations were also incorporated 

to improve the structural performance 

of the building. The scaffolded work 

area at roof level provided for general 

refurbishment work presented an 

opportunity to improve this public 

building’s resistance to accidental 

horizontal loading (noting the existence 

of cast-iron in the primary load path). 

ICE.ORG.UK 


This was done by removing the 

considerable “slack” in the existing 

tie-chords between the feet of the roof 

arches (there had been insufficient 

provision for tightening the tie-chords 

originally), so making the connection 

between the roof structure and the 

column tops more positive. This was 

done by inserting a new longitudinal 

carbon-steel tie-rod at tie-chord level in 

each of the four bays of the roof so that 

the existing tie-chords could be alternately 

displaced sideways and locked off against 

the new tie-rods. The number of bolts 

tapped into the cast-iron of the column 

tops was also increased where space 

permitted, to improve general robustness 

at column-top level. 

Kirklees Metropolitan Council recognised 

that the building, whilst not listed, is in a 

conservation area, and that it was unlikely 

that the local community would have 

accepted replacement of their market hall 

without such repairs. In addition to 

following the chief principle of working 

with historic buildings, viz. minimal 

intervention to the fabric of the building, a 

high degree of sustainability was therefore 

achieved during repair of the market hall. 


New folded-plate splice delivered to site 

New steel splice fitted up on 

existing column top 

Project Statistics: 

Client: 

Kirklees Metropolitan Council 

Architect: 

Aedas Building Surveying Limited 

Structural Engineer: 

WYG Engineering Limited 

Main Contractor: 

Richardson Projects Limited 

Cast-Iron Sub-Contractor: 

Casting Repairs Limited 

Project Cost: 

£1.2 million 

Completed repair awaiting 

grouting and painting 

Exterior view after completion 


The Horniman Museum 


Clive Richardson, a Technical Director 

of URS, and their Conservation Team 

Leader, recounts the surprising case 

of subsidence caused by heat from a 

basement boiler room. 

After 90 years of stability, part of the 

Horniman Museum in South London 

suddenly started to subside. Its heating 

system had baked the clay ground 

beneath it. This adversity was turned 

to advantage with underpinning to 

make new basement space. Top-down 

construction was used for temporary 

stability and to conserve the unique tiled 

ground floor. 

The Horniman Museum was built in 1901 

at Forest Hill in South London. Designed 

by Charles Harrison Townsend in the 

Art Nouveau style for the tea merchant, 

Frederick Horniman, it is now listed 

Grade II star. Behind its stone façade 

are two original exhibition halls with 

brick cladding, founded on concrete strip 

foundations, stepping up the shrinkable 

London Clay hillside. 

The superstructure is distinctive for its use 

of all three metals: riveted wrought iron 

barrel-vaults, cast-iron balcony columns, 

and mild steel filler-joist gallery floors. 

The floors have mass concrete groundbearing 

slabs with perimeter ducts which 

deliver heat through their floor gratings 

by convection from water pipes heated by 

basement boilers. 

One day it was noticed that some of the 

tall glass exhibition cabinets in the south 

hall were tilting. Part of the floor and the 

column supporting the end balcony over it 

had sunk 100mm. 

A trial-pit was dug through the floor, and 

we were greeted by a blast of hot air! The 

clay had shrunk away from the floor leaving 

a gap under the floor slab through which 

hot air was escaping from the heating 

ducts. Fortunately the basement heating of 

the north hall had been de-commissioned 

many years ago, so the problem only 

affected the south hall. 

The clay had been baked as hard as brick 

to a depth of four metres. It had lost its 

clay-like properties. When a lump was 

placed in water, instead of re-hydrating 

and swelling, the clay disintegrated and 

collapsed to a powder. Indeed, the case 

was so singular that the Building Research 

Establishment offered their services free of 

charge. 

There was concern that if the water table 

rose, wholesale collapse of the baked clay 

could occur, which would not just affect the 

floor slab, but also the foundations of the 

hall. It was decided to remove the baked 

clay, and rather than backfill the 4m deep 

excavation, the museum’s Trustees asked 

for a new basement to be created instead, 

as they were short of space. 

Top-down construction was chosen, to 

maintain lateral stability of the existing 

shallow foundations. Mining techniques 

were used to burrow under the tiled ground 

floor between the south and north halls, 

and not a single tile was lost in the process. 

As the museum had always been free and 

the Trustees had never sought funding, 

English Heritage gave them a 100% grant 

of £1.1m to do the work. “Free Museum” 

is still emblazoned in stone over its 

entrance to this day, and it is now free from 

subsidence too! 


Trial pit through ground floor slab, 

revealing clay beneath baked like brick. 

Heating ducts beneath the floor, dropped 

away from floor slab. 

Cracked column casing, hanging from 

balcony above. 



Truss and Soffit of Deck in Roof Void 

Ceiling Support System in Roof Void 

Cherry Picker for Opening Up Work 

St Wilfrid’s Church 


Michael Taylor BSc CEng MICE Conservation Accredited Engineer February 2012 

The church 

St Wilfrid’s is a Grade II* listed Anglican 

Church situated off Selby Road, Halton, 

Leeds, built in 1938 and designed by the arts 

and crafts architect A. Randall Wells. 

The building is steel framed, with stanchions 

and concrete cased beams. The shallow 

pitched roof consists of steel trusses at 

3m centres, spanning 9m across the Nave, 

Transept or Chancel. Between the trusses 

are corrugated asbestos sheets with infill 

reinforced concrete. The deck is then 

waterproofed with mastic asphalt. 

Suspended from the trusses is a vaulted 

ceiling consisting of strawboard and plaster 

skim on a light steel frame. 

The problem 

The asphalt is reaching the end of its life 

and the roof has been leaking for some time. 

With asbestos present, it was undesirable 

to disturb, so over-roofing was proposed, 

using zed purlins, ply decking and either 

asphalt or a single ply membrane. Blackett- 

Od Conservation were engaged to advise on 

structural implications. 

On-Site investigations 

Since the over-roofing scheme represented 

an increase in load, it was necessary to check 

the existing roof structure for this addition. 

No drawings of the existing structure were 

available, so compact mobile elevated 

working platforms were used to inspect 

concealed structure through holes cut in the 

vaulted false ceiling. Some opening up was 

also carried out on the roof to check the 

asphalt thickness and deck construction. 

Asbestos and concrete 

decking system 

The decking system was unusual, so it was 

important to learn more. 

Investigations revealed: 

▪ The decking is a 3” deep corrugated 

asbestos system with concrete filled 

corrugations 

▪ Each corrugation has two steel reinforcing 

bars, each of which consists of two 6mm 

diameter strands twisted together 

▪ Below the corrugated asbestos is a flat 

asbestos soffit board, somehow bonded 

or fixed to the corrugated sheet above. 

We could see no physical fixings 

▪ There were occasional transverse 0.5mm 

cracks in the flat soffit asbestos sheets 

which sounded hollow when tapped, 

calling into question the bond between 

corrugated and flat sheets 

A desk study included contacting the ICE and 

IStructE libraries and the Civil Engineering 

Heritage Exchange (CEHX). The Civils library 

came up with a technical article from the 

Indian Concrete Journal of November 1943 

and an advertisement from a publication 

called “Specification 1937”. It concluded the 

product was “Handcraft Reinforced Decking” 

manufactured by Universal Asbestos, Watford. 

The Indian paper gave load tables suggesting 

that the maximum span for the 3” deep 

section was 6 feet. Since we had 3” sections 

spanning 10 feet, this was of concern. 

Checking by calculation the 3” deep 

reinforced section, we found that strength 

was adequate, but deflection exceeded 

acceptable limits. 

Roof truss analysis 

In parallel to the investigations into the 

decking system, we needed to check the 

roof trusses for increased loads. The trusses 

were made with steel angles, bolted to steel 

gussets. There was some slight surface 

corrosion generally, although more serious 

ICE.ORG.UK 


where the roof had leaked. 

With the trusses made around 1938 we 

used figures from the Historical Structural 

Steelwork Handbook, taking a permissible 

bending stress of 8.0 tons/in2 (123.6 N/ 

mm2) and compressive stress of 7.2 tons/ 

in2 (110.7 N/mm2). Checks were done to BS 

449 with a 5% section loss due to corrosion 

assumed. Calculations suggested 20% 

overstress in the bottom chord which could 

be eliminated by two simple additional ties 

per truss. Unfortunately access to the trusses 

would be difficult. 

Conclusions 

A dilemma existed. The over-roofing was 

possible and relieved the present decking 

system of superimposed load, thus 

minimising the deflection problem. Although 

the bond between sheets was questionable, 

there had been no historic failures and 

should such a failure occur, the vaulted 

ceiling below appeared robust enough to 

prevent any flat sheet falling. However, there 

were disadvantages: 

▪ Possible future failure of the bond 

between asbestos sheets was undesirable 

▪ It would be difficult to inspect and 

maintain the decking system and 

structure, which would be concealed from 

below and above 

▪ Health issues with asbestos 

▪ It would be difficult to properly inspect, 

repair, strengthen and paint the steelwork, 

which all were considered important 

requirements of the present scheme 

The alternative was to remove the concrete 

and asbestos deck entirely replacing it with 

a simple timber joisted roof, thus eliminating 

the above problems and giving good 

temporary access for painting and repairing 

steel. However it would be expensive, 

particularly with the need to erect temporary 

scaffolding roof and devise a means of 

manhandling heavy deck units. 

After much deliberation and discussion 

amongst the design team, the Church and 

English Heritage, it was decided to proceed 

with the decking removal. 

Situation now 

The budget for Phase 1 of the work, which 

includes the Chancel roof, Aisles roof, repairs 

to Chancel windows, concrete repairs and 

other maintenance items is £650,000, 

excluding fees and VAT. Tenders have been 

received but as yet no contractor has been 

appointed. It is anticipated that the work 

will go ahead later this year, when we will 

endeavour to report further. 


External View from South East 

Exterior View from South West 

Acknowledgements: 

Client: 

Design Team: 

Advice and 

Principal Grant: 

The PCC, St Wilfrid’s Church, Halton 

Andrew Boyce (Architect) of Ferry and Mennim, York Blackett-Ord 

Conservation Engineers (Structural Engineers) 

ohn Broomfield (Corrosion and Concrete Repair Specialist) 

Turner and Holman, York, (Quantity Surveyors) Mason Clark Associates 

(CDM Co-ordinator) 

English Heritage 

Truss corrosion at roof leak 


FURTHER INFORMATION 

Competition 

Terms and Conditions 

There is no specific guidance on the 

theme of photograph so we hope 

to receive entries showing the full 

spectrum of conservation, including 

the good and even ‘the bad’ 

Maximum of three entries permitted 

per person.Photographs to be A4 

size at 300 dpi resolution and in 

jpg format.Include a brief title and 

summary of the picture(s). 

By entering you are confirming 

that you hold the copyright of the 

photograph(s) and grant CARE, ICE, 

IStructE and Donhead Publishing 

Ltd the right to use photographs in 

subsequent publicity. 

Closing date for submissions is 

31 August 2012. 

The competition is open to all, with 

the exception of the CARE Panel. 

Winning submissions will be 

notified by 30 September 2012, and 

will be published in the next edition 

of the CARE newsletter. 

Forthcoming Events 


Photographic Competition 

The photographic competition which 

ran in the previous newsletter generated 

some confusion on eligibility for 

submitting entries. The only persons 

excluded from entering were members 

of the CARE Panel, effectively opening 

the competition to all others. To redress 

this, and to ensure those wishing to 

enter are given reasonable opportunity, 

it has been decided to award one book 

in this edition of the newsletter, and to 

extend the completion deadline to the 

31st August 2012 for the remaining two 

publications on offer. All photographs 

currently submitted will remain open 

for consideration. 

Forthcoming events 

The Panel are pleased to confirm that 

the photograph selected from existing 

entries is The Mesquita, Cordoba, Spain 

submitted by John Watt. 

This profoundly peaceful building is an 

11th-Century Moorish mosque with 

a Baroque cathedral built through its 

centre after the retaking of Cordoba by 

the Christian Spanish monarchy. The 

building is a unique and enchanting 

blend of cultures and religions conserved 

to contrast these, at times, co-existing 

philosophies. 

Date Event Location Contact 

18 June Historic Building Condition 

Surveys 

6 July Imagining conservation: the 

next twenty years 

3 - 6 Sept Conservation and repair of 

stone masonry 

9 - 13 Sept RICS and SPAB Building Conservation 

Summer School 

24 - 27 Sept The structural repair of historic 

buildings 

8 - 11 Oct Conservation and repair of 

timber 

RICS London 

York Centre for 

Conservation Studies 

West Dean College 

Royal Agricultural 

College, Cirencester 



http://www.rics.org 

navin.piplani@york.ac.uk 

liz.campbell@westdean. 

org.uk 

hfrankham@rics.org 


org.uk 


org.uk 

7 Nov COTAC Conference BRE Watford cotac@thebcc.ac.uk 

28 June SAVE Conservation book fair London www.savebritainsheritage.org 

2 Oct Annual IHBC day conference London london@ihbc.org.uk 

4-5 Oct Understanding wrought iron Malt Kiln Farm, 

Pentney 

traditional.buildingskills@ 

essex.co.uk 

ICE.ORG.UK 


Ultra sound decay detection 

equipment quickly assesses structural 

timber. 

“The science of conservation” 

We are a small, specialist building diagnostics consultancy based in Mid- 

Devon, operating nationally. 

The microdrill quantifies the extent of 

decay 

Providing scientific assessments of timber decay and other damp related 

building defects and advice on conservation-minded solutions for their 

control. 

We utilise non-destructive ultrasound and microdrill instrumentation to 

assess the sub-surface condition of structural timbers. Tests quantify the 

extent of decay, helping the engineer produce designs which minimise the 

loss of historic timbers and surfaces. 

Decay 

Microdrill readings are displayed 

at a 1:1 scale 

01392 308 239 

www.exposuresurveying.co.uk 

info@exposuresurveying.co.uk 

Unlike chemical treatment companies, we are building conservation 

professionals, who practise the philosophy of minimal intervention. We 

focus on controlling defects by realigning environmental imbalances and 

implementing repair strategies that embrace conservation principles. 

Our in-house Works department provide practical assistance with 

strategies for the control of wood decaying fungal infections and beetle 

infestations. 

We can be entrusted to administer targeted chemical treatments as 

appropriate with projects including historic buildings, scheduled 

monuments, ecclesiastical buildings and modern structures. 

All our services can be undertaken at height utilising rope and powered 

access solutions. 

Exposure Surveying has a long history in building conservation and 

undertake all projects with an environmentally responsible, ethical and 

conservation minded approach. 

Rope access, proving a cost effective 

alternative to traditional scaffolding. 

Projects include historic buildings, 

scheduled monuments, 

ecclesiastical buildings and modern 

structures. 

Dry rot fruiting body, in subfloor 

space, seen through 

borescope visual aid. 

The microdrill assessing concealed 

window lintels in a Grade II* property. 

Collating site data

Institution of Civil Engineers 

One Great George Street 

Westminster 

London SW1P 3AA 

t +44 (0)20 7222 7722 

f +44 (0)20 7222 7500 

www.ice.org.uk 

Registered charity number 210252. 

Charity registered in Scotland number SC038629.

CARE Spring/Summer 2012 newsletter - Engineers Ireland

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