TAFE wet area text.pdf - Mike's Trade Wiki

CARPENTRY - HOUSING 

WET AREA 

CONSTRUCTION 

This text introduces subject matter related to the preparation and installation of wet 

areas and fitments. 

Reference may be made to “Basic Building and Construction Skils”, produced by 

TAFE and Addison, Wesley, Longman Australia Pty Limited, to re-examine and 

reinforce these basic skills. 

The text addresses the preparation of wet areas ready to receive linings and the 

installation of fittings and fixtures. This includes the framing required for support and 

fixing of fittings and fixtures. 

Focus is placed on the frame preparation to allow building-in of moulded bath/spa 

units, pre-fabricated shower bases and sink/vanity installation. 

Reference is made to the current Australian Standard for waterproofing internal wet 

areas. 

Methods are outlined for determining wall lining material quantities and any associated 

flashings. 

A comprehensive ‘Glossary of Terms’ is included at the end of the text, which provides 

a detailed description of trade terms, technical content and some trade jargon. 

©TAFE NSW Construction and Transport Division 

1

WET AREAS 

Definition: 

2 

WET AREA CONSTRUCTION 

A wet area is any area within a residential structure, which will be affected by water usage. 

These areas include bathrooms, ensuites, laundries, kitchens, pool areas, photographic/hobby 

room, partly enclosed balconies, etc. 

Wet areas must be designed and constructed to avoid water damage and/or penetration of the 

interior linings and coverings. This is achieved by following procedures contained within the 

Australian Standard 3740. 

Australian Standard 

The current Australian Standard applicable to wet areas is AS 3740 - 1994, which was 

introduced in 1989 by a standards committee for the industry to address poor waterproofing 

practices. This standard is currently under review with an updated version due for publication 

in 2002. 

The standard sets out requirements for waterproofing internal wet areas and the preferred 

construction materials and methods to be adopted. It should also be noted that all 

manufacturer’s requirements and recommendations be folowed to ensure ultimate performance 

of their products, which in turn reduces the necessity of call-backs and rectification work. 

Fig. 1 Typical residential wet area 

©TAFE NSW Construction and Transport Division

Wall Frame Preparation 


Wall framing to wet areas may be of a steel or timber construction. Ideally where timber 

framing is selected, it is preferable to use well seasoned materials with section sizes as small as 

possible to reduce the effects of shrinkage. One of the most common problems encountered in 

wet areas is as a result of material shrinkage or movement. 

Stud spacings should not exceed 600 mm with a row of noggings placed in-line, not staggered, 

behind all horizontal sheet joins for full edge support. 

The studs may need to be checked out to a maximum depth of 20 mm to accept and support the 

lip of a bath or spa. This allows for wall linings to run down over the lip to provide adequate 

flashing. 

The assembled frame should be rigid and not rely on the wall sheet lining fixing for strength. 

All internal and external wall stud connections should have a nest of three studs, which are well 

fixed and blocked at 600 mm vertical centres. Alternatively, the internal corners may be 

reinforced with a metal 32 x 32 mm plasterer’s angle running from botom to top plate. 

Additional nogging fixing should be included in the following areas: 

� 150 mm up from the floor around the base of a shower recess to provide sheet fixing and/ 

or tray edge support; 

� Additional stud/s for shower screen fixing; 

� Trimmer on flat for shower head support and shower tap bridle-piece mounting; 

� Trimmers on flat for toilet cistern fixing and toilet control cock fixing; and 

� Additional trimming/noggings, as required, for other fittings and fixtures such as a vanity 

cabinet, towel rails, wall mounted heaters/dryers, shaving cabinets, paper holders, etc. 

Common studs 

Noggings 

Bottom wall plate 

600 c/c Max. 

Trimming on flat to 

allow for support of 

WC control cock, 

where required 

Trimming stud 

where required for 

shower screen 

fixing 

Trimmer on flat to 

allow for fixing of 

cistern 

Top wall plate 

Fig. 2 Preparing the wall frames 


Additional trimmer 

to support shower 

head, where 

required 

Corner or end stud 

Additional trimmers 

on flat to support hot 

and cold water 

bridle piece 

Additional trimmers 

to support shower 

tray/flashing, as 

required 

3

Flashings and Sealants 

Flashings 

4 


Perimeter flashings must be used at the floor/wall junction in all general wet areas and must 

extend a minimum of 25 mm above the finished floor surface. 

Alternatives 

� A PVC flashing 75 to 100 mm x 50 mm, similar to ‘Viplas’, is adhered to the floor only 

with a two-part water-based resin, similar to ‘Hardies HydrEpoxy 505’, which allows the 

wider upturn to move independently of the wall frame and linings. 

These angle flashings are available in 3.0 m lengths and should be lapped at all joints 

around the perimeter. It is preferable to cut the narrow side only at internal and external 

corners, which allows the wider upturn to be folded into the corner in a continuous form. 

� A 130 mm wide chlorosulphonated polyethylene flashing, similar to ‘Hypalon’, may be 

adhesive fixed to the floor with a two-part water-based resin, similar to ‘Hardies 

HydrEpoxy 505’. 

� A 150 mm wide fibreglass mat strip may also be used around the perimeter and over floor 

sheet joins sealed with compatible manufacturer’s approved sealing compounds. 

� The vertical internal shower reces corner/s may have a 32 x 32 mm metal plasterer’s 

angle fixed to the studs at 600 mm centres behind the wall linings or a 50 x 50 PVC angle 

may be used as an alternative. In both cases the angle should extend into the shower tray 

or onto the pre-formed shower base and be at least 1800 mm high above the recess floor. 

Sealants 

Sealants may be used in a variety of situations for wet area applications: 

� Junctions between wall linings and floors; 

� Around baths; 

� Around taps if PVC aprons are not used; 

� Cut outs and penetrations. 

Suitable sealants should be 

flexible, similar to the silicone 

types, and specify their use such 

as brick and concrete sealant, 

mould resistant tile sealant or 

other acrylic water resistant 

sealant. 

Fig. 3 Typical tube of sealant 


Wet Area Lining Materials 


Typically, wet area linings are either water-resistant plasterboard or fibre-cement sheeting. 

Plasterboard (Main types available) 

� ‘Boral Wet Area Plasterboard’ is manufactured with recessed edges for water resistant 

jointing in tiled areas and normal jointing beyond tiled areas. The board has face and 

back liners, which are resistant to moisture penetration as well as a moisture resistant 

gypsum core. The board is available in both 10 mm and 13 mm thicknesses. Sheet 

lengths range from 2400 mm to 4200 mm. The board is a distinctive green colour. 

�‘CSR Aquachek’ is a gypsum plasterboard with the core, face and back treated during 

manufacture to make it resistant to moisture and humidity. Available in both 10 mm and 

13 mm thickness, with 1200 mm wide sheets available in 2400 mm to 4200 mm lengths 

and 1350 mm wide sheets available in 3600 mm and 4800 mm. The board is a blue-grey 

colour. 

�‘Lafarge Watershield’ plasterboard. Conforms to ASTM C630. Has a water resistant 

gypsum core and a specially treated heavy duty linerboard. The board is a bluish 

colour. 

Fibre-cement Sheet 

�‘Hardies Vilaboard’ is manufactured to conform to Australian Standard AS2908.2 - 

1992 Cellulose - Cement Products. 

Mass: 

Villaboard is composed of Portland cement, ground sand, cellulose fibre and water and 

manufactured in three thicknesses, e.g. 6 mm, 9 mm and 12 mm. 

The 6 mm board is commonly used as a tile substrate for internal walls. The thicker 

sheets are recommended where there is a requirement for impact resistance. The 6 mm 

board is available in the following sizes: 

Width mm Lengths mm 

900 2400, 3600, 4200 

1200 1800, 2100, 2400, 2700, 3000, 3600, 4200 

1350 2400, 3000, 3600 

6 mm Villaboard has an approx. mass of 8.5 kg/m 2 


5

6 


�‘CSR Fibre-cement Walboard’ is an autoclaved, cellulose fibre reinforced cement sheet, 

which is immune to water damage and will not rot. It conforms to the requirements of 

AS2908.2 - 1992, ‘Celulose-Cement Products Part 2: Flat Sheets’. 

It is manufactured in 900 mm, 1200 mm and 1350 mm widths with lengths ranging from 

1800 mm to 4200 mm. 

The sheet thickness is 6 mm and the mass is approximately 9 kg/m 2 . 

Fibre-cement sheeting 

Fibre cement sheeting is produced by two companies CSR and James Hardie. 

The following details provide a broad overview of cutting and installation methods. 

Cutting 

Cutting fibre-cement sheeting can be achieved in four different ways. The most traditional 

method is to use the Hand Guillotine, as shown below. The guillotine produces clean, straight 

edges, while cutting on the off-cut side of the line to allow for thickness of the blade. 

Hand guillotine 

Fig. 4 Cutting along the line with a hand guillotine (‘Fibro cuters’) 


A more popular method now used is a 

score and snap knife with a tungsten 

tipped edge. 

Score the face side of the sheet against 

a straight edge. Score 4 to 5 times to 

about ½ of the thickness. 

Support the scored edge and snap the 

sheet upwards for a clean break. 

Hardies have produced a third method 

for cutting using electrical powered 

shears for both straight and curved 

cuts. 

Hand sawing can also be used for 

general cutting but is best confined to 

small cuts as it is labour intensive and 

hard wearing. 

Small rectangular or circular holes can 

be achieved by drilling a series of 

holes around the perimeter of the hole 

and tapping out the waste piece from 

the sheet face. 


Tungsten-tipped 

score & snap knife 

Fig. 5 Score, lift and snap 

Drill holes around 

circumference 

Support edges, 

then punch 

through with 

hammer 

Fig. 6 Methods used to create holes 


Straight-edge 

7

Larger rectangular holes or openings 

are formed by scoring around the 

perimeter of the opening, forming a 

large hole in the centre as shown 

below. 

Saw cut from the centre hole to the 

corners of the opening, support the 

edges and snap away the off cuts. 

Installation 

8 

�Sheets should be fixed 

horizontally across studs. 

�Only a single width sheets should 

be placed vertically in a confined 

space. 

�Sheets should be fixed with nails 

or screws only in tiled area. Do 

not fix with adhesive when the 

walls are to be tiled. 

�Internal angles in a Villaboard 

system should be tied together 

with a continuous metal 

plasterer’s angle fixed at 600 mm 

centres. 


Straight-edge 

Score between 

cuts 

Fig. 7 Score, lift and snap 

Fig. 8 Reinforce internal corners 


Lift to snap 

Saw cut 

Continuous 

galvanised 

metal angle

�In shower recesses, or other 

regularly wetted areas, corners 

should be flashed with Hardies 

flash-strip. 

�The flashing strip must extend 

into the shower tray. Metal 

external angles or paper tape must 

not be used. 

�CSR Wallboard in a shower 

recess requires a 50 mm x 50 mm 

PVC angle in the internal corner 

before sheeting. 

�Flashing should be installed 

around the wall/floor junction in 

normal areas (when required by 

regulations). Flashing must be 

installed in shower recess 

systems. Flashings should be 

epoxy glued to the floor only. 


�Sheets should be measured and cut to suit the wall sizes. Tap penetrations etc should be 

carefully located and cut out. 

�Fix sheets to framing allowing a 6 mm gap along the floor. Nail sheets at 200 mm c/c at 

sheet edges, ends, internals, externals and in the body of the sheet. 

6 mm 

gap 

Fix 50 mm min. from edge of 

sheet at corners 

200 mm 

max. 

12 mm min. 

Fibre-cement 

sheeting 

Bearers 

12 mm min. 

200 mm 

max. 

Fig. 10 Typical sheet fixing 

Fig. 9 Flash the internal corner 

200 mm 

max. 

600 mm max. c/c 

Butt joint 


Metal angle 

Hypalon 

flashing 

Noggings must be fixed in 

a straight line behind 

horizontal sheet joints 

Compressed fibrecement 

floor 

sheeting 

9

BATH INSTALLATION 

Types of Baths and Spas 

10 


Most baths and/or spas are manufactured with a fall in the base and a moulded lip around the 

top to provide a finish and a flashing. 

The closed side/s are normally recessed into the wall frame to allow the wall lining to pass over 

the raised lip. This in turn provides a horizontal barrier to water and therefore prevents passage 

of the water into the wall cavity. As they are permanently built into the structure they are 

classed as ‘Fixtures’, as opposed to ‘Fitings’, which have fixings and may be easily removed. 

Common materials used for their construction include: 

� Moulded fibreglass or acrylic; 

� Pressed metal with a baked enamel surface; 

� Stainless steel; and/or 

� Cast iron with a baked enamel finish. 

Pressed metal baths and spas need to be supported around the perimeter only, whereas 

fibreglass/acrylic baths and spas need perimeter and base support. Most fibreglass/acrylic spas 

are manufactured with a steel tube cradle for permanent support under the shell. The base is 

usually packed with a dry sand/cement mix to provide a solid platform for load strength. 

Handling/Protection 

The surface of these fixtures is easily damaged, therefore the utmost care must be taken after 

installation to prevent chipping, scratching or cracking, which would lead to an expensive 

repair or replacement. 

There are some patent type repair kits available for cracked or chipped fibreglass/acrylic types, 

which are quite successful, however enamelled touch-ups rarely work as well. Some companies 

offer a complete enamel surface re-coat, in-situ. 

The best practice is to avoid damage 

in the first place by completely 

cover the unit with plastic, 

cardboard or a sheet of ply and 

avoid standing in the base during 

finishing work. 

Keep gritty materials, such as sand, 

off the surface at all costs. 

Fig. 11 Providing temporary protection 


Preparing the Wall Frames 


The height of the bath is the most critical position in relation to the size of the tiles. Therefore, 

once the size of the wall tiles is determined the bath lip may be located on the side walls. 

Note: Most bathroom wall tiles are 

150 mm square and the depth of the 

average bath/spa is around 450 mm 

or approximately 3 tiles high under 

the perimeter lip. 

Set out the height of the bath lip 

allowing the bottom edge of the 4th 

course of tiles to sit over the bead 

onto the step in the rim. 

Where the tiles on the support side 

must align with the main wall tiles, 

the wall height should be determined 

by working down from a full tile fitted 

onto the flat section of the bath lip. 

This will ensure horizontal tile joint 

continuity around the bathroom and 

allow the cut tile edge on the support 

wall top course to be hidden under 

the rim of the bath. 

Top and bottom plates 

are out of 35 mm 

material 

Fig. 12 Setting the height of the bath 


150 

2 2 

150 

150 

35 

491 

2 

11


Supporting the Rim on the Closed Side 

It is preferable to have continuous edge support where the bath lip is recessed into the stud 

wall. Also, the bottom edge of the wall lining needs continuous support between the studs. 

The simplest method of achieving this is to recess timber battens, one above and one below the 

lip, flush with the wall frame to a depth of 20 mm. This will allow the bath edge to slide into 

the wall and allow the wall lining to pass over the lip to provide a flashing. 

The batten on top provides support and fixing for the length of the sheet between studs. 

An alternative method is to cut and fix noggings between the studs, as shown below: 

12 

Nogging or 

trimmer 

Fig. 13 Method 1 

3 - 5 mm 

flexible 

sealant 

5 - 15 mm 

flexible sealant 

Continuous 

support 

trimmer 

Water resistant wall 

lining 

Wall tiles 

Fig. 14 Method 2 


Water resistant wall 

lining 

3 - 5 mm 

flexible 

sealant 

Wall tiles 

Continuous top 

ribbon batten for 

fixing and support 

5 - 15 mm 

flexible sealant 

Continuous 

bottom ribbon 

batten for 

support


Supporting the Rim on the Open Side 

Supporting frames for the open sides of the bath/spa are usually constructed from seasoned 

timber. 

Note: Treated pine is not necessary, provided the correct amount of ventilation is provided as 

per AS/NZS 2023 - 1995. 

Alternative materials may also be used such as brickwork and ‘Hebel’ block. 

Which ever materials are used, the structure must be rigid to prevent movement during use. 

Any movement may lead to bath/spa damage and tile damage to the perimeter. 

Common Timber Framing methods 

Method: 

STEP 1 Determine the overall size of the frames by plumbing down the outside edge of the 

bath lip on all open sides. 

STEP 2 Measure in from these marks a distance equal to the thickness of the rim, plus the 

thickness of the wall tiles, plus the thickness of the wall lining, e.g. 

3 + 10 + 6 = 19 mm 

Fig. 15 Supporting the open side 

STEP 3 Measure the overall width and length of the frames. 

Measure the height from the floor surface to the underside of flat support section of the 

bath rim. 

Now construct the frames with stud spacings at Max. 450 mm centres. 

Note: The top plate should be placed on edge to allow a clear fit under the rim. 


13


The two methods shown below are used to support the open side of the rim when: 

� The rim sits onto a tiled hob section; or 

� The tiles fit under the rim. 

14 

Flexible bedding 

and sealant 

Support batten 

under bath lip 

70 mm support 

wall framing 

Bath lip onto 

tiled hob 

Fig. 16 Rim resting on a tiled hob 

Tile corner trim 

Waterproof 

wall lining 

Tiled support 

wall 

Floor tiles and 

mortar bed 

70 mm timber support 

wall framing 

Flexible bedding 

and sealant 


Bath lip over 

face of tiled 

support wall 

Waterproof 

wall lining 

Fig. 17 Tiles finish up under the rim 

Tiled support 

wall 

Floor tiles and 

mortar bed

Providing Adequate Ventilation 


Once the frames are complete and sheeted with Villaboard, prepare at least two openings to 

take tile bath vents to allow sufficient ventilation under the bath to dry out any trapped condensation. 

AS/NZS 2023 - 1995 states, “Every enclosed air space under a bath should be provided 

with ventilation openings having an aggregate clear area of not les than 5000 mm²”. 

Note: Where spas are used, access to the pump may be from outside, therefore the access panel may be 

a permanently vented metal plate, which will provide the necessary ventilation. This negates the need 

for vents internally. 


150 

Fig. 18 Fitting vents under the bath 

75 

15

Baths and Bath Framing 

16 


The details below outline a typical bath profile and the completed framing required to support 

this type: 

END ELEVATION 

Nogging/trimmer for 

wall lining support 

and fixing 

PLAN 

ELEVATION 

Fig. 19 Typical bath detail 

Support batten 

under bath lip 

Notch for 

bath lip 

Fig. 20 Completed bath framing 

Open-side 

framing 


Hobs and Hob Walls 


Hobs are generally raised or flat tiled sections at one or both ends of a bath. The main purpose 

of a hob is to close off the area left between the length of the bath and the walls. 

A raised hob is usually formed between the end of the bath and a shower to provide closure 

between them. It may also be used to fix the side panel of a glass shower screen and/or to 

mount the taps for the bath. 

Fig. 21 Flat hob end Fig. 22 Raised hob wall 

Set Out / Construction 

The height of a raised hob wall should be set 

out to suit full wall tiles. The raised section 

of the hob wall is usually one tile course 

above the bath to provide a flashing and a 

finish between bath and shower. 

A gauge rod is used to set the height of the 

wall to allow full tiles from finished floor to 

the top edge. This rod is also used to set the 

height of the bath, so the top of the bath will 

work full tiles. 

The hob wall may be constructed from 

timber framing and lined with Villaboard, 

similar to the support side of the bath, or it 

may be of masonry. Brick, concrete block 

and Hebel block are suitable materials. 

Note: 

� The width of the hob wall should also be set 

out to suit full tiles where possible, however 

this is usually determined by the width of the 

bath. 

� Timber must not be used for shower recess 

hobs. 

Raised hob wall 

Bath 

Finished 

tiled floor 

Fig. 23 Set height using a gauge rod 


Shower screen 

Gauge rod set 

out to top of 

tile courses 

Finished shower 

recess floor 

17


SHOWER BASE INSTALLATION 

A shower base may be described as: 

“A pre-formed, pre-finished vessel, which is installed as the finished floor of a shower 

compartment and which is provided with a connection point to an approved sanitary drainage 

system.”(reference AS 3740) 

A shower base may be used as an 

alternative to a shower tray, or 

waterproof liner, which is tiled on a 

sand/cement bed with a fall to the 

waste. 

The pre-formed shower base may be 

manufactured from: 

� Pressed metal with a baked 

enamel finish; 

� Polymarble/Acrylic; 

� Concrete; or 

� Stainless steel. 

Before installation, the shower base 

should be checked for size to allow 

accurate positioning for the waste 

connection and check out depth for 

wall frames. 

Prepare Wall Frames 

The internal corner where the shower recess area 

is to be formed must be prepared prior to the wall 

frames being erected. Valuable time is wasted, 

tools are readily damaged and the task is made 

more difficult if the frames are modified after 

erection. 

STEP 1 Mark the height of the base from the 

bottom of the wall plate, plus an 

additional 15 mm to allow for 

installation and bedding on a sand/ 

cement ballast. 

STEP 2 Mark the thickness of the lip in from 

the face of the stud. 

STEP 3 Cut out the waste from the studs and rip 

the plates, to form the recess. 

STEP 4 Cut and fix noggings between studs 

around the top of the base to provide 

wall sheet fixing. 

18 

PLAN 

Check length 

(915 x 915 

preformed 

base) 

Fig. 24 Critical measurements 


Check position of 

waste outlet 

Check width 

Fig. 25 Critical measurements 

To allow base lip to fit 

behind face of stud 

Height of base plus 

clearance for mortar 

bedding

Positioning the Base 

Concrete Slab 


Care should be taken to accurately position the shower base in the wall frames to ensure the 

waste pipe will drop into the sewer pipe cast into the slab. A 100 mm diameter cap with an 

opening to take the shower base waste pipe is placed over the sewer pipe end and rotated to 

ensure alignment. 

Note: It is critical that the drainage is accurately placed prior to slab placement, as modifying 

the position with elbows and offsets later is very time consuming and costly. 

Timber Platform Flooring 

The advantage of a suspended timber floor allows the drainage to be easily fitted under the base 

after the base is installed, or the drainage is more easily modified if inaccurately positioned 

before base installation. 

To locate the opening in the floor for the base, before bedding the base, place the base in its 

final position and mark the centre of the floor waste through the hole in the base. 

Once the preparation is complete, the shower base may now be installed on a bed of sand/ 

cement ballast to allow for levelling and full support for the internal area of the base. 

The walls are now ready for lining, as shown below: (Note: plumbing has been omitted) 

Fig. 26 Base bedded into position 


19


INSTALLATION of SINK/VANITY UNITS 

Wet area fitments include the following: 

� Laundry tubs; 

� Bathroom/Ensuite vanity units; 

� Bathroom/Ensuite wall cabinets; 

� Laundry benches; and 

� Laundry cabinets. 

Many plans come with a bathroom or wet area layout plan for fitments. The size of the units, 

position within the room and the finished height of bench tops is usually noted on these details. 

These details are useful for the preparation of wall frames so additional studs, noggings and/or 

fixing blocks may be positioned for future fixing. 

20 

VIEW 1 VIEW 2 VIEW 3 

PLAN of Bathroom and Ensuite 

BATHROOM 

Fig. 27 Wet area fitment details 

ENSUITE 

VIEW 4 


Installing Vanities and Benches 


Normally bathroom vanities and laundry benches are installed after the floors are tiled. 

A levelled base or plinth is fastened to the tiles to provide a sound level surface for the vanity 

carcass to sit on. Some vanities are constructed with the plinth as part of the cabinet. 

The water resistant kickboard facing lifts the carcass off the floor and away from contact with 

surface water. It is normally set at 75 to 150 mm high. 

The vertical face of the carcass is checked for plumb and the top checked for level in both 

directions. The back is fastened to the wall through a batten at the top and the base is fixed 

down to the plinth. Screws are used to hold the vanity tightly into place. 

Screw fixing 

through batten 

Screw fixing to plinth 

Unit checked for level 

Fig. 28 Installing the vanity and checking for position 


Unit checked for plumb 

21

Once the carcass has been 

plumbed and levelled, the 

back rail of the cabinet is 

screw fixed to the stud wall. 

It is advisable to use at least 

two fixings in the length of 

the rail, to provide solid and 

stable attachment. 

The bottom rail, if present, is 

also screwed to the stud wall 

or the base of the cabinet 

may be screwed to the solid 

plinth underneath. 

If the vanity top does not have a 

built-in or moulded upturn at the 

back, to prevent water passing 

behind the cabinet, then a flashing 

should be installed. 

The flashing may be in the form of: 

� An ’L-shaped’ non-corrosive 

metal or plastic flashing strip 

fitted to the wall on top of the 

cabinet fixing rail, before the 

top is secured; 

� An ’L-shaped’ non-corrosive 

metal or plastic flashing strip 

cut into the back edge of the 

top, before the top is fitted; or 

� A full length bead of flexible 

waterproof sealant applied 

between the fitted top and the 

wall lining. 

22 


Fig. 29 Fixing the rail to the stud wall 

Fig. 30 Typical flashing methods 


Sealant between wall 

and fixing batten 

‘L-shaped’ flashing let 

into back edge of top 

Sealant between wall 

tiles and top


Fig. 31 Vanity with splashback - Flashed during assembly 

Fig. 32 Moulded top vanity with built-in upturn - no additional flashing required 


23

Fasteners 

Fixing to Timber Frames 

Standard countersunk wood screws are 

suitable for general carcass fixing, 

however particleboard screws may be used 

for additional holding power or when 

attaching particleboard tops to the carcass. 

Round head screws and cup washers may 

be used where the fixings are exposed. 

Due to loads imposed by wall-mounted 

fixtures the diameter or gauge of the 

screws should be at least 8 to 10 gauge to 

prevent shear. The screws should penetrate 

the timber frame by at least 30 mm to 

resist pulling out. 

Note: 

Toggle bolts may be used for fixing 

through wall sheeting for light loads. 

Fixing to Steel Frames 

Steel wall frames require special fasteners, 

which are capable of drilling and tapping in 

one go. 

Suitable fasteners for this application would 

be ‘Wing-tek’ screws, commonly used for 

general steel frame construction and 

connection. 

24 

Fixing to Masonry Walls 

For light fixing, a plastic ‘Star plug’ and 

fully threaded screw would be suitable. 

For heavy duty fixing where loads are 

expected to be great, a masonry anchor 

would be suitable. 


Countersunk head Raised head 

Fig. 33 Suitable screw fixings 

Fig. 34 Wing-tek screw fixings 

Fig. 35 Star plug and screw Fig. 36 Masonry anchor 


Installing Laundry Cabinets/tubs 


Most laundry cabinets, with a 45 to 60 litre top mounted stainless steel tub, are made of metal 

finished with a baked enamel or powder-coated surface. (plastic cabinets are also available) 

They have metal rails, top and bottom, at the back to allow the cabinet to be screw fixed to the 

wall and the tub is fitted after. 

The stainless steel tubs have an upturn along the back edge, approximately 15 mm high, which 

is also screw-fixed to the wall. The wall tile splashback is then laid over the top to form a 

waterproof joint, which prevents water running down the back. 

Note: Where tubs are fitted to an internal corner of the laundry, a flexible waterproof sealant 

should be run between the tub and wall before the splashback is laid. 

Fig. 37 Typical laundry tub installed to a corner 


25


Water Damage, Decay and Fungal Growth 

Water damage may occur due to poor flashing practices, poor ventilation or using materials, 

which don’t provide adequate resistance to water penetration. 

The result of this water penetration may be: 

� Timber decay in wall framing; 

� Timber decay in floor framing; 

� Fungal damage to surrounding materials; 

� Swelling of manufactured boards such as particleboard; 

� Musty odours from enclosed spaces; 

� Damage or staining to fitments. 

Fungal Growth 

Timber decay is caused by fungal growth feeding on the lignin and cellulose, which makes up 

the bulk of the timber’s structure. 

To exist the fungi will require suitable conditions, as follows: 

� A food source, such as timber; 

� Water or a high moisture content, i.e. above 18%; and 

� Oxygen. 

The fungi, unlike plant forms, does not need light to exist therefore, dark moist places are very 

suitable for it’s existence. 

Fungi produce fruiting bodies, which develop spores. These spores are dispersed and become 

new fungal growths having an appearance like a surface root system, known as mycelium. 

Most fungi or ‘rot’ require high levels of moisture, at least 18% to start, however there is one 

species, Sepula lacrymans (commonly caled ‘Dry rot fungi’), which requires only humid 

conditions to survive. 

(refer to Building Materials and Hand Tools for more details relating to Fungi) 

26 

Fig. 38 Typical result of leakage from a poorly flashed fitment 



GLOSSARY OF TERMS 

Carcass -The main body or frame of a cupboard or vanity. Consists of the sides, 

back and base. 

Fittings -These include any item in a wet area, which may be easily removed. 

They normally are fixed to the wall surface with screws. 

Fixtures -These include any item in a wet area, which is built-in or permanently 

fixed into place and not designed for easy removal. 

Hebel -This is a lightweight, autoclaved, aerated sand/cement product, which 

includes aluminium paste reacting with water to form a gas and create 

trapped air bubbles in the finished product. Used in wet areas in block 

form under baths to support sides. 

Hob -A raised, narrow section of wall forming a partition between fitments 

such as a bath and a shower recess or as a raised edge across the front of 

a shower recess to keep water in. 

Hypalon -A trade name for a chlorosulphonated polyethylene flexible angle for 

use up the vertical corner of a shower recess, behind the wall linings to 

create a waterproof seal. 

Patent -This is a term used to describe a product which has had its design 

registered with the Patents office. It is the original idea of a person or 

persons, which cannot be copied without consent. 

Polycarbonate -A plastic material, which is tough, flexible, waterproof, and resists the 

breakdown effects of the suns UV rays. It is used for roof sheeting 

material, as it is very durable and under most circumstances, hail proof. 

It may be formed into corrugated, ribbed or sandwich panel profiles. 

PVC -Polyvinyl chloride. A plastic product commonly used for sewer pipe 

and fitting production. 

Staggered -This refers to the placement of solid bridging, noggings, trimmers, etc. 

by offsetting every piece from the previous one, when placed in a row. 

Viplas -A trade name for a PVC waterproofing angle product. 

Wet area -Any area within a residential structure, which will be affected by water 

usage. 


27

28 


FURTHER READING 

Australian Standards Committee, 1994, AS 3740 –Waterproofing of wet areas within 

residential buildings, Standards Association of Australia Homebush, Sydney. 

Note: (also refer to 2002 update to this standard) 

Boral and CSR manufacturer’s brochures for the instalation of wal linings to wet areas. 

Hadlington, P., and John Gerozisis, 1995, Urban Pest Control in Australia, NSW University 

Press, Kensington, NSW, Australia. 

Teachers of Building, 1996 Reprinted 1997, 1998, Second Edition 1999, Basic Building and 

Construction Skills, Addison Wesley Longman Australia Pty Ltd, South Melbourne. 

Ward-Harvey K., 1984, Fundamental Building Materials, Sakoga Pty Ltd, Mosman NSW.

TAFE wet area text.pdf - Mike's Trade Wiki

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