October 2022

90
110
Tapered Board Thickness
60
160
Tapered Roofs
STEPPING UP TO THE
COMPARTMENTATION CHALLENGE
By Robert Vass, Chief Technical Officer at TaperedPlus.
Currently, fire and compartmentation are
rightly high on the agenda and in the press
within the construction industry. While
building safety should always take precedence, it is
important to remember that when high focus is on
one area of compliance, others are not bypassed.
typically non-combustible insulation needs to be
Whether the aim is to reduce the risk of fire
thicker than combustible insulation to meet the
spreading over a flat roof from one
same thermal performance (See Pic 1 above).
‘compartment’ to another in the domestic setting
as outlined in in Approved Document B (B3), or Creating steps in insulation like this can become
an insurer’s requirement on a data centre to make further complicated when considering roof
a fire break between the main data storage and drainage, as the steps may result in trapped
back up servers, there is often a request to utilise water if upwards steps are created between
combustible insulants such as PIR
ridgelines and outlets or gutters.
(Polyisocyanurate) or EPS (Expanded Polystyrene)
The right mix
in field areas, and non-combustible insulation like
As an independent designer and supplier of flat
Stonewool or Cellular Glass above a partition wall.
and tapered roof insulation, at TaperedPlus we’re
In these scenarios, specifiers run in to the issue not tied to any material type or manufacturer. We
that most insulation manufacturers will readily have the ability to mix insulation products for the
calculate the thermal performance of their own ideal technical solution and the increasingly
product, whether it be flat board insulation or common compartmentation enquiries tie in well
tapered insulation, but are less willing to consider with the skill set we offer.
the effect of the insulation performance of
Our approach to dual product
another manufacturer’s material, even though a
compartmentalisation specifications is to assess
percentage of the roof area is to be covered with
roof areas and how much of the roofs are covered
an alternative material with a differing thermal
with each product before conducting area
performance.
weighted thermal calculations, with the aim to
If each individual manufacturer targets the
use just enough of each insulation material to
specified U-value (W/m²K) in their material only, the create a smooth top surface, avoiding a step in
result would be numerous steps in the insulation as insulation, while achieving the specified U- value
7200
1500 1500
K 11 11 K
K
J 10 10 J
J
I 9 9 I
I
H 8 8 H
6000
8
G 7
7 G
F
F 6 6 F
F
E
E 5 5 E
E
D D 4 4 D D
C
C 3 3 C
C
Pic 2
K
J
I
H
1500 1500
G
6
5
4
3
6 F
F
5 E
E
1500 1500
11 11 K
K
10 10 J
J
9 9 I
I
8 8 H
8
7
7 G
6 6 F
F
5 5 E
E
4 D
D 4 4 D
D
3 C
C 3 3 C
C
6000
as an area weighted performance.
While this calculation is straight forward with flat
board insulation where falls are provided in the
structure, it can become far more complicated
when tapered insulation is needed. As a tapered
insulation specialist, at TaperedPlus we’re able to
perform insulation calculations to BS EN ISO
6946:2017 Annex E for each roof area effected by
the varying insulation types, lean on our
knowledge of material stock profiles to ensure the
insulation thicknesses tie in with one another,
and provide user-friendly drawings to aid site
installation.
The dual insulation approach is typically taken to
try and reduce material costs versus full
coverage of the non-combustible insulant,
however, projects with close neighbouring party
walls can result in practicality issues and added
labour when mixing products in such proximity
(See Pic 2 left).
For this reason, at TaperedPlus we work closely
with tendering installers as well as specifiers to
work towards the best holistic cost option.
B
A
B 2 2 B
A 1 1 A
1500 1500
B
A
2
1
2
1
1500 1500
Material: Tissue Faced PIR
Multi Layered Tapered Build Up Section - 1:60
(Not To Scale)
90
B
A
100mm Packer Board
100mm Packer Board
A 110 B 30 C 50 D 70 E 90 F 110 G 30 H 50 I 70 J 90 K
310
B
A
2
1
2
1
1500 1500
B
A
Material: Rockwool Multi-fix
Multi Layered Tapered Build Up Section - 1:60
(Not To Scale)
90
120mm Packer Board
30mm Underlay
1 80 2 100 3 120 4 140 5 160 6 60 7 80 8 100 9 120 10 140 11
B
A
310
Contact TaperedPlus
01642 677342
www.taperedplus.co.uk
@TaperedPlus
30 TC OCTOBER 2022