Tf05-Single Layer Blow-in Insulation Between Studs
Tf05 - Timber frame walls - Single layer blow-in-insulation
blanket system
Advantages
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Low cost
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Installed by approved contractor
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Perimeter Plus is a Zero ODP Zero GWP insulation product
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The manufacture of Perimeter Plus has a very low impact on the
environment
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Products
Knauf Perimeter PlusTM blowing
insulation is an unbonded glass mineral wool which is blown into
the cavities between the frame in timber frame construction. It
requires no mixing on site and is dry when installed, adding no
water to the building. Its manufacture has a very low impact on the
environment and is classified as Zero ODP and Zero GWP*.
Knauf Perimeter Plus blowing insulation is the insulation
component of the Knauf Perimeter Plus Blow-in-Blanket System. This
system is installed by a network of nationwide approved installers.
The Blow-in-Blanket system also includes an insulation netting
layer that retains the insulation in the frame cavity during the
blowing process and before the wall is lined with the vapour
control layer and plasterboard.
* Ecohomes and Code for Sustainable Homes
classification
Typical construction
Inner leaf comprising 12.5mm plasterboard, vapour control layer,
Knauf Perimeter Plus Blow-in-Blanket System consisting of the
Perimeter Plus netting layer and Knauf Perimeter Plus blowing
insulation blown between studwork, plywood sheathing and Knauf
Breatheline, breathable membrane. A 50mm cavity separates the
timber frame from the outer leaf, typically of brick. Other
cladding options, such as tile hanging and timber boarding can also
be utilised.
Performance
Thermal performance
Knauf Perimeter Plus blowing insulation has a thermal
conductivity of 0.034 W/mK.
Table 46 gives U-values for typical prefabricated timber frame
walls insulated with the Knauf Perimeter Plus Blow-in-Blanket
System.
Table 46: Typical U-values for
timber frame walls with the Perimeter Plus Blow-in-Blanket
system
| Insulation product |
U-values (W/m2K) |
| |
Thickness
(mm) |
Breather
membrane |
Masonry outer
leaf |
Tile/timber clad outer
leaf |
| Perimeter Plus |
90 |
Knauf Breatheline |
0.38 |
0.42 |
| 140 |
Knauf Breatheline |
0.27 |
0.29 |
| 200 |
Knauf Breatheline |
0.21 |
0.22 |
| 90 |
Low E |
0.34 |
0.42 |
| 140 |
Low E |
0.25 |
0.29 |
| 200 |
Low E |
0.20 |
0.22 |
Notes: The U-values have been calculated to BS EN ISO 6946:
1997 and BR 443. Studs assumed to be 38mm wide at 600mm centres
(allowances for sole plates etc, give a 15% bridging area for the
timber). Stud depth is taken to be the same as the thickness of
insulation specified. Thermal conductivity of timber studs is 0.120
W/mK. Ventilated low emissivity airspace assumed to increase the R
value of the ventilated cavity to 0.29 m2K/W and
unventilated low emissivity airspace assumed to increase R value of
unventilated cavity to 0.44 m2K/W as specified in BR443.
Higher values can be achieved with proprietary products. Please
contact Knauf Insulation Technical Advisory Centre for calculations
that include specific products.
Table 47: Partial fill U-values
| Insulation product |
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|
U-values (W/m2K) |
| |
Timber stud
(mm) |
Crown DriTherm Slab 32
(mm) |
Breather
membrane |
Service void |
Masonry outer
leaf |
Tile/timber outer
leaf |
| Perimeter Plus |
90 |
50 |
Knauf Breatheline |
n/a |
0.23 |
0.25 |
| 65 |
Knauf Breatheline |
n/a |
0.21 |
0.22 |
| 75 |
Knauf Breatheline |
n/a |
0.20 |
0.21 |
| 85 |
Knauf Breatheline |
n/a |
0.19 |
0.19 |
| 140 |
50 |
Knauf Breatheline |
n/a |
0.19 |
0.19 |
| 65 |
Knauf Breatheline |
n/a |
0.17 |
0.18 |
| 75 |
Knauf Breatheline |
n/a |
0.16 |
0.17 |
| 85 |
Knauf Breatheline |
n/a |
0.15 |
0.16 |
| 90 |
50 |
Knauf Breatheline |
Low E |
0.21 |
0.22 |
| 65 |
Knauf Breatheline |
Low E |
0.19 |
0.20 |
| 75 |
Knauf Breatheline |
Low E |
0.18 |
0.19 |
| 85 |
Knauf Breatheline |
Low E |
0.17 |
0.18 |
| 90 |
50 |
Knauf Breatheline |
Low E |
0.17 |
0.18 |
| |
65 |
Knauf Breatheline |
Low E |
0.16 |
0.16 |
| |
75 |
Knauf Breatheline |
Low E |
0.15 |
0.16 |
| |
85 |
Knauf Breatheline |
Low E |
0.14 |
0.15 |
Fire performance
Knauf Perimeter Plus Blowing Insulation is classified as
Euroclass A1 to BS EN ISO 13501-1
Installation
The Perimeter Plus netting layer is stapled across the entire
wall area creating discrete cavities of each stud void. A hole is
then cut in the netting just large enough to accommodate the nozzle
of the Perimeter Plus Blow-in-Blanket System. The nozzle is
inserted into the cut and the cavity is filled with Perimeter Plus
blowing insulation. The Perimeter Plus Blow-in-Blanket System
includes sensors that determine when the cavity has been filled to
the required density and cuts of the flow automatically. When the
nozzle is withdrawn, repair the hole in the netting layer with an
adhesive patch. Continue filling all the cavities until the entire
wall area is insulated.
A vapour control layer is stapled to the studs across the inner
face of the wall before fixing the plasterboard. The vapour control
layer should be free from holes. Any gaps should be made good,
tears repaired and overlaps and apertures for services effectively
sealed. Particular care is necessary around electrical boxes.
Knauf Breatheline or a low emissivity breather membrane should
be stapled or nailed to the sheathing board at maximum 500mm
centres. It should be lapped so that each joint is protected, with
upper layers lapped over lower layers to shed water away from the
sheathing. Horizontal laps should be at least 100mm wide and the
membrane should extend below the lowest timber member. Vertical
laps should be at least 150mm and be staggered.
Crown DriTherm
Crown DriTherm can be used within the cavity in the same manner as
shown in Tf04
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Typical specification
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External wall panels to be insulated betweenstuds using Knauf
Perimeter Plus Blow-in-Blanket System. The breather membrane
stapled*/nailed* to the sheathing and extend below the lowest
timber member (*Delete as appropriate). Cavity barriers and fire
stops should be installed as required to meet the Building
Regulations
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Typical section
