Key Properties
QUINN-therm
- does not readily absorb water, making it suitable for use in damp environments;
- is light, robust and easy to handle; it may be worked using a saw or sharp knife;
- is durable and will perform for the service life of the building.
Meeting Regulations
| Required thicknesses of QUINN-therm QR (mm) | ||||
|---|---|---|---|---|
| U-value (W/m2K) | 0.25 | 0.20 | 0.18 | 0.16 |
| Thickness of QUINN-therm (mm) | 75 | 100 | 115 | 130 |
Results based upon roof construction of:
12.5mm plasterboard, polyethylene
VCL, 150mm deep rafters at 600mm centres, QUINN-therm QR insulation (thickness as
shown), vapour open underlay, 50mm cavity formed by counterbattens and battens, large
format concrete tiles. Calculations performed to BS EN ISO 6946:1997, taking account of repeating thermal bridges.
* Overall heat loss method.
For U-value
calculations for other roof constructions contact Quinn Technical Services.
Design Notes
- a vapour control layer is required behind the surface finish to prevent condensation forming within the structure. Contact Quinn Technical Services for advice on condensation control.
- a vapour open underlay (vapour resistance < 0.25MNs/g) should be installed as a secondary protection against wind-driven rain and snow.
- counterbattens allow rain and snow to drain from the underlay to the gutter and form a vented airspace to minimise condensation risk.
Introduction
QUINN-therm QR (Quinn Roof) is a PIR (polyisocyanurate) insulation for creating warm pitched roofs by insulating above the rafters.
Insulating a pitched roof at rafter line - to create what is usually known as a warm roof - makes full use of the building volume by making the roof space available for occupation. Having the insulation at rafter line can also reduce stress on the structure and, even if the loft space is not utilised, there is still the benefit in having water tanks and other services within the insulated area.
Forming a warm roof by laying in a continuous layer above the rafters avoids thermal bridging, and so minimises the depth of insulation required to meet building regulations. This form of construction is suitable for new build, as well as projects where the roof will be stripped and re-covered.
QUINN-therm QR rigid insulation is well suited to use in warm roof constructions: it is robust enough to span the rafters and withstand transferred loads from the roof covering and will resist moisture. Also, its high thermal resistance enables the required U-value to be achieved with a minimum thickness of insulation, which reduces the loads applied to fixings.
Design
Thermal bridging
To limit heat loss and prevent problems such as condensation, mould growth and staining occurring at cold spots in the construction, it is desirable to design junctions between elements so as to maintain continuity of insulation. For roofs the key junctions are those at eaves and gable, where wall insulation should be continuous with roof insulation.
At eaves, wall insulation should be continued between the rafters until it butts the underside of the QUINN-therm QR boards. Where there is a cavity closer at the wall head the additional wall insulation may be fixed to the wall plate. Gable walls should be insulated for their full height and the insulation extended to meet the underside of the QUINN-therm QR boards.
The details shown here are designed to minimise thermal bridging and air leakage.
Condensation Control
To minimise the risk of interstitial condensation the roof structure should be progressively more vapour open from inside to outside; that may be achieved by using a high resistance insulation such as QUINN-therm QR and a vapour open underlay beneath the roof covering. The use of a vapour control layer between the insulation and the internal finish is recommended.
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To prevent the build up of high moisture levels within the batten space - with the risk of condensation - the space must be adequately vented.
Coverings of tile or natural slate will usually allow enough air movement between the
batten space and atmosphere, for other coverings specific provision for ventilation may be
required
(see BS 5250:2002 for details).
Condensation risk analysis should be conducted on all roofs using the method in ISO 13788:2001: consult Quinn Technical Services for assistance.
Fixings
QUINN-therm QR boards are held in place by the counterbattens which are fixed through to the rafters. The fixings for the counter battens must be strong enough to transfer dead and applied loads from the roof covering to the rafters without significant deflection.
A calculation method to determine the bending stress is given in BS 5534:2003 Annex B. A list of manufacturers of suitable fixings is available from Quinn Technical Services. Depending upon their dimensions and spacing, the fixings may affect the thermal performance of the roof.
A stop batten should be installed across the end of the rafters to prevent boards slipping down the roof. The boards should be nailed to the rafters during the installation process to give a temporary fixing until the counter battens are installed.
Installation Guidance
- Fix a stop batten across the rafters at the line where the insulation will stop.
- Lay the first row of QUINN-therm QR boards across the rafters tight against the stop batten, with long sides running parallel to the eaves. Ensure board ends are supported on rafters.
- Provide a temporary fix by nailing to the rafters.
- Lay and fix subsequent rows of QUINN-therm QR boards. Stagger end joints from row to row.
- Lay the underlay, following manufacturers instructions.
- Fix counterbattens through to the rafters.
- Fix the roof covering.
* for projects where the underlay is draped over the counterbattens reverse the order of items 5 and 6.
Notes
- Butt boards tightly together to form a continuous layer of insulation.
- Cut boards neatly around penetrations. Seal gaps with expanding foam.
- At wall/roof junctions fit boards tight to the wall and seal any gaps with expanding foam.
- At junctions between roof planes cut boards to fit tightly together and seal with expanding foam.
| Product Data | ||
|---|---|---|
| Properties | Value | QUINN-therm QR |
| Board width x length | mm | 2400 x 1200** |
| Board thickness | mm | 60 - 200 |
| Board density | kg/m3 | 26 - 32 |
| Area per board | m2 | 2.88 |
| Edge profiles available | Butt edged | |
| Performance Data | ||
| Properties | Value | QUINN-therm QR |
| Thermal conductivity* | W/mK | 0.022 - 0.023 |
| Water vapour resistivity | MNs/gm | ~ 400 |
| Compressive strength | kPa | >120 |
* quoted in accordance with BS EN 13165:2001 ‘Thermal insulation for Buildings - factory made polyurethane foam products’.
** other sizes may be available upon request.
Key Properties
QUINN-therm QR consists of a core of PIR foam bonded on both faces to composite aluminium facings; the gas filled cells give QUINN-therm its high thermal performance and strength.
When QUINN-therm QR is installed next to an airspace of at least 25mm deep the low emissivity surface of the insulation contributes to the thermal performance of the roof by reducing radiation heat loss across the cavity.
Handling & Storage
QUINN-therm QR boards are supplied in shrink-wrapped packs. Store boards under cover and out of direct sunlight, keeping boards flat. When handling QUINN-therm QR do not knock corners and edges.
Whilst QUINN-therm boards are robust, they are not designed to support people: do not stand on the boards nor use them as a working platform.
