Cold Pitched Roof Construction
Tyvek® and AirGuard® membranes minimise interstitial and surface condensation in cold pitched roof construction, while helping to ensure optimal energy efficiency.
With traditional cold pitched roof construction, more insulation often means more interstitial and surface condensation, too – a danger that is aggravated by precipitation and wind. As a result, cold pitched roofs often need ventilation openings to ‘change the air’. These can reduce thermal efficiency by impairing the performance of fibrous insulation.
Tyvek® membranes are specially designed to alleviate this problem, and provide a holistic solution to cold roof constructions. They permit water vapour in the roof space to permeate through to the batten space, where the natural movement of air through the roof covering disperses it into the atmosphere. This removes the need for ventilation in the insulation – a benefit that is particularly important with cold pitched roof construction. A non-ventilated Tyvek® system will not only prevent excessive condensation but offer substantial gains in energy efficiency.
As a secondary water-shedding layer, Tyvek® membranes also provide a barrier that minimises the wind load acting on the slates and tiles, and helps keep wind-blown snow and dust out of the roof construction.
Tyvek® and AirGuard® in Cold Pitched Roof Applications
The insulation is installed at joist level, with a cold loft space (attic) between the insulation and roofing underlay. Usually, quilt insulation is laid between and over ceiling joists.
Tyvek® and AirGuard® in Room in the Roof Applications
Room in the roof constructions often use a combination of warm and cold roof constructions, with varying types of insulation. Cold roof areas usually include ‘vapour-open’ fibrous insulation (e.g., mineral wool quilt); the sloping ceiling areas include closed-cell or foil-backed rigid board insulants, most of which are highly vapour-resistant. This variation in vapour resistance can create an imbalance in vapour drive. To solve this, we recommend installing an air & vapour control layer (AVCL), such as DuPontTM AirGuard® Control, beneath the ‘vapour-open’ quilt insulation.
Meets Building Requirements
Non-ventilated pitched roof systems that use Tyvek® as rooﬁng underlay satisfy the requirement of Approved Document C2.
BBA certificate 08/4548 approves the use of non-ventilated Tyvek® systems for cold and warm pitched roof constructions. These constructions are categorised as shown; the difference lies in where the insulation is positioned.
DUPONT PRODUCTS & SERVICES
All Tyvek® breather membrane products
A complete listing of all Tyvek® breather membrane products
Tyvek® Supro is the market-leading breather membrane, and is a water resistant membrane suitable for all supported and unsupported pitched roof applications in commercial and residential buildings.
- Tyvek® AirGuard® Smart
DuPont™ AirGuard® Reflective is a low emissivity internal vapour barrier that combined with an airgap can enhance thermal comfort by reflecting up to 95% of radiant heat back into the building.
DuPont™ AirGuard® Control is a tough, transparent vapour control barrier that improves airtightness by reducing convective heat loss and air leakage while also minimising the risk of condensation in roof and wall insulation.
Tyvek® Double-sided Tape
DuPont™ Tyvek® Double-sided Tape is an advanced sealer tape that bonds all Tyvek® membranes to smooth surfaces, and seals membrane overlaps effectively.
Tyvek® Butyl Tape
DuPont™ Tyvek® Butyl Tape provides a moisture- and airtight seal between Tyvek® breather membranes or AirGuard® AVCLs and a wide range of materials.
Tyvek® Metallised Tape
DuPont™ Tyvek® Metallised Tape is a single-sided, reflective waterproof sealing tape that seals overlaps in Tyvek® Enercor® Roof, Tyvek® Reflex, and DuPont™ AirGuard® AVCLs.
Tyvek® Acrylic Tape
DuPont™ Tyvek® Acrylic Tape is the ideal single-sided tape for repair work, or for making good around windows and pipes. It provides strong, durable bonds, and is suitable for use with most Tyvek® and AirGuard® products.
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INFORMATION & IDEAS
Find here all the technical information about DuPont™ Tyvek® & DuPont™ AirGuard®.
- Free CPD Seminars
- An Alternative to Multi-Layer Breathable Roofing Felt
- Building In Energy Efficiency
Give Home Energy Efficiency a Boost
DuPont™ Tyvek® solutions can significantly improve home energy efficiency. The combination of low-emissivity, vapour-open Tyvek® Reflex and AirGuard® Reflective is particularly effective.
- Tyvek® offers unrestricted application when tested in accordance with BS5534:2014
- Tyvek® is compliant to New BS5534 Annex A
Tape Selection Guide
Find the right Tyvek® or DuPont™ FlexWrap tape with our Tape Applications Selection Guide.
Underlayment: Quality and Thickness of Functional Layers Are Critical
Tyvek® membranes are proven to resist ageing better than most common multi-layer underlayments. Even after prolonged exposure to UV radiation and heat, Tyvek® underlayment stays watertight and provides superior condensation control.
- What Makes a Tyvek® Watertight Breather Membrane Unique?
CE Compliant Membranes
All DuPont breather membranes, including Tyvek® and AirGuard®, are fully CE compliant, and carry the CE marking required throughout Europe.
- An Alternative to Roof Ventilation