Dryseal Flat Roofing


In this section we have answered some of the most frequently asked questions associated with Flat Roofing and the Dryseal product range.

If there are any questions that you feel are unanswered we are always happy to help, you can contact us here.

Is Dryseal a ‘wet lay’ GRP system?

No, Dryseal is component based – the semi-rigid membrane is supplied in 6m x 1.25m rolls of Flat or RibTec sheet, complimented by 3 metre lengths of edge detailing trims to fit up to 20 different roof edge profiles. The only ‘wet’ part of the system is on the sheet and edge trim overlaps, where a 450 gramme chopped strand glass fibre matting, laminating tissue and resin are used to fuse the high adhesion surfaces together. This amounts to only 7-10% of the roof area in most cases.

Is Dryseal available in different colours?

Standard Dryseal top coat colours are Dryseal Dark Grey (similar to RAL 7012) or Dryseal Light Grey (similar to RAL 7047).  Most colours can be manufactured to special order to suit project requirements.

If I use Dryseal to replace lead, is there any scrap value in it?

No, Dryseal is completely without scrap value. Although it can be finished in dark grey and with decorative rolls to look like lead, there is no benefit in stealing it. Secured by Design accreditation from the Association of Police Officers signifies that Dryseal is an officially recommended product for lead replacement, to deter theft and reduce the fear of theft.

Can I insulate a Dryseal roof?

Yes, in the usual ‘warm roof’ configuration, Dryseal can be laid over most rigid polyisocyanurate (PIR) flat roof insulation board with a vapour control layer underneath to provide a Thermal Performance or ‘U’ value which complies with Building Regulations and Green Deal requirements. We recommend that our contractors are certified to Competent Roofer standard to help simplify Local Authority Building Control reporting procedures and benefit the customer.

What is the minimum gradient or ‘fall’ required for Dryseal to be used?

Dryseal is usually recommended to be laid to a finished fall of 1:60, as with all flat roof design. There is no detrimental effect on Dryseal if the system is laid flat (e.g. in a box gutter), as it is unaffected by standing water. The recommendation for a 1:60 fall is for aesthetic and roof safety reasons, to encourage surface drainage and minimise ponding. Dryseal is semi-rigid, so it is very suitable for vertical work, e.g. on a mansard or parapet cladding, and needs no extraordinary precautions, as it does not ‘slump’.

Does the existing roof covering have to be stripped before installing Dryseal?

If the roof substrate is in good condition and is suitable for mechanical fixing (i.e. steel, concrete, timber, plywood or Sterling Board) Dryseal can be fixed over the existing coverings and insulation. Pull out tests may be required to ascertain the frequency and security of fixings. NOTE – ‘Stramit’ compressed straw board decking and chipboard are NOT suitable to be mechanically fixed over. They are unlikely to remain serviceable for the life of the Dryseal system.

Is Dryseal suitable for balconies and green roofs?

Dryseal Used on a Green RoofYes. For restricted access areas an anti-slip top coat additive can be applied, but for unrestricted access, recreational/furniture use, normal protection such as timber decking on supports, paving or rubber slabs should be used. With Dryseal, there is no need for a polyester fleece layer to protect the product, as there is no risk of fire from discarded cigarette ends.

Can Dryseal be repaired easily or altered?

Yes, even after a long period since installation. As Dryseal is inert and inherently stable, it can be easily abraded and successfully repaired in situ at any time during its service life. This work should be completed by an Approved Contractor to maintain the validity of the Guarantee.

Can I purchase and install Dryseal?

Only fully trained and accredited Approved Contractors can supply and fit Dryseal. Find your closest approved contractor on our contractor map, these contractors will be able to quote you on your specification.

If you are a bona-fide roofing contractor with high quality standards, you can enquire about training by contacting our Dryseal Manager Andy Fell – andy.fell@hambleside-danelaw.co.uk for details.

What does the Dryseal guarantee cover?

Dryseal materials are guaranteed to remain watertight for 20 years and this is backed by an independent insured warranty for your peace of mind. For more information, please read our materials and installation guarantee.

In some photos, I notice that the surface of Dryseal undulates. Is this a concern?

No. Because the system is mechanically fixed to accommodate differentials of expansion and contraction between the roof covering, insulation and structure, the GRP sheet is allowed to expand and contract according to the exterior temperature. Typically, this undulation will be most evident when the roof covering is new. In time, the product will settle and undulation will reduce. This trait is actually beneficial to the roof structure, as Dryseal allows the venting out of any interstitial moisture and reduces the likelihood of stress cracking which is associated with fully bonding the roof covering to the substrate.