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FIBREGLASS FAQ

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IS DRYSEAL A 'WET LAY' GRP SYSTEM?
No, Dryseal is membrane and component based - the semi-rigid membrane is supplied in 6m x 1.25m rolls of Flat or textured 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.

A 'wet lay' system such as CrysticROOF is adhered fully to the roof deck, which is new OSB (Oriented Strand Board) or plywood.
IS GRP ROOFING AVAILABLE IN DIFFERENT COLOURS?
Yes, many colours can be provided. For Dryseal, standard top coat colours are light grey (close to RAL 7047) and dark grey (close to RAL 7012), but a match to any RAL or BS colour can be made, providing that a minimum quantity of is ordered. Costs will vary according to the colour chosen.

Examples of different colours can be seen in the image to the right:
(please click image to achieve a larger view
IF I USE GRP AS AN ALTERNATIVE TO LEAD OR ZINC, IS THERE ANY SCRAP VALUE IN IT?
No. GRP is completely without scrap value. Although it can be finished in dark grey with decorative rolls to look like lead or ribs to look like zinc, there is no benefit in stealing it. Secured by Design accreditation from the Association of Police Officers in the UK signifies that Dryseal is an officially recommended product for lead replacement, to deter theft and reduce the fear of theft.
HOW DO I INSULATE A GRP ROOF?
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 Control Requirements.

CrysticROOF can also be insulated with an additional layer of OSB being fixed over the insulation, prior to applying the wet lay laminate.
WHAT IS THE MINIMUM GRADIENT OR 'FALL' REQUIRED FOR GRP ROOFING TO BE USED?
GRP roofs are 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 and is BBA approved for 'zero falls'. The recommendation for a 1:60 fall is for aesthetic and roof safety reasons, to encourage surface drainage and minimise ponding.
DOES THE EXISTING ROOF COVERING HAVE TO BE STRIPPED BEFORE INSTALLING A GRP ROOF?
If the roof substrate is in good condition and is suitable for mechanical fixing (i.e. steel, concrete, timber, plywood or OSB) 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, as they are unlikely to remain serviceable for the life of the Dryseal system.

CrysticROOF is always laid onto new OSB or plywood, so in a re-roof, to minimise the risk of interstitial condensation, the original coverings will normally be stripped and the roof deck renewed prior to waterproofing.
IS GRP SUITABLE FOR BALCONIES AND GREEN ROOFS?
Yes. 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 GRP, there is no need for a polyester fleece layer to protect the product, as there is no risk of fire from discarded cigarette ends.

All types of green and brown roofs can be installed over GRP waterproofing, without any need for a root barrier.
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.With CrysticROOF, as it is a fully bonded system, the manufacturer recommends that expansion joints are built into the finished roof covering to allow for the movement of the roof deck during temperature variations.
CAN GRP BE REPAIRED EASILY OR ALTERED?
Yes, even after a long period since installation. As GRP is inert and inherently stable, it can be easily abraded and successfully repaired or modified 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.