And proved to be the ideal solution for repairing the leaky roof at Layfield Primary School in Yarm.
It wasn’t long after the builders had finished it that the Foundation Stage and Children’s Centre at Layfield Primary School’s roof started leaking. While the problem causing the leak was not immediately obvious, the effects were very clear; water was finding a way into the building, running down the internal walls and causing damp patches on the ceilings.
“It was a constant battle for the school,” says Ian Dryden, National Specification Manager – Bituminous Membranes for SIG Design Technology, who worked with contractor Roofix Ltd to make the roof watertight once more.
The leaking area was made up of two pitched oval roofs with a flat roof below. Ian found that water was coming into the building though the detailing around the perimeter upstands and at the intersection with the lower roof.
It was identified early on that both the flat and pitched roofs needed replacing – severe damage to the 450sq m flat roof meant it needed to be stripped right back to deck.
To make that part of the building watertight again Roofix used the SIGnature Torch On System comprised of a Self-Adhesive Vapour Control Layer, tapered insulation, SIGnature Underlay25 and SIGnature AA Cap Sheet.
The system proposed benefited from being EXT.F.AA fire rated and also offered the reassurance of a warranty when used on a new roof or as an overlay, as it was in this situation.
For the 250sq m pitched oval roofs, using the SIGnature system as an overlay meant the original single ply roof could stay in place without needing to be stripped, saving the school a significant amount of money.
Plasticizers help improve a material’s flexibility – plasticizer migration is when the plasticizer migrates out of the old sheet causing it to become brittle. To prevent this process occurring between the old and new roofs, Roofix fitted a 300g separation fleece on the original roof followed by a mechanically fixed SIGnature Underlay25 and a fully-torch bonded layer of underlay and cap sheet.
THE DEVIL’S IN THE DETAILING
To complete the job it was essential to correct the detailing of the junctions with the flat roof and the upstands around the perimeter. To do this Roofix developed a way of close mitre cutting and bending the GRP trim in place so that it formed a complete seal around the upstand.
The time and care Roofix had put into the detailing was second to none. “Good tradespeople come up with good solutions,” said Ian. “And this ticked all the boxes from the client and the local authority’s points of view,” he added. What’s more, the roof has been leak-free for 18 months since the repairs were carried out. Sarah Powell, who works at the school, is delighted with the results: “We’ve had no problems whatsoever ever since. It’s a massive relief!”
The SIGnature Torch On System comes with three underlay options with either 20 or 25 year warranties, when used with the SIGnature Fire Rated Cap Sheet:
• SIGnature Underlay25 (25-year warranty)
A polyester carrier, reinforced, SBS, torch applied intermediate or base layer (dependant on specification).
• SIGnature Underlay20 (20-year warranty)
A glass tissue carrier, reinforced, SBS, torch applied intermedia or base layer (dependant on specification).
• SIGnature UnderlaySA (Self-Adhesive) (25-year warranty)
An elastromeric self-adhesive, polyester fabric reinforced underlay. Coated with SBS modified bitumen that has a smooth upper surface that forms an ideal surface for bonding subsequent cap sheets and has a release film backing.