Sometimes when re-roofing older properties with shallow rafters and an existing ceiling below, there is simply no room to put insulation between the rafters, and St. Mary’s Church in Walkley, Sheffield presented just such a problem. It is a solid Victorian church with a deceptively spacious interior that has earned it the local name of the Tardis. There are exposed rafters both in the nave and the aisles, with a plasterboard ceiling between. Above the rafters, however, was the original lath and plaster ceiling, with the roof consisting of Welsh Blue slates.
Thanks to a Heritage Lottery grant it became possible to re-roof the church, but, in removing the tile battens, the original lath and plaster inevitably came away. This meant that although it was now possible to include insulation between the rafters, the depth was limited to 40mm by the presence of the plasterboard ceiling underneath.
TLX Gold proved the ideal solution here, requiring no more labour costs than for a conventional breather membrane. Once the roof was stripped, it was installed taut over the rafters and then counter-battened, then the tiles and tile battens were replaced. Because the product is 33mm thick, the lower part expands down into the rafter space leaving an unventilated air gap below. The shiny undersurface of the TLX Gold reflects back radiant heat across this gap, improving the U-value from an uninsulated 3.6 W/m2K to 0.67 W/m2K.
All parts of TLX Gold are fully breathable, from the top layer of high tensile UV25 Breather membrane, the internal polyester layers and even the bottom shiny gold layer, so there is no condensation risk. And given the heating costs of a building of this size, being able to insulate as well as re-roof was a big plus.