Keeping the hair shirt under the armour...

Keeping the hair shirt under the armour...

What's a hair shirt anyway?

"Under his armour… a hair shirt always on his body, and it pricked him sorely…" Lancelot, Morte d’Arthur Although Medieval knights wore hair shirts under their armour in order to suffer as penance for their sins, in the case of Christ Church Didsbury these materials – in conjunction with TLX Gold insulating breather membrane – proved to be the way to keep worshippers warm.

Built in 1881

This busy parish church is a solid Victorian structure located right on Manchester’s arterial route south. Built in 1881 thanks to the generosity of a local brewery owner, it has a T&G boarded roof with exposed rafters internally. This boarding is still covered with the original hair-based felt, and over this was more boarding covered by a bitumen felt, with concrete tiles above. The church has received generous funding from English Heritage for re-roofing and restoration work which included new guttering and down-pipes.

Heating bills were on the up tlx gold insulating breather membrane used in restoration of church roof

Given the considerable heating bills, providing roof insulation was an important consideration when re-roofing: the parapets were the limiting factor in how high the roof could be raised. It was decided to remove the old bitumen felt, but to leave the boarding and hair felt in place, repairing where necessary. 50mm of PIR board was laid over this, secured with a 38mm deep counter-batten over which TLX Gold was stretched taut (rather than draped). This created an unventilated air layer so that TLX Gold’s shiny under surface could reflect heat back into the building, resulting in a U-value for the whole build-up of 0.26 W/m2K.

A golden 'hair shirt' for the Church?

tlx gold insulating breather membrane boarded roof pirA 50mm counter-batten maintained a ventilation space underneath the final layer: terne-coated stainless steel supported by 19mm external ply, with Metmat sound insulating membrane between. Unlike the shining armour of Mediaeval Knights, however, this external covering of modern steel provided a weathered appearance whilst being lead-free. Between this armour and the hair shirt TLX Gold, like the quilted wool jackets worn under armour, fulfilled its role of keeping the bodies inside warm.

 

The Problem: How to provide insulation over a boarded roof without creating a condensation risk.

The Solution: TLX Gold: an insulating breathable membrane which also reflects heat – the boarded roof solution.

Click to view our LABC registered TLX Gold (exposed rafter) solution

Click to view our blog based on this solution

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