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Q&As
What’s the waterproof envelope of a flat roof?
We have an eco type house with a flat roof made of fibreglass which is seven years old approx. The roof is laid on a concrete screed and water has been entering the property with tell tale marks on the ceiling. We have new home insurance and a claim has been made.
The policy refers the the waterproof envelope and I was wondering if this is the fibreglass itself or does it include the concrete screed underneath and the board underneath the concrete?
I certainly wouldn’t recommend fibreglass as a roof covering and I’m looking at single ply as mentioned in this Build It article.
Neil Cheney
One Answer
The fibreglass finish is the waterproof layer and therefore forms part of the Waterproof envelope. The screed etc underneath is the make up of the roof structure is often termed at part of the Waterproof envelope and will include the walls and the floors. One could argue the superstructure. Read your policy wording carefully as each insurer will have a slightly definition on what the waterproof envelope is
If you are looking at a single ply membrane to cover the roof, I would recommend sourcing this from a reputable roofer who is experiences with the materials they are proposing for you and can offer an insurance backed guarantee that covers both the materials and the workmanship.
Andy Butchers (Build-Zone Survey Services)