Hi
I'm currently having a single storey kitchen extension built. The architect has specified an EPDM covered warm flat roof. Our builder has built up differently to the design.
The drawings show from bottom up, joists, firrings, plywood deck, vapour barrier, insulation board, membrane. There are valley gutters at the edge, made up of thinner insulation board on top of ply.
The builder has built: joists, firrings, insulation board, plywood deck. Gutters made of ply, with no insulation.
i.e. the difference is - no vapour barrier, and ply on top instead of underneath the insulation boards. I suspect he has done this because he has substituted cheaper boards which you can't apply the membrane onto (unlike the ones he was supposed to use).
I have discussed with the builder who says he intends to insulate under the gutters with insulation board between the joists. He says he has followed his his normal construction and this is fine.
Several things worrying me about this:
1. Potential for condensation due to lack of vapour barrier
2. Potential for insulation boards to compress around joists over time due to no ply deck underneath to spread the load
3. Insulation between joists under gutters likely to worsen any condensation problem / set up potential for damp timbers
4. The (recticel eurothane) boards he has used are according to the manufacturer intended for pitched roofs between rafters / walls, not flat roofs
Am I right to be concerned about these issues / is the builder spinning me a yarn?
Any help / advice appreciated - thanks in advance!
I'm currently having a single storey kitchen extension built. The architect has specified an EPDM covered warm flat roof. Our builder has built up differently to the design.
The drawings show from bottom up, joists, firrings, plywood deck, vapour barrier, insulation board, membrane. There are valley gutters at the edge, made up of thinner insulation board on top of ply.
The builder has built: joists, firrings, insulation board, plywood deck. Gutters made of ply, with no insulation.
i.e. the difference is - no vapour barrier, and ply on top instead of underneath the insulation boards. I suspect he has done this because he has substituted cheaper boards which you can't apply the membrane onto (unlike the ones he was supposed to use).
I have discussed with the builder who says he intends to insulate under the gutters with insulation board between the joists. He says he has followed his his normal construction and this is fine.
Several things worrying me about this:
1. Potential for condensation due to lack of vapour barrier
2. Potential for insulation boards to compress around joists over time due to no ply deck underneath to spread the load
3. Insulation between joists under gutters likely to worsen any condensation problem / set up potential for damp timbers
4. The (recticel eurothane) boards he has used are according to the manufacturer intended for pitched roofs between rafters / walls, not flat roofs
Am I right to be concerned about these issues / is the builder spinning me a yarn?
Any help / advice appreciated - thanks in advance!