Hi All
I like the warm deck idea but would like to limit the roof build-up to the minimum to maximise internal headroom within a single storey extension (PD rules apply).
Rather than the conventional "120mm PIR board above plywood deck" arrangement, I am thinking of the following buildup instead:
(External)
This buildup should achieve a U-Value of 0.16 W/m2K and saving me 70mm in height. I checked condensation risk also in SAP software (attached) and it seems to be okay and no risk.
I just wondering if I have missed anything here, it seems just too good to me (basically warm roof within the cold roof buildup + clear void for services above plasterboard).
Thank you
H
I like the warm deck idea but would like to limit the roof build-up to the minimum to maximise internal headroom within a single storey extension (PD rules apply).
Rather than the conventional "120mm PIR board above plywood deck" arrangement, I am thinking of the following buildup instead:
(External)
- EPDM Waterproofing
- 50mm PIR Board (0.022 W/mK)
- 19mm Plywood
- 150mm Rafters with 100mm PIR Board (0.022 W/mK) between
- Plasterboard below rafters
This buildup should achieve a U-Value of 0.16 W/m2K and saving me 70mm in height. I checked condensation risk also in SAP software (attached) and it seems to be okay and no risk.
I just wondering if I have missed anything here, it seems just too good to me (basically warm roof within the cold roof buildup + clear void for services above plasterboard).
Thank you
H
