We go a slightly different route than old nose.
To achieve 0.18W/m2K, we find the cheapest and easiest way is 126mm TD4000 celotex across top of joists, mechanically fixed.
Note 126mm TD4000 Celotex. This thickness includes built in VCL and 6mm ply cap bonded to top.
This is suitable for built up felt, but for single ply covering you need an additional 6mm ply on top glued and screwed to comply with single ply covering requirements.
Regards oldun
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local