Hi Folks,
Looking to better understand the role of the vcl in a warm pitched roof please, and keen to hear what the general consensus is. If there is post that covers it, apologies and pls do link in/ elaborate.
About to start our first (and possibly only) self build. Planning an insulated slab, icf walls and a truss roof with osb/ ply over rafters with 2 staggered layers of PIR, then battens, membrane, tile battens and then tiles.
Conscious people typically spec a VCL between the osb and the pir. Question is twofold- is this actually doing anything assuming I have properly taped the outside of the osb / junctions with wall plate (and assuming the osb is airtight (?)and given its on warm side too so dew point issues are mitigated ?).
And secondly, if needed, is there a more foolproof way of doing it than laying a vcl given i will be driving long hex screws through pir into osb (ie is there any value in a liquid/ paint applied vcl or perhaps a peal and stick)?
And finally, is there anything you'd do differently. Not keen on hybrid roofs with insulation between rafters and trying to make as simple for me as possible to make airtight given sealing from inside with truss connections will likely be a nightmare.
Thoughts appreciated,
Thanks
Will
