Hi folks,

 

I'm in the process of building a 6x5m timber-framed low-occupancy garden building, which will be used as a massage studio by my wife. I'm current at the stage of insulating the walls, and the makeup so far looks like this:

• Tyvek Housewrap
• 9mm OSB
• Timber frame, with 100mm foil-backed PIR
• <Separate VCL, or just tape the foil?>
• 47mm service battens
• Plasterboard

 

My question is about whether I really need a separate VCL, or whether i would be fine relying on the foil-backed PIR, as long as I make sure everything is taped up really well (including the studs)? And if I really do need a separate VCL, should i go for a proper product like Tyvek Airguard Reflective, or will polythene be fine? I'm seeing really mixed opinions everywhere

 

Thanks in advance for any input anyone has!

 

Oli

In theory, taping over the PIR joints should be fine. I've done both, just out of paranoia, it also allows for a better join at junctions, IMO. 

7 hours ago, jayc89 said:

In theory, taping over the PIR joints should be fine. I've done both, just out of paranoia, it also allows for a better join at junctions, IMO. 

Thanks, that's helpful! I should be good with taping then for the walls and floor.

 

I'll need a separate vcl for the roof since theres a 70mm void for services so taping, would there be any practical difference between a basic polythene and something more advanced like a foil-based reflective one?