SIP Garden Room Base

[EdSta]

Hi all, I’m shortly going to be building a garden room using a SIPS system. I’m getting conflicting advice about the foundations. I’ve laid a reinforced concrete slab. The floor will be a SIPs panel (in hindsight perhaps not the wisest choice!). In some places it looks like the floor panels can be laid directly on the concrete (above a DPM), others suggest it needs to be vented and sit on bearers (say 50mm above the slab). I’m not keen on the bearers idea because it gives a place for vermin to reside and I don’t understand why you would need ventilation if you’ve got a VCL on the inside and a DPM below (and indeed that would be no different from how a SIPs roof would be in terms of ventilation). I’m waiting to hear from my supplier but have sketched out a proposal to put it on 50mm insulation on top of the slab with a DPM above the insulation but below the SIPs floor. Very interested in the views of others whilst I wait to hear. Many thanks, Ed

[Russell griffiths]

Replace the pir with XPS , make sure you put some form of rodent barrier over the ends and sides.