Box profile sheeting vapour barrier

[Grant1234]

Hi,

Has anybody done a steel portal framed shed with timber purlins/sheeting rails and clad the outside with 40mm or so of PIR insulation then just fixed single skin steel sheets right onto the PIR with longer fixings?
No extra plywood/OSB, battens or breathable membrane?

Planwell seem to offer this as an option, just wondering if anybody has any real world experience of doing it?

Seems like it would work well if all the joints were foamed/ taped up as the PIR would give a vapour barrier and stop condensation problems with the steel sheets.

It would probably be more expensive to put in extra timber at 600mm centres, sheet it with OSB, breathable membrane, battens then steel sheets and you still wouldn’t have any insulation that way.

Any thoughts?

 

[noseall]

Hi,

Has anybody done a steel portal framed shed with timber purlins/sheeting rails and clad the outside with 40mm or so of PIR insulation then just fixed single skin steel sheets right onto the PIR with longer fixings?
No extra plywood/OSB, battens or breathable membrane?

Planwell seem to offer this as an option, just wondering if anybody has any real world experience of doing it?

Seems like it would work well if all the joints were foamed/ taped up as the PIR would give a vapour barrier and stop condensation problems with the steel sheets.

It would probably be more expensive to put in extra timber at 600mm centres, sheet it with OSB, breathable membrane, battens then steel sheets and you still wouldn’t have any insulation that way.

Any thoughts?

Steel buildings and the solutions for combatting condensation, are somewhat specialist. I've seen pre-insulated steel sheets with the (PIR) insulation bonded directly to the sheet and I've seen the rockwool/glass-wool sandwich version.

No idea about the vapour barrier detailing though sorry. Principally the idea is that you either prevent internal moisture ridden air from ever getting to the cold steel, or you reduce the cold surfaces with specialist paint or insulation.