Vapour Barrier in Porch?

[Co1]

I’m building a porch at the moment. The whole thing is sheathed and wrapped in breather membrane, and has 150mm of PIR in walls and ceilings (or will have when finished) and 100mm in the slab. It will not be heated on the basis that it is a porch!!

 

The question is whether to fit a vapour barrier internally. The porch will be used to clean off wet dogs and store damp boots and jackets in winter. My concern is that the vapour barrier will actually keep all the damp in there, and I’d much rather it permeated out. Am I out with my logic on this? 
 

Thanks

Col

 

 

[JohnMo]

For what costs and time to do I would add vapour barrier.

 

Reasons

You have PIR insulation, it's not vapour open, so any moisture is likely to be trapped in the structure. So best to keep it out, not allowed moisture in. Every time you open either inside or outside door the air will be replaced.

 

I would also heat it.

[Co1]

Thanks a lot John, makes sense. 

[Bluebaron]

Sounds like you might get quite a bit of moisture in there the vent of the window may help a bit or it might be worth considering a fan?