Vapor Barriers - Southern Florida

Vapor barriers go on the warm side to block moisture intrusion - so in Florida, would they generally not face outwards in wall insulation (towards the wall sheathing)? In my house the paper faces inwards so I’m not understanding how this works.

How about cathedral ceilings in FL? Vapor barrier towards interior or exterior of house?

Short answer…the kraft paper is installed on the conditioned side (not really a vapor barrier). You should not see any visqueen vapor barriers on a South Florida home behind the drywall. If you do, this is bad. A moisture barrier would be installed behind the exterior siding to provide a drainage plane. A moisture barrier with hard coat stucco on block would be the exterior paint.

Okay, thanks. That’s exactly how my new enclosed lanai was built - batts with kraft paper facing in, plywood sheathing, stucco and sealed with primer/paint. While going through the NACHI education they never hit on paint being the moisture barrier but the stucco company mentioned this.

The short answer is no vapor “barrier” in Hot Humid Climates Click Here and another click here

Yeah the Stucco guy is correct. STUCCO IS NOT waterproofing.

The stucco company told me to prime/paint ASAP because they had a case where a customer never painted the stucco and called back a year later to complain that it was peeling off near the grade. The sprinklers had been hitting the unpainted stucco and wicking into the wall.

Sounds more like they did not bond the concrete area or the bottom of the slab…Not sure exactly but sure do not think the paint was the issue. Did you let it cure before you painted it to the proper ph? Did they tell you that? There is a primer that will allow you to paint green stucco in about 1/2 the time.

This was at another customer’s house, not mine - it was relayed to me by the stucco company as a warning to paint asap (after curing). Their process is to dig down about 6 inches, scratch up any painted surfaces and apply a sandy glue to provide grip and then begin applying stucco. They told me that the customer who never painted had the stucco peel off over painted block walls.

I’ve seen whole walls peel away with a stucco veneer over painted block…obviously not prepped and bonded correctly, which was not due to moisture. Some stucco problems are due to excessive exposure to the sun after installation and just dried too quickly. Wait at least 7 days to prime and paint.

Ah, it sounds like the stucco company might have been blaming the customer, when they really didn’t bond it well enough. Thanks.