? On Pier & Beam Foundation

[HogHunter34]

Anyone familiar with a pier & beam home & issues with not enough ventilation underneath to not release moisture? Over time moisture can damage sub flooring & wick through causing eventual damage to moisture sensitive floor covering?
What’s the proper recommendation on handling this issue?
Add more ventilation spaces?
Add fan with moisture sensor switch control?
Thanks

[armadillophil]

I have this issue on a rental. The old thinking was to allow ventilation but now they say you need to seal crawl space complete and put ground barrier with a dehumidifier. It was to pricey for me.

[TxAg]

Air flow is key. Probably lots of ways to get there. Ours just has several vents on each side of the house, and I make sure to keep them open. Weird thing is I see lots of houses with them completely sealed up.

[MRWHITE87]

The two suggestions you made yourself would be the best decision.

[bloodstick]

A mobile home we just bought has cinder block skirting all the way around the house. The inspector did not catch any issues so it was unknown to me. After closing, we pulled some floor out to remodel and found the subfloor was bad in several areas and the closets were condensating. There is 7 south facing vents and only two north facing vents. It looks dry underneath, but it def has issues with moisture. I plan on making it 7 vents on both sides and adding one on either end. Matter of fact, I think i will do it this afternoon and let some of this wind coming in Thursday dry it out some.

[rvd]

I had a house that had a concrete beam around the perimeter and regular pier/beam everywhere else. It had a couple of vents on each side of the house. Always smelled a little musty if you went under the house but never had any moisture issues on the subfloors that’s I know if. It did have a moisture barrier on the ground and a sump pump I never heard run.

[ThisLadyHunts]

I’m not sure what part of the state you live in or what the climate is like, but it seems to me that if you live in an area where the humidity levels are constantly high, then simply adding more ventilation would not help. Particularly if you already have fungal growth.

I’m no expert, but it seems to me if you either 1) add some type sheeting designed as a barrier to moisture (the kind they use when building retaining walls) or 2) spread some kind of non-dissolvable, high pH desiccant underneath (lime, maybe?), you might solve the problem.

[HogHunter34]

^^^ In Tyler, Tx (East Tx). It’s evident moisture damage on laminate flooring inside the house. I’m thinking if moisture is from underneath & doing that kind of damage to floor covering then sub floor has to be dry rotted or damaged as well
Thanks for the feedback

[Pstraw]

Another issue with that much moisture underneath a house is termites. The house I built on pier and beam is 36" off the ground with 28 vents in the brick underpinning. Humidity here is the same as you but if I crawl around under the house, the dust will about choke me down. No moisture issues at all.

[wdtorque]

If you are building, build up site under the house and make sure it has a 24” crawl space, that includes A/C and plumbing, thank me later. Some people go sealed these days, some go vented. I’d go vented on high ground with a couple fans if you are in a humid environment.


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[Mountaineer]

It's a common issue with pier and beam homes. Not just from the lack of ventilation but also poor grading or lack of gutters around the home allowing water to run towards the foundation walls. Almost all of the crawlspaces I go into have plumbing leaks also. Depending on the design and climate, additional ventilation or adding a moisture barrier can be helpful before going towards dehumidifiers or encapsulation.

[kparker158]

Cold contents on the inside to hot humid air on the outside. Sweat like a beer can.

[Draco]

I put about 6" of washed river pea gravel under my house before building and have had no problems and the house is 22 years old.

[Rush2Judge]

Why not just spray a closed cell foam? Insulates and acts as moisture barrier.

Our house was built in '67 and had a terrible moisture problem when we bought it in '91. Over the years we have made drastic improvement and the last on the list will be the foam.

Things we have done:
1) added humidity exhaust vents that go from crawl space up through the roof. This worked fantastic.
2) put plastic down. Not sealed but definitely helped
3) replaced air ducts. They hold mold and leaked so they sucked in air under the house and spread it inside.
4) replaced all cast iron plumbing with PVC. We had a couple leaks and clogging issues so, better to do it while you're under there.

Our lake house is also P&B. It varies from 2' to 5' space. It has the entire subfloor sealed with plastic and there is no ventilation on walls. It's only 12 years old but it has zero smell or mold.