Moisture issues & laminate floors

5,929 Views | 8 Replies | Last: 4 yr ago by schwack schwack
schwack schwack
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We have 2 rental properties that have excessive moisture building up in the crawlspace. In both houses, it's causing the laminate flooring to expand and push up in several areas. So far we have put in a 6 mil plastic vapor barrier on the ground and are increasing the number of vents around the house. When it drys out, I plan to apply a borate mixture to the underside of the subfloor to prevent mildew.

Our friend has the same with much worse results. The original, old wood floors between the subfloor and the laminate have wrapped and buckled. It was bad enough that he thought there must be a broken hot water line under the house. There was not & the sandy soil underneath is dry.

One common denominator is that all these tenants keep the AC very low. One tenant says she keeps it at 65 at night and 69 during the day. The windows and doors are dripping with condensation and beads of condensation were forming on the underside of the subfloor before we installed the vapor barrier.

After we get the problem under control, would it help to spray the underside of the subfloor with foam insulation? Assuming I can afford it & find someone to do it, are there potential problems that it could cause?

Also, we (& our friend) have owned these houses for several years and this is the first time this has occurred. Granted, it seems like we've had more rain & humidity than ever before. Could it be an issue with the vapor barrier between the laminate floors & the original floors? This is happening with both click vinyl & engineered wood laminates.

Obviously, we can't control the temperature for our tenants. Hoping to figure it out, remedy the problem & prevent it on our other properties.
JP76
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Location ? Are you up north ?

Only times I've seen this happen were due to grade issues, pipes leaking or lack of guttering. Find the water source and fix it before worrying about the flooring or you are just wasting time. Make sure you have enough perimeter craw space vents on the beam as well on all sides of the house
AnchorFoundation
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I may get one or two of these type calls in winter months. This summer with all the rain and then the quick transition to hot and humid... I've had 20+

JP76 said it right, this is a flooring problem caused by poor drainage. All the other little tricks and techniques won't hurt, but they won't help as much as working on correcting the drainage around your home... and that's a big undertaking

Here's an article that explains these flooring problems and includes some links for more resources and info that may help.
schwack schwack
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Palestine, TX. We've had these houses for several years & no problem.
schwack schwack
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Thank you - very informative article. Although there is no excessive moisture just sitting under there, you nailed it:
Quote:

So it's hot outside and excessively and unusually wet under your crawl-space home at the same time. What happens when you run the air conditioner is that moisture gets drawn up with considerable force from under your home and causes the flooring to buckle and pop.

It can be even worse for floors that have a floating laminate layered on top of hardwood. The laminate acts as a vapor barrier and makes the force and the damage worse.



We have laminate floors down & will have to figure out what to do now. With tenants it's in there - not gonna be an easy fix - ugh.

If we continue putting new flooring in these older pier & beam houses, do you think tar paper would be an effective underlayment? We had an older neighbor who is a contractor suggest it - he swears by it.




AnchorFoundation
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schwack schwack said:

If we continue putting new flooring in these older pier & beam houses, do you think tar paper would be an effective underlayment? We had an older neighbor who is a contractor suggest it - he swears by it.
Great question, and I'm not 100% sure. I would default to a good hardwood flooring installer.

We do see that paper all the time in old homes and lay it back any time we are doing a subfloor, joist removal and replacement rebuild job. I've never thought of it as a protective moisture barrier but it sure can't hurt.
JP76
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More rain this year than past 2


Do the houses have continuous gutters all the way around them ?


Do the downspouts terminate at the beam or are drain pipes attached that take it at least 10 ft away from the house/ perimeter beam ?
JP76
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schwack schwack said:

Thank you - very informative article. Although there is no excessive moisture just sitting under there, you nailed it:
Quote:

So it's hot outside and excessively and unusually wet under your crawl-space home at the same time. What happens when you run the air conditioner is that moisture gets drawn up with considerable force from under your home and causes the flooring to buckle and pop.

It can be even worse for floors that have a floating laminate layered on top of hardwood. The laminate acts as a vapor barrier and makes the force and the damage worse.



We have laminate floors down & will have to figure out what to do now. With tenants it's in there - not gonna be an easy fix - ugh.

If we continue putting new flooring in these older pier & beam houses, do you think tar paper would be an effective underlayment? We had an older neighbor who is a contractor suggest it - he swears by it.








I've dealt with this issue numerous times and the worst failure I see when wood laminate or engineered is installed over existing hardwood floors. But it has always been cause by a water issue under the house from plumbing, poor grading, lack of guttering or lack of perimeter beam vents.

On these older houses it is normally tongue and groove 3/4 pine ran at an angle. Then 30 on felt is on too of that and the hardwood flooring is then nailed on top. I have installed LVP in these situations and have not had any issues as long as the backer is pvc based and not cellulose like standard wood laminate.
schwack schwack
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We have none of those water issues & this is the first year we've had any moisture/flooring issues: not wet under the house, enough vents, drainage OK, gutters where necessary, good skirting.

It has happened when we put another flooring over the old hardwood floors. On both engineered wood flooring & on some click vinyl we put down a foam under layment vapor barrier per the manufacturer of those floors.

I think it is just the heavy humidity. Normally it is DRY in August.
schwack schwack
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UPDATE: Vapor barriers & additional vents installed & both houses are dry now but I'm thinking about spraying a solution of borate & boric acid on all of the under house to prevent wood rot or mold if moisture is going to be a thing now. Anybody done this?
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