Laminate Flooring
 

Hello,

We would like to install waterproof laminate flooring over existing ceramic tiles in seasonal cottage. We are on a concrete slab foundation. We close in November and the house is unheated for the winter. I'm getting mix opinions about doing this. Some claim because the product has a wood core the product will expand, contract and buckle. My brother uses in down the cape in an unheated cottage on a hardwood subfloor with no issues. Does anyone have any experience with this product on a unheated concrete slab?

The ceramic tiles sweat profusely on humid days so I'm hoping this will resolve the issue.

Any suggestions are welcomed?

I've looked at the solid vinyl flooring planks for our cottage too. Costco has some really nice stuff. Never noticed anything about a wood core but I suspect there are different variations and manufacturers. The stuff I'm looking at is really thin so it can't have a wood core. I'd stick with the "Waterproof / Solid Vinyl" variety. The really nice ones have a pre-installed foam backer layer. The flooring floats on the subfloor (or old flooring) so as long as you don't glue it down and allow some room for expansion around the perimeter it should be fine.

Laminate flooring is known for expanding and contracting. That's why when you install it you're suppose to leave a space all around the floor and usually they cover that space with a 1/4 round corner molding. That way it can move without buckling.

Worse problem than buckling might be mosture from the sweating ceramic tiles getting trapped under whatever flooring you put on top of them, causing mildew and mold. Best to check into this with an expert.

Do you use a dehumidifier?

Moisture
 

Sounds like you may need to solve the moisture problem first. If your ceramic tile 'sweats' and you install something on top of it, won't that just trap the moisture and promote a great place for mold? Where is all the moisture coming from? If the perimeter drainage is bad, is the concrete soaking it up and then releasing it in the house? There are products, mostly designed for finishing basements, that provide a small airspace between a concrete floor and sub-floor. You may want to consider that before the laminate goes down. Of course, the more you add, the more you have to fix door heights, baseboards, etc. If you hire a professional and get some sort of guarantee, that might be a consideration . If you just go to HD and buy material and install it yourself then you're on your own if the moisture continues to be a problem. Let us know.

The sweating is just like the sweating of a toilet tank. The floor is cold and the water in the air condenses on the cold floor. I personally think the laminate floor with the foam backing would cure this problem. I doubt the moisture is coming up from the ground if it happens on humid summer days. A dehumidifier would also help on those humid summer days.

The Home Beautiful...In Belmont
 

Speak to Dawn Ruel ... 603-524-5588.

Very knowledgeable and will have answers to these questions and concerns.

I have laminate in San Fran and love it. However, I have no moisture issues. Sounds like your sweating is condensation from humid air against cool tiles.

On Slab
 

I have had non-waterproof laminate with pre-attached liner on sub flooring over a slab foundation in my condo since 2012 with no problems at all.
A true floating floor installation should take care of buckling issues.

The moisture is in the air. It condenses on the cool surface of the tile. Just like a cold bottle of beer in the summer.

The Cortec Pro plus and pro plus enhanced has a rigid core, manufacture recommends between 18 degrees and 150 is ok. floor has a cork back which makes it mildew resistant, great protect can be floated, and can withstand temperature changes. Any of the other cortec product would need to be glued down to be stable if drastic temperature changes are to be expected. All their products have a great visual. Hope that helps.

As others have said, you most likely are seeing condensation of summer air humidity on the relatively cool slab floor. Air dew points then range from mid-upper 50s (a very nice "dry" summer day) to low-mid 70s (oppressive humidity). Meanwhile the soil under the slab, particularly with no winter heating, likely is well down in the low 50s. So you get condensation on the tile, and since the tile surface is not porous, as just concrete is, you get a film of condensation, likely a slip hazard. I would guess, also, that there is no sub-slab insulation, which would have prevented the problem in the first place.

One solution would be to add a layer of foam insulation, a poly vapor barrier, and finally T&G plywood, screwed through to the slab. Over that would go flooring of your choice. The big problem here is that bringing up the height of the finished floor could well be above the bottoms of doorways. Moving doors up would be some work.

I understand the pieces will unsnap. The best thing to do is to have it installed and find out.

I agree, you could put it down without a border and pull up a piece in humid weather to see if it's wet under the laminate. Personally I think it will be fine. The moisture isn't coming up from the ground, it's coming from the humid air and condensing on the cold tiles. Hopefully the laminate won't get so cold that the moisture condenses on it like the tile. I think the laminate backing would insulate it from the cold tile.
Another thing I did in a bath that had an old flat 50's tile floor, I went over it with Armstrong squares glued down with adhesive. Like the flooring they use to use in schools. It's very thin and very durable. I put it down 5 years ago and it still looks great. You have to seal it after you put it down and it will last forever.

Use a solid vinyl plank flooring and you will have no problems.

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