insulating under hard wood floors

11 years ago

We have Brazilian Cherry floors and are up off the ground about 3 feet in some areas and only one foot in others.

We have only been finished building one year and our floors are already cupping.

We got in a hurry and called someone to come put the batten type insulation under the crawlspace. We have spent 850 on the actual insulation and then 400 to have it put in.

Now an insulation man who sprays the insulation in says that the batten type will make the cupping worse as it can trap and hold moisture.

We are now considering having it taken out and having him spray his in.

My question is that I am desperate for real answers. When we built the house we asked so many times, "don't we need to insulate under the house and the answer was always 'no'.

Now we are dealing with this and I need some facts.

Does anyone know anything that will help us make an informed decision that will save our floors?

Will the spray type be okay?

Please help us. Thank you very much.

Comments (6)

ionized_gw
11 years ago
The answer is climate-dependent and depends on soil conditions. You might insulate or you might not insulate an seal the crawl space. You might not insulate and vent the crawl space.

This can be an example. You might check around at the Building Science web site.

http://www.lsuagcenter.com/NR/rdonlyres/D33F711D-DC4B-4E4C-9ED6-A97DCE9DB026/79805/pub3187insulatingraisedfloorsLOWRES.pdf
pauli12
Original Author
11 years ago
Ionized, thank you very much. At this point we think the best thing to do is to insulate under the floor with the spray on type. We are going to remove the batten type we just had installed. Live and learn.
Thanks again!
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ionized_gw
11 years ago
Fiberglass batts do, indeed, have a reputation for causing rot. I would not think that you should have to worry about it for a few years if it has been applied properly. Is there a vapor barrier on the batts? What is your climate like? The problem is not insulation per se, but moisture migration. Your floor assembly needs to be able to dry to either the interior or exterior. Your choice depends on climate. If you live in a hot, humid climate, the pdf that I linked should be appropriate for you.

Spray foam can be tricky. Are you planning to use hight-density or low-density foam?
glennsfc
11 years ago
I would remove the existing insulation and force out some of the moisture residing in the wood construction before applying foam insulation. Also, you need to look at the differences between open cell and closed cell foams and how each might work with your floor construction and site conditions.

Moisture and wood...yeah, can be difficult...
GreenDesigns
11 years ago
Look at applying a vapor barrier on the soil surface itself. that is usually a much more productive project and can even be easily DIYed. That will save you thousands of dollars. Sprayed foam is costly. And it will be even more costly to you if you choose the wrong kind. The wrong kind will do exactly like the fiberglass batts. It will be like attaching a sponge to your subfloor.
ionized_gw
11 years ago
In some situations (climates) more moisture is available from the air than from the ground. The remedy in that case might be to enclose the crawl space.