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subfloor, new construction

Is it possible, or feasible, or even legal to install solid 3/4" hardwood (either red pine or oak) to the floor joists like they did in the old days and forgetting the subfloor except in areas where I have to have them? (Like bathroom and kitchen where the floor wouldn't be wood) How long would this type of construction hold up? They did it in the old days, right? Should I have sprayed foam insulation underneath the house in the craw space if I do it this way? I live in the southern Indiana climate area. Thanks, Adam

Re: subfloor, new construction

Hey Adam,
I am Gregg with the home depot in Chicago. That’s a good question, but I would say no. In the old days the way the flooring was installed was different because the flooring was different. New hardwood flooring is made to be installed over a level, strong, and smooth surface. If the weight that is coming down on the hardwood flooring isn’t distributed equally to a subfloor then the hardwood flooring with fail. You must have a subfloor.-Gregg

Re: subfloor, new construction

ok,, let me clarify this... that last post is pretty vague

basically with older style hardwood they used wood that came in longer lengths which would span 3 joists minimum, even still this is a weak method of intalling hardwood. the floor framing would have to be 12" o.c if not closer together just to prevent deflection and to allow the hardwood to be properly fastened.

newer hardwood comes in random lenghts, usually the longest piece is 6' and short pieces around 12", this creates a random floor which is because the manufacturers make the peices out of whatever they can use from the tree. also a properly installed floor should have the starter and closer strip glued down with construction adhesive so to prevent the last few rows from spreading.. and for fastening a properly fastened floor is stapled roughly every 8 or 12" some guys do as little as possible but these floors end up having issues with movement. you cant get that with hardwood fastened to joists that are 16" o.c or 19.2" o.c

Re: subfloor, new construction

Older construction (I mean MUCH older) used different construction standards and the materials were a lot different. Yeah, they were still lumber, but a 2x4 was actually 2" by 4", maybe even bigger. Floor joists were made from full-dimension lumber from old growth trees, which were denser and much stronger.

Flooring products should always be installed according to the manufacturer specifications. You risk voiding the warranty and the longevity of the floor. There is no one way to install hardwood flooring. Each manufacturer has their own instructions. Where 8 - 12" nailing patterns are fine with one product, that may be insufficient for another. Some products do NOT come in random lengths. The width of the strip or plank will also have a bearing on the fastening method.



Re: subfloor, new construction

Another problem you will face is that in the areas where you have a sub-floor such as the bathrooms and kitchen these floors will end up higher than the wood floor. Say in the kitchen you have a 3/4" sub-floor, 1/4" backer board, thin-set, and tile you will now be about 3/4" higher than your wood floor that is on the joists. This will be a trip hazard even if you use some sort of threshold.

I actually doubt that it would be even code to do it like this anymore as the plywood or osb tongue and grove sub-floor glued down to the joists provides some structural stability and spreads the load over several joists. A wood floor would not provide the same support.

If you are thinking of doing this to save some money you aren't going to save much and you are going to create many more problems. In the overall price of the house you may save a $1,000 on buying plywood for the sub-floor and that would be for a pretty large house. Also keep in mind that the finished floors are one of the last things to go into a house if you do it the way you want then they would have to be one of the first things to go into the house. They aren't going to be in very good shape after all the heavy construction on them not to mention if it rains or snows before the house is closed in. Plywood can take a little rain or snow but a hardwood floor isn't going to fair to well. Just because they did it in the old days doesn't mean it is the best way, they worked with what they had.


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