3 posts / 0 new
Last post

The builder of our 45 yo house used what appears to be old porch board, or old siding for the subflooring. We have chosen tile and hardwood flooring to install over this. Does the subflooring need to be replaced if we use hardibacker under the tile and the liner under the hardwood flooring?

I don't want to install the new flooring, have to break it all up and redo it, if the subflooring isn't adequate.

Any suggesstions are appreciated!!

Re: Subflooring

If the sub-floor is solid and no squeaks it should be no problem. Solid wood sub-floors where used a lot longer than OSB or ply wood.

Re: Subflooring


I agree with jack, plank sub-flooring has been around for a longer period of time than any sheeting alternative.

In regards to the Tile portion of your question. The planking you have should be around 3/4" thick. Common rule of thumb for sub-flooring under any tile is minimum 1-1/4". This is due to deflection. For example, if you have a 3/4" sub-floor you will need to add a minimum of 1/2" underlayment. In wet locations it is best to use a cement based product. Any less than 1-1/4" and you run the risk of cracking grout lines or even worse, tiles popping up.

Now with the hardwood flooring, You can go right over the current sub-floor. But, keep in mind of flooring heights. For example, If you are laying tile down, the flooring height will be as follows: 3/4" current sub floor + 1/2" new sub floor + 1/4" thinset mortar + 1/4" tile = 1-3/4" of tile flooring height. Now if you calculate your hardwood flooring: 3/4" current sub floor + 3/4" hardwood flooring = 1-1/2". This means the height between your tile and hardwood is off by 1/4". If your budget allows you may want to add sub flooring to your hardwood installation to bring the tile and hardwood to the same height.

Hope my suggestions help you and good luck.


Measure once, Cut twice

Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.