I'm planning to do my first hardwood floor installation. I'll be putting in about 1100 sqft of strand woven bamboo.
I live in the sf bay area and my subfloor is 1.125" thick plywood with 4x6 joists that are spaced 4 ft apart on center. This obviously does not meet the manufacturers recommended subfloor requirements. I've also read on here and other sites that it's a bad idea to install hardwood with this configuration. Ken Fisher recommends putting an extra layer of 1/2" CDX plywood. Is this an adequate fix? I'd prefer not to raise the height of the floor if I don't have to. I'm also considering reinforcing the floor using 2x6's but this could be potentially costly and labor intensive because my subfloor is above a crawlspace.

What are the risks if I were to just install the flooring on the existing subfloor with no modifications? Will I have bouncy/squeaky floors? Or do I risk some sort of large, costly failure?

Thanks in advance.

Hi Vee,

The surface is said to be "floating" because it is not directly attached to any part of the sub-floor. The boards are instead connected to each other via glued joints over a thin sheet of padding. The advantage of this fitting method is that compared to the other two it can be laid over uneven surfaces, is quick to finish and very easy to clean up. There is also a reduction in noise and moisture damage by incorporating the padding.

Joists are 4 ft apart? Thats crazy. Especially in the bay area where building codes are the most stringent in the world!

You didn't say if it was a floating click or fastened down.

Sorry, the floor is not suitable to float. I plan to nail it down using 18ga 1 1/2" cleats (manufacturer recommendation). Planks are 9/16" thick and all are 6ft in length.

Apparently my type of subfloor is not that uncommon around here. My house was built in the late 70's.
I've had two contractors come out to take a look. Both said my floor should hold up fine to any wood flooring. One flat out said it's not worth the cost to reinforce from underneath and I'm waiting for a bid from the second. After their visits I'm leaning toward laying an extra 1/2" sheet of plywood. My concern with this is the height of the floor where it will meet my front door, sliding glass door, kitchen tile, and bathroom linoleum.

Thanks,
Kyle

Kyle, call Jack Klecker my wifes cousin if your willing, lives in the hills near Oakland. He'll give you a bid, needs the work too 510-482-3809

I'd definetely at least go another 3/8 ply.

Thanks