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Repairing a subfloor without demolition

Posted in: Northeast Bedroom

We're very new to this (where "this" is defined as house repair). I'm looking for input from die-hard rennovators.. AKA the houseblog community (and hopefully my Dad).. how would -you- fix this?

While walking around on the hardwood floor in the NE bedroom, both Marc and I noticed a specific piece of hardwood that "flexes" when you step on it. It's about 6-8 inches away from the middle of the north wall of the bedroom. Only one 6 inch section of the hardwood flexes.

This seemed like a "bad thing" so this last Sunday Marc went in to check out the crawlspace. It's our first foray under the house.

He took a lot of pictures but I haven't yet had time to sort through them.

Looking up in the crawlspace, the subfloor looks like it's 2x6 boards set at an angle(ie, subfloor laid at 45° to the hardwood floor). Right under the spot that "flexes" Marc found some termite damage (we treated for termites the week we moved in so no live termites there). I believe it's about the size of the palm of your hand.

I want to fix this... and stop the flexing.. but I don't want to have to tear up the hardwood floor (we just got done refinishing it).

Any suggestions?


EDIT: Visit Repairing a subfloor without demolition (part 2) to see how we actually solved this problem.


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Comments

We've gone through similar issues with our house. A few things come to mind:

1. Make sure the termites are a thing of the past (do you have a warranty)...Because anything you do now will just be a waste of money if the "problem" still exists. Also under the heading of fixing the problem and not maskin it: Termites are often the result of wood and moisture--are there problems areas which allow water to seep into the wood--especially "end grain wood?" These problems, if they exist, need to be corrected.

2. The "sub floor" is likely 1X6 (actually 7/8 by 6)...on diagonal. This was typical subflooring for bungalows/houses built before plywood....As an interesting side note, carpentars used to "break through" these boards quite often as they walked on them as they often had knots in them or were "inferior" wood (but superior to the wood we often use today). Many skinned shins as a result.

3. You could remove the troubling subfloor from below, replace it with solid/sound wood, and then provid some blocking underneath for support.

4. From above, you may need to "re nail" the floor to the joists/subfloor. (you may wish to see a past episode of Ask TOH where the repaired a piece of flooring...sorry forgot the episode).

5. In our house, there were so many "spongy" areas--and we also planned on running new plumbing, electrical, hvac--that we decided to pull up the floor (we didn't have a subfloor), cut out all rotted/suspcious lumber, reinforce the joists by sistering a new one next to each old one, putting dow a real subfloor (Advantec) and laying back down the old floor (which we havn't done yet.)

6. Nash's Book "Renovating old Houses" (I think that's the title) might have some suggestions.

Anyhow, good luck.

Wow. That sounds tricky.

First, are you sure that this is the only spot with termite damage?

We salvaged a lot of flooring from an old house with extensive termite damage. The spongy spots were usually where the worst damage was, but there were typically long, hollow chambers running further down the boards. These weren't apparent until you really started messing with boards (like trying to pry them up).

I would recommend crawling back under the house with something sharp (ice pick, razor, etc) and digging around to see if there is more damage around the problem spot. If there isn't any more damage, you might be able to cut out (skill saw or chisel?)the bad spot, work in a replacement piece, and then brace it all with support run between the floor joists.

If the termite damage is more extensive, things might get real ugly.

Good luck!

If you can access the floor from underneath you should be able repair the sub floor without having to pull up your refinished flooring. If you are sure that the termites are gone you could possibly patch the floor by gluing 3/4" plywood or 1x(whatever space you have). This would then be held in place by nailing 2x4 or 2x6's to your existing joists to secure it. This will work if your existing joists are sound and you are only patching a small area.

I was beneath a bungalow in Jacksonville today. The subfloor is like cardboard in many areas (35% of the house) due to really old termite damage. The joists look good but have been hit by powder post beetles. The current owner has already had to add in and extra joist for added support (he said his floor creeked too much). I'm under contract to close May 12, do I run away now?

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