Rotted Joist

[Sarah Stout]

Some two years ago we purchased a house. Prior to following thru with the contract of sale, we had a licensed House Inspector go thru, requesting an totally thorough inspection. We were VERY specific about one area of concern because we were aware that the house had had a water pipe burst while sitting vacant and on the market almost a year earlier. Specifically, he was told to please check for water rot in the dining room/lower bath area with a screwdriver. After inspection, he indicated there was no problem with joists in this area. However, recently we decided to replace the flooring in the dining/kitchen area, take it down to the subfloor (there were two layers of flooring already down that we knew of and we found two more layers under those two). Also, we found that 5/8-inch particle board on top of 1/2-inch plywood had been used as subflooring material (house built in 64). It was VERY obvious that there had been plumbing problems, large areas of water rot along the dining/bath wall and in front of the sink/dishwasher area and more specifically under the dishwasher in the kitchen area). Contractor began pulling subfloor from the most damaged area first, and we found two joists with water rot, the worst of the two with a three foot section of rot (disolves in your hands) extending down 1/2 way down the width of the joist, the other with a 15-inch section of the same. Joists under the bathroom/dining room wall and those under the bathroom itself will be inspected after the flooring is in place.

My question is are the 6-foot sections of 2X8 that the contractor is using to “Scab” these sections of joists (lag nuts at every foot, staggered top to bottom as they can be) enough to get the integrity of the structure back to where it needs to be?

Thank you.

[t.b.]

It sounds as if he is sistering the joist spanning across the rotten area, that can do the job. However I wouldn’t do that since I don’t like to leave rotten wood hanging around. I would support the floor and cut out what is needed and put in good wood all around – but that’s my preference.

[Daniel E. Fall]

In my opinion, scabbing is okay, but I would only scab after encapsulating the rotten wood with some major paint. See, the rotten wood is highly absorbent, of even humidity, and ….well, you get the picture.

Additionally, scabbing is fine, but bolting into 3 inches isn’t wise, it’d be best to do nothing more than nail into weaker sections, bolts only weaken boards. On a different note, the bolts would be good where the wood is solid for both the scab and the rotten joists.

Also, for proper strength, I’d recommend scabbing no less than one third the distance of the major rot on either side, so for 2 feet of rot, a minimum of 6′ scab. Wood is cheap, the longer the better. The trouble is, there is probably a lot of stuff in the way. I can’t see from my computer. If the scabs aren’t all together in one area, they are glorified nailers.

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