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I’ve got some rotted sills supporting some 2×10 joists. Rather than replacing the sill, I’m thinking about running trtd 2x4s flat side up nailed to the bottom of the 2x10s, a la I-beam. I figure it will stiffen the 2x10s(which are rotted only at the sill area) and serve as the sill. I don’t want to disturb the tile floor above by jacking or lifting. IO realize I could also sister another joist on but getting the lumber down there(crawlspace) requires tearing out a foundation vent. If I do sister one on, do you think I need to go 2×10, or could I go smaller and just stiffen the existing joist?
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I think you are looking for a cheaper, easier way to do what is going to be a difficult job. You have a mental hurdle to get over. Then it will get easier. How hard can it be to replace a foundation vent? Hard? Well this is definitely a crew job- not a onemanjob.
Shortcuts now will likely mean doing it again in a few years. The questions you ask are a little hard to answer correctly without being there to look at all the variables.
*i I don't want to disturb the tile floor above by jacking or lifting.How much is that floor above going to be disturbed when it starts to fall in, because you looked for the easy way out ?
*Just this morning I was in a crawl space where all of the 2x10 joists had been doubled. The work was done 12 years ago and the owners said it took a couple of guys a couple of weeks and cost a fortune. It was being done because the high moisture levels had created so much mold and rot.As near as I can figure, the entry hall had sunk down an inch or so on one side due to the rot, but no one told the guys doing the work. It's hard to see from underneath and I'm betting when they knocked on the front door the owner called them back to the garage just like he did to me so they were never in the entry hall! And so they didn't level it and fit the affected joist with a sister that was notched just a bit more than the others.Recently the owners have been thinking of selling and had a realtor look at the house. He immediately questioned the sloped entry hall. They were amazed. They had never noticed!Rich Beckman
*I had essentially this same problem only my rot was 18 feet of rotted 2x4 sill plate on my attached garage.Do a site search on "replacing sill plate" or "rotten sill plate". I'm basically a wrench turner not a nail banger and I figure if I can do it then well you get the idea. If the plate is rotted then what good would it do to sister joists? 2x4 would add some stiffness but miniscule at best. What length are we talking about that is rotted? The 2x10 that wraps the joist ends - is this rotten also? Time for some screw jacks and 4x4's and perhaps a crew. You just need about 1/8" lift or less.
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I've got some rotted sills supporting some 2x10 joists. Rather than replacing the sill, I'm thinking about running trtd 2x4s flat side up nailed to the bottom of the 2x10s, a la I-beam. I figure it will stiffen the 2x10s(which are rotted only at the sill area) and serve as the sill. I don't want to disturb the tile floor above by jacking or lifting. IO realize I could also sister another joist on but getting the lumber down there(crawlspace) requires tearing out a foundation vent. If I do sister one on, do you think I need to go 2x10, or could I go smaller and just stiffen the existing joist?