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Re: Reinforcing Sagging Joists

From: eslst7@yahoo.com
Category: Structural
Remote Name: 71.240.72.14
Date: 07 Mar 2006
Time: 10:22 PM

Comments

I have a house that's over 100 years old, with 2 stories, a finished attic, and the world's strangest basement. The house looks as if it were built in three stages; however, the only thing I'm certain of is that the kitchen was added within the last 50 years. The basement in the front half is about 6' high from the basement floor to the bottom of the ceiling joists, and the back half is about 5'9" high. The front is wider than the back by about 3 feet. Also, the front half of the house has 2x10 floor joists, and the back half has 2x8 joists.

These joists meet head on in the middle, on a girder made of two 2x10's on one side and two 2x8's on the other. This girder is sitting on the foundation on one end, and is held up by a jack post on the other - it does not reach the other side of the house because the stairs to the basement, which hug the outside wall, parallel to the joists, are in the way. (I'm not making this up!) The joists are not sitting on this girder - instead, the 2x10's are toenailed into it, but the 2x8's are sitting on a 2x8 lying on its face, which itself is toenailed into the girder. This "sill" looks as if it should have a foundation wall holding it up. Instead, it is held up by several jack posts that have been put in within the last 20 years. In fact the jack posts were raised too high - there is a bump on the first floor overlying the beam. For some reason, the 2x8's did not want to come up with the girder. Perhaps the nails joining them to the beam have snapped off?

The first floor in the front half of the house is pretty sturdy. The floor on the back half, however, is sagging and is very bouncy. The 2x8 joists are overspanned - 13 feet when they should only be 10 or so, based on the spacing of 19 inches to 22 inches (the spacing is not uniform!) One of the doubled joists was cut through and through to make room for a waste stack and duct work. They did put in posts on each side of the the stack, but the joist is still sagging at least an inch. The neighboring joist is rotted due to a leaking toilet. Furthermore, half of the face of this rotted joist was shaved off to make room for the stack under the toilet, making it a 1x8 along side the stack instead of a 2x8! Another double joist is holding up a hearth, and has a crack almost halfway through it right where the hearth starts. (The double joist is pierced by a tenon joint because a header is supporting the joists that don't reach the foundation because the hearth is in the way)

Finally, a hole was knocked into the foundation wall to get plumbing and gas into the added kitchen. They did not put in a header above the opening. Instead, 2 joists are sitting on the mud sill that is just floating over the hole. You would think that I would have seen all these problems before buying the house. I was relying on our home inspector because I had no experience before this, and I'm not an engineer. The inspector said nothing about these problems. Unfortunately, he does not think that he is liable for negligence, and it looks like I missed the statute of limitations by about 3 months. I started finding these problems when I decided to remodel the bathroom above it.

Now, I know what to look for, but I still have to fix this place. I had a few contractors take a look at it, and I've gotten several different proposals to fix it. I'm not sure what will be the best, most cost-effective, and least painful way to do it. I was thinking about making 6 beams by screwing together three 2x6's, about 6 feet long, and spacing them every 5 feet or so, with a jack post on each end. I was going to cut the concrete floor out and make 12"x12"x8" concrete footings for each post. Each beam would span 5 joists, which is halfway across the house. I can't go all the way across even if I wanted to, because there is a heating duct in the way. The reason I want 6 beams is that it would allow me to pick up the ends of the cut joists, support the cracked joists, and have some more control over what parts of the floor go how high. It will look something like this: IIIIIIIIIIIIIIIIIIIIIIIIIIII I I (crawl space I d I under kitchen) IIIIIIIIIII-d---IIIIIIIIIIII I d HHH I I______ d _________I I d I Is_____ d __________I (basement under Is d I dining room, 'back' Is_____ d _________I half) Is d I Is d I IsGGGGGGGGGGGGGGGGI Is d I I d I (basement under I d I living room I I 'front' half) IIIIIIIIIIIIIIIIIIIIIIIIIIIIIII key: 'I' - foundation 'G' - center girder ____ proposed beams ----- hole in the foundation 'HHH' - hearth s - stairs d - ducts.

The problem is that we would lose 6 inches of headroom wherever there's a beam. I've thought about sistering each joist, then removing the beams, but there are so many pipes, wires, ducts in the way, and it is such a long span, that it will cost a fortune. I also read that steel straps the length of the joist can be screwed to the bottom of the joists after jacking up the center of the joist. This would allow me to remove the beams after the joists are at the right level and strengthened by the steel. I'm just not sure about how much damage the screws would do to the joists if screwed through the bottom, and how large and what kind of screws it would need. Is this an insane proposal? Any better ideas? I'm really sorry for such a long message. I just thought that describing it in detail would make it easier to respond. Thanks!

Builders Websource® Answer: You certainly win the prize for the most descriptive narrative. More information is always better! You've painted a good picture of your situation. However, given so many obstacles and constraints, it's difficult to make a specific recommendation online without studying all aspects of the situation. Our recommendation is to hire a structural engineer (not a contractor) to evaluate the situation and make specific structural recommendations. Rather than make a bunch of separate beams, we'd rather see you do it right by fixing the girder and reinforcing the 2x8 joists with steel flitch beams or other stiffening mechanism. Furthermore, you need to fix the support at the end near your stairs by replacing the jack post with a properly anchored column and footing. This can certainly be fixed, however in this particular case, the advice of a competent, licensed structural engineer will open up new possibilities that you may not have considered. Keep us posted on your interesting dilemma.

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