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i bought an old 1920’s brick single on mud/lime/stone foundation. several places in the first and second floors sag (the house is and has been dry, no evidence of water or humidity damage. it was extensively remodelled over the years, obviously by persons with no carpenrty training.) in the basement in two places,joists were headed off with a sigle header about 18 inches from the wall at these connections, the nails have slipped,accounting forthe sag above. it looks as if the house was built this way. all the work looks to be of the same age. why would that have been done? am i best served by removing the header, sistering the joist,resting the sister on the foundation, (i’ll have to cut a new pocket) or should i merely reinforce whats there? i have not yet exposed the second floor joists yet, but assuming i find joists that are sound and merely sagging,there are two possibilities: one lay shims or tapered strips of 2x on the existing floor and lay a new subfloor and finished floor. or, tear off the old floor to the joists and nail level sister joists on to each joist, then install a new sub and finished floor. Which way is better? Tom Silva did id one way onthis old house and i think i remember a FH article recommending the other. is it always better to add a new joist or remove yhe old damaged one? does the sister need to rest in a pocket in the wall or is it ok to nail and glue it up tight to the existing joist without its own end support? comments?
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Depending on what is above and what loads the floor carries, I think that you could replace the header with a new double header, use joist hangers, and if the adjoining joists on either side are less than perfect, sister them. I would be cautious when removing the existing header. You will need to support the joist. Again, the loading will determine how much support you need.
The other option of sistering the joists can be a problem when the existing joist has bridging, pipe cutouts, an electrical cuts. You should sister the joist for most if not all of its length. This is why replacing the header may be preferable.
*You have a lot of questions here. It is impossible for anyone to make a really definitive suggestion for your situation. If the header connections are not adequate, they can be replaced with hangers even if those need to be custom made by a local welder. If the joists holding up the headers are sagging under the load, it is possible to sister these joists. It is important that the sister be as long as possible though it need not actually bear on the foundation or girder at its ends IF THE ENDS OF THE EXISTING JOISTS ARE GOOD. If they are split or rotten or you just don't know, try to get bearing for your sisters. Try to level the floor when you are fixing the defects in the framing. If that doesn't work, use shims or whatever it takes to get a plane surface or just live with the character of a funky floor. It's up to you.
*i apologize. i was'nt very clear. the floor is at its worst where there is no load on it. the joists are just swaybacked. the only load will be normal residential foot traffic. thats why it seemed a tossup to me which way to go. both ways will work, but i figure someone has done this a lot and can fill me in on the fine points, the whys and wherefores; the theory. for example, if i put tapered strips or shims on top of the existing joist, will this concentrate the load and tend toward more sag? or, do framing members sag only so much over the years and then stop? isn't it true that if you sister a joist you are relying on just the shear strength of the nails rather than bearing right on both members?i cant make out the species, they're painted. but they are full 2" by 10" on 16" ceters spanning 12' i am confident that i know how to deal with the obvious problem like a cracked or rotted one or where they carry walls or bathtubs etc.thanks i do appreciate hearing from you.
*That size joist should not be sagging this bad. From your description, I was assumoing that you had two by six joists or that the span was over sixteen feet.I would normally recommend sistering because if the joists are too eak to avoid sagging under normal loads, a wedge added to it for straightenning won't strengthen and it will continue to get worse eventually. As to the header - when a joist is shortened and headered off, you have transferred that load it was carrying to the adjacent joists and doubled the load on them - so you need to double them up to carry it. Don't just double the header and use hardware. double the joists it connects to also.My instinct is that altho you report no water signs, there are problems under that paint. What about termites, powderpost beetles, or carpenter ants? Tap, poke with a knife, drill a couple of 1" holes in the center of the joist and finger around. Or drive a few nails into the wood. Is it sound?
*thank you for your feedback. yes, i poked around quite a bit when i looked at the house prior to buying it. i used an ice pick near the wall pockets. the house sits up on somewhat high ground and thete is no moisture in the basement even after susained rains. the only time we saw water was when a rain leader got disconnected at the back.well, i'm going to start in on this. ill post what i find out as i go along. i did find two spots where knots had given way and allowed some movement those joists will have to go.
*keeping the thread alive.could be those two fractured joists never held any weight which added to the load the adjacent ones needed to bear. Then you've got the two missing from where the header joins, Now you're four joists short out of how many? That could explain why the sag.
*? isn't it true that if you sister a joist you are relying on just the shear strength of the nails rather than bearing right on both members?No.Sistered correctly, you will not rely on the strength of nails but on through bolts [1/2"], approximately 1-2' from each end and @4' apart from there on.As long as the ends are not deteriorated of the original joist, you do not need to place the sister in a wall pocket if it is a problem.
*I try to notch at ends or use hangers added to support both. I also glue and nail my sisters. Variables depend on the application and installation.
*thanks to all. when i'm done this mess i'll post a description of what i actually find and do. keep up the good work!
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i bought an old 1920's brick single on mud/lime/stone foundation. several places in the first and second floors sag (the house is and has been dry, no evidence of water or humidity damage. it was extensively remodelled over the years, obviously by persons with no carpenrty training.) in the basement in two places,joists were headed off with a sigle header about 18 inches from the wall at these connections, the nails have slipped,accounting forthe sag above. it looks as if the house was built this way. all the work looks to be of the same age. why would that have been done? am i best served by removing the header, sistering the joist,resting the sister on the foundation, (i'll have to cut a new pocket) or should i merely reinforce whats there? i have not yet exposed the second floor joists yet, but assuming i find joists that are sound and merely sagging,there are two possibilities: one lay shims or tapered strips of 2x on the existing floor and lay a new subfloor and finished floor. or, tear off the old floor to the joists and nail level sister joists on to each joist, then install a new sub and finished floor. Which way is better? Tom Silva did id one way onthis old house and i think i remember a FH article recommending the other. is it always better to add a new joist or remove yhe old damaged one? does the sister need to rest in a pocket in the wall or is it ok to nail and glue it up tight to the existing joist without its own end support? comments?