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I’m doing a 2nd floor remodel on a 90+ year old house and have found that the floors have up to a 2″ bow in them. In FHB #137 Q.&A. they address a situation that is almost the same as what I’ve run in to, except that the floors in that example are “bouncy” and the floors in this house are not. Ripping out the 1x sub floor and sistering in new joists seems like extra work. I was thinking of adding shims ripped out of 2x stock and laying a new sub floor screwed to the old. Any thoughts? Thanks!
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Don't you think that perhaps your method may be addressing the symptoms rather than the problem? You won't know until you analyze the existing framing. Don't keep existing span, joist dimension and spacing a secret. Some thoughts. Randy
*Right - not to mention plumbing modifications (?) wall removals (?) etc.Jeff
*I agree with the two answers so far. If you really want to 'fix' the problem, you could get 1/4" steel plates the length of the span (one for each sagging joist) and bolt them through the sides of the joists once you've braced them from below to bring them back to level. Incidentally, it took years for the sag to develop so you won't be able to simply jack them up in one setting. I usually go a maximum of 1/4" raise per week or two or jack until the house 'tells' me to stop by creaking when it's reached its limit. Yours is a tough fix but still do-able. Good luck.
*Is common occurrence in this area for homeowners to retrofit existing attic space in 1-1/2 story homes into living space. Typically the attic floor joists were only designed to carry the ceiling below and to tie the walls together. The joists are normally 2x6 and I've even seen 2x4's. Some recognize that the joists are a bit unstable BEFORE sheeting and finishing. Some only recognize a problem after finishing when ceilings crack and sag when kids start jumping around upstairs. Obviously retrofitting new joists into that scheme is difficult, thus expensive. Properly supporting a floor should not be "too much trouble". A contractor, being the professional, will be dangling on his own if he doesn't perform properly and something happens. Homeowner will always say, "Gee, I relied on the contractor" even if they really said, "I don't want the expense of floor joists". Get it in writing with proper warnings and even then I wonder. If existing sagged joists are not a cosmetic problem, then may just want to stabilize where they are by sistering alongside. Darn few ceilings around that don't sag to some degree.If ceiling height is a major problem then sistering steel is an option but, personally, I'd rather get a variance for bit lower ceiling in the new space, rather than present bid for steel and installation. Along with the steel comes trying to convince inspector of the adequacy. With wood joists they can always look that up in their tables.That's one opinion. Always like to see others. Randy
*Over time, sagged floor joists (IMHE) can take on a somewhat permanent 'set,' although we see this more with timber framing. In attempting to jack, therefore, you could be raising the entire 'banana' rather than just straightening them out. Careful monitoring required, as you quite rightly note!Jeff
*I'm back with a bit more information.... The joists for the 2nd floor are 2x8, spaced "about" 16"O.C., but the span on some portions is 14'. The sag in the 1st floor ceilings is not an issue to the homeowner, and the first floor is not being remodled.The main bow in the floor actually runs parallel to the joists, with the high spot over a first floor wall. Thanks for the input so far.Jonathan
*"I'm doing a 2nd floor remodel on a 90+ year old house and have found that the floors have up to a 2" bow in them".If they are "bowed" [up??]-- remove the sub floor where the bow is--cut the top of the floor joist level with the other joist. Stiffen up the cut joist with either 3/4 ply or 2x. Put the lid back on. Good to go.If the floor is "sagging"--remove sub floor--straighten joist--add new support[2x or plate steel]--put the lid back on. Good as new!!
*I have got a couple of questions down this road. I want to remodel attic space in my 1912 into a usable 2nd story and have some similar issues. The ceiling joists in this case are just 2x4, as is the existing roof rafters. To make the space function I assume to need to do the work of sistering the ceiling joists into at least a 2x8, or use the newer form of lightweight manufactured joist, as well as sistering the roof rafters to allow for the insulation space required by code, (Oregon). I have original plaster in at least half the house, and 9' ceilings. Is there a great deal of liklhood that the plaster will crack and fall once the attic is used as living space, assuming this works $ wise to go ahead? My longest spans are about 18', and that is over the plaster.Or am I just running into too much trouble and would be better off just adding onto the first floor? I heard of others that added 4x4 between the 2x4 ceiling joists and made it work. Any inputs? Thanks. Justin
*I'm facing the same problem with undersized ceiling joist 2/6 in a 15'span in my 50yr old log house.The ceiling below is plywood 3/8 and the flooring is 1'plywood.I really like the idea of jacking and bolting steel plate to the joists but has anyone really done it and did all the sag andbounce go away?
*Yes, and to add to your questio, David, what does the cost of the steel come out to? Is it a reasonable choice economically compared to more conventional approaches?
*Justin,To prevent plaster ceilings from cracking you need to limit deflection of the ceiling joists. This will require figuring out the load on the added rafters and then looking on a span table (or using calculations) to check size of rafter. 49 degrees and raining in PDX today.
*Thank you Mike. I have not looked it up on the charts yet, and will. I am presuming that I will need some reasonably large joists to by themselves be able to take the weight over the span. It is approx. 18 feet at the widest unsupported part. I guess that my question is if the introduction of steel is effective enough that I could reduce the height of the joist needed to span that length. Every bit takes away from the attic space available, especially considering that I have the 2x4 roof rafters that will have to turn into at least 6" bays to accomodate insulation. All of this starts becoming a question for this project and my resources if I have to build a new roof because I am loosing too much space toward structural support and insullation, or if I just start dropping my plaster all over the place and have to replaster or drywall the lower floor. Those questions are at the core of my asking. I hope that it works well and easily, because it would be sweet. Justin
*to futher the conversation if heard that cutting the bottom af the floor joists and the jacking to a little above leval and then sistering steel along side is a good fix also you don't need to go the total legnth with the steel.what do you think?
*David,The method that you just described would remove bow,but would not strengthen the joist except at the "patch". Both ends would still be 2x6 with the potential for bounce. Sistering in a full length plate would help with the load, but to me would be more work than just adding more 2x6's, say 8" O,C.I still have no firm descision on the original post,but the cost estimate went up....Jonathan
*JONATHAN,I'm thinking that I already have enough 2x6 in my ceiling and all I want to do is take the bounce out of it and not raise my floorheight on the 2nd floor so really all I want is no bounce and stregnth.Having the steel end to end makes no differance in price of steel.there is just waste after legnth up to 20 ft. it also comes in widths of even numbers up to more than we need but back to my orginal ? does it work?i think it has to. I DO MY OWN WORK SO ALL MY COST IS JUST MY OWN WORK I JUST DON'T WANTT TO DO IT INCORECTLY 1ST TIME OUT
This seems to be a fairly finished thread, but here are a few things that may be helpful. We do a lot of steel-to-wood work here in NY for code reasons and because we do a lot of high design, one-off stuff and everyone sleeps better if it is overbuilt. (IMHO)
Steel is cheap, the labor involved in bringing it to heel is not. It will be hard to overestimate the labor involved in drilling the needed holes in the steel, right-angle drilling the holes in the joists, (gosh those bays get tiny all of a sudden), lugging all that steel up there in the first place, etc.
I have a hard time imagining how you are going to be able to move the joists at all without having to redo the ceiling anyway, I don't know much about plaster ceilings, but they don't seem that elastic.
If the bow is that "permanent", and the floor otherwise fine, your first method seems the cheapest and easiest and requires only the redo of the floor above. From what I can gather between the lines, it doesn't sound like the client is looking at this as a heirloom type home they will be in for years and years. If they just want a place to store young children(just kidding) and their toys for 5 years, maybe shimming up the floor is adequate?
Just an idea. Sometimes the "best" way isn't the most situationally appropiate way.
If you do go through with the steel, ask the steel yard about cutting your pieces to length. It is usually less than a dollar a cut, well worth it if you are not already set up for steel fabrication.
Don