I need to build up the top of my existing floor joists to be even with the top of an existing concrete slab. The joists need to come up 3/4″ to be even with the slab. There is a partition wall that the other end of the joists sit on that is 3/4″ too high (2×12 joists running 3/4″ out of level in 12 feet). The floor is removed and I have a finished ceiling below. What would be the best way to level and bring the floor joists up 3/4″? Two thoughts that came to mind were ripping long shims placed on top of the joists and the other was to plane or cut down the joists then go over the top of the joist with a piece of 3/4″ stock. Thanks for any suggestions. -Ed
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You need tapered shims, right? 0" to 3/4" over 12'?
There is a partition wall that the other end of the joists sit on that is 3/4" too high
The party wall is level with the slab? what rough floor system are you going to use? are you allowing for thicknes of rough floor?
Like dad said to college kid, "Send more info." Got any pictures?
12" joists over 12' is plenty strong, planing 3/4" off still leaves 10 3/4" material.
Start your planning from finish floor and design down to joists.
SamT
Sam, yes, I would need tapered shims 0"-3/4" over 12 feet. There is a block wall in the basement that the floor joists sit on. It appears that the block wall is 3/4" too high. As soon as I get the floor joists up 3/4" to the height of the slab then I'm going over the joists and the slab with 3/4" T&G fir plywood. Are you recommending that planing the joist down then going over the entire 12' length with a piece of 3/4" to build up to slab height? -Ed
Ed,
I would just get some 2x6's and sister them along the existing joists, glue up with construction adhesive and nail the crap out of them. Put them at whatever angle you like.
Unless you're putting like a hot tub or a big safe above, it should hold.
Edited 5/7/2003 6:14:17 PM ET by Mad Dog
Nope. Wasn't suggesting at all, just trying to understand better and maybe give you some other viewpoint.
Also, posts around here sometimes need a little fertilizing to get started. if you know what I mean (|;> We've got some real talent and eduction floating around. although MD has maybe consumed toooooo much 20-20. hehehe.
Iffen we get Piffin involved, you'll get real facts, but for rough and ready Mad Dog's close enow.
Actually, I too would go the sister route for ease and time (=money.) Use a string line or straight edge for elevation and clamp in place before nailing.
Let us know how it turns out, will ya?
SamT
Trimming the joists is not code compiant. It will work.
It is trivial to make 6' shims and glue them in place.
Not sure We have enough info. Is it a major traffic area. Are you sure it hasn't sunk? for some reason.
I like to use shimming, on top as a last resort, make sure you glue it and screw it. Make sure you pre drill you don't want to split the shim. What is plywood after all? Thin layers of wood glued together. The glue is critical .Screw it. You don't want it to squeek. Do your subfloor right away and screw thru the shim with 3" screws. Thru the shim into the joist. Deck screws are good. Shimming on top is better than floor leveler. In my opinion. Thats a lot of floor leveler.
Another way: Tear up the first layer of sub floor, put the shim, glued and screwed on top of the 1st. layer. Use floor leveler to even it out, with the floor over the next, level, adjacent joist. Then you can lay down your second layer of 1/2 inch subfloor.
Shimming under the joist would be better. If you are able to jack the floor up enough slowly. Get a piece of 3/4 inch steel stock and place it under the joist. Not good if you are under a wall. you will but a buckle in the roof. But if you have the floor out. and it sounds like you do. You can tear out the ceiling below. Under the joist next to the wall .make a small opening . jack it up. Patch it in later.
Why not replace the joist. with a bigger size and rip it down to the right dimennsion.If you didn't have a finished ceiling and it wasn't important to the owner You can just notch it to rest on the sill, at the right hieght. It will be wider. I guess it all depends on the job and what you trying to achieve. You don't want to tear out the sheet rock right? Everyman's home is his castle. I would not have problem. But its not my house. Make sure its what he wants. Its not going to fail. If thats what you worried about. if you glue it and remember that it is a thin piece of wood you nailing thru. you won't have a problem
"why not replace the joist with a bigger size and rip it down to the right dimension?..."
I don't think EDJW is talking about a single joist that is out of alignment. I think he is talking about ALL the floor joists.
Heck, if it was only a lone joist giving him problems, wouldn't it be less work to just rip down one wooden shim and affix to the top of the existing joist, rather than tearing out the existing joist and still having to rip it before reinstalling? C'mon now.
In regards to tearing out the ceiling and jacking up the floor joist and inserting a 3/4 inch shim plate....why would you go to all that trouble for a single floor joist? And you certainly would not jack up a multitude of floor joists to achieve this goal. Perhaps you meant to say that EDJW could possibly jack up the support beam holding all the joists?
Davo
What exactly is he talking about? And by way I have done exactly what Ihave described and it worked perfectly. But i guess it depends on your ability to use a tape and a level you know Carpentry.Where there's A wheel there's a way, got any wheels?
There is a finished ceiling below. There are most likely electric wires through the joists.
Sisting is about the most expensive way to fix this minor problem.
"Sistering is about the most expensive way to fix this minor problem..."
I agree with you George, though sistering is awfully quick and it will yeild good results, it will cost some $$$.
Another suggestion which (material-wise) would cost next to nothing... ( though it could be a bit time consuming...I know Ralph would argue that point against me...and he would probably win) would be to cut tapered shims. The shims really don't need to be a full 12ft long as the first 5ft or so of such shim will not even be 3/16 inch thick...big glob of construction adhesive can fix this tiny gap.
George, if I recall, when shimming the top was mentioned, you replied; "shimming the tops of joists is trivial.."
Sooo, since you wouldn't advise the use of sistering, or the use of top shimming, please give us your insight as to how you propose to solve the problem. Thanks.
Davo
"shimming the tops of joists is trivial.."
That means it is easy. Thst is what I would do.
I would take some 2x8s 8' long cut them to 4', draw cut lines with my level, saw them with my table saw, gloue and tack them down.
It might hold it up for a while. A shim is on the other hand is in compression.
The nails are holding the sistered 2 x's in place transfering the load to the out of level joist. It would take a lot to shear The nail, but it creates a weak spot in the system. I would glue the hell out of it too. otherwise they might work themselves loose and start to squeek.
Also, If you are hanging them onto the existing joists . You are increasing the dead load with out increasing the live load carrying capabilities of the floorjoists. Because they are unsupported.
And in the mean time why don't you tear it all out and do it right.
Where there's A wheel there's a way, got any wheels?
Guys, thanks for all your help, let me try to explain in more detail. The floor joist run from one side of the house to a bearing block wall in the basement, then they continue from this block wall to the other side of the house where they sit on the bottom flange against the web of a steel beam which runs parallel to the block wall. On the other side of the beam is a concrete slab that is even with the top of the steel beam. The floor joists that sit in the beam are about 1 inch below the top of the beam. When I shot the floor joists sitting on the block wall with my laser they are even with the top of the steel. There is a crown in the floor over the length of the block wall, it appears that the block wall was built about an inch higher than the bottom flange of the beam. Since I'm expanding the living area where the slab is I need to bring the joists up to the the top of the steel then I'll put 3/4" T&G ply over the entire floor. So, I have 15 2x12 12's that run from the exterior wall over the bearing block wall then I have 15 2x12 16's that continue from the bearing block wall to the flange of the steel beam. The end of the joists that sit in the steel beam need to come up about and inch and the end that sits on the exterior wall needs to come up about 3/4". So I'd be cutting shims or replacing floor joists from 3/4" to 0" in 12' and another set 1" to 0" in 15'. Ralph, what is a shooting board? Thanks again for all the advice. -Ed
A shooting board is a guide for cutting tool, whether it be a hand plane, circular saw, table saw, etc.
There are a number commercially available but it's easy to make one to fit the job at hand.
The most common would be one for the circular saw. A base plate of thin material is combined with a raised edge to guide the saw in a straight line. The base can be made of plywood, maybe 3/8 like mine and 8' long, too. This base is originally made slightly over sized in width so that the first time you run the saw on it you get a cut edge that will be used to line up any future cuts, whether they be straight or tapered on the cut material.
For your application you would determine the taper (straight line) that you need, mark the work piece, line up the cut edge of your shooting board, tack the board to the work piece so it doesn't wander and buzz it off. You could also just snap a line and cut it freehand for the shims because a little raggedness in the cut will not affect the function of a rough shim.
For a tablesaw I would use a length of thin plywood with a good factory edge to ride against the fence (forget the raised guide edge) and tack it to the bottom of the work piece with an 18ga stapler. Since the plywood is running straight along the fence you would determine the angle of the taper that you need and mount the workpiece on the plywood at that angle. When the plywood sled is pushed through the saw you end up with a very straight taper on the workpiece. I use this method for jamb extensions and cabinet end shims.
Someone else (you) can do the research for the shooting board article in FHB. Maybe it was by Jim Blodgett?
GOOGLE on shooting board for an article on using one with a plane.
You'll have to decide if a shooting board or the freehand method is right for your application. As I posted earlier, your taper could be compromised by a sag in the joist(s) which would then be more like scribing the cut to compensate. (Unless you shimmed the shim)<G>
Post back how you solved your problem.
Ralph, thanks for taking the time to explain that. That's a good point about the sag in the joists, I'll check that first. If they're fairly straight then I may just use the shims, that would save the time in tearing out and reinstaling all the bridging plus save me a few dollars. I'll let you know how it goes. Thanks again for all your help. -Ed
Last year I turned a porch into a kitchen. The subfloor height matched coming onto the porch, but dropped with the slope of the porch (1" over 8'). We were installing new hardwood throughout the house and into the new kitchen. Using a strip of plywood clamped to my workpiece, we ripped 8' shims that tapered from 0 to 1", out of 2x6's. These were lightly nailed onto the joists before the new subfloor went down on top. The new hardwood crossed the threshold smooth as silk and the new space was dead level.
what time is it ?Where there's A wheel there's a way, got any wheels?
The time is now here, I don't know about where you're at.
SamT
what i would do if i was you and thank god im not would be to do some carefull layout with the laser and then use a power planer to remove the excess material to a level grade then rebuild it with plywood to desired grade. it shouldnt be to much to remove 1 inch of material at the high point
Skids, that was another option that I was considering but up until now didn't get anyone's blessing on that idea. -Ed
EDJW,
I kinda agree with Skids. Now that I've read your latest posting outlining all the details, you basically have a "high spot" or crown located in the middle of your entire joist span. For curiosity sake, mark the entire span of one joist on the face side with a chalkline. Have someone hold the line even with the height of the concrete pad, and hold the other end even with the outside bearing wall. Now chalk it and see how much wood you would have to remove.
An electric power plane would make quick work of it. The biggest bite to be taken out of the 2X12 will be where the joists rest on the middle block wall. Only removing 3/4 of an inch right over a supported area, should not affect the overall joist strength one bit.
Originally when you first posted, you did mention planing, but if I remember correctly, you were discussing the idea of planing a 3/4 inch trough the entire length so you could use a 3/4 inch thick shim; rather than having to cut a tapered shim.
Heck, I bet you will have to plane an area of approx. 12 ft in length total...and I bet that all but 6 inches of that area "scheduled" for power planing, can be planed off in 1 or 2 passes. Except for the very middle, most of the taper should be less than 3/8 inch thick.
I remember someone mentioning that cutting down the thickness off a joist is not code compliant...but, just so you know...your 2X12s spanning 15 feet could actually span up to around 19 feet and still meet code. A 2X10 nailed 16 inch OC can span anywhere from 15 ft( minimum) to 17 ft; depending upon grade and species of wood ( ie...Doug Fir No. 2 grade or Hemp Fir No. 1 or Souther Pine No. 1...etc) And I'm talking about meeting code for a 40# live load, plus 10# dead load, with an l/360 deflection...this is normally the "heaviest" loading requirements for residential structures. Removing 3/4 of an inch, your joists are still thicker and stronger than a 2X10 joist. And as earlier mentioned...for the most part, most wood removal is barely negligible ( 1/4 inch or so here and there) and the area to recieve the biggest "bite" from the power plane will be resting overtop a block wall support. Again, I seriously doubt any loss of joist strength by planing the high spots.
If you don't have a power plane, you could possibly rent one. Mine is just a cheapie ( Sears brand...plastic motor housing ect.) but it would easily tackle this planing job. Don't think for one minute that you must go out and buy that $400 Porter Cable model....unless you need an "excuse" to buy yourself another toy...er, I mean tool. ha! ha!
Yes, by all means please run a chalkline along the joist and see how much wood needs removing ...you may be mildly surprised.
LOL.
Davo
Davo, that's the other method that I was considering just as you described. After the joists are planed down I could rip some 1x stock and attach to the top of the joists the entire length. This would get me level with the top of the slab. I had my eye on a Makita power plane for around $140. Sounds like I have three good options, I guess four if I take Mule's advice and tear everything down and go with the racquetball court. -Ed
So the steel beam is, in effect, low? Are there screw posts holding it up? See where I'm going with this?
Mad Dog, no screw posts under the beam. The top of the joist that sit in the beam are level with the floor joists that are on the opposite side of the house. The block wall is 15 feet in towards the middle of the house from the beam side and 11 feet in from the exterior wall. The high spot is directly over the wall.
Cut the shims, glue them on with hot melt or contact cement,. use extra long ring shanked nails or screws when you lay the subfloor so that you have plenty of bite into the joists below the shims.
better if you can find some sloooow setting construction adhesive and sheath as you glue shims. two or three small nails to hold shim in place till you get the subfloor down. Still gotta use long fasteners to get the bite to the joists.
SamT
Still a little fuzzy here. This is the 3rd picture I have in My Mind, and if I am seeing it right. 3/4 ovr 12' is about 1/16th " per foot not too dramatic, but enough. But , I don't see what you are going to do with the slab if you bring the joists flush your subfloor will be an inch or more high.
I will assume you have that figured out since you don't think it significant to mention.
I don't know what you can do ,But I would just rip a tapered shim. 11' long from 3/4" to 1/8th" use the shooting board, if you must. I rip them with my circular saw . We aint building no piano. I am pretty good with my saw.
Another Idea If only you didn't need to save the ceiling below, You might consider shimming the entire floor system up with a thin strip of 3/4" steel. You can run a saw kerf across all of your joist a 1/2", from the steel. Make it about a 1" deep then take a sharp chisel and bang out a notch ( it should pop out with one smack if your lucky.) It doesn't have to be perfect .It is just to allow the joists to rise above the the flange of the steel. 3/4" ( Unless the blocking between the joists,won't allow you to jack it up.) Then jack up all your joists and slide a peice of 3/4" steel under the joists. Tack weld it in place at a few spots.
Mule, I'm bringing the floor joist up to the height of the slab, then my 3/4" ply will go over top of the joists and the slab. The shims will start at 1 inch at the slab end then 0" the the end that sits on the block wall. This should give me a nice level floor. -Ed
This is over a finsihed ceiling. There are most likely electric wires in the way.
Sistering is a very expensive way to do this minor repair.
I agree with Mad Dog, sister some 2xs and set these to your proper grade angle. Fast and easy...and...it works.
Davo
What is so difficult about cutting a 12' long tapered shim from the edge of a 2by? Snap a line and have at it with a sidewinder (or worm if you're on the left coast).
If you're picky-picky about cutting a straight line you can tack a shooting board to the underside of the 2by (at the appropriate angle) and run it through your table saw.
It's only a little more work to make the shims if the joists belly down in the middle as well as being 3/4" under at the slab junction.
Tack your shims to the top of the joists with staples or 16ga's from a finish nailer, with a bead of glue under and a bead over when you put down the flooring and then use the screws or ringshanks or whatever you use in your neck of the woods. Floor will be right.
Shooting board LOL I never heard it called that Bhut iknow what you mean.Where there's A wheel there's a way, got any wheels?
Excuse me maybe I didn't understand the question. Are you saying that your floor is out an inch and a 1/2 overall? being level somewhere in the middle. east and west? To Hig on one side ? too low on the other?
There is a partition wall that the other end of the joists sit on that is 3/4" too high (2x12 joists running 3/4" out of level in 12 feet).
so where it meets the slab the floor is level? Is th slab out of level too?
The joists need to come up 3/4" to be even with the slab.
Is this bad work or is it sinking? if what you mean is that the partition wall is where it is supposed to be and the floor is 3/4" too low . we still don't have enough info because your floor is out. are you trying to make it flush with the slab? you don't have enough room for a proper subfloor in that case. so where is your problem the slab or the floor? I guess i assumed again . you know what they say about that.
Maybe you can jack up the top plate of the partition wall over the bottom plate and under the top plate. with lolly poles cut out the studs and lower the entire floor 3/4 on that end?and replace the studs. If there is no chance, that you will lower the roof. you did say it was a partition wall. but it is holding up the floor is that right?
Of course there is always the situation that your not trying to make it level. I assumed the slab was level. In that case, you have to make a descesion and live with it. On the slippery slope, of an imperfect world. depending on which floor it is . It might not bother you , over 12 feet.
Where there's A wheel there's a way, got any wheels?
Ed
Dont want to really read "All" the replies as I need to get back to work but....In my 1680 house what I "just" did to make the floors in my new laundry and bathroom that backs it was....Ripped out the 1950's flooring then..
I started out cutting 12' wedges but after I finished the laundry room which was only six feet wide I decieded the realistic way was "sistering" using some lag bolts, polyurethane tubes of glue and nails.
My floors were as crooked as you can get ina ll directions. The sistering method worked the fastest and IMO, the best because I could make it perfect.
The lag bolts along with nails and glue is seriously strong....and now "almost" dead level.
Be floored
Namaste
andy
PS....I'll post pics in a cpl a weeks
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Tear out the block wall and the floor and excvate for a sunken raquet ball court and steam room then you can relax a bit when its done.Where there's A wheel there's a way, got any wheels?