Hello All.. I trying to figure out the best way to level an old floor. I have stripped all the old 1x off of it and now I’m down to the the bare joists. I was thinking about using a string to get my two points across the floor and then holding up (or clamping) a 2x next to the joist under the string to get a mark. Then ripping it down similar to how you would cut a end filler (going against an uneven wall) for a cabinet. Thinking about this idea and how many joists there are, I’ve realized this would take forever. So now I’m considering just glueing and screwing that 2×4 next to the joist under the guide string… But I’m concerned that this might not be enough support for the weight of people walking over the floor, or maybe would lead to squeaking. I’ve seen this done before and it’s worked.. Any ideas?? And also, what kind of glue/screw should I use? Or maybe not screw and use a ring-shank nail instead??
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How undersized are the existing joists? a 2x4 might not prevent the same thing from happening again as the load in the center causes the floor to continue to resag..
To properly size the leveling joist you need to know how much span and how rigid you want the floor..
This can sound really difficult but it's reasonably easy to figure out.
As for screws versis nails it's primarily a matter of how much time you have. Screws will take a great deal longer to install than nails.
The existing joists are 2x10's on 12 inch centers! Way overkill for only spanning about 12 feet. The problem is some of the joists are sagging in the center, and the steel I beam that their resting on at one end settled more than the outside of the house has. The house is from 1952. Maybe explains the overkill
Also from just eyeballing it I would say the most I would be coming up from the original joist is 3/4-1".
OK, sounds good..
then your idea of sistering a 2x4 should work (assuming the sagging end has reached stability)
If possible,I'd try and jack the beam back up first. Then, sister Two by's till level. Yes, the Screw/Nail debate is
about to get going again, but ignore it as much as possible. Either will work for this application and screws will probably
be easier to set to the line. We use three inch Torx head deck screws for this sort of thing.
2x10's on 12 inch centers! ........ sagging in the center,
gotta ask,
are the joists cottonwood or has the floor been used for a strorage area for pallets of sacks of concrete?? How do you get a 12" center 2x10 12 ft span floor to sag if not gross overload or poor lumber??
I've done it both ways.
last one I had to flatten we decided to run tapered 2x's set on top of the joists.
room was small enough my 7ft level hit the halfway mark from the edge of the room.
I simply held up the level then drove a long drywall screw down to that exact height.
made for quick measuring.
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa
Screws are actually not as good for sistering as nails.
Screws work much better for pull-out stress than nails, but nails work better under shear loads than screws because screws are harder and therefor relatively brittle. That's why only common nails are allowed for shear panel.
here we go...
k
Ha I was thinking the same thing...
Daniel Neumansky
Restoring our second Victorian home this time in Alamdea CA. Check out the blog http://www.chezneumansky.blogspot.com/
Oakland CA
Crazy Homeowner-Victorian Restorer
If you use good glue then the nails or screws are really just there to clamp things up until the glue dries.
The hesitation on specifying screws is from not all screws being hard and brittle, but some screws being hard and brittle. And, too many people being ignorant of the fact that different screws, made of different materials have different, tensile and shear strengths, even though they look the same.
I have some screws that Simpson made to use with their structural plates, that would be perfectly adequate, for most shear applications. I also know that if I specified those screws, there is some percentage of carpenters / builders, who would substitute a screw from a different manufacturer, that looks the same, and not realize they just screwed the pooch.
Point taken. I should have said "most screws" or some such. Of course the screws that everyone has readily at hand and that are most mis-used are drywall screws which are the worst performers under shear.BruceT
Plus many people will install screws wrong.. It's pretty important to predrill the first board so you don't get thread standoff..
What kind of screws were you refering to?
Size, head and drive, Cost?
A friend wants to screw his stick framed octigone roof.
I imagine he's referring to Simpson SDS screws, which are typically 1/4" diameter, hex head, and are very expensive. Kind of like "lag screws".
I'd actually say they are more like self-drilling bolts than screws, but that might be semantics.
Does GRK give a shear value for its screws?
Otherwise, a typical 3"deck screw might have 2/3 to 3/4 the shear value of a 16d common nail. Then there's the time and expense...
k
edited to add: Actually, Ledgerlok makes some pretty wild claims about the shear value of their screws. I think they say their screws have more shear strength than a 1/2" lag. I do like using them, although I don't really believe the manufacturer's shear comparisons...
Edited 4/17/2009 8:24 pm ET by KFC
If I use screws I wouldn't spend twice as long predrilling. I would make sure and get the screws that are smooth for 1-1/4" at the head end of the shaft. Those pull 2x lumber tight.
But I wouldn't use screws. I'd shoot it full of spikes and be done with it. A lot is said here about why screws can be used, but nothing about why the should be used. Maybe if I didn't have a nailer, but then I'd figure it's a good time to get one.
Also, I would scribe and fur up, rather than sistering. 2x10s on 12" centers is plenty beefy enough. I'm guessing there must have been something really heavy in the middle of the floor for a long time to make them sag like that. Maybe 150 gal aquarium... can't imagine what else, but something.
~ Ted W ~
Cheap Tools! - MyToolbox.netMeet me at House & Builder!
Edited 4/17/2009 8:54 pm by Ted W.
I think the sistering was for speed, not strength. Why scribe when you can just slap a 2x against the existing joist, hold it to a line and pop pop pop.
And, I'm in the nails is better (and cheaper, and faster) camp too, fwiw.
Hence the comment that nails are stronger than screws, generally. (and cheaper, and faster).
But, Ledgerloks are cool too, in certain circumstances. And they make some pretty crazy claims about strength.
k
I was thinking sistering would be with full 2x10s, while ripping and furring I would use any available 2x stock. Wasn't thinking about sistering 2x4s.
The biggest reason I would opt for furring up is to keep the centers for plywood subflooring, especially if it's going to be T&G. ~ Ted W ~
Cheap Tools! - MyToolbox.netMeet me at House & Builder!
You don't loose your lay out by sistering. the whole thing just shifts over. An extra rip or two is to be expected on repairs and remodels.
Furring it up is for when you have to, as the amount of time
needed is much greater.
I was thinking sistering would be with full 2x10s, while ripping and furring I would use any available 2x stock. Wasn't thinking about sistering 2x4s.
Well, you're right, if you look at it just as materials, scribing will save wood (which is a good thing!). If it was my own place and I wasn't rushed for time, I might scribe, I guess. I'd have a hard time selling that on a paying job, though (unfortunately).
I was actually imagining 2x6's, just to be able to stagger some nails and avoid splits. but even if it's just 2x4's, you're still going to use more wood than scribing from scraps, it's true.
k
Wouldn't furring become problematic due to splitting from subflooring nails/screws and the fact of 1" less of nail/screw penetration into the joists at the low points in the existing floor?
BruceT
If it's well glued it basically becomes part of the original joist. I wouldn't do it without gluing 100% of the surface. Also, I'd use Titebond II rather than liquid nail or similar. Run the RO sander with 60 grit over the top of the joist real quick, so I have new wood to new wood connecting.
The one nice thing about doing it this way is the looks from the basement underneath. If you sister the joist, we all know it's good and rock solid. But try explaining that to a future buyer if the house ever goes up for sale. The sistered 2x's looks really bad. ~ Ted W ~
Cheap Tools! - MyToolbox.netMeet me at House & Builder!
Try ledgerloc truss screws they work awesome to snug up LVL carriers
Try ledgerloc truss screws they work awesome to snug up LVL carriers
Yeah, I already mentioned Ledgerlok screws. They make some pretty wild claims about shear strength, and they do drive nice, I'll grant that.
Kinda spendy, though. A 5 lb. sack of hand drive 16d's would probably do just fine...
k
Kinda tough to have to swing a hammer in only 9 inches.. My framming hammer is 6 3/4 inches long add a 3 1/2 inch nail and something doesn't fit..
Oh sure you can turn the hammer sideways and tap, tap, tapity, tap forever but it might be faster to screw.
Yeah but 12" centers doesnt leave much swing room perfect spot for my makita impact with truss locks.
No Danair?
k
You are right when comparing 16d nails to deck screws. Deck screws are usually #10 screws at the largest, so the root diameter is only 7/64, or 0.109-inches, while the 16d have a diameter of 0.135-inches. So, there is only about 65% as much area. And, shear strength is proportional to the cross sectional area. However, if you get some dedicated #10 framing screws where the thread is only on the first 1-1/4-inch, and the shank is 1-5/8 long, so the thicker, (0.1875-inches thick), shank is in shear, it will have nearly twice the cross sectional area of the 16d nail, and thus be roughly twice as strong as the 16d nail. The same dedicated framing screw in a #8 still has a larger diameter than the 16d nail, and is at least as strong in shear. But realistically the failure mode won't be in shear, it will be in pull out, or lateral movement when the hole in the wood expands. And, the screw will work as well as the nail. GRK has a bunch of tests done on shear failure of screws. The wood fails first in almost all instances. And, the nail screw war is once more on going. About as much chance of this getting settled as the Arab / Israeli mess.
Edited 4/18/2009 5:11 pm ET by Jigs-n-fixtures
one reason to use screws in my case would be that my impact would fit between 12" on center joists my nail gun wouldnt.
one reason to use screws in my case would be that my impact would fit between 12" on center joists my nail gun wouldnt.
That's a good point. I was trying to picture my smallest framer at a slight (horizontal) angle, and I think it would work, but it'd be tight. And don't forget, by the time you get that sister on there, the real gap is like 9"...
Maybe screws after all. Or hand nails started in the board before you hold it in the bay...
k
You must be a lot stronger than I am, and better with a hammer. I know it would take me about five minutes a nail, to drive them that last 1-1/2-inch. Figure your hammer head is 6-inches long, the space between the nail head and adjacent joist will be about 7-1/2-inches. So, you get to do little 1-1/2-inch baby swings, one at a time with no rythm. I think it would be tight to get the right angle impacter in there.
Oh No! Not the dreaded Palm Nailer... Makes for a long day.
I know it would take me about five minutes a nail, to drive them that last 1-1/2-inch. Figure your hammer head is 6-inches long, the space between the nail head and adjacent joist will be about 7-1/2-inches. So, you get to do little 1-1/2-inch baby swings, one at a time with no rythm
I do mostly remodel, so I can hand nail almost anywhere. I've gotten pretty good at using that almost flat spot on the side of the hammer when neccessary. I bet I could probably arc a full swing just right and miss the adjacent joist, too.
But, even so, probably a good place for the ol' Danair.
Or screws, depending on how far away my compressor was...
k