Level top plate prior to installing TJI?
I’m starting to install the BCI (TJI) 11 7/8 joists for the 2nd floor (the office) in my shop. The top plate of the bearing wall isn’t perfectly level. At one extreme end it is “down” maybe 3/8, tapering over about 20 inches to fairly flat. The rest of it is pretty good (within a sixteenth or less).
For the first couple, I slipped shims under the end of the BCI’s so they were level with the rimboard. While pushing the third joist up there, the thought occurred to me that since this floor will also support a bearing wall, do I need to do more than just shim under the joists?
I will be installing squash blocks from the top plate to 1/16th above the top of the joists, per the install specs. Do I need to shim the rimboard, too, or even worse, shim the top plates (or the whole wall) up to make the top plate level?
I should mention that the reason there is this “ripple” across the top of the plate is the idiot who finished off the slab floor (me), and it didn’t occur to me to check this before building the wall and tipping it in place…….but surely not everyone works on a perfectly flat surface?
I’m going to have a similar issue on the other end of the joists, so would appreciate feedback. Thanks! –Ken
Replies
I'd shim the entire wall so the top plate is level.
Steel shims under the studs between the sole plate and the slab and around the anchor bolts as well.
It'll make the rest of the job go a whole lot beddah fastah.
Just curious - Why the squash blocks AND the rim board?
If you use Boise Cascade's rim board, I've never seen a detail that required squash blocks.
Seems like a lot of unnecessary work.
A: You take your cleats off before jumping on the trampoline.
I guess mainly because the installer's guide doesn't just say you don't need them when using the rimboard.....it just says you do need them when there is a bearing wall above. I suppose I could actually call BC's engineering department and ask them. Here's the link to the guide I was looking at....detail F9:
http://www.boisecascade.com/wood/ewp/documents/western/west%20install%20guide.pdf
And in any event, there are only about 15 joists and I have some scrap 2x material from the walls I can use up here instead of using for campfire wood...
Detail F9 shows squash blocks at an INTERIOR load bearing wall, where there's a lod bearing wall stacked above it. Detail F7 is the one to use for en EXTERIOR wall. It won't hurt anything to put them in. I just don't want anyone to get the idea that they're required when they aren't. Squash blocks get brought up here frequently.
If a deaf guy fell off of a 20 story building, would his life flash before his ears?
Yes, I was reading the other recent thread on those, too.....
You don't need the squash blocks at the rim board. Surley your time is worth something...
Not much, apparently, based on my flatwork skills.....
Re your flatwork skills, even if you had hired it out, chances are you would have had some slight elevation variances.
He may be looking at F1-F2, or F8 which all show solid blocking.
Right - but in addition to following the instructions you have to understand the material you are working with... Rim board is designed to give load bearing support although it too needs continious support. That is it's porpose, in addition to stableizing the joist ends. The only time blocking is required up next to the rim board is where there are point loads.
Correct, I just wanted to make sure he saw the details with the supporting built up post.
Details F1 and F2 show an I-joist being used instead of rim board. Detail F8 is where you have a point load, such as a girder truss.So none of them apply, since he's indicated he's using rim board.
There are two kinds of people, those who do the work and those who take the credit. Try to be in the first group; there is less competition there. [Indira Gandhi]
Correct, I just wanted to make sure he saw those options and the post support
"I should mention that the reason there is this "ripple" across the top of the plate is the idiot who finished off the slab floor (me), and it didn't occur to me to check this before building the wall and tipping it in place.......but surely not everyone works on a perfectly flat surface?"
I hate to say it but even though your mason had a bad slab your first move was to check the slab no matter what. No slab is perfect that why you have to check it first so it doesn't screw up the rest of the house.
To do so, what I do on a bad slab you have to nail your shoe/soleplate down first and then nail your two outside corners up plumb first and string a chalk like on top of the corners and then hold every stud on the 16 center marks and slid the stud against the chalkline and that will mark your studs the exact height and once there cut you can frame the wall and raise it and you will have a nice straight top plate.
Unfortunately with a bad slab you have no choice but to fix it when you frame the walls. Doing it the way I described is the fastest way and most accurate way and you don't have to use one shim.
Joe, I've used that method in certain situations. I get bored very fast doing that though and only do it for very small walls.
To prevent boredom on longer walls, I have used a somewhat similar technique: I set the sill plate down tight. I snap a line on it's edge. Then, I drop all the studs at the layouts. Assuming that the studs are all precuts, I cut a smidgeon of those that indicate that an adjustment is needed according the the snapped line on the edge of the plate. Of course, I do all the cutting by eye.
If I was working with long stock, and had to mark each stud: I'd mark them all the same with a pattern, then make the adjustment by eye as I cut each one, the same as if I was using pre-cuts.
I've done this many times on poor blockwork walls. Sometimes, I just snap a line on the side of the block to give me a guage.
If I regularly worked on bad slabs, I think I'd use a different solution. Since I pre fab everything, my walls are straight on the bottom. When I swing them in, there would be gaps everywhere where the low points are. Might it be possible to just shim the low points with mortar like the old timer used to do?
blue
Joe:
That's a great technique. I hope someone else learns from it (much as I've learned a lot from posting threads I've read here over the years). A little late for me now, though.....
Fortunately, this is my workshop rather than a house, but all the same, it would have been nice to think this fully through first.... --Ken
Well, after some consideration and figuring that the cost of replacement studs was only about $25 at this stage, I simply pulled everything back apart, and replaced about 7 studs using the stringline technique. Came out fine, and I like it better than my scabbed together shims.
--Ken
Globaldiver, you've already gotten several bits of advice, most of which tells you what you SHOULD have done. I'll tell you what I WOULD DO NOW.
First a bit of regional history here. We don't work on slabs. If a slab is poured, it is normally poured inside of a one-course block wall. The block is normally level.
In my career, I have done a few remods that forced us to frame on a slab. I remember one that I did in the late 70's/early 80's. Since we were not accoustomed to working on slabs, we did exactly like you: we framed and stood up the wall, only to find out that they were wavy-up and down. We solved our little dilema by snapping a straight line on the top plate, then housing the plate where the joist would land. Basically all we did was pull the nail, then set our saw to the depth that the snapped line indicated, then ran the saw through till it was cleaned out.
Now that I know what I know, I'd probably just taper each joist. I also wouldn't hesitate to place shimstock under each high joist. I prefer to cut specific shims of the exact thickness, rather than using tapered shims. It just looks neater when I'm done.
blue
Thanks, Blue. I'm in reading this after being out this evening working on an alternate solution.
The one end of the wall which caused me to post the original post isn't far off...mainly about 3/8 at one end for about 18 or 20 inches, max. This is due to the slab rising up slightly from the stemwall (which my "crew" used as the screed rail). You work with volunteers from family and friends and you take what you get...happily (and in truth, I'm pretty happy with the slab overall).
The other end of the wall was a lot more out...about 3/4 in one place (that side of the slab begins a slope for an auto storage area where I wanted water to run out the garage door).
So what I did was use my bandsaw to rip a short wedge from pressure treated for the one wall which was only out over about 20 inches.
The other wall I shimmed under the rimboard the 5 feet or so where the ripple is. I took a piece of 3/4 plywood (saved from a kitchen remodel about 5 years ago...the old, hard, 12 or 13 ply very good plywood) and set it behind the rimboard and scribed the proper line. I then cut it on my bandsaw and slipped it in.....pretty damn good fit, too.
If I wasn't as far along on that wall as I was, I'd re-cut the studs, and slip them in as Joe suggested, but this should work fine....
As I said, I'm hoping someone else learns something from this to avoid the problem to begin with.....
--Ken
Stack the joists over the studs and dry shims will be fine; load will transfer straight down