Once again I’m soliciting help from an ignorance point. This may not be important to those who know but it is causing me some loss of sleep. Maybe some can help me out.
I have a 40′ slab that is to be spanned by trusses. Of course, there are two exterior walls and there are two interior walls, approximately equally spaced between the two exteriors. The trusses have been designed to rest on all four walls structurally. I have detected a small variance in the slabs levelness of about 1/4″ to 1/2″ under the two interior walls (maybe up to -but not exceeding- 3/4″ – 1″ ). Since I can’t do anything about the slab, I’m wondering how to make the top plates all line up evenly so the trusses will fall on each wall equally. The thought I have is to try to adjust the length of the studs in the interior walls to compensate for the slab uneveness (a guess, at best). I have taken approximate measurements at the interior wall lines and have a close measurements of the variances.
But, perhaps, I am making too much of this?
Replies
I'm sure the experts will chime in soon buy here's how I would do it. If the interior walls are truly for support, I would temporarily shim up to them where the slab is low. Then I would install the roof. Then I would remove shims to let the trusses deflect with weight on the roof. Then if necessary, reshim the walls to meet the trusses.
You get out of life what you put into it......minus taxes.
Marv
JimJ, you're not making too much out of this.
If one of the interior walls is high by 1/2", it will cause the truss to float at the wall.
I'm curious though about trusses that are built using interior walls as bearing points. On a 40' truss, I've never heard of such a thing, unless you have some very elaborate ceiling systems. In that case, you'd have no need for trusses anyways.
Anyways, I've ran into this sort of thing in various situations. I use a variety of fixes.
1) build all the wall to the low point and shim the trusses where needed.
2) custom cut each stud. This isn't that big of a deal: I use a line or laser to check the waviness of the plate line. I take a measurement at each stud location and mark on the plate a + or- of 1/8". I drop all the uncut studs on the layout. I then mark every stud with a standard pattern. When I cut them, I look at the notation on the plate and either cut it on the mark, or make the adjustment (by eye) as needed.
Could you elaborate on your design methods?
blue
Maybe he is talking about floor trusses????That is what I kinda of read into it.
>> Maybe he is talking about floor trusses????
That is what I kinda of read into it. <<
I was wondering the same thing. It's amazing how many people post Qs with only their own motives on their mind rather than actually thinking about how their text will be received from reader's perspective. I think we have one of everything else here, now we just need someone with ESP :-)
I think I'll coin a new acronym: LQQ - Low quality question... ;-)
Matt, I'm not sure I like the new acronym: LQQ - Low quality question. It sounds a bit snooty or perhaps condescending.
Mabye YQLSID,PGUM = your questiobn lacks some important detail, please give us more!
Aww forget it. I'll second your nomination for the LQQ. Shall we have a roll call?
blue
I can't imagine why the trusses would have to bear on the interior walls. Is there a reason for that? A 40' clean span truss isn't even CLOSE to being a challenge.
Assuming there's a reason that you have to have interior bearings on these trusses - You MIGHT be able to have the truss designer design the trusses to be clear span initially. Then the interior bearing walls could be made to fit after the roof was on.
The bottom chords of trusses aren't necessarily flat. Some companies add camber to their trusses, which would affect your wall heights.
.
There was a thread here a while back about using a chalk line to mark the height of your studs on uneven slabs/foundations. I don't recall the exact procedure, but maybe someone else will.
we need more details, a truss with 4 load points?, how'd they do that, even if they bear evenly in 4 spots what about truss lift??? ..
"...a truss with 4 load points?, how'd they do that.."
Piece of cake. We just put a joint at every bearing wall location. I do it almost every day for one reason or another.
The politicians don't just want your money. They want your soul. They want you to be worn down by taxes until you are dependent and helpless. When you subsidize poverty and failure, you get more of both. [James Dale Davidson]
We often frame pony walls or walls on an uneven slab by framing the wall with no top plate. It is instead tacked into the inside of the studs about a foot below the top of the wall. We stand the walls up, mark the corners level with a transit, snap a line between the marks and cut the tops of the studs in place. Though this gives a perfectly level top plate, it requires you to do a lot of cutting from a ladder at or above eye level. This is not a job for an inexperienced carpenter.
I would use blue's first suggestion in this case. Frame it low and shim on the interior walls.
That was my shop project.....the thread still ought to be around. I was trying to fix the uneveness in the slab for my shop project (caused by the idiot concrete finisher.....me...).
I started off shimming, and then figured that the easiest way was to measure and mark each stud with a stringline (someone suggested using a chalkline and just setting the studs in place and rubbing against the chalkline). Either way, you're custom fitting each stud. Doing so worked pretty good for me.
As an additional hint, be sure you take into account the waviness in the slab when you lay out your walls on the slab prior to tip-up. You'll need to make sure the studs all line up on the right side of the top plate edge or you have an uneven wall from studs being slightly off center on the top (or bottom) plate. This would probably telegraph through the drywall.
--Ken
Take a look at the thread beginning with 63111.1 I had a similar issue with my shop. --Ken
Ken,Maybe it was me who who told you what I do by nailing the two outside corners up plumb and setting a chalkline on top and stand your studs on the 16" center marks and slide the stud until it touches the chalkline and puts your mark on the studs. It works great.http://forums.taunton.com/tp-breaktime/messages?msg=63111.10Joe Carola
Your method is the one I was thinking about. Looks like the original poster has read the thread, but has not responsded to any questions. I wonder why that is ???
A snooze button is a poor substitute for no alarm clock at all.
Maybe this is a dumb question, but why wouldn't you just shim underneath the walls at the low points? What if you cut strips of plywood (varying widths 1/4", 1/2", etc) to bring the base of the walls up to even height?
shimming is fine........unless he has high spots. If it's just one or two high spots one might be able to chisel or knock it down. aside from that it is usually easier to cut down those studs. It was not specified wether the discrepancies are low or high, so it is assumed that there are some of both.
having said that. if the low spots are lower than your pre cut stud length, cut the ones that are too long and shim where they are too short. If you are dealing with only a few low spots you are right, all you will need are a few shims.
If he's got to cut all his studs to length, then might as well cut them to the length that fits. Iv'e always used the builders level to get the height at each stud layout mark. But I'd be up for trying the chalk line method suggested provided it wasn't to great a stretch for the string and I could get the string tight enough to have no sag.
I see you've come back and read the replies to your original post. But you haven't resonded or answered any of the questions that were asked of you. What's the deal?
If a child lives with approval, he learns to live with himself.
"But I'd be up for trying the chalk line method suggested provided it wasn't to great a stretch for the string and I could get the string tight enough to have no sag."If the wall is too long I just shoot my laser across and at the middle nail another stud plumb and the chalk line sits on top of that.I've done this for years and it's the fastest way and most accurate way with a bad slab. You bolt your sills down tight and you don't have to waste time using a million shims."having said that. if the low spots are lower than your pre cut stud length, cut the ones that are too long and shim where they are too short. If you are dealing with only a few low spots you are right, all you will need are a few shims."You can also just add another sill so that you don't have to shim and then your precuts will work.Joe Carola
Edited 11/3/2005 1:32 pm ET by Framer
"You can also just add another sill so that you don't have to shim and then your precuts will work."
have done that too. But if I only need a few shims, I prefer to shim. If adding another plates make smore sense for the circumstance then I do that, or sometimes rip some plywwod that works for the height.
Bottom line is there's more than one way to skin a cat. some work better than others depending on circumstance, but it sure is good to know the different ways that cat can be skinned.
"Bottom line is there's more than one way to skin a cat. some work better than others depending on circumstance, but it sure is good to know the different ways that cat can be skinned."It's like when guys who frame the walls and sheath them before they raise them works great on a nice flat surface. To sheath the walls first with the shoe not nailed down on a bad slab that's high and low would be a nightmare. So changing the way you frame the walls by nailing the shoe down first and cutting your studs to the proper length would make the job a heck of a lot easier. Or if you frame and sheath the walls first with a slab that's out of level, once your walls go up, side to side they will be out of plumb.Joe Carola
To sheath the walls first with the shoe not nailed down on a bad slab that's high and low would be a nightmare.
On the contrary! Sheathing the walls straight and true first, turn a nightmare situation into a casual walk in the park!
We do this all the time on our garage walls. Occasionally, the blockwork on the garage is very bad, wavy up and down and in and out. The advantage to pre-framing it is: the top plate is straight when we set the wall. The bottom is straight too and it rides on top of the high points. The gaps are very easy to see and to shim/fix.
The low points are dealt with in a variety of ways. The most common is: steel shims under each stud in the low areas. Another method might be: set the wall down on a bed of mortar (never saw this done, but this was the way old time carpenters set mudsills).
On the worst 30' wall, we can have it shimmed in a couple of minutes. It usually involves inserting one or two shims under 5 or 6 spots.
For those that don't want to see any daylight, the addition of a foam seal, or actually foaming with an expanded product would be suitable after the steel shims are inserted.
blue
> Another method might be: set the wall down on a bed of mortar (never saw this done, but this was the way old time carpenters set mudsills).
That's what I ended up doing when I screwed up and didn't have enough of the J bolts above the concrete. Chipped out a bit more than needed, and re-made the flat surface by setting the sill in mortar.
-- J.S.
"Looks like the original poster has read the thread, but has not responsded to any questions. I wonder why that is ???"Me too!Joe Carola
Indeed you did.....and I appreciate the info. I used a string line instead since I already had the whole wall up and was pre-marking before I took it back down. I would have used my chalk line to snap it but was out of chalk.........why is it the can is always empty when you need it? --Ken
Have dealt with the problem of a few high spots on the outside bearing walls in the past with a power plane.
Wall was already tipped up, but not sheeted. Sighting down could see a few high spots in the middle. Snapped a chalk line where top of plate should be. Went along and power planed down to the line at truss layout. Gotta set nails of course so you don't wreck the planer blades.
Seems we used similar method for some low spots. Marked truss layout, ran string line and shimmed up to line where needed - just where the truss would sit.
"Wall was already tipped up, but not sheeted. Sighting down could see a few high spots in the middle. Snapped a chalk line where top of plate should be. Went along and power planed down to the line at truss layout. Gotta set nails of course so you don't wreck the planer blades."Since the wall wasn't sheathed, why not string a line just cut the studs down and let the top plate drop down straight to the line?Joe Carola
Might not have been very clear. Both top plates where already nailed down.
Suppose it might have been just about as quick to snap a line and get out the sawzall and cut down the studs that were too long and then toenail back into top plate. Seemed to work quite well to just snap line on side of top plate and simply notch down to the line in the couple spots that needed it where the truss would sit.
Many ways to skin a cat - just thought I would bring up one more option.
I was thinking that the bottom of the studs weren't nailed and once you raised the wall you could just tilt the bottom of the studs sideways and cut them before you nailed them into the shoe. That's if you frame the way I do and nail your shoe down first and then nail the tops of the studs into the top plate and then raise the wall up and toenail the bottoms later. This way you don't need any sawzall.Any idea is always worth listening too. I've just worked on some bad slabs over the years and tried everything and the way I described above with the chalkline is the fastest and most accurate way to do it for me.Joe Carola
I understood and liked your method. Don't even have to get out a pencil.
My post was just to throw out other alternatives for those that might not have caught the uneven slab till further down the line. Guy I was working with at the time framed the walls flat and then tipped up - new construction.
About the only time I put down the sole or shoe (whatever it is called the bottom one) plate first is when I am finishing existing basements where there really isn't much room for tipping up walls and the floor and joists often vary quite a bit.
Like you mentioned - most ideas are worth at least giving a listen - that's why I log in - learn different methods
"Like you mentioned - most ideas are worth at least giving a listen - that's why I log in - learn different methods"I agree with you 100%. Sometimes you can combine methods together and they work fine.Just watch out for Tim Uhler. He's the crazy guy around here.......;-)Joe Carola
Well, first off, I don't have time to check every day for replies. But here I am now.
To reply to the questions (which I didn't realize were direct questions):
The truss manufacturer reassured me that there would be NO truss lift (I specifically asked about that).
I don't know what a 'floor truss' is - so I cannot respond to that.
There are both low and high points on the floor at the interior sole plates lines.
I don't think much of your LQQ idea - I thought the forum was for beginners to ask all sorts of 'dumb questions' - that's how one learns - didn't you (?). Putting down a question as LQQ will only discourage beginners (like me) from participating. Who knows, there may be something I DO know that could help someone else. Maybe even what I learn from putting up this shop.
There are interior wall supports for the trusses as there is an elaborate overhead storage system that will be suspended from the trusses (did I mention that the walls were 12' feet high?). Floor space is limited, so I decided to raise the wall height to allow 4' of overhead storage. Since there is no way to support the storage from the floor, it was decided to hang it from the trusses. The truss engineer was quite helpful in 'freestyling' the design so it would support the storage weight, provided that it rested on the interior walls (roughly equally spaced between the exterior walls).
This is a shop, so there is no interior drywalling to put up, only the exterior sheathing.
I know I will hear all kinds of redicule about it (I do tend to go my own way) but it is essential that the interior walls be set up before the exterior (I'm doing this totally on my own).
From what I have read, I think I'll set all of the sole plates (interior and exterior), do very tight stringline checking (or maybe rig up some sort of laser) to see where the interior plates have hi's and low's and custom cut the studs to match. Of course, this will assume that the exterior plates are level (I'll check). It may be tedious but seems the best way to ensure I get even close to a level top plate.
Many thanks for all of the input - sorry I was late in coming back.
Thanks for replying to us. When someone posts a message they sometimes never come back and/or don't answer questions. So we're naturally curious. Being as I'm a truss designer, I'm curious as to what the heck they've designed for you. Even with smoe storage load, I have a hard time believeing they can't some up with a clear span truss. Did they give you a design drawing that you might be willing and able to post somehow?.Some of the answers you got were very helpful, others weren't. That's the nature of this forum. The forum is for EVERYONE, not just beginners. So you'll have evertyting from pros to DIYs, smart people to idiots, nice people to jerks. You just have to be a little thick skinned to hang around in here.
Federal Expresso: When you absolutely, positively have to stay up all night.
Jim,Unfortunately with a bad slab that's high and low you have to fix it no matter what. The last house I framed was 5000 s/f with the worst slab I've ever framed on. It took almost 2 weeks to frame the first floor. It was horrible.With the laser and setting all the outside corners and using the technique I've described with the chalkline and scribing the studs it works the best. There's no shimming at all especially when the slab is high and low. Shimming takes way to much extra time and an extra step. You don't even have to take your tape out and measure anything.Whether you shim or not you still have to string a line. With shimming you have to string the line and then cut studs and then shim and then nail down your shoe. The way I do it your shoe is nailed already and your chalkline is up at the top of your corner studs at the exact height the studs should be cut at and then you just tap your stud on the chalkline and your stud is scribed already and then cut it right there and lay it down.Now do this all the way down the whole wall and then nail your studs to the top plate and raise the wall and nail it to the shoe and your done.I've seen it where the wall was raised with a couple studs to hold up the top plate and then string a line on the top plate and push the plate up or down to the line and measure the stud and then cut. That takes to much time.You can snap a line on the up and down shoe and measure or eyeball the height that you need to cut but that takes to much time also.Even if you raised the wall up and the bottoms weren't nailed and there was a high spot you can just sled the stud sideways and cut it down if your comfortable with a saw but I wouldn't recommend that for someone who's not used to a saw.Here's a little drawing just in case I confused you. I hope this will help you.Joe Carola
Here's another drawing showing how to scribe the stud.Joe Carola
Joe,
That is the way I was taught to frame on slabs. I thought that was such a cool method, because you could have a 6" high spot in a wall, but the top plate will be perfect.
By the way, nice explanation, I was going to try and explain that method, but I made it too complicated. I figured you'd come along and explain it nice and simple :-)
I try to explain things as best as I can but sometimes I go off and make it sound more difficult then it really is when it's a simple procedure. So drawings can shut me up for a while. Now my wife would like to shut me up for a little longer.....;-)Joe Carola
To ALL, and Joe (Framer),
Many thanks to all for the input and, especially, to Joe for the pictures.
Geeeezzzz, I thought it was just a 'little' question.