Alright, I’m no framer, but I like to think I understand the basics of a house being put together. I went to visit my brother’s new house (well, new to him – it was built around 85) and now I’m stumped…
He pulled off all of the baseboard and carpet on the second floor of the house, and if you put your face down on the subfloor and look towards the walls you can see a gap (sometimes as big as 1/4″) between the plywood and the bottom plate of the 2×6 walls. You can easily see daylight under some of the partition walls, too.
He was thinking maybe the rim joists were slightly taller than the floor joists, causing the wall plates to be lifted a bit on the exterior walls – but that doesn’t explain the interior parition walls. The floor feels sturdy, but the best way to describe woudl be that the floor “sank” a bit or something. But I can’t figure how the plates and the subfloor would manage to separate unless the roof is being lifted off…Any ideas?
p.s. – I’m going to have him snap some pics of the area to post here, but I wondered if anybody had a simple answer to why this would happen? I’m not worried, just curious as hell!
be stumped.
Justin Fink – FHB Editorial
“Everybody wants to know what I’m on…
What I’m on? I’m on my bike, busting my
# 6 hours a day…
…What are you on?”
– Lance Armstrong
Edited 8/27/2007 10:43 am ET by JFink
Replies
Justin,
you're not clear as to whether you can see daylight at the exterior walls, But I'm guessing it's just the interior partition walls that show "daylight". Probably just the joists shrinking, they probably only nailed through the subfloor sheathing to attach the partitions so there was no reason for the plate to be pulled down when the joists shrank....as for the exterior walls, it could be as your Bro' guessed (rims were talller) or the rims didn't shrink as much, hence the gap.
Geoff
Maybe they put in "squash blocks" at the bearing walls?
Blocks put in length wise so as not to shrink along the grain the way the floor joists would.
Maybe the joists shrank up but the blocks held firm?
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...and the squash blocks woudl typically be put insdie the rim, but above the top wall plate, correct?
I thought they were mostly used in I-Joist floors? these are dimensional lumber, by the way. Justin Fink - FHB Editorial
"Everybody wants to know what I’m on...
What I'm on? I’m on my bike, busting my ### 6 hours a day…
...What are you on?"
- Lance Armstrong
I've used squash blocks on dimensional joists a couple times.
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Why?
The second floor walls are more than adequately supported on the perpendicular joists. Why squash boxes?
Measure the floor joist depth. They are probably 3/16" shorter than when they were installed.
I observed the same thing in a new house recently, the gaps were about the same as the joist shrinkage.
Edited 8/27/2007 5:25 pm ET by arrowpov
Ok, are the walls hanging from the ceiling then?
Or are you saying the rim joist was LVL or something other than dimensional? If the rim is the same 2x10 as the 2x10 joist then there would be no gap.
unless ....
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No, if they used squash block the walls would be resting on the blocks and thus no gap.
It sounded to me like the gap wasn't continuous.
If it's a continuous gap then that is really weird!
The reason I'm pushing the squash blocks is because we framed a simple rectangular house but it was three stories. All 2x12 Kiln dried joists. It was a very wet winter and everything was soaking wet. After it had been closed in a while the joists had shrunk up to a 1/4" each and the 2x12 rim did not seam to shrink the same as the lap at the cener bearing walls, creating a sag by the time you got to the third floor. We had to add in the squash blocks and it was a pain. I often thought that if we had the squash blocks in from the start and the joists had shrunk like this it would have made it appear that the bearing walls were up off the sub floor.
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No, the exterior sheathing seemed to be holding it together. The original 2x10 floor joists measured 9" to 9 1/8". They started out at 9 1/4", the second floor deck lowered itself from the bottom wall plate. Also the floor was starting to squeak because the joists were pulling away from the nails.
The squeaking was the homeowners original complaint.
It's the second floor of a two-story house, so the floor system is fully enclosed.Justin Fink - FHB Editorial
"Everybody wants to know what I’m on...
What I'm on? I’m on my bike, busting my ### 6 hours a day…
...What are you on?"
- Lance Armstrong
This house was the second floor also.
Trusses or stick frame roof?
It's a stick frame roof, Brian. If the joists throughout the house are the same as they are in the exposed part of the basement (which, I assume they are) - it's 2x8 floor framing.Justin Fink - FHB Editorial
"Everybody wants to know what I’m on...
What I'm on? I’m on my bike, busting my ### 6 hours a day…
...What are you on?"
- Lance Armstrong
My guess is the framers didn't have the first floor perfectly flat, they framed the walls and floor of the second floor without adjusting anything and put the second story wall together on the 2nd floor deck. If they sheathed the wall before standing it, there will be gaps unless both the floor is flat and the bottom plate of the wall is flat.
Partition walls often have gaps under them as various combinations of floor joists and plates dry out, sag, twist, or whatnot. Sheetrock can hold a wall fairly solidly and if the floor drops a little in short sections the plate can come off the floor.
Also, the exterior portions of the foundation usually settle more than the interior because of uneven loads and other such stuff, and it's not uncommon for interior posts to appear to be pushing up a small section of floor, when in reality the outside is settling more. This unevenness will make gaps all over the place.
Then there is always normal shrinkage of lumber. Some framers build ablivious to shrinkage and don't know why it's bad to rest girder trusses on green 4x10 headers if there happens to be a window there. Mixing green horizontal wood of any kind is asking for trouble.
To really know what's going on with your friends place you'd want to set up a transit or use a water level and get an accurate refference line to see what is level and what isn't . It will probably be depressing so only do that as a last resort. Even if it was built within 1/16" of level across the entire structure (not likely) it can easily be 1/2" or more out of whack from uneven settling. If it's in a development that's been recontoured and houses are on deep sections of "compacted" backfill, that settling could easily be doubled or trippled.
For anyone curious about house settling, a one ended water level (bottle on one end) and 100' of 1/4" id tubing is very easy to use and snakes around corners better than anything that has to be line of sight.
Good building!
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bingo!
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Thanks for the thorough reply Don - I doubt he cares enough to check the house for level. I'm pretty sure it was more of a "what the hell caused this?" bout of curiosity.Justin Fink - FHB Editorial
"Everybody wants to know what I’m on...
What I'm on? I’m on my bike, busting my ### 6 hours a day…
...What are you on?"
- Lance Armstrong
I don't know why, but the last year I've been terribly curious about houses and how they settle and measure one when I get the chance and have the water level handy. Truth be told I've also been checking out neighborhood foundations with a transit when the elevation makes for easy looking.
Good foundation peeping
Beer was created so carpenters wouldn't rule the world.
IdahoDon
I think you are dead on target here.
In addition, I see rim joists that do not shrink as much as common joists because only one side is exposed to the air. The inside loses water and shrinks at nearly the same rate as the common joists. Movement and shrinkage of the inside face of the rim stops while the outside is still wet. The dryer inside edge of the rim holds the outside solidly to close to its original dimension. Shrinkage of the outside surface is taken up in splitting intead of dimensional changes, leaving the rim higher than the commons.
This is why larger pieces of wood, even 4 x 4's are nearly always split on the outside. The outside dries, shrinks and splits while the inside is still swollen with water.
I'd be careful with a one-ended water level. A little warming or cooling in the hose will change a reading fast. Compare to the bottle level often.
Ron
I'd be careful with a one-ended water level. A little warming or cooling in the hose will change a reading fast. Compare to the bottle level often.
Agreed. Just like any measurement tool, the user must regularly use some method of checking accuracy. The method that seems to work well for me is to return and check the first mark. It's impressive how the level can be plumbed with 200' of tubing, checking all corners of a house and remain within 1/32" or less of the first mark.
I also like to use the rather stiff clear polyurethane tubing that is more resistant to bending, crushing, or otherwise changing its shape. I picked up 300' of it for dirt cheap from a surplus catalog a few years back and I should have bought 1000' more. With this tubing there has been very little change when going from cool basements to direct sun.
I'm quite surprised that these levels aren't used more often since they can be put together for under $10 and are extremely accurate over long distances. Of course they are easy to get screwed up measurements with if the opperator doesn't have his head screwed on. Maybe it's not idiot proof enough.
Good building
Beer was created so carpenters wouldn't rule the world.