Thread: Shims under sill plate

House built in 81. Cedar shims have been placed under this sill, the length of the sill. The sill is supporting the joists but the joists are also appear to be bearing on the foundtion. Is this acceptable.

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How did the shims look? Any compression? Cedar is a soft wood and not my idea of good structural shim. Were there any anchor bolts on the bottom plate of that stud wall?

I see crap shims all the time. Wood scraps, slate pieces.

I know this is residential but we worked public works projects for years and most all structures were shimmed, but later dry-packed below the sill between the stem.

If load is on studs and on shimmed sill way not meet code for your area.
There is a concern that the shims will compress, so non compressive material may be required.

The frame wall is not sufficiently, nor prescriptively, built to be structurally supporting anything, as pictured.

Originally Posted by H.G. Watson, Sr.

The frame wall is not sufficiently, nor prescriptively, built to be structurally supporting anything, as pictured.

I admit looking at that photo and over looking your point/s H.G. I , ( now ), see inadequate framing / studs, the plate does not appear to be bolted down and no vapor barrier. What else am I missing ? Is a double plate code required ?

Is that a concrete wall behind the 2x4's? What's the deal with that? The floor joists land on top of the 2x4 wall or continue on to the concrete?

Originally Posted by Jim Robinson

Is that a concrete wall behind the 2x4's? What's the deal with that? The floor joists land on top of the 2x4 wall or continue on to the concrete?

What 2x4's? Do you see 2x4's somewhere?

Here is another photo.

geez... sheesh...

I don't understand the poured concrete walls and then the addition of stud wall framing. Around here, the top of the poured concrete wall is always the bearing point for the sill plate and joists. There should be no need for stud walls that extend down below the top of the foundation wall.

Matt, what's up with the patchwork quilt style pattern on those foundation walls?

Originally Posted by H.G. Watson, Sr.

What 2x4's? Do you see 2x4's somewhere?

I guess you can tell that those are 2x6 studs from the photo. I guessed that they are 2x4 studs, but I'm not sure how that changes my question. You do see the studs and the concrete wall behind them, I assume.

Originally Posted by H.G. Watson, Sr.

What 2x4's? Do you see 2x4's somewhere?

I see 2x4s, unless you want to argue about today's true lumber dimensions. I assumed beyond the original photo 2x4s was some reused form plywood, but perhaps concrete. If concrete, I do not get what's going on w/ the framing at all. Even in the added photos, I do not understand why there is framing in the crawl area. Is that a central vac canister in the crawl space ? It's a mess.

Sorry. 2x6s they are.

Pic #1 - looks fairly normal, wrong but normal. Approved Plans/Permit typically call for that gap to be fully filled with grout. Shimming is common to start framing. That shimming however is poorly done. It doesn't look like it was really used to compensate for foundation wall irregularities.
Pic #2 - looks like somebody decided to build another support structure under the original floor joists. Maybe the original joists failed, maybe that header the joists in the foreground of the pic tie into isn't sufficient, maybe they had a Piano up there, maybe who knows. Unless they poured footings are real foundation walls under those 2x4 studs the support is only as sound as the ground/concrete pad its all sitting on.
My big concern would be trying to figure out WHY, the structure was built so that my client has an idea of what's going on.
Pic #3 - looks like an old foundation wall section, not 1981; but I could be wrong. Lots of signs of seepage. Definitely want to let the client know about costs and implications.
Hope that helps.

Its not a central vac, it is likely a blower unit for a hot tub or pool. The other pvc lines are pool or hot tub related.

This leads me to ask if there is a hot tub above the area in photo 2?

Also no junction box on the lose hanging wire, and not strung properly.

I see this done occasionally when the floor joists are not carried by the foundation perimeter wall. Maybe there was a design change or the floor is dropped down a step in that area. This may all be related to the arrival of the new hot tub. The stud wall carries the floor, but not the exterior wall. The cedar shims are holding up the floor. If that is the case, and there is no sign of sagging, I would describe it and move on.

Man, that is just scary. I suppose the shims are there because the concrete wasn't flat - either that or to keep the wood off damp concrete . The studs almost look spaced as if for drywall, but that doesn't make sense. I agree with HG. They're too far apart to carry even a floor (but I agree with others that they look like 2X4s). The structure under the hot tub is terrible. At the very least the ends of the I beams should be boxed and blocking added (can't tell if that's there). The webbing is more meant to be a spacer than to carry load. What are the floor joists, 3' OC?!

Makes me want to know more about the rest of the structure.

That second picture went in by mistake. That is just support under a small tub in the bathroom. I did'nt really look to be supporting much.

Originally Posted by mathew stouffer

Cedar shims have been placed under this sill, ... Is this acceptable.

Cedar shims may be suitable for shimming interior doors, maybe even for leveling furniture, but not much else.

Basically, a shim needs to be at least the strength of the material being shimmed to, i.e., the framing under the sill or the sill, the framing around a window, etc.

The shims need to be strong enough to transfer all loads to the structure the shim is to - thus cedar shims are basically not suitable for anything related to structural support.

Without added support the shims will compress, an ugly job. I did enjoy all the pest bait and sewage drain that seemed to have no slope.

Too many are missing the forest for the trees (and mis-identifing "trees"),


This isn't providing structural 'anything', it is serving nothing except promoting further deterioration & damage.

The shims mean nothing - this lumber is serving no structural or other function. It is merely tacked in place via horizontal 'blocks' every-other pair of non-studs, it is not structurally supporting anything. This is akin to residual lumber left in attic from raising a ridge beam.

First is the left top of the same stem, Second photo (original first photo) is same stem to the right foreground. (common corner view). Look carefully at the top, review carefully the 'construction'.

Originally Posted by H.G. Watson, Sr.

Too many are missing the forest for the trees (and mis-identifing "trees"),

This isn't providing structural 'anything',

Not according to the original post ... those *are* serving some structural purpose according to the original poster.

(bold and underlining is mine)

Originally Posted by mathew stouffer

House built in 81. Cedar shims have been placed under this sill, the length of the sill. The sill is supporting the joists but the joists are also appear to be bearing on the foundtion. Is this acceptable.

Mathew, unrelated, but is that a mold farm in the HVAC line in the 2nd photo?
Curt Downs Licensed HIC CT

I am not as concerned with the shims as much as the lack of anchorage of the mudsill (IRC R403.1.6), untreated wood in contact with concrete (R317.1), improper stud spacing (R602.3.1), lack of double top plate (R602.3.2), lack of clearance to earth (R317.1, picture #2) and lack of lateral bracing of the studs (R602.9). If this wall was only used for temporary bracing it should be removed (R408.5).

Originally Posted by Jerry Peck

Not according to the original post ... those *are* serving some structural purpose according to the original poster.

(bold and underlining is mine)

I know what Mat "opined" and "theorized". It is incorrect, and his theories are disproven by the evidence in the first posted photo (esp. upper left of same) and the third photo of the same stem.

IT IS NOT structural, nor is it supporting anything.

Originally Posted by H.G. Watson, Sr.

I know what Mat "opined" and "theorized". It is incorrect, and his theories are disproven by the evidence in the first posted photo (esp. upper left of same) and the third photo of the same stem.

IT IS NOT structural, nor is it supporting anything.

Please provide proof of your opinion as, even when zoomed in, I do not see any evidence which disproves his statement.

In my opinion,
Matts first opening photo looks like a poured concrete foundation with some additional supports added under the floor joist point loads. With out knowing the facts of the rest of the framing asembly, those may just be point loads to bear to the footing (maybe over loaded floor) and then actually that plate could be then just a lateral support. If it was an out of level foundation, I agree, you would slick mortar under the total bearing shear wall. The missing sill anchors or proper hold down for the continuous load path is a no brainer.

I started in carpentry in 1975, I saw and installed many cedar shake shims with great master carpenters in damp locations, thats the key word damp and cedars naturally are decay resistent and accepted practice at the time by inspectors. We also were using older growth lumber then.

Rule of thumb under the BOCA 1975 code adopted here in Jersey in 1977, and it may have been also been with the timber association at the time, a shim was to be of the same species, max 1/2' inch thick before you went to the next nominal lumber, end grain has to be quarter sawn, and can not compress more than an 1/8 inch. Then it was right at 1979 to 80 we shimmed with steel plates at girders and basically you were using transits and shot the elevations, make the corners level and pull a line across point to point and cut individual studs.

Those other photos and all those pipes and the added floor joists, is that a hot tub up there? thats just jumpin out theres further information needed.

Call it all out, state the owner needs to provide a permit and passed inspection, and if they cant, they require an engineer check it out and provide report.

I'm just a home-owner (& this is my first post). Since this thread appears finished, I wanted to ask: Is it possible the person doing this shimming job thought they were raising the wood off the concrete to prevent moisture issues from the concrete? Not that its a correct way, I'm just curious if someone crossing this thread later has a thought about this. (I come from a long line of jerry-riggers but am learning why that doesn't always help matters. ) Thanks guys (I've been learning SO much from all your posts & different points of view.)

Its anyones guess as to what actually motivated the person who did this.
So is it possible the shims were installed as you suggest? Yes quite possibly.

I'd venture a guess that the shims and 2x4 wall have more to do with the history of how the house was built. The concrete wall is the structure. 2x4's @ 24" O.C. aren't enough to hold up the first floor of a residence for very long.

I'd guess that the wall is temporary shoring (shims used to push the thing up into place) which was put in place so the addition (concrete wall adjacent) could be poured. Explains the lack of anchor bolts, the maximum stud spacing, the shims, and the gap all in one fell swoop.

Course I can't verify without seeing more of the structure.

Mathew,

Since we do not know what those walls are supporting everyone is just making some assumptions.

Is it a single story home? What is the snow load for your area? Has those loads changed dramatically?

They may have allowed 24" on center at the time of build.


Also a pest inspector that crawl has some issues that need to be addressed.

Originally Posted by Marc M

I know this is residential but we worked public works projects for years and most all structures were shimmed, but later dry-packed below the sill between the stem.

Okay, first post and hate to bring up such an old thread. But I have a question regarding shimming between a P.T. 2 x 4 bottom plate. How would you "dry-pack" an 1/8" or 1/4"? I have a need for doing this and am trying to figure out the correct way... Was going to use shims cut from the same 2x under each stud.
This is on an exterior wall of a single story 14'x20" garage.

The fresh cut surface of PT is not PT and it will rot or harbor insects.

Here is what dry pack is, I googled it fer y'all.

"By
Concrete Construction Staff

A specification requires us to use "dry pack" mortar to fill deep holes in a concrete wall. What is dry pack mortar and how is it installed?Dry pack mortar is a stiff sand-cement mortar that is typically used to repair small areas that are deeper than they are wide. According to the Bureau of Reclamation's Guide to Concrete Repair, dry pack mortar contains (by dry volume or weight) one part cement, 2 1/2 parts sand, and enough water to produce a mortar that will just stick together while being molded into a ball with the hands. The ball should neither slump when placed on a flat surface, nor crumble due to lack of moisture. Place dry pack mortar immediately after mixing it. Compact the mortar in the hole by striking a hardwood dowel or stick with a hammer. The sticks are usually about eight to 12 inches long and no more than one inch in diameter. Use a wooden stick instead of a metal one because metal tends to polish the surface of the mortar, making bonding less certain and filling less uniform. Place and pack the mortar in layers to a compacted thickness of about 3/8 inch. Direct the tamping at a slight angle toward the sides of the hole to ensure maximum compaction in these areas. Overfill the hole slightly, then place the flat side of a hardwood piece against the hole and strike it several times with a hammer. If necessary, a few light strokes with a rag may improve its appearance."

Originally Posted by John Kogel

I googled it fer y'all.

That is how I found this thread

Originally Posted by John Kogel

The fresh cut surface of PT is not PT and it will rot or harbor insects.

Here is what dry pack is, I googled it fer y'all.

"By
Concrete Construction Staff

A specification requires us to use "dry pack" mortar to fill deep holes in a concrete wall. What is dry pack mortar and how is it installed?Dry pack mortar is a stiff sand-cement mortar that is typically used to repair small areas that are deeper than they are wide. According to the Bureau of Reclamation's Guide to Concrete Repair, dry pack mortar contains (by dry volume or weight) one part cement, 2 1/2 parts sand, and enough water to produce a mortar that will just stick together while being molded into a ball with the hands. The ball should neither slump when placed on a flat surface, nor crumble due to lack of moisture. Place dry pack mortar immediately after mixing it. Compact the mortar in the hole by striking a hardwood dowel or stick with a hammer. The sticks are usually about eight to 12 inches long and no more than one inch in diameter. Use a wooden stick instead of a metal one because metal tends to polish the surface of the mortar, making bonding less certain and filling less uniform. Place and pack the mortar in layers to a compacted thickness of about 3/8 inch. Direct the tamping at a slight angle toward the sides of the hole to ensure maximum compaction in these areas. Overfill the hole slightly, then place the flat side of a hardwood piece against the hole and strike it several times with a hammer. If necessary, a few light strokes with a rag may improve its appearance."

Thanks JK...
I dont remember how much they shimmed the sill off of the stem but i do remember it was every single project i was on. Must have been in the spec..Our trade was hollow metal doors / frames / hardware so we would have to set frames and grout in our frames, which is where i started noticing it.

h wasm,

I wonder if using an epoxy in a tube would work. It seems like it would inject into a fairly small space and function like dry pack. The guns aren't cheap, but a rental yard might carry them. You could give Strong-Tie a call to see if they are ok with that application.