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Foundation piers, main beam, and shims


s welch

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After our house was built, I took a close look at our crawlspace, concrete block foundation piers, main beam and floor joist. I noticed that the pier tops were not level, the main beam was tilted, there were 1 1/2" wide wood shims between the piers and the main beam, these shims only went in about 1" on both sides and the floor joist were floating -not touching the top of the main beam. Contacted the building inspector and he told the building to fix the problems. The builder came and the work he did was not acceptable. I contacted a structural engineer. He inspected the piers, main beam, floor joist and shim. The engineer said it was not acceptable and gave me paper work and drawings on how it should be built. I gave a copy to the building inspector and he in turn gave the builder a copy of the drawings and told him to fix the problems per the engineer's drawings. The builder came out and still his work was not acceptable. The building inspector told the builder to contact the engineer and get his guidance. Now for some reason the engineer told the builder it would be okay to put 3 1/2" wood shims parallel to the floor joist not perpendicular and only on one side between the beam and floor joist. None of these shims go in the full width of the 6 " beam. What are your opinions?

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I think that the gaps could be filled with flat metal shims as opposed to wedged wood shims. If everything can be made snug with the floors level and solid and the piers don't sink or move, I can't see much of an issue.

Did you notice any issues with the floor from the interior of the house before exploring the crawl?

Many times things don't look quite right but in reality do not cause problems.

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When you say "building inspector", are you referring to an independent home inspector that you hired to look at the house before you closed?

Wood is the least acceptable material for shimming. Metal is better, but more $$$. Which is why most builders use wood. I've actually seen cardboard used as shims.

Whats up with the blue tape?

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Any non-compressible material can be used. Wood is compressible. Besides steel shims, I've seen slate used. Did you receive a letter from the Engineer that explained wood shims were allowable? Is the Engineer going to sign-off on the change and the installation of wood shims? Don't take the word of the contractor. If you hired the Structural Engineer, why is he communicating directly with the contractor? You may have Virginia Code 55-70.1, "Implied Warranties on New Homes" on your side if the house is less than 2 years old. Suggestion, all communications should be in writing. Phone calls and other verbal communications don't carry much weight.

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Solid OAK wedge shims would work as well as steel flat shims -if properly installed. That is to say, wedged tight, perpendicular to the beam. As I see it, the primary issue here is not the type of shim, but the pier surface upon which they rest. The pier consists of open core CMU's, and if not fully grouted, there is less than adequate surface to support shims of ANY type. The pier should be topped with 4" (nominal) solid blocks. What's up with the blue tape--some attempt to dam mortar-as-shim material?

Edit:typo

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Since I contacted the Town Building Inspector regarding my concerns, I have communicated directly with him. He has discussed these items and concerns with the builder. After the Building Inspector sent the builder back, a couple of times to fix the problems, we noticed there were gaps between some door jams and hard wood floor. The floor has sagged about ¼â€

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  • 2 weeks later...

For bearing of floor joists on wood girder, I recommend the direct approach.....constant-thickness wood shims filling the entire gap. Plywood is perfectly acceptable assuming the gap is at least 1/4 inch thick. Bearing pressure will be very low. You may need to lift joists very slightly during installation.

Lifting the girder seems completely out of line unless there is an obvious sagging problem............in which case there should be additioanal supports under the girder.........especially if the joists are not bearing on the girder to being with!

It is important that the top of the girder is braced laterally.........by connection to at least a few of the floor joists at regular intervals....say 4 feet or so. At the girder, there should also be some bracing to prevent bottom of girder from "kicking" out.........especially if the girder is relativley deep and narrow. If there is space available.........wood "keeper" blocks usually work just fine, nailed to treated wood plate on top of support pier.

For bearing of a girder on block pier........treated wood plate is best for new construction, with block pier filled solid.

If foundation piers are tilted noticably........they were probably built on compressible soil that was loosened during construction but not removed. Or......the girder is applying highly eccentric load.....off-center. Either way, the pier might have to be replaced..........or, another pier installed nearby.

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