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foundation settlement or something else I am not seeing?

foundation settlement or something else I am not seeing?

foundation settlement or something else I am not seeing?

(OP)
Looking for comments.

Please reference attached photographs.

I have a 32-foot by 58-foot one-story modular building constructed over a crawlspace. The building is two years old. The crawlspace walls are block w/ 2-inch rigid insulation along the entire inside face of the block. Cracks are visible in the concrete slab-on-grade only. The cracks in the slab-on-grade traverse perpendicular to the long walls of the building.

The ground slopes surrounding the building are poor (i.e. they slope toward the foundation in some areas).

I see no apparent issues with roof or first-floor framing in the form of fractures or excessive deflections.

The rigid insulation is jammed tight against the inside face of the crawlspace walls and held in place by the bottom of the floor joists (i.e. I did not get a good look at the inside face of the block walls).

I observed many vertical cracks in the drywall along the joint between intersecting exterior and interior wall panels located around the perimeter of the structure. The cracks are so small that I can't even tell if they are larger at the top vs. their bottom.

A door is jamming at one end of the building in an area where an asphalt parking lot is directing water toward the foundation. I believe the threshold is pushing the door upward. This is possibly from frost heave, any comments?

I do not know what type of soil is under the building. The building could possibly be built on expansive clay, compressible or improperly compacted fill.

I usually lean toward contributing these cracks to foundation settlement due to one of the aforementioned reasons. I just want to make sure I am not missing other possible contributing factors to the small cracks, any comments?

Thank you.

RE: foundation settlement or something else I am not seeing?

There may be reasons other than settlement or heave for the cracks; such as temperature, sloppy-wet concrete slab then shrinks, etc. If you think you have actual settlement, one way to decipher what goes on is to know your elevations. In that crawl space you can check elevations quite easily at the under side of the floor joists. I would use a garden hose with a clear plastic hose on each end. Fill with water so both clear hoses show same elev. Then it is easy to go from one place to another, measuring the difference in elevation of the water levels, shot spot to bench mark. After that you may find if you have a settlement and where and then relate that to conditions observed. As given in the photos, it looks like a pretty good building situation to me.

While checking the outside and any soils info, find location of all trees,since they can cause grief in some soil conditions.

RE: foundation settlement or something else I am not seeing?

Photos 6 and 7 look like heaving of the slab. That is quite common in Alberta and is often caused by swelling clay soil. Holding a straightedge across the crack may indicate that the floor is high at the crack location.

Improving the drainage on the exterior of the building is probably the main area to focus on.

BA

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