Bulge in cement basement / garage floor - causes?

[Tripp Knightly]

In my older (1930) home I have an upward bulge in the garage/basement
cement floor. The affected area is maybe 2 feet square, and it has
risen maybe 1-2 inches, causing the cement to crack/break some. The
foundation walls do not *appear* to be bulging inward, and the bulge
is several feet away away from the foundation.

What would cause this-

- Moisture / evaporation in the cement (maybe there's a leaknig
drain pipe)?

- Some kind of similar issue in the ground underneath the floor?

- Gophers? (Ok, maybe not)

Thx for input,

- TK

[Eric Tonks]

Possibly settling around the edge leaving the original undisturbed soil to
support the center, this is if it was filled under the floor. Possibly a
boulder under the floor being pushed up, particularly in an unheated garage
in areas that have frost.

You may have to break up the concrete and investigate.

"Tripp Knightly" <trippk...@hotmail.com> wrote in message
news:120d8f1c.03013...@posting.google.com...

[Speedy Jim]

Tripp Knightly wrote:
>
> In my older (1930) home I have an upward bulge in the garage/basement
> cement floor. The affected area is maybe 2 feet square, and it has
> risen maybe 1-2 inches, causing the cement to crack/break some. The
> foundation walls do not *appear* to be bulging inward, and the bulge
> is several feet away away from the foundation.
>
> What would cause this-
>
> - Moisture / evaporation in the cement (maybe there's a leaknig
> drain pipe)?

See if you can locate where the house sewer runs; see if it could be
in that area. Ditto for the water service line.

Any large trees near there? They will send roots under the floor.

Jim

[JBgoode]

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"Tripp Knightly" <trippk...@hotmail.com> wrote in message
news:120d8f1c.03013...@posting.google.com...

> In my older (1930) home I have an upward bulge in the garage/basement
> cement floor. The affected area is maybe 2 feet square, and it has
> risen maybe 1-2 inches, causing the cement to crack/break some. The
> foundation walls do not *appear* to be bulging inward, and the bulge
> is several feet away away from the foundation.

Do you know when the bulge formed (e.g., the past year)?

If it is recently occuring, and the home's foundation loads didn't increase
significantly just before the occurance, then it is probably not settling.
The house should be done settling by now.

It could be high plastic clay beneath the slab that has increased in
moisture content and swelled. Hard to tell, without seeing it and asking a
lot more questions. If you want a pro to look at it, call a geotechnical
engineer.

Jon