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fartman 05-14-2007 03:26 PM

crack in ceiling and crawlspace
My wife and I are getting ready to buy a house, but we have a major concern before we move forward. The house has a crack in the ceiling were the living room joins the dining room and also in the entryway almost adjacent to the first crack. I decided to check the crawlspace directly under these cracks and there is crack in the cement floor running almost the length of the crawlspace if I remember right. The crawlspace crack is just slightly more towards the front of the house. What might have caused this and how would someone fix it or prevent it from worsening. There is a big tree right next to the house, not sure if this could have cause this or foundation shifting, etc.

glennjanie 05-14-2007 06:25 PM

Welcome Fman:
You are correct in saying the crack could be caused by the tree or shifting of the foundation. If it is the tree, there should be evidence of the foundation rising. Roots grow under the foundation and continue to grow in diameter, thus pushing the foundation up.
If the tree is the cause it should be cut down and the stump should be dug out, removing all visible wood, dig down to undisturbed earth and filling the void under the foundation with concrete. This will prevent further movement and the cracks may be filled and finished off.
It would not be out of line to ask the seller to make the repairs as a condition of the sale. Believe me, if it were a federally insured loan (FHA, VA, FmHA) they would require the seller to make the repairs.

asbestos 05-15-2007 12:24 AM

This could either be normal settling that happens in the first few years of a house or it could be the sign of something more serious. get a qualified person to take a look.

fartman 05-15-2007 04:01 PM

the house is about 50 years old and these are the only cracks I could find, but the basement is carpeted so there may be some under there. If it is not the tree should I have it removed anyway as a precautionary measure?(it is about 3ft. from the house. If I cut down the tree but leave the stump will the roots still expand? Also, will a home inspector be sufficient or should I get someone more qualified. I was checking into structural engineers but it might be expensive, and I don't think there's too many in my area.

glennjanie 05-16-2007 10:20 AM

I vote to take down the tree and remove all signs of any stump, because it can still grow again from any root. I wold use a back hoe to do the digging and have him to under-cut the foundation a little to be sure all roots are out. After the undercut, you will need to clean out all loose dirt down to undisturbed earth and pour new concrete to support the affected area.

fartman 05-17-2007 02:10 PM

aren't the roots supposed to be as big as the tree? They could be underneath the whole house. This is a black walnut tree(about 75 ft tall). Sounds like an extensive job that could possibly cause more problems :) Yippee

Mephistopheles 05-19-2007 02:06 PM

engineer time...
Tree could be the culprit, find out first then ck for any necess. permits. Where I live, cutting down a tree is $5000 fine without going through review process. We can't even cut a limb off greater than 1/4 inch in diameter.

You should contact a local geo engineer and get a report, otherwise major replacement construction might be money wasted.

Cracking foundations/slabs can be caused by a variety of reasons; moisture, expansive soil, earthquake damage, old inadequate design and faulty construction ect..not only trees.

If the structure is on a grade of greater than 6% there are more factors to consider.

fartman 05-19-2007 04:31 PM

the tree is on the opposite side of the house away from the crack I was describing. I was thinking if it was from the tree it would've just cracked the concrete floor in the crawlspace and wouldn't have caused a crack in the ceiling on the first floor. By the way it is a block foundation with a poured concrete floor. I am wondering if it is a floating floor(not connected to the foundation). If it is a floating concrete floor, I would be less worried because the crack might be the result of something not affecting the foundation and the 1st floor adjacent crack might just be a coincedence. Does anybody know how I would determine if it is a floating concrete slab?

glennjanie 05-19-2007 08:44 PM

Drill a hole in the floor within 2" of the wall. You should hit a soft spot after 4" of depth; if it continues to be hard concrete, the floor is resting on the footer. How tall is the first concrete block above the floor? If it is 8" tall, the floor was probably poured and the concrete blocks were laid on top of the floor. If the first concrete block is only 4" tall you can expect to find a footer, concrete block wall laid on the footer and the floor poured inside the walls. Also check to see if there is an expansion joint (probably 1/2" thick) around the peremiter of the floor. This also indicates the floor is poured inside the walls.

Square Eye 05-20-2007 07:08 AM

Concrete spatter on the block walls is the clearest first sign of a floating floor, separation from the walls is the second sure sign. Third sign of a floating floor is a floor that does not follow a mortar joint, though this is not very reliable because contractors often use the mortar joints as a gauge to level the floor as they pour.

Drilling near the walls could be misleading because many contractors leave a drop near the walls in the fill thinking that thicker concrete will make the edges of the concrete stronger and that it may slow the cracking.

Another way to check is to smack a hole in the lowest block and look inside.

90% of basement construction is done with floating floors though.

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