Cracked wall / slab foundation question

[Hubert A. Miles]

I have a question about interior wall cracking in a townhome with a slab foundation. There are several interior walls through the middle of the unit where the sheetrock around the wall openings downstairs is buckling at the corners. The buckling is isolated to these areas, but nearly all the door frames have cracks above them. Only one door if sticking. There is also some slight bulging of the sheetrock in the stairwell.

There is also some interior cracking around the exterior walls on the rear of the home. I feel the likely cause is a large tree that is located directly beside the townhome, but the brick veneer around the exterior is not cracked where the tree is located. There is a small crack above the window on the rear that has already been repointed once and has cracked again.

All the interior walls were plumb and level vertically. The opening that is the most concern is slightly out of level by about 1/16" to 1/8" with the corners being higher than the middle when viewed with a 3 foot level horizontally.

I told the client that the tree root system could be putting pressure on the slab pushing it slightly upwards, thus causing the cracking and the buckling to the metal corner bead. I suggested the tree be cut down and a killer be put on the tree to prevent furthur movement and that I would not try to uproot the tree as that will likely cause major settling.

See pictures. Thoughts? Suggestions?

[Larry D. Kage]

Originally Posted by hmiles

I have a question about interior wall cracking in a townhome with a slab foundation. There are several interior walls through the middle of the unit where the sheetrock around the wall openings downstairs is buckling at the corners. The buckling is isolated to these areas, but nearly all the door frames have cracks above them. Only one door if sticking. There is also some slight bulging of the sheetrock in the stairwell.

There is also some interior cracking around the exterior walls on the rear of the home. I feel the likely cause is a large tree that is located directly beside the townhome, but the brick veneer around the exterior is not cracked where the tree is located. There is a small crack above the window on the rear that has already been repointed once and has cracked again.

All the interior walls were plumb and level vertically. The opening that is the most concern is slightly out of level by about 1/16" to 1/8" with the corners being higher than the middle when viewed with a 3 foot level horizontally.

I told the client that the tree root system could be putting pressure on the slab pushing it slightly upwards, thus causing the cracking and the buckling to the metal corner bead. I suggested the tree be cut down and a killer be put on the tree to prevent furthur movement and that I would not try to uproot the tree as that will likely cause major settling.

See pictures. Thoughts? Suggestions?

Regardless the cause, if you tell a client what he needs to do to repair it and that does not cure the problem. Where are you? Do you want that responsibility on this one?

You may want to consider referring the problem to a qualified professional as needed.

[Hubert A. Miles]

I told the client and wrote it up in the report that without further testing that it would be impossible to determine if it was a serious issue or not and to contact a few foundation specialists and let them evaluate it to see if they thought it was a problem or not. Just thought I would get some input from here as well.

[Mark Thorman]

That tree looks to be a plumaria and if it is I doutb that its the cause of the cracks to that extent. Yes its too close to the home but I would look for other issues also like drainage or the type of soil (expansive).

www.MauiHomeInspections.com

[Randy L. Mayo, PE]

Mr. Miles

From a structural engineer's point of view based on your description and photos it appears the cracking is most likely due to a combination of lumber shrinkage and compressive loads of the second floor on the first floor walls.

To verify this you would need to carefully inspect the exposed foundation and brick work for cracks and movement as well as any movement of the interior slab.

The interior walls on the ground floor have to carry the dead loads and live loads from the second story. If the supporting wall is continuous the load is distributed evenly however when you have stairwell openings and door ways in the supporting walls the loads are transfered causing stress to concentrate. It is not uncommon for the stud holding up the header over an opening (cripple) to carry twice the load as the adjacent studs.