CANPRO
Structural
- Nov 4, 2010
- 1,110
A friend of mine is building a house and he recently noticed his foundation walls have started to push inward. I looked at the walls, which had cracked badly and he showed me the line he had strung to measure the deflection of the wall. Three of the four corners of the house have cracks starting in the bottom intersection of the foundation walls and extend diagonally upward the top of the wall. Pictures are attached (left and right referenced from standing in the driveway and looking at the front). The right side wall has moved over 1.5". I don't think the file names are coming through with the link...most of the pictures are along the back right corner and the right side wall.
I told him that the wall can be fixed/braced, whatever needs to be done. But first he needs to determine the cause. I recommended he talk to a Geotechnical Engineer to determine the cause and then I could help with the structural fix.
I have attached a few pictures, a grading plan and the basement plan. Some other relevant information:
•Local Frost Line is 4 feet.
•He described the native soil as a heavy clay.
•The foundation was poured in the fall, it set for 1 week and then was backfilled. He said he took precautions to prevent frost from getting into the ground when he poured the footings and the foundation.
•Shortly after backfilling the ponywalls and first floor were built along with the rest of the house. No significant variations in the foundation noted.
•We have had a couple stints of unseasonably warm and cold temperatures this winter. The mean temperature in the weeks leading up to the noticeable damage was about -6C to -7C.
•The walls are 8" thick poured concrete. He says they put a few bars into the walls but nothing that you could call reinforced.
•Basement has been unheated until he noticed the movement in the walls (a few days ago). The excavator operator said it was likely frost and he should keep the basement heated. He has had a propane heater in the basement since.
•When I was on site, it was around 0C and the previous day was above 0C for most of the day. The ground was very wet.
I wasn't sure if it would be a waste of money for him to talk to the geotech, it seems likely the damage is from the frost. I don't know much about clay and thought that might complicate the problem/fix. I figured at the very least the problem would be properly documented.
I am looking for opinions on what you think could be the likely cause. I would also like to know if anyone knows how the lateral force produced from frost compares to the vertical force.
I told him that the wall can be fixed/braced, whatever needs to be done. But first he needs to determine the cause. I recommended he talk to a Geotechnical Engineer to determine the cause and then I could help with the structural fix.
I have attached a few pictures, a grading plan and the basement plan. Some other relevant information:
•Local Frost Line is 4 feet.
•He described the native soil as a heavy clay.
•The foundation was poured in the fall, it set for 1 week and then was backfilled. He said he took precautions to prevent frost from getting into the ground when he poured the footings and the foundation.
•Shortly after backfilling the ponywalls and first floor were built along with the rest of the house. No significant variations in the foundation noted.
•We have had a couple stints of unseasonably warm and cold temperatures this winter. The mean temperature in the weeks leading up to the noticeable damage was about -6C to -7C.
•The walls are 8" thick poured concrete. He says they put a few bars into the walls but nothing that you could call reinforced.
•Basement has been unheated until he noticed the movement in the walls (a few days ago). The excavator operator said it was likely frost and he should keep the basement heated. He has had a propane heater in the basement since.
•When I was on site, it was around 0C and the previous day was above 0C for most of the day. The ground was very wet.
I wasn't sure if it would be a waste of money for him to talk to the geotech, it seems likely the damage is from the frost. I don't know much about clay and thought that might complicate the problem/fix. I figured at the very least the problem would be properly documented.
I am looking for opinions on what you think could be the likely cause. I would also like to know if anyone knows how the lateral force produced from frost compares to the vertical force.
