RARE PROBLEMS, but they do happen. Let’s talk about some rare and interesting construction problems that we have encountered over the years.
THE BIG SQUEEZE
This family purchased a newly constructed house in a sub-division. The house had poured concrete full basement foundation walls, had a 2 car attached garage projecting out of the front elevation and sat in the center of a cul-de-sac.
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During the first year, the homeowner encountered severe foundation cracking only on the front foundation wall of the house. None of the adjacent neighbors experienced anything similar. After some investigation, it was noted that the garage floor, driveway, city walk, and curb system also had non-conventional and excessive cracks (especially for newer concrete).
In addition, we found that the concrete street was poured in late autumn and the cracking condition in the house appeared in the middle of summer. What appears to have happened is that the street sub-contractor did not install enough expansion joints.
Now, in the heat of summer, the streets expanded and placed pressure on the curb, which pushed the city walk, then applied pressure to the driveway which “plowed” the garage concrete slab into that foundation wall.
Curiously, this was the only house in the sub-division and cul-de-sac to perfectly line up so as to get the expansion pressure from a full city block of concrete street.
After approx. 1 year of communication between attorneys, the road commission accepted responsibility and made the necessary very expensive repairs to the house and modifications to the street.
THE INVISIBLE EXCAVATOR:
This homeowner called and said he was experiencing strange occurrences in his 15-year-old house and felt that it was moving. The most recent happening was when he came home late from bowling, went to his bedroom, placed his bowling ball on the floor and went to sleep. During the night he woke up to the sound of a strange “rumbling” noise that culminated with a loud “bang”. He turned on the light and initially saw nothing out of place. However, the next morning, he noticed that his bi-fold closet door at the opposite end of the bedroom was knocked off the track and his bowling ball was now sitting right next to the door. The bowling ball appears to have rolled across the room and impacted the door. We found the homeowner to have some very legitimate concerns.
Upon inspecting the house we found cracks in the brick, drywall, and concrete. When we researched the basement area there were indications of large hollow areas beneath the floor. We also noted that the sump pump almost ran constantly, the water in the sump basket was crystal clear and that there was a relatively large pile of sand at the end of the sump pump discharge line approx. 30 ft. from the house. We came to realize that this property currently had a very active groundwater condition at approx. 4 ft. below grade (basement was approx. 8 ft. deep), the soils were very sandy and that the original builder did not put an adequate amount of washed “pea pebble” filtration stone over the exterior perimeter drain tiles.
As the underground water ran it eventually disturbed the sandy soil because it had the ability to infiltrate through the inadequate filtration stone. It then took water and sand into the drain tile pipes. The groundwater was strong enough to actually carry the sand through the pipes, into the sump pump basket and then was pumped away from the house. The system was excavating holes under the house. When we broke out parts of the basement floor there were large holes with a stream of water running through it. If the house was to be saved the final solution was to abandon the basement, fill it in and create a crawl space.
This was all done after a utility room addition was added at the rear of the garage and the mechanical systems (furnace, electrical panel, hot water tank, etc.) were relocated. The house was then re-leveled where possible and all past cracks were patched and repaired.
The house still sits 15 years later. A question that arises, is how was the original builder able to construct this house with this soil condition. First of all, remember that sand is a preferred compactable soil for builders, but it does have the ability to lose that stability if disturbed (like a sandcastle on the beach). Also, the groundwater table level changes just as the lake and river water levels vary. This house was built on a nice stable sandy soil when the water was lower.
Inspections By MJK
Mitch & Celeste Kuffa
627 N Riverside
St. Clair, MI 48079