Concrete foundation wall cracking 1

[mfstructural]

I inspected a foundation wall the other day to assess the condition of the existing foundation walls. We were also asked to assess the condition of the wall going forward. It was a full basement, walls approximately 7' in height.

The homeowner stated that most of the cracks in the concrete foundations were there before he bought the house 27 years ago and they had also been repaired before he bought it. The only cracks that he repaired have been in the last year and were horizontally orientated cracks along the foundation wall about 24" above the basement slab.

The remainder of the repaired cracks were there 27 years ago. this is telling me that there was initial settlement. espeically since the house is 100 years old. this was visible because the basement slab was cracked throughout with the slab sloping down around the perimeter. this is a sign of uniform settlement over the years, particularly in the years following completion of construction.

The horizontal cracks 24" up and the bowing of the wall (about 2" inward) tell me there is distress in the wall as a result of hydrostatic loading. the reinforcement is unknown. these basements were never meant to be finished.

It's difficult to talk about the wall going forward. it seems pretty stable right now but has to be monitored and if the cracks open up, reinforcing of the concrete foundation walls in the form of vertical steel sections at about 4' would probably be required to prevent further inward bowing. this would be a permanent fix and should reduce any further foundation problems.

No movement in the floor framing, sill plates was observed. no separations or cracking at baseboards or drywall in upper level. the slab was cracked but old, dirty repairs were visible.

I think it's ok for right now and there is no life safety issues, but the horizontal cracks in particular have to be monitored. if they open up again and bowing continues, the vertical WF reinforcing members will be required at some point. the rate at which the wall will be in unknown as many factors like water levels, and precipitation rate play a part. no drain tile was installed around the house as it's 100 years old.

I've attached some pictures to see what is exactly going on. Thanks

 

[oldestguy]

You are right. It's an old house and no important movements have taken place. I'd expect another 100 years of good service.

 

[PEinc]

When did the horizontal cracking occur? I have been involved with a number of residential buildings that had horizontal cracks in the foundation wall. In each case, I believe that the cause of the cracking was extended freeze-thaw weather with snow melting and poor drainage along the outside of the basement wall. Each time, this cracking occurred along the north wall of the house. I believe that horizontal pressure from the saturated, freezing ground surface pushed and cracked the wall.

Based on the photos and basement window elevation, it looks like the cracking is relatively close to the ground surface. Does this wall have northern exposure? Is this the only wall with horizontal cracking? Is there proper drainage away from the house? Has the grading along the wall changed recently? Based on the photos and basement window elevation, it looks like the cracking is relatively close to the ground surface.

http://www.PeirceEngineering.com

 

[mfstructural]

The horizontal cracking is about 36 inches below the bottom of the windows which are 4" above grade. owner said that the horizontal cracking occurred (noticed) a year ago, at which time he patched the walls. the crack was around the entire perimeter of the front portion of the basement. The house is about 100 years old, most likely no drain tile. The owner said he got a quote from a company to installed interior around the perimeter but never went through with it. Grade slopes away from the house but he did say that when there is a lot of rain they get standing water on driveway, etc. At times in the past with heavy rain, water has accumulated and ponded on street in front of the house.

PEinc? what's your thoughts about the horizontal cracking going forward? there is obviously going to be freeze/thaw and water in the future around the foundation.

 

[mfstructural]

Also, in terms of prevention of further excessive bowing and reopening of the horiz crack, I was thinking vertical reinforcements at 5' on center. I don't think they're necessary yet and won't be for a while, at least 10 years. but again you never know the rate at which the bowing/cracking could increase.

 

[PEinc]

My thoughts:
[li]Make sure the ground slopes down and away from the house.[/li]
[li]Make sure the gutters and downspouts do not discharge rain water close to the base of the walls.[/li]
[li]Re-point the horizontal crack.[/li]
[li]You could grout the block walls' voids. If the wall is 100 years old, it is probably solid stone, not blocks.[/li]
[li]You could inject epoxy into any cracks in a stone wall.[/li]
[li]You could possibly install a French drain around the outside perimeter of the house as long as you have some downhill place to discharge the water.[/li]
Call RamJack

http://www.PeirceEngineering.com

 

[oldestguy]

If there is fear of more inward push of wall due to frost, remove the backfill out about 3 feet. Replace with non-frost susceptible fill, which likely is sand with less than 5% passing the number 200 sieve. Then there will be no horizontal push. Do not use single sized stone, since that will eventually have silt moving into the voids and frost happens again. If you think you need a perimeter drain do not use single sized stone. That eventually plugs. Instead use ASTM-C33 concrete sand.

 

[mfstructural]

Those are good recommendations, thanks. The foundation walls are actually poured concrete, which is rare for a 100 year old residential foundation wall.