What Am I Dealing With??

[Rick Marton]

I inspected a house today that was built on a slab in the 1950's. There is a crack in the slab running the width from one side of the house to the other. There is a second crack running from the front to the back of the house. Like a plus sign. I chiseled out the crack and its 1 inch deep. The crack is even meaning that one part of the slab is not higher or lower than the other. The house from a macro view looks level from all four sides. For those of you who do structural installations for a living can this be repaired? Has the house settled to this point and if it was built 60 years ago, this is the worst we will see or can it get worse? I advised further evaluation, but I would like to know for myself. Thanks Rick

[Brian E. Kelly]

From the pictures the first two cracks look typical to me, from my living room vantage point.

The crack shown in the third picture looks a little larger than typical to me... it also looks like it is near the wall???

If in doubt recommend repair by a Foundation Contractor or Concrete Contractor.

Also put a little more info in your profile so we know what part of the country you are in...

[Brian E. Kelly]

There is some excellent reading material here.....you need to log in

http://education.nachi.org/show.php?...element_id=228

[Rick Marton]

Brian, you are correct. That crack is near the wall that run the width of the house. The other crack from front to back is dead center of the living room and dining room. The cracks are continuous. I am from northern N.J. Thanks for the link. The house is a foreclosure so there are no sellers to ask about the history. Thanks Rick

[Scott Gilligan, CMI]

Rat slab or full thickness slab?

[Marcel R. Cyr]

None of those cracks would concern me for that age. Control joints were not invented yet.

[Randy L. Mayo, PE]

Rick

From a structural perspective the first question I would ask is when these cracks occurred. Did they occurred 50 years ago or within the last 2 years? That information would help me decide the rate of crack growth. Then I would take accurate floor elevations to determine any movement that may not be evident just by looking. You can estimate unreinforced concrete slabs to shrink about 0.05% of the slab width, 60%-70% of that will occur within the first 6 months. At this point the evidence and your experience will help determine where to go next.

[Dale Duffy]

Originally Posted by mcyr

None of those cracks would concern me for that age. Control joints were not invented yet.

Ditto, Ditto

[Rick Marton]

Originally Posted by sgilligan1

Rat slab or full thickness slab?

Scott, I am thinking of geeting back into this house and drill a small 1/4 hole with a hammer drill to check thickness. Thanks Rick

[Rick Marton]

Originally Posted by rmayo

Rick

From a structural perspective the first question I would ask is when these cracks occurred. Did they occurred 50 years ago or within the last 2 years? That information would help me decide the rate of crack growth. Then I would take accurate floor elevations to determine any movement that may not be evident just by looking. You can estimate unreinforced concrete slabs to shrink about 0.05% of the slab width, 60%-70% of that will occur within the first 6 months. At this point the evidence and your experience will help determine where to go next.

Randy, I am thinking about getting back into the house to check elevations and thickness of the slab. I don't have a laser level but I do have a 6 foot level which can give me so sort of an idea. If it is out of elevation would self leveling cement work or how would you approach this?? (epoxy injection?) (Jack hammer the crack out and use a bonding agent then fill?) This is a foreclosure so I can't get any history about when the cracks occurred. Thanks Rick

[James F. McKee]

what Marcel said...

[Randy L. Mayo, PE]

Rick
You still need to determine if the crack is still moving before doing any significant repairs. The third picture with the widest crack concerns me the most. If that crack is very old it should be nearly full of debris, if its fairly clean and the exposed edges are sharp (no signs of wear) I would be inclined to say the crack was recent. You say this house was a foreclosure, how long has it been empty? If it set over one or more winters without any heat then water lines in and/or under the floor could have ruptured. Maybe moist soil under the slab froze and frost expansion contributed to the crack. Just a few ideas.... If you go back take some close up shots of the cracks and maybe draw a scaled floor plan showing the crack locations & widths. Sometimes its hard to see the big picture until you map out the entire foundation showing the cracks.

[Marcel R. Cyr]

Looks like the 9"x9" asbestos tile have just recently been abated, that would explain the fresh looking cracks. They've been covered up for half a century.

[Rick Marton]

Originally Posted by rmayo

Rick
You still need to determine if the crack is still moving before doing any significant repairs. The third picture with the widest crack concerns me the most. If that crack is very old it should be nearly full of debris, if its fairly clean and the exposed edges are sharp (no signs of wear) I would be inclined to say the crack was recent. You say this house was a foreclosure, how long has it been empty? If it set over one or more winters without any heat then water lines in and/or under the floor could have ruptured. Maybe moist soil under the slab froze and frost expansion contributed to the crack. Just a few ideas.... If you go back take some close up shots of the cracks and maybe draw a scaled floor plan showing the crack locations & widths. Sometimes its hard to see the big picture until you map out the entire foundation showing the cracks.

Randy, you hit the nail on the head. I just finished some digging on the MLS and the house did have a water main break from the last MLS listing. It looks like it went through a winter up here in the northeast vacant. And there are no baseboard heaters on the first floor, only water baseboard heat was up in the two bedrooms on the second floor when I was there. I think your theory is right on with the ruptured pipes being in the slab. Rick