I noticed lastnight a gap between the concrete slap and block. It is on a end wall. The wall is 34 ft long the gap starts at one corner and goes about 25ft along the wall. it is not cracked it is just smooth gap all the way. The gap is about 5/32 of a inch. Is this going to be a problem, will it get worse or is this normal? The concrete was poured about 8 months ago. All the other wall n the garage are fine.
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Concrete slab Is this serious
- Thread starter 64auto
- Start date
Kevin54
MEMBER EMERITUS
Thanks for the info. The concrete outside has not been poured yet. So i was worried about water getting around the foundation and maybe it was sinking.
Look at the opposite wall. The slab has probably settled a little along with the concrete shrinking a small amount. This is a normal thing to happen in the garage, especially when it is not supported underneath the edges by anything any more solid than gravel. Over a period of a few months, the gravel will settle more, letting the wall pull away ever so slightly. Any water will go through the gravel or if a vapor barrier is tight against the edges, just caulk the gap shut.
Kevin
I noticed Saturday on the outside of that wall there was about 8" of water standing between that wall and the retaining wall. We got alot of rain SAT. Probley 1 1/2 in two hours. There is no way I can get the tractor to grade it so it will run out, because they have a roll off sitting in the way. Would this be causing the wall to sink? Hopefully before long I will be pouring councrete in this area so it will drain out.
boiler7904
Well-known member
I wouldn't worry about minor shrinkage between the slab and the block wall. It's normal. Fill it with an elastomeric caulk if you really want to make the gap go away. There should have been an expansioin joint filler around the perimeter of the slab to help absorb some of this movement.
As far as the building possibly sinking, that will turn into a nightmare. I just got done with that same problem on a commercial job. Couple of questions:
Was there a large amount of fill needed to build up the pad before you built the garage? If so, was it properly compacted in 8"-12" lifts as it was built up?
Are you seeing cracking or gaps anywhere else in the building that would indicate differential movement?
First thing to do is get the exterior trench to drain even if you have to dig it buy hand or use a bucket to move most of the water. Saturated soil has very little if any structural bearing capacity.
Second thing to do is make a couple of reference marks about 1 foot above the slab every few feet along wall in the area that you think the foundation is sinking. Check those measurements every couple of days. If you start seeing changes in the measurements, you need to hold off on pouring anymore concrete and get a foundation repair company in to take a look at things.
If you have to stabilize the foundation, there are a few options that a structural engineer can design for you. From my experience, steel push piers can be installed at roughly 5'-0" o.c. and cost about $3000 each depending on how deep they have to go. For a 34' wall, you'd probably need about 8 or 9 piers.
As far as the building possibly sinking, that will turn into a nightmare. I just got done with that same problem on a commercial job. Couple of questions:
Was there a large amount of fill needed to build up the pad before you built the garage? If so, was it properly compacted in 8"-12" lifts as it was built up?
Are you seeing cracking or gaps anywhere else in the building that would indicate differential movement?
First thing to do is get the exterior trench to drain even if you have to dig it buy hand or use a bucket to move most of the water. Saturated soil has very little if any structural bearing capacity.
Second thing to do is make a couple of reference marks about 1 foot above the slab every few feet along wall in the area that you think the foundation is sinking. Check those measurements every couple of days. If you start seeing changes in the measurements, you need to hold off on pouring anymore concrete and get a foundation repair company in to take a look at things.
If you have to stabilize the foundation, there are a few options that a structural engineer can design for you. From my experience, steel push piers can be installed at roughly 5'-0" o.c. and cost about $3000 each depending on how deep they have to go. For a 34' wall, you'd probably need about 8 or 9 piers.
I wouldn't worry about minor shrinkage between the slab and the block wall. It's normal. Fill it with an elastomeric caulk if you really want to make the gap go away. There should have been an expansioin joint filler around the perimeter of the slab to help absorb some of this movement.
As far as the building possibly sinking, that will turn into a nightmare. I just got done with that same problem on a commercial job. Couple of questions:
Was there a large amount of fill needed to build up the pad before you built the garage? If so, was it properly compacted in 8"-12" lifts as it was built up?
Are you seeing cracking or gaps anywhere else in the building that would indicate differential movement?
First thing to do is get the exterior trench to drain even if you have to dig it buy hand or use a bucket to move most of the water. Saturated soil has very little if any structural bearing capacity.
Second thing to do is make a couple of reference marks about 1 foot above the slab every few feet along wall in the area that you think the foundation is sinking. Check those measurements every couple of days. If you start seeing changes in the measurements, you need to hold off on pouring anymore concrete and get a foundation repair company in to take a look at things.
If you have to stabilize the foundation, there are a few options that a structural engineer can design for you. From my experience, steel push piers can be installed at roughly 5'-0" o.c. and cost about $3000 each depending on how deep they have to go. For a 34' wall, you'd probably need about 8 or 9 piers.
There was no fill needed I had to cut down about 4' on the retaining wall end and this is where the water is standing, between the garage wall and retaining wall. I have trenched as far as I can by hand then i get to where the roll off is sitting. I have no way around it. I thought about putting a pump in for now.
Steve in Mi
Well-known member
There was no fill needed I had to cut down about 4' on the retaining wall end and this is where the water is standing, between the garage wall and retaining wall. I have trenched as far as I can by hand then i get to where the roll off is sitting. I have no way around it. I thought about putting a pump in for now.
Pump is a good idea for now. A slab poured within a surrounding block wall will shrink upon drying out/curing (it's a given). After the shrinkage if water is allowed to stand in this gap and it goes thru a few freeze-thaw cycles - well walls and or slabs do move when the forces are high enough. BTW, shrinkage is generally pretty uniform for a given pour so where the gap narrows to no gap what is the situation at the wall directly opposite? I didn't look for your location before posting so if you don't have any freezing where you are forget the high forces it produces as part of a possible problem and of coarse if your space is and has been heated all along you can rule out ice as a prime-mover.