I have a couple of cracks in my foundation wall. From the top of the footing to the top of the wall. I looked around for someone to fix it and found a guy seems to know what he's talking about. He wants to break out the concrete on both sides of the crack, about a foot each way, then drill holes in the open wall about every foot, pound some rebar into the holes and make a cage, then make a form and fill it with concrete. Has anyone done this kind of work and can offer some pointers? I'm taking a few days off to help out and finish this thing.

 

That will work great and be stronger then the wall itself!

 

Now I'm not the expert on foundations, but it seems like he wants to bandaid the symptom and not fix the problem. If you don't fix the underlying problem, you could just end up with a new crack somewhere else.


How old is your house? How wide it the crack? Over how long has the crack developed? How much rainfall have you had this year?

It could be any number of things such as a newer house settling or the ground being so dry that it has contracted enough to cause a crack.

If it has been pretty stable, I'd just patch it over. If it's been pretty dry, I'd wait to see if some moisture closes it back up. (For example my driveway joints have pulled way apart since we were almost 13 inches below normal rainfall)

What I have heard is that before you call a contractor, call an engineer. They can actually figure out what is going on and the price is usually resonable. You can then make an informed decision on what repairs to make.

Mike

 

What BLK94150 said.

The underlying problem causing the crack needs to be determined before you rush into "fixing" it.

If it's footing settlement or horizontal displacement due to earth pressure surcharge, you will likely have two cracks where you now have one if patched without checking into and remedying the underlying cause.

 

There are foundation repair companies that specialize in that type of repair. I don't know a lot about it, but they repair the cause of the crack. I have a friend that works for one of them. The company he works for is called Ramjack, they are out of Raleigh / Durham, NC area. I am sure there are some near where you live. A structural engineer as advised by BLK94F150 is a good idea, he/she can advise you as to what needs to be repaired if anything and who to get for repairs.

Good Luck.

 

Make sure you have good run off from the house to shed water and if you don't have gutters get them these two will help out alot or it will still continue to crack and shift.

 

The guys that did my work here said concrete was guaranteed to crack. The only two things it is guaranteed against are fire and theft.

I realize that in no way does that help you whatsoever.

 

My most common reasons why basement walls crack are:

1) The concrete was poured to wet and lost most of its strength.

2) The area around the basement was back-filled too soon and by too heavy a piece of equipment


Rarely when the footing is placed on stable ground, weeping tile/hose is installed,concrete is placed correctly,earth back filled after 21 days of pouring,normal material located around the perimeter, rain downspouts are directed at least 6 ft from the house ...... will the walls crack.


The contractor in the OP is making a valid attempt at repairing the wall.
He will need to apply special glue to both exposed surfaces before pouring.

The fix mentioned is NOT a guarantee of the wall not cracking again.

Think of the fix as scar tissue in the human body.

 

House is single story, 6'+ basement, built in 1959. There's no french drain around the footing, and no re-bar in the foundation wall.

What is the special glue used on the exposed surface?
Do I need to use anything special to clean the exposed surfaces before applying the glue?

Should I wait 21 days to backfill the repair?

 

I would say yes, what would eb the hurry otherwise.....Concrete needs 21 day at about 64*-68*F to cure to maximum strength.

 

Concrete does not lose strength because it is poured too wet. It never develops sufficient strength due to the excess water in the mix. That may be splitting hairs, but is the case anyway.

The "glue" you speak of is a bonding agent, usually latex, but is not required for structural repairs. It will actually form a plane of weakness between the old and new concrete. Bonding agents are usually used for thin patch situations for patching surface irregularities.

One place you will need to use epoxy adhesive is where the rebar is inserted into the drilled holes in the remaining wall. Otherwise there will be no tension bond between the reinforcing that is inserted into the existing concrete. There would be a shear resistance to horizontal movement of the wall but no resistance to shrinkage of the new concrete patch. A chipped surface on the existing wall would be better than a sawed one to enhance the mechanical bond between the existing concrete and the patch.

All concrete shrinks and the mix water should be minimized to reduce shrinkage. Some additional water is necessary to aid in placement and consolidation, but the mix should have strength of not less than 3000 psi and a "slump" of 4 to 5 inches with no additional water added to the mix. Slump is a measurement of the plasticity of concrete. You can order the concrete from the plant to those specifications. Don't let the placer add water to make his job easier or you will reduce the strength of the mix considerably resulting is excess shrinkage and future cracks.

Above all, the concrete should be added slowly to the forms, preferably not more than 2 vertical feet at a time and it should be well consolidated either by a vibrator or by "rodding" before the next 2 foot thick "lift" is added to the form. Each lift should be vibrated or rodded into the lift below by consolidation to avoid "cold joints" that can manifest themselves as horizontal cracks. Allow the concrete to cure in the forms for 3 to 5 days before stripping the formwork. Patch any surface irregularities such as "bugholes" (air bubbles that form at the face of the form) or rock pockets (poorly consolidated concrete) with a rich portland cement/sand paste rubbed on. Allow the concrete to cure without "loading" by backfill or structure above for 21 to 30 days.

I assume your wall is not currently waterproofed. If it isn't, you may want to apply self-adhesive membrane waterproofing (Bituthene) over the patched area to at least 2 feet beyond the patch on each side. Extend the membrane down onto the footing that has been cleaned of dirt and debris. Install a 1" thick polystyrene protection board (to protect the membrane from backfilling work) over the membrane waterproofing to at least 1' beyond the edge of the membrane. Install backfill and tamp in 12" thick lifts to prevent future settlement of the backfill.

Have fun.