Compacted Fill

"grade beam" is a typo, should be "bond beam"..sorry.

First let me say that I am not a Structural Engineer so what I say is based on simple observation and restating findings of others after the fact.

I have seen foundation walls bow as you describe twice before. The first one was from not making the side wall thick enough for the total length and height which allowed for the bowing (the contractor did not follow directions in order to save a buck or two). The second was due to not allowing enough time for the concrete to cure, actually the contractor failed to realize that the outside air temp was 40°F when doing the cure time calculations.

I would say that as long as you have had your structural plans reviewed by a third party engineer with his P.E. you should be fine as long as the contractor follows the structural plans.

look for another contractor.....he lied to you.

what he should have done was filled the voids, and backfilled equally on both sides of the wall, compacting in a max 4" lift.

he was trying to take a shortcut and created more problems for himself and the people he's building the house for. that foundation is already compromised, and will fail in short order.

Hole in one get a gold cup and a certificate for your prowess.

He couldn't fill on both sides of the wall because the whole point is to raise the house floor level above the outside surrounding grades. So there is nothing to fill around the outside. The wall needs to be built in such a way that it can take the lateral pressure on one side, which is what I need to know how to achieve.

The first thing I don't understand is Why would you use block instead of a poured foundation wall? Secondly,How are you supporting the slab 3' in the air? I have seen and heard of some really goofy ways of building buildings but never heard of anything like this. If they bowed the wall while compacting around it then 1;it wasn't very strong to start with or 2;the morter hadn't set. In any case I think I would be looking for a different contractor. Sounds like they are doing a half assed job.

Something is hinky! I agree with hilltopper - I would find another contractor. Around here we have problems (sometimes very serious) with expansive soil, so floating floor slabs are common. They aren't tied into the foundation - they float independantly so they don't torque the foundation walls. There are different treatments that are applied to the bottom of the foundation walls to prevent them from lifting (depending on where in the city the structure is), so movement there isn't usually a problem. To prevent the slabs from lifting up the floors above, any stud walls in the basements have double soul plates (a 2"x4" is turned on it's side for the spacing, then removed when the stud wall is finished) - that gives you a few inches of lift by your slab before it starts doing any real damage. Regular checks should catch any movement.

Beware, contractors including foundation ones, are not to be trusted unless you have seen their public liability insurance cover to see if their Insurance Company will still be around by the time their warranty expires. So look at that first.

Secondly piling (and there are countless methods) - timber push piles,timber piles, pipes, screw-piles , driven piles and you should also look at using: old rails , yes from the railways -they are cheap and good value .

Thirdly you should have the soil tested by an accredited laboratory if you have ANY FEAR of what is known as : differential settlement . This very often occurs in soils that are clay-ish . They look sound enough when humid , but they shrink and crack in dry weather spells. These soils when they have been rammed or vibrated look good .That is until the water gets at them, later on, and the drying process leaves you cracks not only in : your foundations, but equally as bad : in the elevated section of your building.

Labor Omnia Vincit.

As #3 commented, it sounds like the contractor tried to save a couple of weeks using a single pour, i.e. grout the blocks and pour the slab all in the same day. But one cannot compact against an unreinforced block wall as he discovered. The block wall needs to be grouted solid, then the concrete grout left to cure and reach full strength (this is defined in the building code). The next step would be back filling and compaction. The final step would be the slab pour.

Thanks, dzinegrp. So you think simply grouting the walls and allowing the grout to cure would have prevented the wall from being bowed out? I was thinking about adding dura-wall remesh to 1 of the hortizontal mortar joints to further enforce it. Prehaps that's overkill, but I'm a bit gunshy now.

What's the difference in a concrete block wall being 3' in the air with a slab on top of it vs 10' below grade with a basement below it? Seems to me that 10' of fill on the outside would exert much more lateral force on a wall than what I'm doing. Point being I just want the wall to hold the compacted backfill. The structural slab (ie block slab, supported slab) is a very common means of constructing a foundation around these parts. Especially on sloping lots where a basement or crawlspace is not desired. And a geotech did test the soil and he recommended this foundation type for the clay soils that are present. Again, I was merely interested in how to reinforce the block walls.

Here in the great Southwest desert we build on floated slabs at an alarming rate. When raising a floor off grade is required, we rebar every hole in the blocks, then grout. When the grout reaches 75% of design strength (a week usually) we put the carefully screeded soil into the area to be floored over. We compact that with machines (Whackers). A soils test engineer comes and checks the compaction. We then cover with a layer 3" or so deep of gravel called ABC. When that is properly leveled, we pour the design strength concrete, and finish the floor. Leave out a step, save money by being a scoundrel and you have a lawsuit on your hands for a cracked floor, blown out foundation and various and sundry legal expenses. 90% of our homes are slab on grade, but the 10% built on slopes, or on raised floors are carefully built. The lawsuits bloom, and the lawyers get rich!

This is a common occurrence, bracing is not the solution. Typically, all the earthwork compaction is completed prior to installataion of block. The mass earthwork is rolled with a sheepsfoot and tested for compliance. Then the foundation walls trenched in. All excavation occurs prior to installation of block. The bottom of excavations are compacted sometimes with a jumping jack, but this is a very bad practice for backfills behind walls (All earthwork contractors want to do it though). Masonry or concrete foundation wall is installed (and grouted). Then a clean granular fill is placed behind it and compacted with something like a vibratory plate in thin lifts of 6 to 8 inches maximum. This will be a drain and clean material readily compacts. They can use a filter fabric and a pea gravel drain rock, which is considered 100 % compacted on placement. I would still recommend vibraplating it every couple feet to lock up. Any heavy equipment or a jumping jack should not be used near a wall until the wall is supported with compacted backfill on both sides.

hi my name is katia im from aka civil australia we are also into building so i have seing it happen many times after building the perimeter walls , all they can do is put clay and using a bobcat and a jumping compactor they spray water so the mud fills up the holes and keep compacting its a normal procedure but however if the brick walls colapse they may have applied a little more compaction then neccessary .