I am a former general contractor who doesn’t have much knowledge in the way of concrete/block foundation and basement flooring. I have a newly constructed (Nov ’03) modular home with a 32′ x 48′ concrete slab basement floor, and a ten-course block basement wall. There are (I believe) adequate footer drains, and a good performing sump to manage my high water table issues. My problem is that the company constructed the basement floor so that it doesn’t quite reach the wall, and I have moisture issues. There is about a 1″ gap between the floor and the wall that is (I am told) a “drainage channel.” I currently have moisture seepage problems up two courses of block, as evidenced by “chalking.” Also, there is a problem with one wall which remains to be fixed by steel “L” posts being installed to brace the wall to prevent further movement of the wall from its current, slightly concave status (another contractor-caused issue). I am told the company wishes to then fir and drywall the braced wall, but I am concerned about trapping moisture and creating a wonderful mold farm. Currently there is fiberglass blanket insulation on all basement walls, terminating about 2 feet above the floor level.
Can (should) the channel be filled- possibly with caulk backer to prevent evaporating moisture? What should I insist on for repair for the wall after the angle iron is appropriatelly installed?
I have no plans as yet to finish the basement (I need my work space!), but I have a growing family, and an allergy to mold…
Replies
first that isnt a "drainage channel" that should'nt be like that.i dont think you should cover anything up until you figure something out about the water problem.the wall you refer to as bowing out is one of the foundation walls?if so then you might have some real issues here.if the block foundation(which im not really fond of any way)was sealed water tight on the outside properly and the weeping tile is installed properly and the landscaping is sloping the right way you shouldnt have a problem.so,i would investigate these areas.if you try patching these problems from the inside you will spend a lot of money over the next years to come until you relize you have to dig up around the foundation to expose shawdy workmenship.unless im not understanding the question of course.
"drainage tile"he he he thats funny.
Best I can tell is that the floor pad rests on the footer. I cannot speak to continueing leakage becauseI refused to allow the contractor to backfill against that portion of the wall until it was fixed- partially because I wasn't convinced the outside was watertight, partially because there was excessive moisture in the wall itself from the original break that needed to dry out, and mostly because I knew I would never see them again if i didn't leave things hanging. I have pulled the insulation from the wall (again- back when i discovered the crack). I don't intend to let them cover the interior wall with anything, because I want to monitor the crack for a few seasons.
I had an extensive (and expensive!) engineering report done, by a local professional. The point of maximum deflection is four courses from the top, 3/4" in the ten course block. Teh crack runs about 35 feet along the 48' foot wall, and they tuck pointed (against what would have been my wishes, had they not gotten to it before I got home that day)where it was the worst, about a 1/2" gap near the step cracks which radiates into the corner of the wall. The corner remains true.
My soil is heavy clay and silt, and the water table here is fairly high. I am sure foundation drains are in place, though I would have hoped for more gravel coverage.
I'll go along with manimal....there have been some errors in construction methods by the basement contractor and your probable route of correction is a complete rebuild or installation of a wall anchoring system.
There is a neat retrofit block wall anchoring system made and installed by GripTite franchised dealers. Check out http://www.griptite.com for more info and local dealer listings. The $ numbers I've seen I would consider very reasonable at an estimated $50-$100 lineal foot of wall. Especially in light of jacking and rebuilding....or the legal thing in the next paragraph. Also http://www.helitech.com .
Who pays? Good question...should be the contractor, BUT it may require a trip to the courthouse and a lawyer. More $$$ for the lawyer and when you go to court it is a crap-shoot as to who wins.
AND if you win and the courts orders the contractor to pay you may still have to bring a second action against the contractor to squeeze the $$$ out of his wallet/bank account. And again that will require a $$$ lawyer!
A "bond course" in a concrete block wall is a horizontal run of specially made blocks within the wall that accepts a horizontal rebar ( also tied to the vertical rebars @ 4' OC) and is filled with concrete along with the rest of the wall. It is locally a common practice on a 10 course filled wall to use a a bond course at the 5th and 10th course.
You stated that there are rebars inserted every 4th block, but you did not confirm that all the block voids were concrete filled. If not totally filled then the rebar is useless.
The soils you describe are notorius for holding water and becoming very heavy and plastic in nature. They do not drain well at all! Secondly when the original undisturbed soils are opened to the weather the added water to the backfill and that backcut wall causes them to "flow" or slip past one another in an active zone of movement. The cut wall can actually shear away and push against the basement wall adding to the weight of the soggy backfill.
compacted clay-109 #/cf excavated dry clay-68#/cf wet excavated clay-114#/cf
Long concrete block walls without pilasters or other added structural components are subject to distortion and/or collapse when the heavy wet clay soils wedge against it.
More questions...........
How much gravel backfill was used? What size of gravel? Was the basement backfilled without the modular in place to support against the weight of the backfill? Did they install a geotextile on top of the gravel prior to backfill? Where(at what vertical position) were the perimeter drains installed? Do they exit to daylight or to a sump? And do they show that they drain water when it rains? What type of foundation sealer was used?
What a sad mess..........good luck!
...............Iron Helix
Hi All: I am an ICF and concrete contractor.
Blocks are an inferior method of foundation construction, when compared to poured concrete. In fact, where I live and work, you would be hard pressed to find anyone to lay up a block wall. Only real pro's with lots of exp. will attempt it, or real out and out novices, looking to save a buck.
From where I sit, the problem looks to be frost or water induced heaving from the heavy clay backfill.
My view is that the cause of the problem, lies with the instructions given to the excavator who backfilled the foundation walls.
Before backfill can occur, the process requires inspection and report filing, from the local building official. He would surely notice if the perimeter footing weeper tile was poorly constructed, and ask for remedial. A sceond inspection would always follow up to make sure the repair was done.
The waterproofing and parging layer applied to a block wall will fail immediately, once any movement occurs. Upon failure, due to the open block cores, water can travel anywhere within the wall, and create more havoc.
If the foundation was inspected, and passed, then anylize whether or not freedraining material was used throughout the backfill process.
When you do your remedial excavation and backfill, with your new sand, allow for a layer of drainage board on the exterior foundation wall, as well. Then you will be able to sleep at night !
I will agree with your judgement about concrete block foundations, but many consumers know no difference and contract for same as a matter of price, or other mitigating circumstance.
I inspect houses with block basements...with a high percentage in assorted states of bow & bulge! Some new, some very old!
Kinda doubt that it was coded/permitted or seriously inspected...at least no reference has been made to that.
Poor ol' Tripletime already has his broken block basement....guess we could single side form and pour inside the existing....lots of shoring! Would be a daring cool project! I'll watch from my lawn chair outside on the lawn!
But in the end he needs a reasonable expedient affordable & satisfactory solution to his dilemma without going to the bank for a second & third mortgage.
Yup....poured basements by form or ICF...only way to go!
...........Iron Helix
Hi Iron Helix : Would you tend to agree that the problems here were not created by the block guys...but by the excavator and the backfill materials ?
No need to get lawyers involved, as their fees would likely cover off, re-excavating and repairing the damage.
About the floor guys trench at the basemnet floor/wall joint...were they anticipating water infiltration? I think they were.
I have seen this done locally, foundation guys anticipating future shrink cracks in their poured walls. Theory is, when the wall cracks ( inevitably) they don't get a call back to deal with water infiltration. There are some proprietary drainage boards that provide this type service... I forget what they are called.
Cheers.
How are the L-channels attached?
Do not cover any of your walls! Out of site....out of mind! At least until it is too late!
How much bow....measure it please? Vertically & Horizontzlly for the full length of the wall.
Rule of thumb...when a column or wall bow more than 1/3 of its thickness, then it is potentially structurally unstable. ie....If the block wall is 8" thick then a bow more than 2.67" is a big problem.
Monitor, monitor, monitor....record your "bow"data for all walls! Both vertical and horizontal axis.
Are the blocks unfilled?
Is there a bond course middle & top?
Are there horizontal cracks in the walls? Vertical cracks?
What are the lenghts of the 10 course walls.....or the dimensions and shape of the footprint....I assume it is a rectangle.....size=?
What is your soil type?
What is your annual rainfall?
Heavy spring rains added to heavy clay soils can produce a wedge effect that can collapse block walls. The taller and longer the wall is the more likely to bow.
The chalking two blocks high indicates water being held at that level and migrating through the blocks...therefore the drainage field may be absent or faulty and or there is no applied foundation coating.
Make sure your gutters are piped at least 10ft away from the modular and then continue to flow "away" from the structure. If there are no gutters....install same ASAP!
The ground around the foundation should be landscaped to drop a minimum of 6" in the first 10 ft from the modular. Fill all depressions/low spots...monitor for settlement.
..................Iron Helix
This doesn't sound good, Tripletime. We don't use blocks for foundations in my area. One that is bowing in, usually means the backfill is improper material, is freezing and destroying the wall. The typical basement slab would sit on the footing. A gap of 1" around the perimeter wouldn't do anything for drainage. If you can poke a stick in the gap and don't feel concrete, there may not be a footing. The slab against the foundation wall also helps to keep the bottom of the wall from being pushed in by the weight of the backfill over time. I don't know where you live but this would scare me. Effervescing is a sign of water leakage, which may mean no waterproofing material was applied to the exterior of the block. If the block is moving, this would break the seal anyway. When insulating a basement wall, the insulation would be installed from the living space floor to below the frost line. This is why it doesn't go all the way to the slab. I would remove the insulation so that I could inspect all the walls given the problems you have stated.
Shoring up walls with steel is something for old masonry work where rebuilding the walls isn't a viable option. What's to say there won't be issues with other areas in the future? The steel may help to prevent the wall from collapsing but it won't do anything to stop water from seeping in if the blocks are moving. I think you need a knowledgeable engineer to look at your situation. You may also need a lawyer, this sounds like a lawsuit in the making. In the worst case, you may be looking at jacking the house and redoing the foundation properly. I may be overreacting based on your post. I wouldn't let the contractor make the decision for me at this point, they are just going to cover their butts with a stop gap measure. You'll be stuck with the consequences in the future.
You may want to contact the State Attorney Generals office and ask about consumer fraud. They may be able to help you find professional help at no charge. I assume you have already had the code enforcement officer look at the situation. Even if there are no real structural issues, you can't stop water migration from the inside.
Beat it to fit / Paint it to match