Foundation resources


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Old 02-26-06, 12:09 PM
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Foundation resources

I posted this under the concrete board as well, please delete if required (I do not know which forum would be most appropriate).

I am building a garage and really the only question I have is in regard to the required foundation. The land where the garage will be is at about a 4 degree slope (front to back) which will require about 2 feet of block at the back of the building plus that needed to build up from the footer.

I do not plan on doing this part on my own (for obvious reasons), but when I hire a contractor, I want to be reasonably sure he knows what he is doing (and I need to know what questions to ask). Is there a good web resource for foundation basics? Code requirements? (for a garage).

Thanks,

Dave
 
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Old 02-26-06, 12:12 PM
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Foundation resources

I posted this under the garage forum as well, please delete if required (I do not know which forum would be most appropriate).

I am building a garage and really the only question I have is in regard to the required foundation. The land where the garage will be is at about a 4 degree slope (front to back) which will require about 2 feet of block at the back of the building plus that needed to build up from the footer.

I do not plan on doing this part on my own (for obvious reasons), but when I hire a contractor, I want to be reasonably sure he knows what he is doing (and I need to know what questions to ask). Is there a good web resource for foundation basics? Code requirements? (for a garage).

Thanks,

Dave
 
  #3  
Old 02-26-06, 12:39 PM
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Hi Dave - Quick question. Why block and not poured concrete? Will the garage have a poured slab?
 
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Old 02-26-06, 01:02 PM
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Poured vs. Block

Yes, the garage will have a poured slab. As I said, this is the part of the construction I am having the hardest time getting info on. I am looking for economical and (of course) up to code construction. I do not want to be told I need "nuclear grade" when I do not need it and I do not want someone to come in and tell me I need less than needed.

The one contractor I talked to led me to believe I needed the block, in part because I need a brick vaneer (subdivision rules) on all exposed exterior concrete. While talking to the contractor, I thought he was building up the requirements (to charge me more) than the county made it sound. Then again, the county had not seen the location.

This is what I think we (the contractor, the county, and I) agreed on. Code requires the footer to be at least 18" deep. I believe 4" minimum slab (range 4-6"), it appears the county requires any foundation with greater than 24" of fill be certified by an engineer (this will be close).

I plan on checking with the county tomorrow to see if they have any resources. I just need to be able to tell a contractor what I need and not have one tell me what I "need".

Thanks,
Dave
 
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Old 02-26-06, 01:58 PM
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Your local code office can give you the requirements for building a garage. Codes vary so much from area to area, it's hard to give you a correct answer. When I lived in Florida, a concrete contractor could not pull the permit. I had to take my contractor with me to get the permit because I knew nothing about masonry work. Glad I did as there were so many terms I did not understand. Make sure you get a permit to do the work and the final inspection. Tearing out concrete that is not up to code is not a fun job. Good luck.
 
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Old 02-26-06, 02:09 PM
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Foundation resources

You probably have to get a building permit that will require some drawings. This will require a design that is probably beyond your area of expertise and qualifications since your are asking for assistance.

Have your contractor provide the design or get a design made yourself if you want to shop out the work and choose a contractor.

There are no "cookie-cutter" designs for structural situations like yours unless your local code authority has established some standards because the repetitive similar situations.

You will probably end up with a continuous footing below the frost line (per code) and concrete block up to about a foot or so above finished grade. Your garage structure wood or block will sit on this. This will put your foundation walls slightly above the floor to ease cleaning and isolate the wood from critters. The garage floor slab would then be a floating slab supported by the compacted soil inside the block foundation. The amount of reinforcing and grouting in the block will be determined by the unsupported height and the load on the garage floor.

It is possible to use a floor slab bearing on the foundation walls, but the floor would have to be thicker and reinforced since you cannot expect the soil under the slab to support the slab since the possible settlement of the soil under the floor would leave the slab unsupported and will crack if not thicker and more heavily reinforced. This is the reason for the use of a floating slab that is separated from the foundation.

Two feet is not that much, but is enough to cause the wall to move out when the soil under the gargae gets saturated and there are a couple of cars in the garage. This is the case where a vertical load causes a horizontal lod on a wall. I have seen many cases, especially when water/salt from a car gets through a floor crack and saturates the soil.

Good luck.

Dick
 

Last edited by Concretemasonry; 02-26-06 at 03:53 PM.
  #7  
Old 02-26-06, 03:20 PM
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Visit WWW.concretenetwork.com. They may have some info. I think a poured foundation would be less expensive because it is less labor intensive than block. It is also quicker and stronger. Your contractor should also be using rebar (1") and steel mesh in your slab.
 
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Old 02-26-06, 03:41 PM
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Foundation resources

The 1" rebar is a rediculous and is totally unnecessary. That is for heavy construction and can lead to cracks if spaced according to code minimums. Lighter steel at a closer spacing is more effective and much more economical.

The two threads should be merged to avoid confusion.

Dick
 
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Old 02-26-06, 04:01 PM
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Concretemasonry,

Threads have been merged.

I totally agree that 1" rebar is just plain overkill. Residential construction and commerical are 2 different animals.

#4 rebar - 1/2" is most commonoly used for footings and vertical applications whether it be block or poured foundations. 6x6 wwm (welded wire mesh) would be sufficient as well for the slab. A simple 18" deep garage foundation doesn't need anything larger than this even if the foundation is deeper on the one end.

Just some thoughts!
 
 

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