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Home Addition's foundation question?

6K views 16 replies 9 participants last post by  chandler48 
#1 · (Edited)
Home Addition foundation-Remove / extend Deck and change to Master Suite & Deck.

Hi,

I have a question on Home Addition Foundation. Currently I have a deck 12' X 44'. The deck is about 8' 6" from the concrete floor. The property is in Duluth, GA.
I didn't get architecture draw out the plan yet but I had 3 contractors gave me an estimate. All of them gave me different way to complete this project. Therefore I need to research more to understand which contractor is the most reliable one.

I would like to tear down the deck and build 22' X 28' Master Bedroom Suite with W/C and Bathroom. And the rest of the area will be a deck with 22' X 16' dimension. so that would be 10' X 44' addition to the existing plan. I hope you guy get the picture.

The area underneath the new master suite and deck will be some concrete floor and the rest is the grass ground. The concrete area will be the existing concrete area. I don't want to conver all the ground area with concrete.

What type of foundation do I need for this addition project?
Should I build the long square TEE (Spread) foundation? or can I just use the 6' x 6' post(column) with slab pad? Or is there any other way.

Answer of "talking to architect or home designer" wouldn't help. I just want to have some general idea. Of course, the condition of the soil, location of the property are some of the factors that I have to consider. But there must be just a couple of universal way or the safest way to build no matter of those condition factors.

Thanks and Happy Holiday
 

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#2 ·
Not much good information. Do you have a plan prepared by a designer for your permit?

What part of the world are you in and what is the climate? Judging by the type of trees you may have some minimum depth for footinings.

A 6' x 6' post does not sould reasonable. Any structural post should never be set on a slab unless it is a specially designed slab. 6" x 6" posts with Sonotubes and Simpson connectors may be accceptable is usually a commonly used method. Then, you can use a common 4" concrete slab.

All of this will take a professional designer to get a permit.

Dick
 
#3 ·
Hi ConcreteMasonary,
I had 3 contractors giving me estimates and they all gave me different ways to complete this project.
Therefore I start to research and try to pick one contractor. I just want to get some idea and see which contractor is the most reliable.
BTW, the property is in Duluth, GA. Do you have any suggestion?

Thanks,
Chai
 
#4 ·
I had 3 contractors giving me estimates and they all gave me different ways to complete this project.
Therefore I start to research and try to pick one contractor. I just want to get some idea and see which contractor is the most reliable.
BTW, the property is in Duluth, GA. Do you have any suggestion?
 
#5 ·
Using the existing slab for the floor of the addition poses a multitude of problems.
  • The walls must bear on foundation, or slab supported by a continuous footing/foundation. Habitable space has to have footings.
  • There's no moisture barrier (6mil poly) under the exterior slab which will now be interior. That's a big moisture issue and a code requirement.
  • Frost heave would be a big problem since there isn't a continuous footing.
You need to hire an architect or a design-builder, and secure the appropriate permit to make sure it gets done right.
 
#8 ·
you are missing a step. you need to submit to the city for a permit your arch. plans, and then pass it on to the contractor.
Not necessarily. You cannot get a permit without plans. You don't need a permit for the plans, you need a permit for the work. If you hire a design-build contractor...Of which there are many...The contractor will draw the plans, submit them, and get the permit before beginning work. If you hire an architect, you'll have plans you can show to builders to get bids. The winning bidder/builder would then take the plans to secure the permit. NEVER pull the permit yourself if you're using a contractor...Make them do it since they'll be doing the work. Doing that gives you and the City some recourse if they don't do satisfactory work. If the permit is in your name and the builder skips town, you're left with the responsibility of fixing their mistakes.
 
#11 ·
Thanks for the "Talk to architect or home designer" answer.
But again I need some general idea how the foundation could be built?
There must be only a few ways to build the footing of the addition project? Once I know all those ways, so I could make a comparison of what the contractors would do. I thought that why there is this forum, so people can share their knowledge and help?

Thanks & Happy New Year :thumbup:
 
#14 ·
Have you considered talking to an independent architect or engineer that is not connected to any builder or contractor? A consultation with someone that is independent might only cost you $100-$200 for a couple hours of there time. Then should be able to give you some much more specific answers so you know the pro's and con's of each method in your area. Then you don't have to feel pressured or confused by proposals by a builder.

Or you can also do what thekctermite suggested and contact your local building inspector, he/she might be a nice person on a slow afternoon, and spend a bit of time with you explaining the exact answers to these questions for free.

The people here are great and very helpful, If you had questions that people here were able to answer, they would.

Good Luck;
Jamie
 
#12 ·
This forum is not here for design assistance, and it would be irresponsible for us to provide it. Nobody knows the loads that will be imposed by the structure, nobody knows your lot's soil bearing capacity, nobody knows your specific area's requirements. What would work where I live might not work or be legal where you live, or it might be overkill.

Possible ways to construct the footing for the addition include:
  • Spread footings and foundation stem walls
  • Trench footings that serve as footing and foundation
  • Grade beams
  • Thickened portions of the slab for interior bearing points
  • Pad footings for interior bearing points
  • Numerous columnar footings for load points on the perimeter
So unfortunately, the best answer that you can possibly get is to talk to an architect, engineer, your town's building inspector, or work only with reputable design-builders.

Once you get some bids and proposals, let us know if you need some clarification or understanding of the differences between the methods they plan to employ.
 
#16 ·
Thanks thekctermite .

I will wait to hear the proposal from those 3 contractors.
They will have some architects draw up plan let me know.

Thanks and happy new year 2009.
I think you have a misunderstanding as to how to go about it.
Never go to a contractor before you have a solution for any concerns you have.
A contractor will propose to give you the moon when he can only give you lumber at inflated prices.
What you should give us are the options from the contractors. Then we’ll tell you if it’s feasable or if he is talking nonsense.
Your structure is not that easy.
You also need to think about drainage. You already have funny roofs sloping towards the driveway and a concrete driveway heading down to the main entry. You have impervious elements which are adding to water runoff. That is a big issue you need to fix first.
 
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