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Discussion Starter · #1 ·
In our ranch home, the owner added on a master bath to the master bedroom. The master bath was an addition to the house, but only went 1/2 way across the width of the bedroom. Please see picture below. What I want to do is continue the addition across in order to add a walk-in closet. I live in NY so I will need to dig down 4' to be below the frost line. I'm assuming I will pour a cement slab and then add cinder blocks as they did for the bathroom addition. If this is the case, I am assuming that I need to do something so that the slab and the cinder blocks are attached to the existing basement and the existing addition. How would I do this?

Thanks in advance!
 

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This would need to be a project that requires a permit and therefore plans from an architect or engineer. The plans would detail the building requirements.
When I built the kitchen addition, it was required that the new footing and poured concrete foundation be attached to the old by way of 5/8" rebar.
Ron
 

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Hey Brianpaul - my firm does quite a bit of addition work, and attaching new footings to old is frequent. Most of the time we specify drilling into the existing footing, filling the holes with epoxy, and inserting the new rebar. Then the new concrete is poured, encasing the exposed ends of the new rebar in the new footing.

I hope this is helpful!

Richard Taylor, AIA
Architect
www.rtastudio.com
 

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I did my own design work on a 24x36 3 story addition without an architect or an engineer. Foundation I had poured & they drilled the existing foundation & put in the rebar
 

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Discussion Starter · #6 ·
The master bath shown in the picture is an existing addition and it only goes down 4' deep and the basement is about 8' deep. In other words, the concrete in the basement is not connected to the concrete of the new addition. Maybe it's connected to the cinder blocks of the basement. Would this be a problem?
 

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BP - depends on the way the original house and the addition were backfilled. Normally, you want your new foundations to go on "undisturbed" soil...so that it won't settle. When you dig for a foundation, however, you end up making the excavation wider than the footing and foundation wall, and have to "backfill" on the outside of the new foundation.

That means the backfill material won't be "undisturbed" soil. If the original and the bath addition were backfilled correctly (meaning compacted soil, or gravel) then you probably have a good base to build on.

If not however, then anything you put on the backfill will likely settle. So if you attach the new to old with rebar, and the new settles, you'll be affecting the existing wall. Not a good thing!

But it the existing bath addition's been around for a while, and hasn't settled, it should be fine. Your job is to make sure you do it right with the closet addition. Just be sure the new footings are on undisturbed soil and/or compacted fill, and you'll be fine. I would consider attaching the new footings to the bath footings, since they'll be at the same level, but I wouldn't attach the new footings to the concrete block of the house. Hollow block isn't meant for that kind of bearing.

If you have any questions about this once you dig, you need to find a qualified pro in your area to work with. It's a cliche, but the foundation really is the most important part - everything above depends on it!

Hope this helps,

Richard Taylor, AIA
www.rtastudio.com
www.rtaplans.com
 

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Discussion Starter · #8 ·
Thanks for all the good information! Can someone give me a ballpark figure on the cost of this addition if I have it done by a contractor? The inside dimensions would be approximately 12' x 8'. The room will not need heat, but it will need a light.
 
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