Building a porch

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greengoblin67
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Building a porch

Post by greengoblin67 » Sat Feb 09, 2019 8:54 pm

Hello
I have a cabin that is built on a concrete slab. I want to put on a covered porch. I know normally you attach a ledger board to the structures floor joists. However with a concrete slab there only the sill plate 1.5 inch thick and the bottom wall plate so an additional 1.5 inch. So I need to subtract the thickness of the deck boards so that leaves only about 2 inches to attach the ledger board. Is this enough or do I have to attach the ledger board another way? I’m leary about drilling into the slab because I’m not sure if it’s quality of construction. I’d appreciate any help you can give me. I live in Wisconsin in an unincorporated area and don’t have many building restrictions. Again thanks for your help.
Erik


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Shannon
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Re: Building a porch

Post by Shannon » Sat Feb 09, 2019 9:38 pm

You would excavate and pour footings and slab to build off. You don’t want to bury wood in the ground for this type of thing.
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greengoblin67
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Re: Building a porch

Post by greengoblin67 » Sat Feb 09, 2019 9:48 pm

Hello
To clarify the slab is about 6-8 inches above the outside dirt. So non of the wood would hit the soil. Here is a picture to best show what I mean.
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D85890E2-1147-478B-ACC1-C047AE0CE716.png
This is where the porch will be
D85890E2-1147-478B-ACC1-C047AE0CE716.png (799.03 KiB) Viewed 79 times

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A. Spruce
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Re: Building a porch

Post by A. Spruce » Sun Feb 10, 2019 12:22 am

For the area of porch over the slab, simply attach sleepers to the slab and lay your decking over them. The height of the sleeper will be 1-1/2" less than the distance from the top of the slab to the bottom of the door threshold, by your calculation about 2". If you expand the size of the porch beyond the existing slab, then you will need to install piers and support beams to carry those areas.
If the women don't find you handsome, they should at least find you handy.

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Shannon
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Re: Building a porch

Post by Shannon » Sun Feb 10, 2019 8:51 am

A. Spruce wrote:
Sun Feb 10, 2019 12:22 am
For the area of porch over the slab, simply attach sleepers to the slab and lay your decking over them. The height of the sleeper will be 1-1/2" less than the distance from the top of the slab to the bottom of the door threshold, by your calculation about 2". If you expand the size of the porch beyond the existing slab, then you will need to install piers and support beams to carry those areas.
There is no existing porch slab
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Shannon
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Re: Building a porch

Post by Shannon » Sun Feb 10, 2019 8:58 am

You will have to attach to the concrete edge. You should just have a bottom wall plate sitting on the slab? I’d be surprised if you actually have 3” of wood plates above the concrete.
I would pour some piles/piers at the outer edge of the porch to support a flush beam and build up from there. If this porch will not be completely closed in then I would also plan the floor to be sloping from the house at about an 1/8” per foot at the least.
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greengoblin67
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Re: Building a porch

Post by greengoblin67 » Sun Feb 10, 2019 9:07 am

Hello
I actually have a sill plate bolted to the concrete slab and then the wall plate it nailed to that. As far as the flush beam.... what your saying is have piers as close to the existing foundation would that beam attach in any way to the house structure besides the roof then or would it be like a free standing or floating deck? Sorry about all the questions just want to make sure I understand. I really appreciate your help.

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Shannon
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Re: Building a porch

Post by Shannon » Sun Feb 10, 2019 9:14 am

Ok I stand corrected on the double bottom plates.😄

If you don’t want to attach directly to the slab edge you could use piers against the house and another row out at the other end.
Alternatively you could run the joists of the porch parallel to the wall of the house and placebyour piers and beams at the left and tight ends. This will actually make things a little easier because you don’t need the pier to be right against the house slab. They could be a couple feet away and the beams would cantilever over them towards the house.
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greengoblin67
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Re: Building a porch

Post by greengoblin67 » Sun Feb 10, 2019 9:34 am

I like the 2nd way you mentioned. That way I can utilize the diamond pier system instead of digging 4ft piers.
Again your channel is awesome and very helpful to us weekend DIY’rs.
Thanks so much!!!!

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Shannon
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Re: Building a porch

Post by Shannon » Sun Feb 10, 2019 9:47 am

Glad to help
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