# Elevated Concrete Porch



## Redbud (May 17, 2015)

I am replacing what was a wooden front porch in very bad shape with a concrete porch. The porch is 6' X 19'. I am very handy, very little concrete experience. I will have some folks helping me that have some experience. A few questions.... The slab will sit approx 3.5 feet off the ground, do you recommend poured walls or block walls? Also, 2 sides of the porch will be against the house, is it necessary to pour a foundation there? I plan to fill the foundation with gravel. I have attached a picture and would welcome any feedback, suggestions or ideas.

ThAnks!


----------



## SeniorSitizen (Sep 10, 2012)

Please get very experienced concrete / construction help for that job.

Personally I don't pour concrete on gravel. I pour it on clean inorganic soil that is compactable , very compactabel . Have you considered treating the soil for termites if applicable.


----------



## joecaption (Nov 30, 2011)

That's one job I always hire out.
So how do you plan on getting under the house if you cover up that crawl space door?

Your going to have to dig a 24" wide X 8" thick footing, below the frost line in your area with rows of rebar sitting on chairs.
I have mine built with the first 2 rows being 12" block to spread out the foot print.
I'd be removing some of the siding and waterproofing the wall to about 6" below the foundation, and at least 12" up the wall.
The top of that slab needs to be a minimum of 2" below that door opening, it can be up to 7" lower.
Needs to be back filled in 6" layers with compactable fill and compacted with a plate compactor.
When it's time for the slab it needs to be formed up so there's an over hang so water does not run down the block.
Trying to pore and finish a slab is a challange and requires special tools and skills.
I've never seen anyone add another foundation along the house wall.


----------



## Fix'n it (Mar 12, 2012)

i don't want to jack this thread. but why don't you put a new wood deck there ? a LOT MORE DIY , and probably a lot cheaper.


----------



## jomama45 (Nov 13, 2008)

A little more info is needed before giving too much guidance. 

How deep is the foundation under the house, crawlspace (4') or full basement (8-9')?

What is your local frost depth, or at least, what area are you in?


As joecaption noted, you'll need to remove some of the siding and flash up the wall a ways, and down over the top of foundation as well. Do NOT pour directly over the Tyvek, unless you'd like to replace the sill plate and rim joist in the future..............


----------



## Redbud (May 17, 2015)

SeniorSitizen, thanks for the question. I do plan to treat for termites.

Joecaption, most of the house has a basement under it with the exception of 2 front bedrooms, which have a crawlspace. There is plenty of room on the other side to make a new opening. Are you of the opinion block walls would be better than poured? I do plan to add the flashing.

Jomama45, the long wall across the back is a 9' basement wall. The short block wall is 4' crawlspace. Also, I'm in Kentucky, best I can tell, the frost line is 18-24".

Thanks for the replies...I'm open to advice and suggestions.


----------



## Yodaman (Mar 9, 2015)

would a suspended slab be a better option here? it would take out the possibility of slab failure due to the deep back fill settling. 

Keep the crawl space accessible as a storm shelter.

Not a mason, just thinking out loud


----------



## ron45 (Feb 25, 2014)

Mine was a tad smaller then yours...
Frost line 32".
Took it out after 32 years. no problems
No footer, 4 blocks deep, 3 blocks above, fill with compacted dirt, + 4" of concrete for slab.


Sorry miscalculated, house was built in 1963. I was told by a neighbor the porch was added 1987, that's would make it 27 years.


----------



## Msradell (Sep 1, 2011)

Yodaman said:


> Keep the crawl space accessible as a storm shelter.


Why bother? He already said he has a partial basement which is a much better storm shelter than a crawlspace.:yes:


----------



## Yodaman (Mar 9, 2015)

Msradell said:


> Why bother? He already said he has a partial basement which is a much better storm shelter than a crawlspace.:yes:



a tornado could sweep the house clean off but I bet this slab will still be there :yes:


----------



## jomama45 (Nov 13, 2008)

Redbud said:


> SeniorSitizen, thanks for the question. I do plan to treat for termites.
> 
> Joecaption, most of the house has a basement under it with the exception of 2 front bedrooms, which have a crawlspace. There is plenty of room on the other side to make a new opening. Are you of the opinion block walls would be better than poured? I do plan to add the flashing.
> 
> ...


In a perfect world, you would have a bearing edge along the 9' deep wall, something that went down to the footing. THat's obviously easier said than done at this point. You could "probably" dowel a number of rebar into the foundation at the house side, but you are adding a new dynamic to the load on the foundation wall.

For the other 2 sides of the porch, you really only need a 20" wide by 8" thick footing below the frost line, on virgin soil, whichever is deeper. Laying block up on the footing is generally going to be easier to DIY than a poured wall, and 8" block are more than adequate for this. You could use split faced block above grade if you like the look or even plaster the block.

When it comes to fill, if you have decent bearing on the 2 long sides, as well as the short side away from the crawlspace, the fill is somewhat insignificant; a well installed slab with re-enforcement will easily span the distance........


----------

