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Extending Front Porch

Posted: Mon Jun 10, 2019 11:13 am
by alexaklson
Hi Shannon,

I would like to extend my front porch. I live in a raised bungalow and my porch was measuring 12ft by 4ft with steps leading up to it, as shown in the attached image.
Original_Porch_Stairs.jpg
Original_Porch_Stairs.jpg (683.84 KiB) Viewed 186 times
I would like to build a concrete porch that is 25ft by 8ft, so I started by demolishing the steps and the current porch and I broke them into smaller pieces, as shown in the attached image.
Broken_Porch_New_Wall.jpg
Broken_Porch_New_Wall.jpg (602.37 KiB) Viewed 186 times


As I was doing that, I decided to remove the bricks that would be covered by the porch, just to have extra bricks in case I needed any, especially that these bricks are now discontinued. However, now I want to fill the space that was filled by the bricks, the space where the 2x4s are placed to prop up the bricks above.
Removed_Bricks.jpg
Removed_Bricks.jpg (575.21 KiB) Viewed 186 times
I am thinking of just mixing concrete and adding it to the foundation and building it up to fill the space. But what was behind the bricks was, I believe, compressed wood boards along with some black plastic layer to direct water or moisture away from the house I am guessing, as shown in the attached image.
Wood_Boards.jpg
Wood_Boards.jpg (583.03 KiB) Viewed 186 times
So would it be safe to pour concrete against these wood boards, because I know that when framing a wall, wood can't be touching the concrete floor otherwise it rots, but I am not sure if the same things applies here. Or would I need to isolate these wood boards with vapor barrier or some sort of insulation like foam insulation. I would really appreciate any input here.

Re: Extending Front Porch

Posted: Mon Jun 10, 2019 12:34 pm
by A. Spruce
It would probably be easiest to fill the area from the foundation to the brick with cement block, then backfill as necessary, then pour your new concrete.

If you wanted to do it with wood, use pressure treated lumber and plywood, then you can put the dirt/concrete against that.

Re: Extending Front Porch

Posted: Mon Jun 10, 2019 4:57 pm
by Shannon
ya if this is going to be a crawl space or something I would simply frame it in with PT lumber. Pouring concrete in there is really not worth the trouble IMO.

Re: Extending Front Porch

Posted: Thu Jun 20, 2019 7:20 pm
by JamesJaz
First there is a Lintel over that window and the weight above is carried to either side of it. Have a look at your supports. If you are planning on pouring concrete make sure to drill and epoxy rebar and run a hydrophilic seal strip the entire length of the wall on the exterior side of the rebar. Spray some Bondcrete(chemical bonding agent) on the surface of the old concrete prior to pouring. Use 20mpa or 25mpa concrete with 6-8% air. Give it 2 days 2 cure before taking the forms off and keep the sun off of it.

Take off that black wrap and install Blueskin(or something equivalent) on the sheathing. You can pour concrete against that. After the pour apply non shrink grout over the seam(cold joint) minimum 6mm thick. Then for added benifit you can tar over that.

Re: Extending Front Porch

Posted: Thu Jun 20, 2019 8:56 pm
by JamesJaz
Blueskin inbehind the brick 2 coarse high and a few inchs on the top of the wall. Keep the top of your slab a few inchs down from the top of wall. You shouldnt pour against brick especially in this case.