How Would You Frame This Porch Rebuild?

karma_carpentry

We're submitting a bid for this porch rebuild - if we submit a reasonable bud we're likely to get it because we've done work for this person before.

We're dropping the level one step, creating a step-down from the entry alcove. The main reason is to correct the rise heights. The old stairs have too much rise and there's no room for another step because they drop right onto the sidewalk.


We're keeping the roof, rebuilding the bottom - that's why we can't just set the edge back further.

But the main question is how to support the back edge of the porch - how to hang a ledger basically. It's a stone and mortar foundation and the old porch just hung off the rim joist. We're dropping a step below it.

We thought about hanging with straps from the house's rim but the foundation has stones that would hold out the ledger a few inches and it would make the straps hang at an angle.

We thought about pouring back footings in addition to the front ones, but it's likely that if we dig down we'll hit some big rocks that are part of the foundation.

Is there an easy solution that comes to anyone's mind?

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The other question - the entry alcove is tongue and groove decking laid on what is essentially the floor joists of the house's interior space. How can we waterproof this up to modern standards without adding height?

Thanks in advance for any help.

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PS - the other reason for dropping the main porch one step is so the railings won't be too much higher than the old ones were because we have to build to the current codes. So the window view will be similar.

Riversong

It's hard to say without seeing the site, but I built an addition onto an old farmhouse with a dry-stacked stone foundation. I dug down to where the stones tapered outward enough and formed and poured a continous concrete bearing wall, basically sitting on the stone foundation (it was just a few inches thick at the bottom and 8 inches at the top - vertical on the outer face).

This would not only give you solid bearing for the deck but also tie it in well to the existing foundation (and reinforce an old foundation to boot).

- Robert

Framer33884

maybe use a Simpson THA in some conviguration and hang it off the old ledger or rim joist. Too hard to tell with out a detail drawing, elevation or picture.

JustaFramer

Rotohammer,all thread and epoxy

A+Carpenter

How about 3 post installed accordingly.Ledger off the house WALLA

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karma_carpentry

Thanks for the advice guys.

Adam, your solution is the simplest and I wish we could do it, but there is no house at the new porch level - it's lowered down a step so it's level with the stone foundation that juts out from the house in random places like a stone wall.

JustaFramer, that's an interesting idea. I guess you mean drill holes in the foundation stone and set in threaded rod with epoxy right? That sounds like it could work.

RiverSong, I have a feeling that might be what we do - pour a bearing wall instead of posts. Even if we can't make the wall all the way to the foundation, we'll be able to support the backside by a 1 foot cantilever - set the post 1 foot from the house foundation. I'm worried about pouring a cold joint onto the rough stone foundation and then water seeping in above the frost line and freeze/thaw over the years pushing in the foundation. That's the concern against pouring right onto the foundation, as well as difficulty making a form against a stone wall.

Framer33884 - That's an interesting idea. I'm going to think about that - instead of hanging a ledger against the stones which would be kicked out too far, we could chisel out pockets and hang a pair of double 2x8 or 2x10 beams at the correct level with that Simpson tie then hang our "ledger" across between those. The tallest of the Simpson THA hangers are around 26 inches which gives us enough beef to hang even dropping 8 inches for the step. That might work out.

Thanks for all the suggestions - I'll post how it goes when we start.

rhbhammer

you could come off the alcove 2' drop some piers in with a beam and cantilever your joist back to the house, that would give you enough support then if you didn't want it free standing bring out the rotohammer

N.E.Bldg&Rest.LLC

Thats what I would do, I don't think riversong's Idea would work In the northeast. Frost heave could push and pull on that dry stack foundation and cause BIG problems.

Just my 2 cents

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"Man is a tool-using animal. Without tools he is nothing, with tools he is all."

Thomas Carlyle (1795-1881)

JustaFramer

Not actually knowing the stablility of the rocks used in the foundation it may or not be feasible. However I have done think on cmu and tilt up walls for roof ledgers.

I suggest epoxy over redhead because redheads could cause stress fractures furthering unstability.

karma_carpentry

JustaFramer - Those are the same concerns I have. Same reason is why we'll probably go with pouring a bearing wall instead of tying into the foundation stones -because I'm afraid of them stones being loosened by the drilling and/or the stress of hanging the porch ledger from them if any of that stress becomes torque, not pure downward bearing.

trianglecustom

RHBHAMMER had the right ideain my opinion!!! cantilever solves all problems as to getting anywhere near the foundation walls.