Foundation work

[lampskin]

Hi all,

I'm trying to complete a bit of foundation work. My foundation has a few layers of parging over top of it.

The parging is deteriorating, cracking in some places, and in other places it just sounds hollow when tapping.

With my trusty hammer and chisel, I chipped away as much bad concrete as I could. I went to home depot and got a bag of hydraulic cement and some sand mix concrete.

Now, my question is: What do I do about this? I was going to fasten some chicken wire and put some hydraulic cement on it. What do I do with the hole/space behind it? Do i spray expanding foam sealant behind it?

It looks really bad. I have a crawlspace under my house, and I can see some rotten wood in there. Will the hydraulic cement be adequate to fill in the hole? Should I just keep pouring hydraulic cement in the hole until it's all filled?

Thanks in advance for the help. Oh yeah, I posted on another forum too. I showed the part that I did so far. I managed to fill in some cracks at the front of the foundation. I think i did a decent job.

[HayZee518]

Wow! have you got a problem! The plate looks like it isn't there anymore - all rotted out. I do not think that by just replacing the mortar between the house and the block you're gonna solve anything. AND you say you got wood rot in the crawlspace. to do it right would require jacking up the whole house, chipping out all the concrete, removing all the plate and replacing it with a treated board. then put a sheet metal U piece between the plate and block and drop the house down on top of that. incorporate a flashing that would send water AWAY from the house so it doesn't weep underneath the new plate.

[pushkins]

I agree, no matter how much cement you force in there your not going to "fix" the problem. You need to remove that rotted wood, replace it with treated lumber, add a large drip edge over the wood, down the side and then over the top of the wall, then build new run off parges.
If you don't remove the rotted wood and try to cover it up you will be in for much greater hurt down the track.

What you have was never a great idea, but I've seen it done on many homes with a similar design with almost always the same problem you are facing.

[lampskin]

I'm not sure how everything's attached to the foundation. I would assume the framing is embedded into the concrete foundation, or attached to rebar in the concrete. So do I have to replace all the wood framing?

Is this kind of what you're talking about(see attached diagram please)? Is this how everything's supposed to fit together? I have no experience doing this kind of stuff. Is it something I can do myself?

It sounds to me like you're recommending putting flashing around the lower part of the wood framing behind the concrete to direct the water.

How would the water have got in behind to rot the wood?
My crawlspace is not paved. It's just dirt.
Could water moisture have condensed up from the earth floor of the crawlspace and got into the wood, or should i be concerned about moisture seeping through from the outside of the foundation?

If I call someone in to do this job, should it break the bank? I wasn't counting on doing this work, so it's a nasty surprise that it should be a difficult fix...

thanks for your help though, and the quick response!

[HayZee518]

From the looks of things, your slab was poured, then a bedding layer of mortar mix was put down and two courses of concrete block was put down. I can't see inside the block's cells so I can only assume the bottom plate was just laid on top of the blocks. there's nothing but the sheer weight of the house holding everything down. normally the cells are filled with concrete and a sill anchor is put in. a hole is drilled in the plate and bolted to the sill hook then your regular construction is started and the house goes up plate, floor joists and fascia, floor sheathing, floor plate, studs, top plate, ceiling joists, rafters and ridge pole, roof sheathing and roof. the joists may be nailed into the fascia or may be notched to fit over the bottom plate. that bottom plate is rotting so everything else is gonna go downhill as far as wall integrity is gonna be. for your answer about water, the concrete is angled to run water off the block but there is no bond between the concrete and the plate so by cappillary action water goes between the concrete and wood and settles into the wood and starts to rot it. a sheet metal block cap and flashing eliminates this weeping of the water and wood.

[pushkins]

The downspout may have been a major player in the problem and it also looks like the cement has been cracked and or missing for a long period of time.
You may be lucky, that damaged area looks to be from your pictures about 3'-4' long, the work may involve some minor lifting, cutting out the rot and replacing the sill plate and reattaching the floor joists, then repair of he external mortar work to weather seal it. If you have never done this sort of work before, do not attempt it now, it's not an easy job and can be dangerous if you don't know what your doing.
You could always contract out the wood repair and then finish the concrete work yourself.
The skill level needed would probably be 8 - 9 (on a 1-10 scale).
Cost wise to have the wood repaired could range around the $500 mark, it's hard to judge from just the pictures.
Make sure you use a licensed contractor and that they use pressure treated lumber for any lumber touching any cement, concrete or exposed.