[ardpub]

Hi there. New Homeowner here.

My house has a small sun room built on the side of the garage and built quite poorly, at that. They built three of the frame walls right on a big patio slab that extends way beyond and as one would expect, water has gotten under the walls and door thresholds and rotted the bottom plate, sheathing and studs.

My plan is to work one wall at a time following these steps:
1) Build temp wall to support pre-fab roof and walls via roof
2) Cut and remove damaged timber
3) Pour a 2-3" "sill" or "footer" with self-leveling concrete using adhesive to bond to existing slab and tie in with other sills.
4) Replace framing with pressure-treated wood over a moisture barrier
5) Reset original thresholds in grout (if room under doors) or tapcon thing metal thresholds that have less height.
6) Seal up further with 100% silicone and float drywall

Is this the best path forward? There is good grade to the slab so there really isn't much water along the bases of the walls.

 

[ratherbefishing]

Sounds to me like you're on the right track. But I'd go higher than 2-3". You may be able to run a couple courses of brick, if that would be easier than pouring concrete.

 

[ardpub]

Sounds to me like you're on the right track. But I'd go higher than 2-3". You may be able to run a couple courses of brick, if that would be easier than pouring concrete.

Unfortunately, the ground clearance for the windows won't allow for much more but I have a 3" in my garage that seems to get the job done. Hadn't thought of bricks but as I'm no mason, I feel like concrete will have less chance of seepage.

One thing I'm debating is whether to have equal height sills under the doors, building the subfloor up to match, or making them lower so its less of a step up.

 

[RustNeverSleeps]

Unfortunately, the ground clearance for the windows won't allow for much more but I have a 3" in my garage that seems to get the job done. Hadn't thought of bricks but as I'm no mason, I feel like concrete will have less chance of seepage.

One thing I'm debating is whether to have equal height sills under the doors, building the subfloor up to match, or making them lower so its less of a step up.

I am a novice on your question, so take my comments with a grain of salt, but I think 2"-3" is more than enough, that the key thing is to avoid having wood being in direct contact with the wet footings. Something to create a gap to prevent capillary action.

I would also be inclined to minimize the sill height under to doors, perhaps skipping that area altogether. If your doors are well constructed, have a sufficient gap underneath, use a metal/waterproof threshold, and have sufficient roof overhang....all that should help minimize problems. It is only my opinion but I would rather keep the entry way as level as possible(except sloped away for drainage) and deal with any door damage that might possibly occur as a result. Not having any tripping hazard, wheel chair access impediment, etc, is worth it IMO.

 

[ardpub]

I am a novice on your question, so take my comments with a grain of salt, but I think 2"-3" is more than enough, that the key thing is to avoid having wood being in direct contact with the wet footings. Something to create a gap to prevent capillary action.

I would also be inclined to minimize the sill height under to doors, perhaps skipping that area altogether. If your doors are well constructed, have a sufficient gap underneath, use a metal/waterproof threshold, and have sufficient roof overhang....all that should help minimize problems. It is only my opinion but I would rather keep the entry way as level as possible(except sloped away for drainage) and deal with any door damage that might possibly occur as a result. Not having any tripping hazard, wheel chair access impediment, etc, is worth it IMO.

Thanks for the reply. Yep, even if I added grade to the concrete under the door thresholds, I think it would be a trip hazard and doubt it would meet code, plus I would have to lay down subfloor and flooring to match the floor height to the sill.

Most of the current water damage seems to have come in under the sides of the thresholds and into the walls from there but so long as I have good footers that extend to the edge of each threshold, I think I'll be ok. I'm not too concerned with minor flooding from storms as I can always sandbag the doors when tropical weather is expected.

 

[HandyAndyInNC]

Concrete is porous. It will not stop water. It will soak it up. Stop the water from getting on the concrete. As for the room. Tear it down and start over. Except this time, do things right. Never do you want to have pressure treated lumber in a living area. That stuff has a poison that is injected into the wood. Do you really want that in your living area so that you can breathe it? Use Ipe, teak or even Cedar. But stop the water from sitting on the concrete and running in toward the structure.

 

[ardpub]

Concrete is porous. It will not stop water. It will soak it up. Stop the water from getting on the concrete. As for the room. Tear it down and start over. Except this time, do things right. Never do you want to have pressure treated lumber in a living area. That stuff has a poison that is injected into the wood. Do you really want that in your living area so that you can breathe it? Use Ipe, teak or even Cedar. But stop the water from sitting on the concrete and running in toward the structure.

Thanks for the comment. I know concrete is porous and was planning to consult with a concrete expert as to best approach but curious—what would you suggest doing differently that would require a total rebuild?

The whole back yard is basically a slab patio but there’s actually good grade away from the structure so there isn’t really pooling at the bases of walls, even in heavy rain. I could perhaps cut away the slab outside the walls, or add a French drain, etc.

Basically, planning to replace everything but roof, doors/windows and hopefully, most of sheathing and stucco, anyway. Good point about dangers of treated wood. This is a detached office, not exactly living space, but may go with cedar or something, per your suggestion.

 

[HotRodx10]

Never do you want to have pressure treated lumber in a living area. That stuff has a poison that is injected into the wood. Do you really want that in your living area so that you can breathe it?

I understood it was common to use PT lumber for sill plates in walls. My understanding is that what is used today (ACQ) is safe unless you're preparing food on it or eating directly off of it. There were concerns with prolonged direct contact with CCA treated lumber (like for playsets, where kids would have their hands all over it).

 

[HandyAndyInNC]

I don't mean to re-pour the concrete. I mean tear off the wood structure that has been damaged. You may be able to get away with the curb as a way to divert the water. But if you look at the concrete, there are cut lines in it. That is a perfect water way into the places where you to not want water. You will always fight the damaged parts, it will never been the same as starting new and knowing exactly how things are. Maybe have a company grind down the surface to remove the cut lines. That will remove the trough that goes into the wood structure. I have never used cut lines in any concrete I have had poured, or have poured myself. I have a few workshops at different houses, the largest being a 80x120 feet. Not a single cut line any where in the floor. I had it ground down and polished to that the floor is smooth. I then poured resin over it. Since I own a resin company, I had to be able to show what can be done. Walk into any dept store, big box store. Look at the floor. No cut lines. That is done by properly building the area where the concrete will sit and using more than is needed for the thickness. The workshop I described above has a 12 inch pour and a 12 inch curb up the walls. I the curb so that if needed, I would use a water hose to clean the floor without damaging any wood structure. It is all about the prep.

 

[ardpub]

I don't mean to re-pour the concrete. I mean tear off the wood structure that has been damaged. You may be able to get away with the curb as a way to divert the water. But if you look at the concrete, there are cut lines in it. That is a perfect water way into the places where you to not want water. You will always fight the damaged parts, it will never been the same as starting new and knowing exactly how things are. Maybe have a company grind down the surface to remove the cut lines. That will remove the trough that goes into the wood structure. I have never used cut lines in any concrete I have had poured, or have poured myself. I have a few workshops at different houses, the largest being a 80x120 feet. Not a single cut line any where in the floor. I had it ground down and polished to that the floor is smooth. I then poured resin over it. Since I own a resin company, I had to be able to show what can be done. Walk into any dept store, big box store. Look at the floor. No cut lines. That is done by properly building the area where the concrete will sit and using more than is needed for the thickness. The workshop I described above has a 12 inch pour and a 12 inch curb up the walls. I the curb so that if needed, I would use a water hose to clean the floor without damaging any wood structure. It is all about the prep.

Ok—I understand what you’re saying. Thanks for clarifying. Yes, I definitely plan to replace all the studs, bottom plates, and much of the sheathing to get any moisture out.

I hear you on the cut lines. There were many poor decisions made by whomever built this thing. Fortunately, my uncle has decades of professional experience with all things concrete so I’ll consult with him as to how to best adhere the new footers and will ask about the cut lines, specifically.

Thanks again.

 

[Nealtw]

You still need to water proof concrete, so if you plan the waterproofing right you can do it with wood.

 

[3onthetree]

There were many poor decisions made by whomever built this thing.

there isn’t really pooling at the bases of walls, even in heavy rain.

Everything seems as is commonly done, a patio was poured (with control joints as is necessary in concrete), then homeowner creep took over - probably was roofed, screened in, then later walled in, then later finished like the house proper. The patio slab was never meant to house this room, or be conditioned.

You're in Lousiana, which I thought is pretty wet. If you want the best watertight seal for this situation, you'd have to do what Neal's link is showing, cut a slot and perimeter flashing. You seem hung up on "pooling," but don't discount water running down the side of the wall, heavy downpours creating a "depth" of water before it can drain away, rain blowing around, and water wicking.

A 2"-3" pour of a new stemwall does more harm than good IMO. You can't seal the cold joint against the concrete (put sealant at the crack, but that's the same as if the sill was wood). You need to fasten the wood sill to/through this new concrete stemwall (hurricanes?), so it'll probably crack, giving more points for water to wick.

Looking at your responses you're probably gonna ask "then what is your solution?" I don't know if anything complicated is worth it, considering what it was conceived as. Maybe just monitoring the sealant and replacing the wood every 10years is good enough.

 

[Hidyi]

To give you an alternative, you can raise the door sill without affecting your subfloor. Just make a raised landing inside the doorway say 3'x3' if you're not concerned about Ada access.

 

[AllanJ]

How about PVC board instead of lumber for the sole plates (sill plates), which rest on the concrete?

Never use pressure treated lumber indoors? "Everyone" uses PT for the sole plates when finishng a basement.
i

 

[Nealtw]

How about PVC board instead of lumber for the sole plates (sill plates), which rest on the concrete?

Never use pressure treated lumber indoors? "Everyone" uses PT for the sole plates when finishng a basement.
i

So you would accept water coming in just find ways deal with it when it is in?
The answer has to be, keep the water out.

 

[HotRodx10]

The answer has to be, keep the water out.

I'd agree with that, as I think most everyone would. However, few solutions will be completely effective at keeping the sill plate dry. Even a concrete curb will absorb and wick some water.

If you can find it, marine-grade plywood along the bottom foot or so, with an elastomeric caulk to seal between it and the concrete, probably comes the closest, but if the caulk fails somewhere, then the sill, at least, will still get wet.



I have section of a garage wall in a similar situation. My solution is going to be concrete board for the bottom foot, sealed with an elastomeric roof coating on the face and roof mastic along the bottom edge, and of course a PT sill plate, just in case.

 

[Nealtw]

I'd agree with that, as I think most everyone would. However, few solutions will be completely effective at keeping the sill plate dry. Even a concrete curb will absorb and wick some water.

If you can find it, marine-grade plywood along the bottom foot or so, with an elastomeric caulk to seal between it and the concrete, probably comes the closest, but if the caulk fails somewhere, then the sill, at least, will still get wet.



I have section of a garage wall in a similar situation. My solution is going to be concrete board for the bottom foot, sealed with an elastomeric roof coating on the face and roof mastic along the bottom edge, and of course a PT sill plate, just in case.

There are solutions and it would be better if people read all the suggestions before just repeating that it is impossible. This stuff is done everyday.

 

[Nealtw]

Put in a door pan with a back lip add blueskin to the wall and add a flashing.

 

[ardpub]

You still need to water proof concrete, so if you plan the waterproofing right you can do it with wood.
https://www.youtube.com/watch?v=ZKV63kXYtx4

Thanks for all the replies. Sorry for the late response. For some reason, the notifications weren't coming through.


Anyway, I like the idea of the kerf cut plus flashing but where would I get the flashing? I'm assuming a standard z flashing wouldn't work, as it doesn't have the back lip. Also, I wasn't planning to do any flooring in the room to cover the lip but I'd be open to tiling it if the result would be better waterproofed than the alternative.

 

[Nealtw]

Thanks for all the replies. Sorry for the late response. For some reason, the notifications weren't coming through.


Anyway, I like the idea of the kerf cut plus flashing but where would I get the flashing? I'm assuming a standard z flashing wouldn't work, as it doesn't have the back lip. Also, I wasn't planning to do any flooring in the room to cover the lip but I'd be open to tiling it if the result would be better waterproofed than the alternative.

Your best bet is to find sheet metal shop and get it made out of Stainless.

I would also do the primer and the blueskin peel and stick first and then flashing

Do you have room above the door to put a 2x under the threshold and raise the door