Water leaks between bottom wall plate and concrete sill.

So After a few rain storms I have noticed water coming in between bottom wall treated wood plate and concrete curb wall. The siding on the outside just sits above concrete curb wall rather then having 1/4 over hang. What have the folks on this forum done to seal this gap?

A few ideas and thoughts from friends.

1. Silicone between bottom wallplate and concrete.(outside) and on inside use gap filler.

2. Use Drip flashing off bottom of siding.

3. Use sticky membrane used for around windows (blue) (adhesive to concrete and bottom wall plate), then use flashing to go underneath siding and glue to concrete and bury 1 ft into ground.

Suggestions???????

Is your concrete curb well above the grade?

z-metal aka: drip flashing.
Slip it under the siding, and the bottom jogs out and overhangs your curb. A few well-placed nails through the siding to hold it in place, and you're good.

5lima30 said:

Is your concrete curb well above the grade?

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Yes it is. 4 inches

I have done quite a lot of siding and I haven't seen any flashing there unless there is a water table, which you don't appear to have. The Z metal is meant for a water table and wouldn't look right without it. What I would do use polyurethane caulk and seal the gap. The siding and the plywood should come down a bit over the sill plate for future reference.

+1 on the Z-metal flashing and use a good quality caulk where the concrete meets the sill plate.

MrMark said:

I have done quite a lot of siding and I haven't seen any flashing there unless there is a water table, which you don't appear to have. The Z metal is meant for a water table and wouldn't look right without it. What I would do use polyurethane caulk and seal the gap. The siding and the plywood should come down a bit over the sill plate for future reference.

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Normally we would have put the sheathing and siding a little bit over the sill plate but because the concrete curb wall pour was so out of whack (not straight at all) we just butted them up. If we had extended over the curb wall the siding would have followed the line of the curb wall and we would have had warped looking siding. I will have a look at this polyurethane caulk and give it a try.

Thanks very much.

You didn't mention the type of siding. If it's vinyl, I would take up the first course and the starter strip, attach a piece of lead flashing to the sheathing and let it hang down at least half an inch over the concrete. If the sill and sheathing of the building was intentionally held above the concrete to address an uneven concrerte job, you will have no problem working the lead to conform to the concrete. In any event, that detail you're describing is just plain wrong. The sheathing and siding should always overhang the top of the concrete. If the concrete is not straight, the sill should have been run outboard of the concrete enough to bury the discrepency. This detail forms a built in "drip" that keeps water dripping off the lower edge of the siding job and none of the wood frame of the building or the sheathing will ever get wet.

If you have a wood clapboard or other lap siding, although it's more work, I would still suggest removing the first course and installing a flashing.

Caulking would be a last resort approach and only used if you just don't want to go through the trouble of flashing the joint. Caulking has three big drawbacks, 2 of which are linked together: Drawback 1, It will most likely look like ***. Drawback 2, the caulking or any caulking for that matter is a temporary repair. Temporary means not permenant, it does not mean that it won't last quite a long time, that's dependent on a zillion variables. Drawback 3, follow the logic here...water runs down the sidewall, ideally your structure has a "drip" meaning that the water gets to a point where it collects in the form of a drop until such time then the surface tension of the drop can no longer hold it to the surface it's clinging to and the it drops off. Look at typical outside drip details, the drip edge on your roof, the little groove on the underside of your window sills. Both of these detials are designed to take into account that the water will cling to a surface and follow it until such time that the water drop is large enough to fall of as described above. The caulking you are proposing provides even more of a path for the water to get to your building since it does not provide a drip point for the water to collect and fall off. Given that a caulking job is seldom perfect and failures are nearly impossible to detect visually, you may well be providing an optimal path for the water to get to your sheathing and framing. So, if you understand the technology behind the caulking approach, you can see how drawbacks 2 & 3are linked together. Fix it right.

BTW: 4" between the grade and the structure is not well above the grade. In my area code is 6 inches minimum and just from a paint maintenance standpoint higher is better, But, there's nothin to be done about that now. If you are in an area prone to termites, a walk around the place every week or so to look for mud tubes up the concrete is advisable.

tcianci said:

You didn't mention the type of siding. If it's vinyl, I would take up the first course and the starter strip, attach a piece of lead flashing to the sheathing and let it hang down at least half an inch over the concrete. If the sill and sheathing of the building was intentionally held above the concrete to address an uneven concrerte job, you will have no problem working the lead to conform to the concrete. In any event, that detail you're describing is just plain wrong. The sheathing and siding should always overhang the top of the concrete. If the concrete is not straight, the sill should have been run outboard of the concrete enough to bury the discrepency. This detail forms a built in "drip" that keeps water dripping off the lower edge of the siding job and none of the wood frame of the building or the sheathing will ever get wet.

If you have a wood clapboard or other lap siding, although it's more work, I would still suggest removing the first course and installing a flashing.

Caulking would be a last resort approach and only used if you just don't want to go through the trouble of flashing the joint. Caulking has three big drawbacks, 2 of which are linked together: Drawback 1, It will most likely look like ***. Drawback 2, the caulking or any caulking for that matter is a temporary repair. Temporary means not permenant, it does not mean that it won't last quite a long time, that's dependent on a zillion variables. Drawback 3, follow the logic here...water runs down the sidewall, ideally your structure has a "drip" meaning that the water gets to a point where it collects in the form of a drop until such time then the surface tension of the drop can no longer hold it to the surface it's clinging to and the it drops off. Look at typical outside drip details, the drip edge on your roof, the little groove on the underside of your window sills. Both of these detials are designed to take into account that the water will cling to a surface and follow it until such time that the water drop is large enough to fall of as described above. The caulking you are proposing provides even more of a path for the water to get to your building since it does not provide a drip point for the water to collect and fall off. Given that a caulking job is seldom perfect and failures are nearly impossible to detect visually, you may well be providing an optimal path for the water to get to your sheathing and framing. So, if you understand the technology behind the caulking approach, you can see how drawbacks 2 & 3are linked together. Fix it right.

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Thank You for suggestions. Yeah one of the thoughts my builder suggested was doing the flashing suggestion. Talking to roofers around my area, I would be paying $5 a ft which is incredibaly high. I was hoping to find a cheaper solution. It makes me angry too, cause I pointed out to my friend/builder that the Vinyl siding should have been over hanging and his explanation was the not so straight curb wall.

If the top of you concrete is 4 inches above grade you are either getting a whole lot of splash from overflowing gutters (assuming you have them.), or the water is getting there from behind the siding due to a leak up high.

If you don’t have gutters, get them.

Otherwise get an umbrella and go stand in the rain a see where the water is coming from.

The "1% Rule" asserts that 99% of the sources of rainwater damage are found at 1% of the building envelope. While this maybe a catchy expression, all building professionals would agree that leakage problems at exterior walls typically are found at changes-in-plane and changes-in-material such as window and door perimeters and wall intersections with decks and balconies.
In other words, rainwater infiltration usually occurs at the transitions between the work carried out by different trades. In most cases, successful long-term weatherproofing of these transitions requires careful design and installation of flashing crafted from corrosion-resistant metal or flexible waterproof membrane.
It makes no sense or cents to put good work over bad. If the siding contractor knew there was a problem with the concrete that would hinder an acceptable install- he should of said something before he started. I have made many a contractor tear-out and re-do because of stupidity. And it was their dime.

You can do it the right way- or you can jerri-rig it. The flashing and caulk are temporary at best- because the flashing isn't being used correctly and the caulk will eventually fail. Sill seal would have been a great start- just a note for future reference.
The correct action would be to remove the first couple of courses of siding and get the concrete guy to cut the concrete flush with the wall sheathing. Since you can't "stretch" vinyl siding, a skirt board maybe the answer to getting below the plate- as illustrated in the attached pic.

K'ledgeBldr said:

The "1% Rule" asserts that 99% of the sources of rainwater damage are found at 1% of the building envelope. While this maybe a catchy expression, all building professionals would agree that leakage problems at exterior walls typically are found at changes-in-plane and changes-in-material such as window and door perimeters and wall intersections with decks and balconies.
In other words, rainwater infiltration usually occurs at the transitions between the work carried out by different trades. In most cases, successful long-term weatherproofing of these transitions requires careful design and installation of flashing crafted from corrosion-resistant metal or flexible waterproof membrane.
It makes no sense or cents to put good work over bad. If the siding contractor knew there was a problem with the concrete that would hinder an acceptable install- he should of said something before he started. I have made many a contractor tear-out and re-do because of stupidity. And it was their dime.

You can do it the right way- or you can jerri-rig it. The flashing and caulk are temporary at best- because the flashing isn't being used correctly and the caulk will eventually fail. Sill seal would have been a great start- just a note for future reference.
The correct action would be to remove the first couple of courses of siding and get the concrete guy to cut the concrete flush with the wall sheathing. Since you can't "stretch" vinyl siding, a skirt board maybe the answer to getting below the plate- as illustrated in the attached pic.

Click to expand...

Thank You for the detailed information. In regards to the water coming in, it is between the concrete and the bottom wall plate. I haven't actually stood outside and watched the rain but from my findings, it really looks like it is dripping off the edge of the siding onto the concrete curb wall and then dripping inside the garage. In Alberta the rain falls sideways. I have Sill Seal (foam material) installed under all walls. I think for this winter I will try the drip flashing and caulk as a temporary solution and in the spring pull the siding off and do as your diagram shows with a skirt board.

A proper flashing detail is not a short term solution. The flashing properly installed would perform a function identical to the proposed skirt and have the same function and service life as any other flashing on your structure. The reason I didn't suggest a skirt as a drip detail is that you would be dealing with a fairly rigid piece of material that would have to interface with the errant concrete. Taking the siding up and grinding the concrete where it interferes with the skirt will look like hell and the skirt would require a flashing of its own but we all know "flashing is temporary at best" so I don't know where that leaves you.

Resurrecting this old thread because it talks about a problem similar to mine. Hopefully keeping the information in this thread, in one place, helps someone else who Googles their way here.

It appears the bottom of my fully detached garage walls are starting to rot. The structure is 70 years old but was updated with a poured concrete floor about 40 years ago. Unfortunately the slab has heaved causing the outside painted stucco to fail where it meets the concrete floor.

The likely cause of heaving is too much water pooling at a gutter down spout. This is being addressed with much better water management (new gutters, concrete trough to channel the water to the city street, and footer drain along the back of the structure where heaving was the worst).

There is no flashing of any kind around the bottom perimeter of the structure. The concrete slab extends past the outer wall on three sides, about 4" or so, and is flush on the forth side where it meets a paved driveway.

My neighbor is a concrete foundation guy. I'm certain he can help. What materials and technique should I be doing to get this rot under control?

Attached picture from installing a new entry door. Yup. I know there are other issues. I'm trying to keep things a bit focused on this specific problem but all advice is appreciated.

Rick