Ideas for Sealing the Bottom of a Wall Framing Plate Sitting on Top of Concrete Slab

www.homebuildingandrepairs.com Click on this link if you're interested in learning more about wall framing, concrete building foundations and home repairs. This video will provide you with a few examples that can be used for sealing the bottom of a wall framing plate or the bottom of an exterior wall that's sitting on top of a concrete slab. Not at the edge of a concrete slab like most construction, but about a foot or two from the edge. Remember these are only suggestions and you might need to check with local building authorities for more information.

[@Natedoc808]

Another option is to cut a channel into the concrete just outboard of the bottom plate, z-flash from the plate into the channel, and insert drain track like we put in pool decking. The bottom plate should still have a barrier such as 30lb felt, with an adhesive sealant such as Lexel.

[@davidkafka2452]

I believe this is similar to the solution Matt Risinger used without the drain track. Drain track seems to be a nice addition.

[@Natedoc808]

@@davidkafka2452 really? Well that’s fine company to be mentioned alongside.

[@bamc3835]

subscribed! just found you and love the visuals as i am a very visual person and need resources before we start framing next week. do you have any video showing the wall details for a zip r3/zip sheathing with 2x4 wall studs on top of a slab foundation with a brick ledge for a full-brick house? most things i see do not have the brick ledge detail so they are probably using hardi siding or stucco...tnx and looking forward to watching more of your videos

[@gregvancom]

Not yet and thanks for the subscribe and keep learning.

[@clubjumping]

You could use composite plastic posts 3x3 or 4x4 as your "to the floor" wooden part of the frame and mastic and screw direct to the floor, even stack it in layers to become a type of composite party wall

[@randallsmerna384]

Not to code. Best to start out with a plan that keeps any wood product from ever making contact with exterior water such as a raised concrete foundation.

[@kimlewis8276]

I have a question ? I had water problems, I live in Florida. I built a French drain around the 12 by 15 room which was on a slab. Existing walls I cut the baseboard out cleaned it all out vacuumed it let it dry out for a month and then what I did was I ended up getting concrete with rocks and I mixed it up and I put it in between the two-by-fours on the ground in between the floor plate. I then put the 4 in baseboard on it and I let it dry turn down the air conditioner for a month after it dried I put another baseboard on it raise it up higher with the concrete in the wall I blew some foam insulation on top of the concrete and then proceeded Lee to put the paneling back down over the insulation and the concrete. I went out and I got skills and I painted all the boards on the floor with Kilz and then I ended up getting a roofing compound and just painted that on several layers thick and then I glued everything back together again and every 5 years I have to reseal with a roofing compound I have not really experienced any water inside the room since I did the concrete and the foam and the roof sealer a small little bit but not as much as I normally get in this room. I live in New Port Richey Florida and when it floods my backyard we usually get two or three feet of water I sealed the door right up to four foot with the roof sealer and it has not been leaking since I had seal it. My question is can I put concrete all the way up in the framing of the walls will it hold it in place along with plywood against the wall I just want a more secure place because I live in a area where it's very bad on drugs and if there could be concrete I prefer to have concrete considering that it will slow a bullet down if it ever Strays this way

[@gregvancom]

I've seen what you're suggesting done before, but most of the time people build block walls.

[@danielbuckner2167]

I would use a flashed membrane against the framing and then continue it to the outside edge of the exposed slab. I would suggest something suitable for exterior like a waterproof decoupling membrane. I would suggest something like an exterior tile or cementacious coating suitable for an exterior surface. This assembly keeps water from entering the slab and wicking beneath the wall.👍

[@gregvancom]

That sounds good.

[@ryanyork837]

If take a grinder wheel in some Z flashing. Cut a groove in the concrete about a 1/2 an inch deep with a thin blade. Put some calking down in the groove and slip your flashing down into the concrete and then put your side down over the upper half and it will Stop the leak because mechanically the water cannot go under if it's glued into the concrete even if the concrete's not perfectly flat it has to penetrate Under that lip and then wickets way back upward and that's not typically the case.

[@MoOoNiEz]

Hi Greg, probably in the same family as that comment that was looking at something similar for brick ledge. I have an extension off the kitchen (7x8 room) that only has a mat of “peel and stick” (you can really peel it right up) separating it from the elevated concrete slab. The room itself is framed up on wood studs and its exterior walls are adjacent to the brick veneer (but built away from it, like you say here). I think the concrete is wicking too much moisture (the side door sill plate or threshold are messed up and allowing water… long story), which is going to rot up the framing. What all can I do as a retrofit solution?

[@gregvancom]

If you can't find something in our videos, then email me picture of your problem and I will see if I can help.

[@mikecrawford5331]

What about first putting down a plastic trex type synthetic 2x4 under your sill and then flashing around that ?

[@1omarrr]

Yes. Weep screed is not available . can I use instead aluminium flashing like the one used for cladding or roof flashing?.thank you .great video.

[@gregvancom]

I've seen other types of metal used, so I would say maybe, but I would hate to say yes and in ten years the metal is rusting or damaged. Check with your local contractors or building departments.

[@vm8515]

Gregvancom. In the last example you give (6:20), Does pressure treated plywood sheathing go first then metal you mention then water/ice paper then tyvek?

[@gregvancom]

That is a bit over doing it, but if you live in the snow or where it rains a lot, then go for it. Please keep in mind that these examples might not work in extreme climates.

[@randallsmerna384]

Forget the j-metal. Wrap the bottom of both the plate and the bottom of the sheathing. Still use polyurathane sealeant everywhere you can. Then overlap the wall covering , (tyvek, etc.), over the bituthane - seal this too. Use a polyurathane sealant at EVERY joint and contact point as well. NEVER have concrete continue from the exterior of the home to the interior. Always have moisture and thermal break between the them. SLOPE your concrete AWAY from the structure. Have it ground down if it isn't already. SEAL THE CONCRETE. Use overhangs and gutters to further limit that portion of the concrete from ever seeing moisture. Have your yard sloped and draining AWAY from your structure.

[@analarson2920]

Interesting. Seems like the best is to create an ankle or knee wall of cement on a slab with a solid build. Waterproof and build on that.

[@kevinhornbuckle]

One approach would be to put strips of thin concrete board under the studs. Roofing felt should be stapled to the bottom of the plate even if the plate is pressure treated. So intentionally create and air space under the plate. Fill that with backer rod. The air space is serviceable. Also spend the extra money on stainless or copper flashing and don't let it contact the slab.

[@gregvancom]

Yes, always open to more suggestions. Good point about the metal, any metal that touches a concrete slab "with moisture" could rust a little faster.

[@AngelX]

Put the concrete board under the studs or the plate? I'm a newbie so I'm not sure how you do that if it will be under the studs.

[@troofseeker100]

Good video

[@gregvancom]

Glad you enjoyed

[@robbyvenetian]

Great vide as always! I was looking for info about how to seal a wall plate on concrete. Do you think it's possible to make a garage extension on a driveway directly on the driveway concrete without foundations? The extension to build would be 12x23x12.

[@gregvancom]

I've built over slabs 4 inches thick before, but most building departments and engineers would probably never approve it.

[@robbyvenetian]

@@gregvancom, thank you very much.

[@H_o_g_a_n]

this is the exact situation i need to fix. thank you

[@gregvancom]

You're welcome.

[@staple_gun6367]

Same

[@egold33311]

Thanks for the video. Do you know of an alternative to Weep Screed as its not available where I am?

[@gregvancom]

It's not the best idea but I've seen j metal installed on the bottom, but don't like that idea because it often deteriorates from moisture. If you can't find anything, then maybe leave the metal off.

[@xavierlanggaman8474]

Hi, what do you think of making a concrete bed first, like a barrier curb on the existing concrete slab - to lay on the sill plate timber/metal? thanks!

[@gregvancom]

As long as it's structurally sturdy, then absolutely.

[@Natedoc808]

A single course of proper doweled, bonded and mortared concrete block, all cells filled with J bolts per code. Then you could liquid flash it same as you would if you were back filling a block wall basement for extra protection, you could then overlap the sheathing with counter flashing sealed to the block, house wrap shingling over the counter flashing and it would be absolutely bombproof. We are doing. 2K square foot additional onto a house with this exact method as it will stand up to the very wet and rainy weather in GA.

[@randallsmerna384]

Water ALWAYS wins and ALWAYS finds a path. ANY concrete slab which extends from exterior to interior under a wall or sill plate will ALWAYS escort moisture under it. There MUST be a moisture/thermal break between the outside and inside concrete. The sill plate must be higher than the exterior grade. Pouring a concrete raised stem wall on top of the existing concrete may keep the wood from direct moisture contact but water will always wick under.

[@rokgrabnar]

i would add hydro insulation all over the concrete slab ... approx. 3mm in two layers ... so overall thickness would be 6mm. And then when installing studs to the slab, I would put thick layer of caulk between a hydro and a stud ... and also later caulk around edges so no cold air could penetrate inside flooring and create condensation. I used in my project at home caulk sika 11fc and when it cures it's like a really hard rubber and it will last forever probably.

[@urf808]

Rok Grabnar eventually water wins..

[@danno8852]

Cut a 1” wide channel into the concrete with angle grinder as close to the sill plate as possible, install and extend either lead flashing or ice and water shield from framing to bottom of channel, fill in channel (wet set flashing into) with hydraulic cement/good quality mortar. Done.

[@gregvancom]

Let us know how it worked in few years.

[@danno8852]

@@gregvancom I’ve never done it, just thinking of ideas. Can you think of any reason it wouldn’t work? Just curious.

[@randallsmerna384]

​@@danno8852 Yeah - you can't stop water. While I do like the idea and recessing an edge of flashing into a kerf cut into the concrete, the fact is that if water is allowed to reach the flashing then it will surely eventually devour that metal. Moisture can always weep through the concrete itself - esp. if there are any cracks. I used this kerf method on a stucco house when I added a small overhang with metal roofing over a sliding door. Reasons why it was successful are: * The roof of the new overhang was pitched away from the house so water didn't just sit there. * It's in the southwest which has limited annual rainfall.

[@centexan]

I thought all the person was concerned about was laying the wood directly on the concrete slab and soaking moisture from the concrete. All that metal is totally useless. Some kind of waterproofing membrane under the bottom pressure treated sill should suffice. Long ago there was a rubber membrane that was used. It was about 3/16" thick. There are probably better products today. I believe you way over thought it. If there is a lot of water in the basement, nothing will help without a drain or sump pump system.

[@urf808]

Why not cut a 2” key way into the existing slab on grade and make a raised 1”lip 3” key way depth. And than seal the concrete with a self leveling Crete. The extending “toe jam” threshold Could extend 1/4” beyond the edge of the concrete key way pour and cover the door jamb area with a molded wood. Thus having a inner floor level with tile install just about. 1/4 below the jamb. The exterior walls could be as you state with flashing, but I would add a 50 year weather barrier below the flashing and studs. Then caulk and seal after adding the exterior wall sheathing, vapor barrier and siding. That way no water ever unless there is a flood. But is his slab on grade above county standards for flood. Is he in a flood zone. Is he in a 100 year flood zone. If he is not in a flood zone than his existing grade has to be 6” below the slab on grade.

[@gregvancom]

Have you tried this method before and doesn't work or is it just a suggestion?

[@faheyiiip]

Basically I still don't know what to do or how. Thanks

[@Luqman899]

i feel the exact same way lol

[@Natedoc808]

In this case, I’d simply set concrete block on top of the slab, properly bonded, doweled and anchored and build my new wall on top of that single course of block perimeter :-)

[@gregvancom]

I like it.

[@Mantis858585]

This is actually my plan, came here to look at other ideas.

[@stoneyj1a1]

Any videos on how to pitch away from a building? Like a how to?

[@gregvancom]

How to pitch soil, concrete or other???

[@stoneyj1a1]

@@gregvancom concrete. my garage is leaking

[@richardrumplik7023]

I did the urethane under the wall sill plate and treated lumber. To the patio foundation. Which didn’t have a raise hi

[@richardrumplik7023]

To protect water entry. It has been in use for 17 years! Still working well and no adhesion issues.

[@gregvancom]

Thanks for sharing and I'm wondering why you used it. What made you select expanding foam?

[@richardrumplik7023]

@@gregvancom I didn’t use foam I used urethane caulking.

[@johnromans732]

what did you call the flashing that has the holes for drainage

[@gregvancom]

Stucco weep screed.

[@daveg7314]

on the out side the metalis uesyually for termites in California.

[@vrea77]

It's a house you're always going to have problems eventually with the weather elements just like a car needs maintenance

[@baruchba7503]

This is the main reason why I prefer raised flooring with a crawl space. The rule of thumb is there are 2 types of concrete, concrete that hasn't cracked and another that is cracked.

[@gregvancom]

I like your two rules, concrete that is already cracked and of course concrete that will crack eventually.

[@rokgrabnar]

that's why we need to add hydro insulation all over a concrete slab so it could hide potential cracks and also before pouring cement, we should add enough of rebars for reinforcement and concrete shouldn't crack. Here in Europe nowadays we even add xps insulation before concrete is added so that no moisture travels through the slab and also increases the energy efficiency of the house.

[@randallsmerna384]

More importantly, the concrete slabs need to have a thermal and moisture barrier. Preferably the interior slab (and/or stem wall), should also be higher.

[@robertmccarty3897]

i do this if you want a good sealant polyurethane is the best ir dries to a RUBBER WILL NOT CRACK

[@jonathanochoa4560]

Came on here for sealant recommendation lol

[@kai6424]

I would say pour a footing

[@urf808]

Gregvancom... is he in a flood zone should have been your first question to a slab on grade build. You could get away with a garage or storage shed but not a home.

[@gregvancom]

I don't know this individual is in a flood zone, but I don't know if it would matter either. The amount of water on top of concrete is the problem and that could come from rain snow or even a garden hose.

[@mikecrawford5331]

Probably just need a raised curb.

[@ram43x80]

Jist say z-bar will work or caulking geez

[@gregvancom]

What about the other examples?