Curb around my shop necessary?

[Dreamshop]

My shop is currently being excavated for now.

The design is a slab on grade and I mentioned to the contractor that I wanted to have a 6" "curb" poured around the perimeter for the walls to sit off the floor. My contractor doesn't think it's necessary as he uses sill plate gasket and vapour barrier wrapped a foot of so up the wall.

Thoughts?

 

[zc15]

Pole building or stick framed?

 

[Dreamshop]

Stick frame. Sorry should have mentioned that.

 

[Big Bad Dad]

It's going to be a pain in the backside to form, and to pour and finish while doing the slab. Can you have him put in some rebar stubbed up and then lay one course of block tied into the rebar as your curb?

 

[Leaflessshadetree]

For sure it is not necessary. I would want it especially if the slab is close to the surrounding ground. If the interior walls will be drywall (or other material that may absorb moisture).

 

[Dreamshop]

He says if I want it, it has to be formed and poured after the slab is poured and it would be extra cost to me.

 

[Dreamshop]

I'm not sure what my inside finishes will be yet.

 

[NUTTSGT]

He doesn't want to do it because it's more work.


Give it time, it'll leak, especially when that snow drifted up starts to melt.



From Owens-Corning.

ComfortSeal™ Sill Gasket is a polyethylene foam gasket, which provides resilient sealing in new and retrofit construction. ComfortSeal™ Framing Gasket is a low cost, durable, easy to install, compressible polyethylene foam gasket specially designed to seal air leakage.


Sill seal, designed to stop air leakage, not water.

 

[Dreamshop]

He doesn't want to do it because it's more work.


Give it time, it'll leak, especially when that snow drifted up starts to melt.

Yeah. I think I'm going to insist on it.

 

[Zeke]

He's doesn't know how to place a monolithic slab with stem wall. Code requires 6" of non organic material above grade. If you have a flat slab you still need 6" high edges sitting on top of grade. Steel buildings are exempt. Ask folks with pole barns how any organic materials other than the poles are holding up the are close to soil.

 

[ConCretin]

The main value of the curb is that it lifts your wall framing above the interior and exterior grades and protects the wood framing from moisture damage. It can be poured monolithically with the slab but would still cost more than just the slab.

How much distance do you have from finish grade to the top of the slab? How much pitch is there away from the building? Are you installing gutters? How much water will you track inside? I almost always add a curb to a mono-slab but you are the only one who can decide it it's worth the extra $$.

 

[dcg9381]

Make sure the slab is elevated enough that you're not going to have water against it.
Here, they do a "rat lip" - which is basically a 1x1" square cut out around the perimeter for the R-panel to fit into. Water don't flow up hill.

 

[jack stand]

He doesn't want to do it because it's more work.

Probably he doesn't want to do it for free because it's more work.
Sounds like you're building new, have him thicken the edges and raise the slab elevation 4". Outside water is what you need to worry about and if it's inside water, a double, triple pt bottom plate is simple.

 

[TractorJeff]

Other than outside water getting in.
My main concern is welding BB's/Slag rolling over to rest against the wall. (FIRE?)
I didn't have the curb done. Instead I got some steel plating that rests on the floor and is bolted to the wall in my fab/weld area.
Honestly though I do 80% of my welding outside to prevent hot slag spalling the concrete.

 

[cmandp]

The minimum I would accept is the slab being a few inches above grade. I'd really like a curb on our current shop but the slab was built at or settled below grade and water can flow under the sill if we get a really heavy rain.

 

[racecougar]

IMO, a stem wall is absolutely worth pursuing. You won't regret doing it; you may regret not.

 

[yeldogt]

The main value of the curb is that it lifts your wall framing above the interior and exterior grades and protects the wood framing from moisture damage. It can be poured monolithically with the slab but would still cost more than just the slab.

How much distance do you have from finish grade to the top of the slab? How much pitch is there away from the building? Are you installing gutters? How much water will you track inside? I almost always add a curb to a mono-slab but you are the only one who can decide it it's worth the extra $$.

Does sound like a lot of work .... but in snow country getting it up I'm sure is important.

 

[yeldogt]

I can't say I have ever done that ..... but, I do elevate the slab. There is no perfect construction method ....

 

[Stuart in MN]

Is adding a course or two of concrete block on top of the slab an option? Either way I think it's important to keep the wood framing up and away from moisture. Also, over time it's not uncommon for soil to gradually build up against the base of the garage wall, and you don't want that happening against the siding.

 

[larry4406]

Stem wall with slab pour can be done in one shot. Yes more work. Often a reason folks change to stem wall on footing with slab on ledge (3-pours).

We do integral stem wall with slab with a certain house type of ours; rear load garage in basement. The stem wall length is not very long though.

Sorry these pictures are not the best.

 

[NUTTSGT]

Probably he doesn't want to do it for free because it's more work.
Sounds like you're building new, have him thicken the edges and raise the slab elevation 4". Outside water is what you need to worry about and if it's inside water, a double, triple pt bottom plate is simple.

Anybody that thinks they're going to get extra work for free, might just want to put a dunce cap on and sit in the corner. I sure wouldn't expect the contractor to do it for free.

The OP wants his building a certain way and if it was in the original plan, the contractor should be doing it that way, no excuses. If it wasn't in the original plan, it's a change order and the OP needs to pay the up charge.

 

[Walkers]

What part of the world are you in? Makes a big difference. Here in Phoenix Az, they almost never do that, just pour the slab, build on top of it. Current height above highest point within 10’ is 16” for the slab According to the code we are using. Maybe if your allows shallower slab, then add the curb.

 

[u2slow]

My stem wall was done first, slab after. It's about 16" above grade. I did NOT want to deal with moisture, ants, or termites wrecking my structure.

 

[andyvh1959]

I have built three garages since 1980, all were floating/edge-lock slabs, two with a single row of 8" block on the slab, last one with two rows of block on top of the slab. Never had any water issues (all three here in east central WI). Latest build was on the side of my lot with a slight grade on the east lot line that required two rows of block to get the sill plate at least 4" above grade.

 

[Dreamshop]

What part of the world are you in? Makes a big difference. Here in Phoenix Az, they almost never do that, just pour the slab, build on top of it. Current height above highest point within 10’ is 16” for the slab According to the code we are using. Maybe if your allows shallower slab, then add the curb.

I live in ontario Canada in the country. We get a fair amount of snow and rain up here. The shop will have evestrough.

 

[Walkers]

I live in ontario Canada in the country. We get a fair amount of snow and rain up here. The shop will have evestrough.

I would imagine if you have eaves, gutters, and decent grading it would be fine, but I know very little of harsh snowy winters, so it is a little but out of my purview.

 

[BombShelter]

Like Stuart said, most buildings have a "course of block" using CMU (cinder blocks) on top of the poured slab, I'm pretty sure it's code here, you want space for bugs and water between the ground and wood. Pouring a curb would be very expensive compared to just laying down one or two layers of block. I don't think I've ever seen a monolithic edge curb and I've looked at thousands of garages, I think some food and medicine prep buildings use something similar but it's for hygienics.

The contractor will core fill some of the blocks with threaded rod so you can bolt the wood sill plate to the top of the block. Do not put put the wood on the slab, water will eventially get inside. Gutters are awesome, get the water away, if it's an important space I'd add heat cord to the roof, gutters and downspouts so it drains year round. Do not drain right at the foundation, use extensions or underground piping to get that water away from the foundation.

 

[ddurrett896]

Course Of block and be done with it.

 

[CraigStu]

I can see why he would rather not do the curb/stem wall. Larry does it and he and his crew are used to it. For anyone else I could see doing that all in one pour would easily double the labor time. A course or three of block on top of the slab is much easier and works well. 3 courses gives you about 2ft height so you can get a 10ft ceiling while still building 8ft wood walls. For me that is the only way to go.

 

[yeldogt]

I can see why he would rather not do the curb/stem wall. Larry does it and he and his crew are used to it. For anyone else I could see doing that all in one pour would easily double the labor time. A course or three of block on top of the slab is much easier and works well. 3 courses gives you about 2ft height so you can get a 10ft ceiling while still building 8ft wood walls. For me that is the only way to go.

Exactly ....

Building a garage/ utility building is not the same as building a house. Crown the placement spot and pour the slab is not the same as putting in a foundation w/ footing and pouring the slab inside or building a mono with stem wall.

I have never had to do the block over slab - seems reasonable if ground conditions don't allow for just the slab. Slab to me is utility .... the next step is foundation and slab inside

 

[racecougar]

It all comes down to the quality of building you're after.

 

[larry4406]

Keep in mind that the mortar bed joint between first course of block and the slab will allow moisture to seep thru as will the porous block. So depending on your grade, you might want to look into water proofing options if you go this route.

My barn project is a dead flat slab, no stem wall. My grade is dropped relative to slab.

 

[larry4406]

I can see why he would rather not do the curb/stem wall. Larry does it and he and his crew are used to it. For anyone else I could see doing that all in one pour would easily double the labor time. A course or three of block on top of the slab is much easier and works well. 3 courses gives you about 2ft height so you can get a 10ft ceiling while still building 8ft wood walls. For me that is the only way to go.

The approach is actually quite similar to how street crews pour curbs and gutter pans all in one shot.

 

[Glemon]

I did a course of block over the slab on both garages I have built. Think it is pretty standard around here. Did it myself the first time, brick guy that was doing the brick the second, anyway, not very hard or expensive, put rebar in the slab to come up through the block to tie the sill plates to, easy peasy

 

[Zeke]

Like Stuart said, most buildings have a "course of block" using CMU (cinder blocks) on top of the poured slab, I'm pretty sure it's code here, you want space for bugs and water between the ground and wood. Pouring a curb would be very expensive compared to just laying down one or two layers of block. I don't think I've ever seen a monolithic edge curb and I've looked at thousands of garages, I think some food and medicine prep buildings use something similar but it's for hygienics.

The contractor will core fill some of the blocks with threaded rod so you can bolt the wood sill plate to the top of the block. Do not put put the wood on the slab, water will eventially get inside. Gutters are awesome, get the water away, if it's an important space I'd add heat cord to the roof, gutters and downspouts so it drains year round. Do not drain right at the foundation, use extensions or underground piping to get that water away from the foundation.

You never been to CA. According to history (or lore), sequentially built houses (tracts) were started in Lakewood, CA next to the Douglas Aircraft plant copying aircraft assembling line techniques. This was at the close of WWII when 1000's of homes were needed for new families. Starting there and in every tract since (millions of homes) all garages had stem walls placed at the same time as the garage concrete floor and house foundation walls. (At the time, houses were built raised with a crawl space.) Even the front porch was placed at the time. There was no way a concrete truck was going to visit a lot a second time. In 3 days 3 separate crews had a roof with sheathing ready for shingles.

The plumbers were already walking up to the framing with pipe. When housing was being sold by a lottery and a block at a time came up for sale, there was no time wasted. I don't see that much more labor involved. I was a general contractor for 50 years though I wasn't involved with new house construction. My business had me giving out around 100 estimates a year and doing 50 to 60 jobs a year. I've seen a few houses of every vintage.

 

[Dreamshop]

This is what I want done. Only downfall is I guess I'll loose some internal size unless I have him do a 6" x 6" stem wall

 

[yeldogt]

This is what I want done. Only downfall is I guess I'll loose some internal size unless I have him do a 6" x 6" stem wall

That's not a typical slab ..... slab is slab

 

[Dreamshop]

That's not a typical slab ..... slab is slab

That's an engineered slab up here.

 

[NDJ]

Is that typical leveling of a subgrade before pour ? Apparently I have been doing it far too smoothly....

 

[yeldogt]

That's an engineered slab up here.

Right .... But if you asked for a slab and did not give pictures or specification to the guy providing the quote he is not going to think you want that