Structural question, I need advise

[bmacz06]

I am having a 22' wide X 40' deep garage built with 12' walls and a gable on the 22' front and back. I went with 2x6 walls due to the height. The concrete slab was poured yesterday and is flat on the back 20' and slopes to the front for drainage on the first 20'. The problem is they built the sill for the front half of the garage as if it was a 2x4 wall construction. I did not notice this until today and called the builder. He said that this was an oversight but that it would still be structurally sound and that they would fill it in after the wall is up with grout. He stated that it would be worse to try and cut it off and redo it.

Are there any builders or structural engineers that can tell me if he is on the level and it is ok to go ahead with construction. I don't have a good feeling about this. I am also putting attic trusses in the first 16' so the load on the walls will be increased slightly with the additional storage. Thanks in advance for the help.

 

[Sundowner]

I'm a structural engineer.
I'd need to see some pics, but it doesn't sound like a big deal.

 

[CraigFL]

So if I'm following you correctly, in order to make the sill plate mounting level for the front half, they built up the concrete on the front half sides and front wall (because the floor slopes). This built-up concrete should have been about 6" wide so that the sill plate would lay flat on it. Apparently, they forgot about the 6" walls and only made the concrete about 4" wide for a 2X4 sill plate.

I'm sure code says they need a 6" surface to mount the 2X6 sill plate. It would seem to me that grouting afterwards would not really be the right thing to do because the concrete would tend to shrink back and not provide support for the overhung 2X6 because of gravity settling.

I can't think of a really easy, inexpensive fix for this. The right way is to put the grout/concrete in before you put the sill plate on. This would mean you would need to attach this little sliver of added concrete in some way to the existing concrete. Using a sliver of pressure treated wood might work but you would still have to attach it to the concrete and you would have the PT wood touching the floor where water may be draining.

 

[bmacz06]

So if I'm following you correctly, in order to make the sill plate mounting level for the front half, they built up the concrete on the front half sides and front wall (because the floor slopes). This built-up concrete should have been about 6" wide so that the sill plate would lay flat on it. Apparently, they forgot about the 6" walls and only made the concrete about 4" wide for a 2X4 sill plate.

I'm sure code says they need a 6" surface to mount the 2X6 sill plate. It would seem to me that grouting afterwards would not really be the right thing to do because the concrete would tend to shrink back and not provide support for the overhung 2X6 because of gravity settling.

I can't think of a really easy, inexpensive fix for this. The right way is to put the grout/concrete in before you put the sill plate on. This would mean you would need to attach this little sliver of added concrete in some way to the existing concrete. Using a sliver of pressure treated wood might work but you would still have to attach it to the concrete and you would have the PT wood touching the floor where water may be draining.

You are correct, the built up portion is set for a 2x4. I will try to take some pics.

 

[bmacz06]

Here are the pics.

 

[Wardster]

There are a number of high strength grouts available to remedy this problem either before or after the sill is in place. The use of a bonding agent for whatever grout is used is highly recommended to ensure proper adhesion to the existing concrete.

-Wardster

 

[Sundowner]

So if I'm following you correctly, in order to make the sill plate mounting level for the front half, they built up the concrete on the front half sides and front wall (because the floor slopes). This built-up concrete should have been about 6" wide so that the sill plate would lay flat on it. Apparently, they forgot about the 6" walls and only made the concrete about 4" wide for a 2X4 sill plate.

I'm sure code says they need a 6" surface to mount the 2X6 sill plate. It would seem to me that grouting afterwards would not really be the right thing to do because the concrete would tend to shrink back and not provide support for the overhung 2X6 because of gravity settling.

I can't think of a really easy, inexpensive fix for this. The right way is to put the grout/concrete in before you put the sill plate on. This would mean you would need to attach this little sliver of added concrete in some way to the existing concrete. Using a sliver of pressure treated wood might work but you would still have to attach it to the concrete and you would have the PT wood touching the floor where water may be draining.

it's probably not that big a deal.
worst case scenario, I'd make the Contractor rip 1 5/8" off of a PT 2x6 and bevel rip a PT 2x4 to follow the slope of the floor. Then just make him use some stainless steel screws to face screw the beveled 2x4 to the ripped edge of the 2x6. If I was in a particularly bad mood, I might make him cap plate it with 2x6 over that, but it might be a problem if his hold-down bolts cast into the concrete aren't long enough to reach through the double plate.

Still, it's all conjecture until we see the pics.

 

[Sundowner]

can't see the pics.
can you email them to me?

 

[bmacz06]

can't see the pics.
can you email them to me?

I sent the pics via PM. I could not send you an email.

 

[Old Moparz]

it's probably not that big a deal.
worst case scenario, I'd make the Contractor rip 1 5/8" off of a PT 2x6 and bevel rip a PT 2x4 to follow the slope of the floor. Then just make him use some stainless steel screws to face screw the beveled 2x4 to the ripped edge of the 2x6. If I was in a particularly bad mood, I might make him cap plate it with 2x6 over that, but it might be a problem if his hold-down bolts cast into the concrete aren't long enough to reach through the double plate.

Still, it's all conjecture until we see the pics.

I agree with the above statement, but no matter which method you & the builder agree on & choose, it's still doesn't appear to be a major problem. (Adding concrete, or adding pressure treated wood.) Although if the builder made an oversight like this in the very beginning of the project, I'd now be scrutinizing all his work from here on.

Maybe I'm not able to clearly see the photo you posted, but I do not see any anchor bolts for the walls set in the already completed concrete.

 

[PAToyota]

I agree with Old Moparz - where are the anchor bolts?

Also, sort of looks like the "curb" was just poured on top of the slab? Is there any reinforcing from the slab to the curb? I can see that curb crumbling and causing problems over time - the corner has already fallen off in the one picture.

Not the way I'd have detailed it for any of my projects...

 

[bmacz06]

I agree with the above statement, but no matter which method you & the builder agree on & choose, it's still doesn't appear to be a major problem. (Adding concrete, or adding pressure treated wood.) Although if the builder made an oversight like this in the very beginning of the project, I'd now be scrutinizing all his work from here on.

Maybe I'm not able to clearly see the photo you posted, but I do not see any anchor bolts for the walls set in the already completed concrete.

You are seeing things correctly. They did not set anchor bolts in the concrete.

 

[PAToyota]

So, are you going to go back and drill holes in the slab/curb for the anchor bolts? Or what is the plan?

 

[Old Moparz]

The bolts can still be set after, but that will require drilling & using grout. It will still work, but like PAToyota stated, it does appear that the concrete is chipped off at the corner & may not be as strong. Drilling into the narrow "curblike" part, might cause further damage. If the raised part was added & not cast with the original pour, it could be weaker.

I still think it isn't a major problem, but if the anchor bolts are shown on the submitted plans, the building inspector will be looking for them.

 

[bmacz06]

The bolts can still be set after, but that will require drilling & using grout. It will still work, but like PAToyota stated, it does appear that the concrete is chipped off at the corner & may not be as strong. Drilling into the narrow "curblike" part, might cause further damage. If the raised part was added & not cast with the original pour, it could be weaker.

I still think it isn't a major problem, but if the anchor bolts are shown on the submitted plans, the building inspector will be looking for them.

I spoke with the buider and he stated that they drill for the mounting bolts. The raised part was cast as part of the original pour.

 

[Wardster]

I spoke with the buider and he stated that they drill for the mounting bolts. The raised part was cast as part of the original pour.

He will most likely use a wedge anchor, but they have minimum edge distances listed for them. I am pretty sure that you will be fine because of the type of loading your application has.

-Wardster

 

[Kevin54]

That is the first time I have ever seen anything like that. Going from nothing to a raised curb. I would have rather had a raised section all the way around all for the fact that any water on the floor in the back or sides, will wick up a 2x even if it is pressure treated. And any wall covering that you have will come down onto the bottom plate and can stand a chance of mildew or rust. But that being said, what is done is done. the contractor can fill in the void beneath the bottom plate but it will probably look like a patch job. What I WOULD be more concerned about is how he will bolt the bottom plate down. there are a variety of anchors out there. Some get epoxyied in and other get drilled and drove in and when you tighten the bolt the anchor pulls and swells out. With the curb only being 3 1/2" wide it could bust.

 

[BooUrns!]

The concrete being set for 2x4 seems to be more of an asthetic issue rather than a structural problem (I defer to Sundowners' opinion here). When I'm framing garages, as long as there is at least 3" of bearing surface I don't get concerned, regardless of the dimension of lumber resting upon it.

We typically pour floating pads here for detached garages and fasten the bottom plates down by drilling holes and fastening with Tapcons.

We have a somewhat dry climate so water on the garage floor isn't a big issue. I don't know of anyone that uses a lot of water inside their garage anyway.

 

[Old Moparz]

The concrete being set for 2x4 seems to be more of an asthetic issue rather than a structural problem (I defer to Sundowners' opinion here). When I'm framing garages, as long as there is at least 3" of bearing surface I don't get concerned, regardless of the dimension of lumber resting upon it.

We typically pour floating pads here for detached garages and fasten the bottom plates down by drilling holes and fastening with Tapcons.

We have a somewhat dry climate so water on the garage floor isn't a big issue. I don't know of anyone that uses a lot of water inside their garage anyway.

He mentioned that he pitched the floor in front 2" for drainage. I know a couple of people that wash cars inside, & up here in the northeast, melting snow from the car needs to go somewhere. I pitched the entire floor in my garage 2" as well, but it's a pole building & the floor is within the walls & isn't an issue like his. I'm willing to bet the curblike part was done so that precut studs wouldn't have to be all cut individually to different sizes.

 

[Charles (in GA)]

We have an aircraft hangar that was poured like this, in my neighborhood (fly in community). Front half slopes with a level sill all the way to the front. This was done on a pole structure. I thought it kinda strange and when I built my shop/hangar (metal building) I told my contractor I wanted a perfectly level floor. I have squeegees for times when I hose down the floor, which is not very often, too much junk, I usually sweep and wet mop.

Charles

 

[blkhonda1991]

that is a different detail than im used to see in construction...im used to seeing the foundation wall come up and be the part you put your sill plate on and the slab is poured inside of the walls, weird that the curb doesnt look like part of the original pour, probably due to the fact that it isnt textured like the floor

 

[BooUrns!]

that is a different detail than im used to see in construction...im used to seeing the foundation wall come up and be the part you put your sill plate on and the slab is poured inside of the walls, weird that the curb doesnt look like part of the original pour, probably due to the fact that it isnt textured like the floor

What you're describing is called a grade beam. It's a short concete wall poured onto piles with void form beneath to relieve pressure from frost heaving. I typically only see grade beams when they are part of an attached garage configuration.

 

[nissan_crawler]

I like the concrete stem wall (or whatever it's called). I have it in mine, however, mine is on all 3 sides (although sloped towards the front). I love it, I pressure wash the floor, then squeegee right out the front, walls don't get wet.

 

[PAToyota]

What you're describing is called a grade beam.

No, he is describing a stem wall. Grade beams are an entirely different animal.

 

[blkhonda1991]

What you're describing is called a grade beam. It's a short concete wall poured onto piles with void form beneath to relieve pressure from frost heaving. I typically only see grade beams when they are part of an attached garage configuration.

Grade beam? never heard of those before...but yeah like someone else mentioned i was talking about a frost wall pretty much but the term slipped out of my head while i made the other post

 

[BooUrns!]

Grade beam.

Perhaps you folks have a different building technique that is more suited to your temperate climate. This is what we typical use in lieu of floating slabs or when building attached garages.

I think we're veering away from the topic with our potato vs. potAtoe debate...

 

[PAToyota]

We do grade beams (with piles) for situations where the soil conditions are not suitable. But it isn't cost effective for residential construction. The OP does not say where he is at, but I'm guessing that he could have gotten by with a stem wall construction - poured footing, foundation wall, and floating slab. Basically what you are showing but substituting the footing and wall for the piles and grade beam.

Which really doesn't help the OP anyway as he already has things poured...

 

[PAToyota]

Oh, and for pictures...

Stem Wall

You don't have to keep the top of the wall flush with the slab - the wall can be higher. That would have allowed him to slope the slab as he pleased without affecting the wall.

 

[shift2sixth]

I'm not as concerned with the stem wall as I am with the amount of pitch on the floor. You stated that there is a 2" overall downward pitch in 20 linear feet. That's quite shy of the recommended 1/4" per foot when draining water. If my math is correct, 20 feet of floor should pitch down about 5".
My 22' floor pitches down about 3.5 inches and its is NOT enough. Water still pools in places because of the waves in the floor.
And I would have recommended a "beavertail" on the first foot or so at the door. A beavertail is an even more pronounced pitch under the door that keeps water from collecting under the door gasket. I highly recommend that.
Unfortunately your floor would need to be done over to make that happen. It would not be the first slab I have seen be re-done...
Good luck whatever you do!

 

[comp]

I'm not as concerned with the stem wall as I am with the amount of pitch on the floor. You stated that there is a 2" overall downward pitch in 20 linear feet. That's quite shy of the recommended 1/4" per foot when draining water. If my math is correct, 20 feet of floor should pitch down about 5".
My 22' floor pitches down about 3.5 inches and its is NOT enough. Water still pools in places because of the waves in the floor.
And I would have recommended a "beavertail" on the first foot or so at the door. A beavertail is an even more pronounced pitch under the door that keeps water from collecting under the door gasket. I highly recommend that.
Unfortunately your floor would need to be done over to make that happen. It would not be the first slab I have seen be re-done...
Good luck whatever you do!

is that # for a roof ???

 

[Justanoldguy]

5" in 20' ?
That would be like parking on a hill.

 

[bmacz06]

I chose to have the back 20' of the garage slab flat as I am installing a lift and I wanted a flat floor. I don't need any drainage in the back 1/2 of the garage because there will not be any water back there.

The first 20' slopes 3 1/2 inches which is as much as I need.

 

[shift2sixth]

Quote: "That would be like parking on a hill."

That's the idea! Water flows downhill. Like I said, I have 3.5" of pitch over 22' in my garage, and water still pools in there due to the slight waves in the floor.
Its common knowledge that .25" per foot is the standard for getting water to flow be it plumbing, garage floors, gutters, or whatever. Less than that, its like molasass in january....
I feel like I'm being criticized for poiunting out common knowledge. I was only trying to help.....
I can only imagine what your house would smell like if your plumber didn't pitch your toilet stack! LOL!
I've been in many a garage with too little pitch. You can tell right away by the water puddle stains here and there from water that pooled until it dried.

 

[blkhonda1991]

Like I said, I have 3.5" of pitch over 22' in my garage, and water still pools in there due to the slight waves in the floor.
Its common knowledge that .25" per foot is the standard for getting water to flow be it plumbing, garage floors, gutters, or whatever. Less than that, its like molasass in january....
I feel like I'm being criticized for poiunting out common knowledge. I was only trying to help.....

1/4" per foot is what we spec on all the garages i design, so you're not alone

 

[shift2sixth]

Thanks blkhonda1991,

Its nice to know that theres somebody out there that realizes how intelligent I am!

Now can you convince my wife of this please ?

 

[FunfDreisig]

I think the issue of floor slope largely depends on whether the structure is primarily a "garage" or a "workshop".

In the case of a "garage" cars are likely to be driven in soaking wet or covered with snow etc. - hence drainage is a concern.

OTOH in a "workshop" having a level or nearly level floor facilitates moving large objects around by simply pushing them by hand: cars, large tools, rolling carts. etc.

It sounds like to OP will have both - part flat "workshop" and part sloping "garage".

Funf Dreisig

 

[bmacz06]

I think the issue of floor slope largely depends on whether the structure is primarily a "garage" or a "workshop".

In the case of a "garage" cars are likely to be driven in soaking wet or covered with snow etc. - hence drainage is a concern.

OTOH in a "workshop" having a level or nearly level floor facilitates moving large objects around by simply pushing them by hand: cars, large tools, rolling carts. etc.

It sounds like to OP will have both - part flat "workshop" and part sloping "garage".

Funf Dreisig

That's the plan. Since the garage is 40' deep I will be using the back half to store a car on one side and work on cars with a 2 post lift on the other side. I will be using the front half of the garage for the 2 other cars that I drive on a regular basis. My wife will continue to put her truck in our current attached garage. I will no longer have to be concerned about her lack of parking skills.

 

[JohnS]

There are two problems:

1) The wall base plate should attach to bolts cast into the concrete 24" O.C.
At this point, I would bore holes and install the bolts with epoxy formulated
for concrete. This is available at a contractor supply house.

2) Yes non shrink grout is strong hold enough to take the load of the wall.
But, only 2"wide may not adhere to the concrete. There are bonding
agents that can be mixed into the grout. Ask for an extended warranty
from the contractor.


JS
North Carolina GC License 38530

 

[Pritch]

1/4" in 12" is too steep, IMO, for a garage floor. OK for a sidewalk but not a garage. 1% is fine for concrete and 2% for asphalt. That's what we see spec'ed around here, on commercial projects, anyway. 1%=1' of fall in 100' or 3" in 25', which is a little flatter than what he has. I would use a non-shrink grout under the bottom plate and never give it another thought. I would also use a threaded rod and epoxy for anchor bolts, a redhead will blow out the side of the curb. Maybe move the hole for the anchor bolt to just inside the curb. This would still catch plenty of bottom plate, and give an exellent place to attach some reinforcing for the non-shrink, maybe some 3 bar or a 1/4" all thread behind the anchor bolts.

 

[SCOOTER]

Goofy wedge poured on top of a slab...Seems a lil hokey anyway, Just sil it, drill it and using threaded rod epoxy them into the slab for your hold downs.

Fill the void with mortar after putting on ''bonding agent'', Jam it in with a trowl like your grouting tile, And just move on with your life...Oh ya one more thing tell your contractor he is a Jackoff!!!