Foundation openings for doors?

[Innovate1]

What's the generally accepted method to accommodate doors, both people and OHDs in the foundation? I think the OHD opening is generally 3" wider than the nominal size of the door which allows the track and brackets to be attached to the 2 x that is on each side of the door. Only downside I see to this is that the 2x go to the floor and will wick up moisture. I suppose they could be held up off the floor an inch or two so only the trim goes to the slab.

On people doors I cut a 45 degree cut on the inside of the foundation on each side so the door could swing past 90 degrees as I don't have a wall to stop the door. Again I think the notch in the foundation would be 3" wider than the rough opening needed for the door with a bit extra for shimming perhaps.

Looking to be enlightened on this...

 

[Innovate1]

A few more details...
Foundation walls are 8" and extend 8" above the floor. I am thinking I should cover the stub walls with foam since our winters are pretty cold so that will increase the thickness a bit. The walls are 2x6.

A couple foundation contractors suggested ending the stub wall at the floor height (pouring a footing first and then foundation walls and floor at once) but not sure how that would meet the needed 8" from framed walls to grade that local code requires. For sections without doors the outside grade could be that low and the driveway/apron could be 8" above the turf grade beside it too I suppose.

 

[mike93lx]

wood touching concrete should be pressure treated anyway, so moisture shouldn't be a problem. I'd still keep it off the ground a little, less than an inch. For any trim near ground level, I use PVC (Azek, Veranda, etc).

 

[Kaizen]

That was how wide my overhead openings were. I kept the pt off the ground by a few inches and covered with aztek trim boards.


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[Leaflessshadetree]

My contractor poured the walls leaving the sills for the man doors and overhead doors 8 inches below floor height. I'm not sure why. I had to pour sills for the man doors to bring them up to floor height. For the overhead doors I just made the slab 8" thick at the doors.
Width on the doors was a couple inches wider than the doors to allow for the jams/trim.
All of my framing is 10" above my finished floor level.

 

[matt_i]

I had an 8 inch poured wall on which I ended the wood (e.g. flush with the end of the concrete wall, wood does not go any lower). The inner piece of wood is a vertical 2x8, also a 2x8 under the header, and I bent the trim to the 7-1/4" plus 1/2" sheathing dimension. Slight bit of concrete grinding on the end of the wall so the last bend would wrap cleanly around.

We will see if the trim coil reacts with the concrete, my fix would be to bend new trim and place peel & stick on the concrete then.

I trimmed the opening with a 1x4 to add some dimension, I used a 24" long piece of Azek on each side before switching to the "white wood" for the vertical and horizontal pieces.

Here's a couple of pics. It looks like I only have a 2 ply LVL header but its 3 plies at the end of the day. Its important to think thru & commit to this detail when making block-outs in your foundation wall forms before pouring.

 

[kbs2244]

The door mfg will have documentation on this.

 

[Jlbc212]

I specify an additional 6" between the width of the concrete foundation. A 10 foot wide door will then have a 10 feet, 6 inch space between the foundation. The same thing for a man door - a 3 foot wide door will have a 3 foot, 6 inch space between the foundation.

At the door openings I specify the foundation top to be 12 inches below the top of the finished floor. This provides for a nice 12 inch thick concrete floor right below the doors. This extra floor thickness helps to prevent concrete crack development under the door. This is an area where there can be large temperature contrasts between cold outside temps and warm inside temps.

 

[ant.foste]

I specify an additional 6" between the width of the concrete foundation. A 10 foot wide door will then have a 10 feet, 6 inch space between the foundation. The same thing for a man door - a 3 foot wide door will have a 3 foot, 6 inch space between the foundation.

At the door openings I specify the foundation top to be 12 inches below the top of the finished floor. This provides for a nice 12 inch thick concrete floor right below the doors. This extra floor thickness helps to prevent concrete crack development under the door. This is an area where there can be large temperature contrasts between cold outside temps and warm inside temps.

For my (our) education here, why does the large temperature contrast dictate the need for 12" worth of concrete "sill"? Does the cold joint between the separate pour sea provide a measurable thermal break?

One additional question: what is your role? Architect? Concrete contractor? GC?

 

[gnpenning]

With a 8" stem wall above the slab depending on finish trim I agree with the extra 6" opening. The bottom stand off bracket for the OHD will work much better having the extra stud. You have a trimmer there already that you will be cutting a wasted 8" both sides. Make sure you have good drainage out of and away from the garage. If done properly rot should not be a issue.

 

[Jlbc212]

For my (our) education here, why does the large temperature contrast dictate the need for 12" worth of concrete "sill"? Does the cold joint between the separate pour sea provide a measurable thermal break?

One additional question: what is your role? Architect? Concrete contractor? GC?

Many, many years ago I worked full time as a garage door mechanic. I had to deal with many broken, heaved concrete floors at the door opening. Later in life I worked part-time as a residential designer and contractor. The most important thing at the door openings is having a foundation wall with a footing that is set into the ground at the lowest expected frost depth for the region. Having the 12" thickness of concrete for the floor adds extra strength to the floor at the door opening where there is often a sharp temperature contrast. From many years of experience and observation I know it works. However, like most other projects involving concrete, proper preparation of the sub-base, a good mix of concrete (not watered down or "hot") and keeping the concrete surface damp after the pour are all essential elements in preventing settling, cracks, spalling and powdering.

 

[gnpenning]

As mentioned above I have seen many slabs heaved and cracked at the opening where the rest of the floor is fine.

 

[Innovate1]

Just measured my current garage. 36" man door has 42" foundation opening. That looks great as it gives room for the casing with a bit to spare. The OHD framing is not visible. The foundation wall was trimmed to 4" thick back about 4" to allow a flat 2 x 6 on the inside to thicken the wall for trim I guess. The inside of the rough frame is 2" bigger than the door (1" per side) which is just covered by the 1" trim boards. Then a rubber seal to cover the minimal remaining gap. I am guessing one 2x inside the foundation opening each side but can't really see that detail. Rough opening in foundation would be door width + 5". Does the door trim normally overlap the door slightly or just the seal?

 

[gnpenning]

The trim overlap will give you a much better perimeter seal. I prefer the finished opening to be 1" under on width and 1/2" on height this what I tell my clients.

 

[Innovate1]

Was just noticing on my current garage that the interior slab is about 3" short of the outside of the foundation wall. The outside slab sits on that 3" ledge. Seems like a great way to do it but apparently a lot of them are run to the outside edge and the outside slab isn't tied to the building.

The interior slab still extends well past the OHD.