Hello,
Hoping someone can help. I'm building a 24X26 detached garage and was wondering what the dimensions the concrete pad should be. The garage will be purchased as a package from a local building supply store. Do I pour is exactly 24x26 or would I need to subtract for the vinyl siding?
thanks
John Balzac, AB, Canada
Check with the store. There must be drawings of the assembled building that will give the outer dimensions. The completed garage may not be exactly the advertised dimensions. I would guess that the dimensions will be for the framing. Sheathing and siding will be in addition to that and do not need a foundation.
Don't forget to thicken the slab below bearing partitions and columns. TB
The plans should tell you the needed size. Don't forget the footer, and when in doubt, use more steel thicker concrete and deeper footers.
When you pour the footers for the pad make sure that you stub up a piece of rebar at the location were your electrical supply will enter the building. The piece that you stub up should be galvanized or stainless steel the latter being better but much harder to obtain. As long as the piece you stub up is well tied to the rest of the footer steel it will be a really good grounding electrode for the buildings electrical system providing that you do not use plastic sheeting or any other non conductive material to line the footer trenches. If you do not include this simple step in the footer prep you will be stuck with a markedly inferior grounding system.
In Alberta, you have frost, in most areas, severe frost. Your foundation will need to have the perimeter deeper than your local frost line. Your local town or building committee will tell you how deep this needs to be, also check out needs for a permit.
Failure to address the frost problem may result >> Hello,
Ideally you build garage with a raised concrete edge / curb around the permiter, so the wood sills are well away from ground and water
install a empty pvc conduit or pipe to make getting power indoors easy. way easier than drilling later
Doesn't a raised edge trap rain water around the sill, like a swinmming pool?
My friend built a longer than 2-car garage with a kit from 84 Lumber, and I think he arranged to copy the instructions before he took delivery of the kit. Not sure, but I could ask.
His garage came out very well, with a propane furnace and AC, and room in front of the cars for bulky tools and parts etc.
He had one friend who knew some carpentry and had a power nailer, along with a group of friends, build the garage in 2 days (minus the single overhead door). Then he did details later.
As to foundations, he had that professionally done, with a trench in the middle and black plastic grills covering the trench, and the floor sloped down to the trench. This way he can wash cars inside the garage. This was important to him, I guess, or maybe he added it after he realized he was hiring a pro for the slab anyhow.
As to garage doors, my own opiniion is that one for two cars is a lot better than 2 one-car doors. This way if you have a lot of junk you can park in the middle, and even if you park at the side, it cuts in half your chances of hitting the garage with your car. There must be loads of people who hit that thing in the middle.
He'll want to ensure that the footers go below the frost line... Here in Houston, we don't have to worry about frost, but I see 30" footers around the perimeter of the detached garages on the new houses that are currently being built...
No the building sits directly on the raised edge, kinda a concrete sill.
Its pretty common around here for better garages and adds just a little to construction cost
There's also the issue that if you have a fairly large car, the standard 8 ft door is *very* narrow... I have a new Dodge pickup and I would probably need to fold the mirros in if I wanted to put it in my garage... If I was putting in a garage with single doors, I would go with 10 ft doors instead with more than just a column between the two doors... A minimum of 2 ft between the doors, possibly 4 ft... I prefer if it is possible to open the doors to the cars inside of the garage and they not hit the car parked in the other spot...
Basically, spend a couple extra dollars now and do it right...
Uh, no. The idea is that the sill plate should be one or two courses of block above the slab, inside and out, so water never can pond up against it. It won't rain inside the garage, but you should still slope the floor so whatever does get in or drips off car will flow back out the big door. Around here, garages usually have foundations just like a house, down below frostline, and include an inside ledge to catch the inside slab, which is usually poured almost last, once the structure is roofed in. Makes it a lot easier to get the slopes right, to rough in any utilities, etc. If I was going to drop a kit garage on a prefinished slab, I'd include monolithic footers in the pour, and either form up a 12" curb to catch the wall, or have rebar sticking up to drop block over and mud into place. Lumberyard should have a stack of the foundation layout drawings to go with each kit they sell. When framing, make sure the garage door opening and/or door you order match the header to slab distance. Same with the service door. IMHO, an extra course of block does wonderful things for interior headroom, and is real cheap to add when building the thing.
aem sends...
FTR, the kit didn't include the furnace or the AC. ;-)
No, hopefully it will be built well enough to keep the rain 'out' . You need the raised (6" min above the outside final (soil) grade) foundation to keep the siding out of the dirt etc.
You pour the stemwall/foundation( which sits on the footings you poured below the local frost line..Alberta, I'm guessing min 36" deep) first. Leave the area of the foundation where the overhead door(s) are going to be
4" short so that once the 4" floor is poured, you are at the proper grade. Also, allow an 'extra' 1.5" on each side of the door(s) foundation cut so you can run the framing 2X6's down to floor level at the side of each door. After those forms are stripped at a later date, you snap a chalk line along the inner perimeter where the floor is going, allowing 1/8" per foot slope, back to front (down) toward the door(s). This slope takes care of any sno melting or water that gets into the garage. I'd put down at least 4" of compacted 3/4 minus gravel where the floor is going to go, Then you pour the floor to the line and "out" thru the spaces left for the door(s)So to sum up, inside the garage, I'd have about 4" of foundation wall above the floor (chalk) line [at the back-more at the front because of the slope],
4" of concrete floor below the line and 4"' of gravel below the concrete for a total of 12" total 'dug out' depth relative to the top of the foundation. I'd put rebar in the floor too 24" on center. Some use wire mesh, some use a chopped fiberglass additive in the concrete instead of rebar. RHomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.