I know 16'x7' is the average sized two car garage car entry door but it makes it tight for 2 wide cars.

Are 18' x 8' doors or 18 x 7 doors feasible?

Posted By Lbear on 25 Jun 2016 06:21 PM
I know 16'x7' is the average sized two car garage car entry door but it makes it tight for 2 wide cars.

Are 18' x 8' doors or 18 x 7 doors feasible?

YES

Garage doors (and garages) always seem to be a bit tight. Cars these days are wide. My wife's Olds is 12' wide with both doors open, and the 'small' SUV's we've been looking at aren't that much narrower. Other than really tiny cars, most cars run about 6' wide. If you could pull in with zero clearance on each side of a 16' door, that still only leaves 4' between the cars. A 16' door isn't actually 16' once you add trim, plus no one would expect to pull in with zero clearance, so the resulting space would be very tight. Even an 18' door is fairly tight, but workable. We built an oversize one car attached garage with a 9' wide door, and my wife still has trouble backing in. For some reason, the use of side mirrors escapes her, and she did take a mirror off one day trying to back in. If she pulls in forward instead, she has to do a lot of backing up on a poorly lit gravel driveway at 0-dark-thirty in the AM when she leaves for work. Oh yeah- I pinned a concrete curb in place to keep her from making our garage a rear exit.

If I wanted two cars, and had the room, I'd have two 9' doors with 2-3' in between them. Another thing- If you ever think you might have a taller vehicle, go for an 8' high door. My 3/4 ton van won't fit under our 7' door. If you favor an extended cab long bed pick-up like some folks have, a 20' deep garage won't work either. You have to consider the size of the cars, plus driver error, plus having enough room to open the doors and get stuff out without doing gymnastics.

16'x7' garage doors are common on lower end spec homes in this area. 18'x7' are more common on higher end homes. 18'x8' doors are also available. Two 9'x7' or 9'x8' or 10'x7' or 10'x8' doors with a mid-span support are also available. I have a brick exterior and installed two 10' wide x 8' tall garage doors to get the mid-span support for the header and brick lintel. It takes a heavy duty header and steel lintel to span 18' and support the roof and brick veneer. If you install the garage door on the gable end of the garage, support requirements are less, but 18' or even 16' is still a long span.

Lesson learned: I had a friend that recently built a new home and he has an 18' garage door on the non-gable end of his roof. The builder ordered an 18' Power Header which is laminated 2x4s and comes 18'9" long so that you can put 3 cripple studs under each end to support the load. The builder ended up cutting the header down to 18'3" long and only using a single 2x4 cripple stud under each end. Dumb, dumb, dumb. My friend ended up scabbing an extra 2x4 cripple under each end to provide long term support for the load, but now reduced his garage door width by 3". I used double cripple studs on my 10' wide doorways.

Posted By jdebree on 26 Jun 2016 06:24 AM
... For some reason, the use of side mirrors escapes her,

Same here.  I don't understand it.

I plan on doing an 18 x 8 foot wide garage door.

The garage will be 24 wide x 28 deep

I CANNOT STAND small tight garages, which most builders do, getting in and out of the vehicle requires squeezing out of the drivers door or hitting the door of the other parked vehicle.

My other question now is if the garage is ICF, spanning that 18 feet will require a thick, deep concrete header.

A steel I-beam can span that distance easily. Contact a steel supply house and they can calculate the size necessary. Also make sure you have the headroom for the track on an 8 foot door

Posted By Nashvegas on 26 Jun 2016 11:17 PM
A steel I-beam can span that distance easily. Contact a steel supply house and they can calculate the size necessary. Also make sure you have the headroom for the track on an 8 foot door

There is 3 feet of space above the garage door

Per ICC you will be able to span that if you put 2-#6 rebars, with sturups.

http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_6_sec011.htm

Posted By newbostonconst on 27 Jun 2016 06:44 AM
Per ICC you will be able to span that if you put 2-#6 rebars, with sturups.

http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_6_sec011.htm

the chart says 2 bars in the top and bottom (4 bars total) and the design is further restricted by roof span and load

Some 6" block examples... For a 18' opening width and 24" lintel depth, the Nudura ICF lintel tables call for three (3) #5 bottom bars, a 77” stirrup distance and a 12” stirrup spacing. For a 16’ opening width and 24" lintel depth, the tables call for one (1) #5 and one (1) #6 bottom bars, a 65” stirrup distance and a 12” stirrup spacing. It is the bottom bars that provide the required tension strength. As such, Nudura always calls for one (1) #4 top bar to hold the stirrups and two (2) vertical #4 bars on each side no matter how wide the opening width. In both these 6" block examples, these lintels are rated for 1250 lb/ft uniformly distributed load. 1250 lb/ft is likely more than adequate for most buildings, however, this ultimately depends on the actual building design loads.

You say you have 3' over the opening, is that a continuous 3' or will there be a pour boundary/division in there somewhere?

Is this in a gable end or loadbearing wall?

Posted By ronmar on 27 Jun 2016 06:15 PM
You say you have 3' over the opening, is that a continuous 3' or will there be a pour boundary/division in there somewhere?

Is this in a gable end or loadbearing wall?

It will be continuous and the roof is a shed roof design, no gable.

Can one use a GluLam beam to span the 18' instead of creating a concrete header?

Do the ends of the roof joist sit on the wall that you want this garage door opening to be in?

Thought the building was ICF? Putting a few pieces or rebar inside the wall is easy. I am sure the person you are buying your icf material from can help you.

Posted By Lbear on 28 Jul 2016 03:25 AM
Can one use a GluLam beam to span the 18' instead of creating a concrete header?

You will need to calculate the loads it needs to support and the allowable load of the beam to get your answer,
I usually don't like to mix materials/ wood - concrete unless there is some compelling reason do do so. If you have a masonry or ICF wall , a poured header/ tie beam is the best method

Lear, an 18' span isn't very large for a concrete beam, but it is pretty big for glulam. I have 2 20' beams that the engineer at my icf company designed for me and it took an hour to build the rebar cage that goes inside. At $4.20 for a 20' stick of #4 bar, it was way cheaper than glulam. And, since the beams are resting on short walls before the corner, it is nice to have the concrete beam in tension holding the walls in place, too.

Lbear, you didn't answer if the wall with the garage door is the load bearing wall for the roof or not? If it is not the load bearing wall I agree with MTicf that you can make a very strong CC header with 36" of uninterrupted height to work with... Even if it is the load bearing wall, depending on the roof load numbers you need to meet, it may still be possible. What are your roof design requirements and the span of the roof joists?

It's easy enough to span with a CC beam, but depending on the width of the block, the prescription can vary quite a bit. On the house we are currently building in NM, we have a 16' lintel on three floors. On the first floor with 12" cores, it needs a 27" depth, 2 - #6 at the bottom, a #4 at the top and #3 stirrups. Next level with 8" cores, same rebar schedule, but over a 33" depth, and third level with 6" cores, 33" depth, and three #6 at the bottom, 1 #4 at the top.

The 18' garage door ( 12" core ) was bridged with same schedule as the first one above. I assume that if you were using 6" cores, it could be similar to the last one discussed above.

I would consider another factor: trailers.  If you have (or ever plan to have) a boat, camper, or utility trailer, these tend to be wider than all but the widest dually truck.  I restore classic cars as a hobby, and it sure would be nice just to back a trailer, with a car on top, directly into a garage.  Heck, if you are designing from scratch and have the option, make your opening >10' high and 20' wide.  Don't even bother looking at residential-targeted doors.  There is a vast world of commercial rollup doors that offer custom sizing, wind ratings exceeding anything residential, and roll compactly directly over the opening, allowing you to reclaim the ceiling space inside the garage.  Residential products generally suck.