Two garage doors into one

[beetlespin]

I live in central NJ in a new development. Standard size garage doors are 8' and I could not change when house was being built. It looks to me that the beam is hefty enough since it is only supporting a trussed roof. This should be as simple as chopping out the middle section, redoing the top trim and replacing the two garage doors with a single 18'. Am I over simplifying this? Has anyone done this? Cost estimate?

 

[ishiboo]

I am assuming based on the downspout that the trusses land on the front. If so you would definitely want to do the calculations to make sure that LSL is up to it. It looks hefty but 18' is a long way to span carrying a roof. It's not going to fall. But you definitely don't want it to sag.

 

[beetlespin]

Was just thinking the same thing. Might be best just to make the left side a 9' door and leave a support in the middle. Was trying not to mess this the fake stone.

 

[MoonRise]

Not quite as simple as you think.

The beam has to be sized to support the load above it AND the posts/studs supporting the beam have to properly be able to support beam and its load.

And you need to check the bearing capacity of the beam onto the studs and the studs onto the wall plate.

The wall has to have sufficient shear strength to resist racking as well. Removing the 'little' support section between the two existing single garage doors changes the wall structure. A LOT.

And the sheathing nailing pattern to comply with the 'narrow wall bracing requirements' is also pretty specific (3" OC to ALL studs and sills). As well as the requirement for interior strapping connecting the header/beam to the studs (can't see it from the outside pictures you posted).

Draw up your plans, submit them to your local building department with the required forms and payment and (hopefully) get your building permit.

And, YES you do actually need a building permit for something like this.

 

[wayne55]

This does not help, but I have an 18 ft. door and wish I had 2 singles instead.

 

[ddurrett896]

This does not help, but I have an 18 ft. door and wish I had 2 singles instead.

Why?

 

[RoadBeater]

This does not help, but I have an 18 ft. door and wish I had 2 singles instead.

Me too. can't open the inside car doors without worrying about banging the other car

 

[Tinkerman66]

This does not help, but I have an 18 ft. door and wish I had 2 singles instead.

Same here!

 

[Tinkerman66]

Why?

What RoadBeater said. To seperate the vehicles more.

 

[wayne55]

For me, I could just open one door which would be about a 9 ft. opening and have less exposure to the outdoors. With the 18 ft. door open, it seems like every bug and leaf in my yard find their way inside.

 

[matt_i]

Since we are talking 6 figures of investment (guessing) at stake I would urge appropriate due diligence before taking action.

Its time to go see your P.E. and run some analysis on the beam, when it comes back OK then you can proceed. The world is afly with people knocking out supports to make open concept spaces so I think its very common.

I don't fully understand the loads above it but the amount of bearing which is left after the center studs are removed seems light to me.

 

[blkhonda1991]

im actually pretty shocked that framed as is passed inspection, the framing requirements for garage door openings have gotten much more stringent recently...that said you need the span and load rating of that beam...im sure they didnt size it to clear span that opening since its a builder and they dont oversize things for the hell of it.

 

[Radix2]

is it a gable or an eve over those doors?

Certainly if a eve it will not work, most likely not for a gable either, but most likely not -

so the assumption would be that to make it work you need to remove the interior or exterior finish, temporarily support the wall, modify the framing to accept the new properly sized header, install and re-finish, install new door, etc.

I'd guess something like $5-10k?, but who knows, the doors could be resold at least.

 

[vavet]

I have a 16' double and wish I had a 18' double or two 8' singles.

It's been a while since I did beam deflection calcs, but here's my take.

deflection of a simply supported beam = (load * length) / (48 * E * I)
E is a something called Modulus of Elasticity. The value is based on the material (wood, steel, etc). I is the second moment of inertia - the value is calculated based on the shape of the beam. For a rectangle, I=(b*h^3) / 12.

I think (not sure) you can treat each 8 foot span as a simply supported beam. If I'm correct, that means your deflection over an 18 foot span is going to be 5x as much as it is over an 8 foot span. Your load on the 18 foot span is 2.25x as much as it was on the 8 foot span and your length is 2.25x as much. Nothing else in the equation is changing.

Some code or building standard dictated to the architect/truss designer how to size that beam. They didn't upgrade it to a steel I-beam or oversize it because the builder wants to build things as cheaply as possible. Whatever their acceptable deflection was, you're proposing you would be ok with 5x as much deflection. Maybe they were OK with 1/8". Now you're going to have 5/8". Seems like a lot.

 

[bullnerd]

In the pic on the right, does the car on the left even fit under that door? Looks close!

Around here the architects oversize everything.

 

[rlwhitetr3b]

Do you have a HOA to contend with? I like the looks of two smaller doors instead of single huge one. YMMV

 

[K'ledgeBldr]

Only a PE can tell you for sure.

There is one option if the calc doesn't quite meet the requirements. Ask about adding a flitch plate, instead of having to install another hefty beam.

 

[SuDZ]

Me too. can't open the inside car doors without worrying about banging the other car

Exactly why I'd like to go from my 16' to 2 8'ers.

 

[headwrench]

Looks to me like you could sister another beam to the one already there to get the proper strength for your support...just a guess tho

 

[ishiboo]

im actually pretty shocked that framed as is passed inspection, the framing requirements for garage door openings have gotten much more stringent recently...that said you need the span and load rating of that beam...im sure they didnt size it to clear span that opening since its a builder and they dont oversize things for the hell of it.

What's wrong with the framing, looks fine to me.

 

[ddurrett896]

I getting ready to build a 22’ garage. Was planning (1) 18’ with 2’ on each side. Really just wanted space to get in and out without restriction.

Would I be better off doing (2) 8’ doors with 2’ on each side and 2’ in middle?

 

[beetlespin]

I getting ready to build a 22’ garage. Was planning (1) 18’ with 2’ on each side. Really just wanted space to get in and out without restriction.

Would I be better off doing (2) 8’ doors with 2’ on each side and 2’ in middle?

Not if you plan on putting a boat in the garage. A 8' door greatly reduces your choices. Very few boats will fit through a 8' opening which isn't a full 8'.

Framing is fine on my garage. Inspectors are VERY **** around here.

 

[blkhonda1991]

Not if you plan on putting a boat in the garage. A 8' door greatly reduces your choices. Very few boats will fit through a 8' opening which isn't a full 8'.

Framing is fine on my garage. Inspectors are VERY **** around here.

truth...a family member found out the hard way after he built a garage then bought a new boat...he has 1" of play in width, thats a tough boat to park...

 

[beetlespin]

truth...a family member found out the hard way after he built a garage then bought a new boat...he has 1" of play in width, thats a tough boat to park...

My current boat is 84" wide and the opening is 94" since you loose some inches due to trim. I can pull the boat out and put it back in while attached to the F-150 supercrew. It is still like threading a needle. You need to be perfectly straight.

I can tell you 1" is not enough even pushing or pulling the boat in and out by hand.

Even though the boat may list as 90" beam most trailers extent past that making the package at least 100"

 

[spudley]

8' wide doors should be illegal, unless you own motorcycles... or your brother runs a body shop.

 

[CraigStu]

With the cost of LVL beams in mind, I can't think that the builder installed a beam that will span 18ft just for the heck of it.

 

[strutaeng]

8' wide doors should be illegal, unless you own motorcycles... or your brother runs a body shop.

Yes, I would agree with this. I have a detached garage with two 10' doors, separated by about 2' (25'x25'). My driveway is such that my Silverado ECSB barely fits to get it inside. Once I straighten it up, opening the truck doors is pretty roomy. A regular car would make it much roomier.

10' doors are nice. I would never do 8' doors if I had the option.

While we are at it, 24" entry doors should be outlawed too. Have you gone though a restroom with 24" doors? What a joke, especially if you are on the larger side.

 

[Homerr]

What Moonrise said about it being a portal opening for lateral resistance.

Also, for just gravity loading the LSL likely won't work if the center bearing was removed.

You need a PE to check this out.

 

[bullnerd]

We just had a 26 by 28 attached built. (detached burnt down)

18' door uses an 18" LVL.

Door is on the 28 side with full roof load on it.

 

[Falcon67]

Not if you plan on putting a boat in the garage. A 8' door greatly reduces your choices. Very few boats will fit through a 8' opening which isn't a full 8'.

Most open bed trailers are 9' wide, so there's one thing. Also if you bring a truck in through an 8' door you'll at minimum have to fold the ears back. I set my 16' door 36" off the closest wall and I'd consider that a minimum. Note - 24" from wall to door opening, if you put in a 36" man door anywhere on that wall you may not have complete open swing with a vehicle parked in the space.

Also, I debated the 2 door vs 1 door thing when I built. I went with a single 16' because dual 9' doors took up too much wall space. Also, very limiting for access. As noted previously, I can get two cars through a 16' door even with 2 post lift in the door space. Before the lift, no problem parking a car and a 20' long F350 through a 16' door.