garage roof framing question - Contractor Talk - Professional Construction and Remodeling Forum

basslander2008 · 04-26-2008, 06:50 PM

I'm a liscensed Plumber, not a Carpenter, so i need help with this one. I had my garage roof collapse after a heavy snow in March, I live in N.E. Ohio. Garage is approx 20x20 and has a flat roof with an eve, previous roof framing was 2x6's running front to back seperated and nailed to a triple 2x6 running side to side at center. I hired a friend to take on the job and his idea is using 2x8's running side to side, 24 oc, with no center support beam and decking with 5/8's ply. Does this sound sufficient, I don't believe it does, but i'm not a Carpenter. We salvaged sidewalls and wall framing, backwall will be replaced.. Thanx

neolitic · 04-26-2008, 07:41 PM

I can't engineer it from here
sight unseen, but your buddy
isn't doing any better, and he
is there.
20' 2X8's 24"oc for a flat roof
with your snow loads is asking
for more of the same.
You need to hire someone
who knows how to do it right.

Bill · 04-26-2008, 07:45 PM

20' span? I would go 2x10x16" oc or "I" beams 16" oc.

**genecarp** · 04-26-2008, 07:59 PM

welcome to the site, maybe i am missing something, the original collapse does not make sense. where did it fail? if you had a triple 2x6 installed properly spliting the span, your 2x6 rafters are only spanning 10 ft . i would have used 2x8 or a 2x10 triple, but where did it fail exactly?

neolitic · 04-26-2008, 08:12 PM

Quote:

Originally Posted by genecarp

welcome to the site, maybe i am missing something, the original collapse does not make sense. where did it fail? if you had a triple 2x6 installed properly spliting the span, your 2x6 rafters are only spanning 10 ft . i would have used 2x8 or a 2x10 triple, but where did it fail exactly?

He also had a 6X6X20' beam.
The center of that beam wasn't
doing anything but holding
itself up.

cmansmith · 04-26-2008, 09:05 PM

I would suggest using I beams or 2x12s with a bunch of blocking.. Prolly best if you just use I beams. Either way you swing it, you are going to run into problems that will require experience to resolve. Are the walls 2x4 or what? cause if they are 2x4 and you use I beams you might want to run some type of ledger board flush with the top plate on the inside just to give you a little more to sit on. Since you have already gone that far might as well run a rim joist around it, deck it with sub floor and you get a friggin tank. Ok maybe thats alittle over kill. i guess you could go with 2x8 all the way across on 16 inch centers and slap a couple of lvl beams under them. Thats pretty simple.

Brock · 04-26-2008, 09:13 PM

Rip it off and go with engineered roof trusses with a minimum 5/12 pitch.

wallmaxx · 04-26-2008, 09:19 PM

Quote:

Originally Posted by basslander2008

I'm a licensed Plumber, not a Carpenter, so i need help with this one. I had my garage roof collapse after a heavy snow in March, I live in N.E. Ohio. Garage is approx 20x20 and has a flat roof with an eve, previous roof framing was 2x6's running front to back separated and nailed to a triple 2x6 running side to side at center. I hired a friend to take on the job and his idea is using 2x8's running side to side, 24 oc, with no center support beam and decking with 5/8's ply. Does this sound sufficient, I don't believe it does, but I'm not a Carpenter. We salvaged sidewalls and wall framing, back wall will be replaced.. Thanx

Do you want to keep the flat style roof?

Snow loads are tough...who can really predict them? You need to see what your county/city does for their code adjustments that are bound to come down after this winter.

A very stout center drop beam or flush top beam would be my thinking.

The only flat roofs I've done were commercial, and they were very "engineered" for water loads. Some we sloped with long ripped shim sleepers and some we left flat and the roof guy had sloped rigid foam underlayment.

If you can go pitched roof -

that would be my primary suggestion

neolitic · 04-26-2008, 11:09 PM

Any specific design advice you
get here is pure guess work!
No one can see your house or your garage.
I'm guessing you had maybe 3 or 4' of snow
on three last winter? More????
Some guys here have only seen snow at
the movies.
Most of us have no idea what your codes
are in...Akron??? Where ever.
We might be drunk (some of us are).
You might be getting information from
a 14 year-old girl.

Get some one who knows what they
are doing, in the area, to at least take
a look and give you an opinion.
Better yet pay for a design that'll
keep you out of trouble.
Your buddy doesn't have the experience
to tackle this without guidance...believe me.

wallmaxx · 04-26-2008, 11:44 PM

Quote:

Originally Posted by neolitic

You might be getting information from
a 14 year-old girl.

I don't usually laugh out loud at the computer...but I made an exception this time.

Damn NEO, now I have to start another new "handle"...my cover is blown. Its just soooo hard for us 14 yr old girls to be taken seriously in the construction industry.

Thanks for the visual...

neolitic · 04-26-2008, 11:52 PM

Quote:

Originally Posted by wallmaxx

I don't usually laugh out loud at the computer...but I made an exception this time.

Damn NEO, now I have to start another new "handle"...my cover is blown. Its just soooo hard for us 14 yr old girls to be taken seriously in the construction industry.

Thanks for the visual...

Glad to be of service.

cmansmith · 04-27-2008, 01:46 AM

berf

cmansmith · 04-27-2008, 02:09 AM

[quote=neolitic;428959
[SIZE=5] We might be drunk (some of us are).
You might be getting information from
a 14 year-old girl.[quote][/size]

Hell some of us are drunk and dressed like a 14 year old girl. Is that like two birds with one stone or what? I think this is your best bet the only catch is you have to grow two trees. I wont explain it cause the picture i drew on my cad program says it all...

**genecarp** · 04-27-2008, 02:24 AM

that should work great; i recomend cherry trees. lololol

72chevy4x4 · 04-27-2008, 08:27 AM

seems the OP hasn't been back...something like this how cold you not go w/ a simple 2x4 truss-it's economical, easily strong enough for the situation and fast. For the life of me, I can't understand how a tripple 2x6 would have held up the roof for that long.

neolitic · 04-27-2008, 10:10 AM

Quote:

Originally Posted by 72chevy4x4

seems the OP hasn't been back...something like this how cold you not go w/ a simple 2x4 truss-it's economical, easily strong enough for the situation and fast. For the life of me, I can't understand how a tripple 2x6 would have held up the roof for that long.

Often the difference between
sag and failure is just time.

cmansmith · 04-27-2008, 02:04 PM

Quote:

Originally Posted by 72chevy4x4

seems the OP hasn't been back...something like this how cold you not go w/ a simple 2x4 truss-it's economical, easily strong enough for the situation and fast. For the life of me, I can't understand how a tripple 2x6 would have held up the roof for that long.

I hate trusses. I also agree with you completely.

send_it_all · 04-27-2008, 02:26 PM

Quote:

Originally Posted by basslander2008

previous roof framing was 2x6's running front to back seperated and nailed to a triple 2x6 running side to side at center.

Can't imagine how this could have failed.

basslander2008 · 04-27-2008, 03:21 PM

he ran a ledger on both walls front to back to support the side to side 2x8's

basslander2008 · 04-27-2008, 03:26 PM

the collapse was due to an old roof with water damage, the old center support was a double 2x6, not triple.