Garage roof re-do. (What would you do)?
JCM
I'm looking for some advice. I've read previous posts as well. First
the background.:
The garage is 20' wide by 22' long. There is a single-width steel door
on one end. The walls are standard 2x4 16" o.c., about 8'+/-.
The 6" gable roof is supported by 2x6 rafters 24" o.c.. Figure they
are about 11' and change long, based on the rise & run of the roof.
There is no storage in the ceiling.
Sheathing is 6-8" plank t&g, on walls and roof.
Ceiling joists are 2x4 (yes you read that right) that run straight
from side to side with apparently no support in the middle, as far as
I can tell. They are also 24" o.c. There is some truss work in the
middle of the roof, but it appears to have been added later to try to
support the sagging ridge. There are no other trusses.
Based on the preceeding paragraph, it should come as no surprise that
the roof is sagging in the middle. The ridge has bowed inward at least
2"... similarly, the side walls are bowed outward.
To make matters worse, the roof has failed. There is some water damage
to the roof sheathing in spots, and some minor damage to the wall
framing. My guess is that one or two of the rafters will need to be
replaced.
Here's what I want (have) to do, not necessarily in order:
1. Replace the roof. I'm going to reshingle the whole damn thing.
2. Straigten the roof line.
3. Pull the walls together
4. Add a two-car doorway.
My primary concern is that the ceiling joists are simply inadequate to
hold the walls and rafters together. We're in New England, so snow is
an issue. I know that 2x4 joists won't come close to cutting it across
a 20' span. I'd like to put up some new joists, but I need to figure
the right size and structure. Option one would be to use 20' long
lumber to span the whole length. The drawback is that it would be
expensive. Option two would be to run a laminated girder down the
middle of the garage (parallel with the ridge) and then use joist
hangers to tie in joists that span half the distance (thereby costing
less). Is either option preferable? Can the girder (option two) be
accomodated with laminated 2x lumber (e.g., 2x10 or 12, three ply and
nailed) or would I need to go with an engineered product.
In addition, I'm doubtful that I can, or would want to for that
matter, salvage the roof framing. The ridge is badly bowed -- can it
be replaced without removing the rest of the roof? I do plan on
replacing the roof sheating.
Of course there's always the possibility of ripping the whole damn
thing down and replacing it with something solid.
Let me know you thoughts. I understand that a structural engineer can
give me a better answer, but before I go to one, I'm trying to
determine if I can figure it out myself. I'm skilled at carpentry (not
a contractor, though) but I'm not an engineer.
-jcm
Mark
one method over the other. Why have you not proposed the option of a
floor-to-ceiling support post? Especially since you are installing 2 garage
doors which would provide a convenient location for a post.
Mark
"JCM" <jcmi...@hotmail.com> wrote in message
news:6354cb98.02040...@posting.google.com...
Gfretwell
bucks trying to patch up what you have but in the long run starting over may be
the easiest solution.
Goedjn
tension members. Their only purpose is to pull the tops of the
walls inward, to resist the outward thrust of the rafters.
I don't know what's failing, but it's not a function of the 2x4's
being inadequate for the span.
If the tops of the walls are bulging out, then either the join
between the joists and the walls is coming loose, or
the joists are in 2-parts, and they're coming apart at the join.
Either that, or the 2x4s are stretching, which I consider unlikely...
Fix that problem, and either the ridge-line will straighten out
by itself, or the rafters will tear loose from the top of the wall,
and the roof will butterfly out, crash through the joists, and
kill you.
Seriously, though, it's not the 2x4s, it's the fasteners.
You could try getting steel-cable and turnbuckles, and pulling the
tops of the wall back in.
--Goedjn
db...@sprynet.com
Goodheart-willcox co., Inc. copyright 1979.. its a 478 page book that i
paid $13.95 for in 1985 and it covered all forms of wood frame
construction.. also it is the identical book that the US govt. printing
office printed in previous years called Wood Frame Construction.. back
then the us gov. printing office did not copyright their publications...
anyway go to the library and look for this or similar book or go to book
store and see if you can get it.... it will covere the strengths of the
various ceiling joists and tell you what to use..... with a span of 20
feet you might need something like a 3 by 12??? not very common, but
thats what is in the old homes/apt. buildings that are being stripped
down and rebuilt, or was it 3 by 18's. just be glad if you dont have to
use something like this for price cost.... the opening of the one end of
the garage will also be a problem from a one car door opening to a two
car opening???? is there enough support from a side to side to support
this thing???
Eric Ryder
a dropped ridge is rot at the slab/foundation - or a failing foundation. If
the lumber is in OK shape, I'd strip the roof then raise the ridge by
jacking it and pulling the walls in at the same time. Refasten what's there
(some of Simpson's fine products http://www.strongtie.com/ might come in
handy). If the CJ's are in poor shape, 2X6 20's won't run you too much.
Don't worry about the present curve in the ridge (2X6??) it will straighten.
You might have to cut loose any added bracing if it's resisting the repair.
"Goedjn" <Goe...@pobox.com> wrote in message
news:3CA8C3E9...@pobox.com...
JCM
Thanks for the advice...
I guess that's true... I would doubt the 2x4s are stretching as well,
I'm sure when I get some more of the paneling off the walls inside
I'll find some fasters coming loose. There is water damage so it's
likely there is some rot somewhere. Did I mention that there's a bunch
of the previus owner's crap still up in the attic... on the 2x4
joists... And on closer inspection, it seems that one or two of the
joists may be missing altogether! No wonder things may have pulled
loose with all that added strain on the framing. Who knows what else
he had up there before he sold the house? Anyway, I figure all that
load, plus a couple of good New England snowfalls have wreaked havoc
on the whole thing.
I'm thinking I'll rip off the existing roof sheathing (replace the
rotted parts and make it stronger with plywood). According to some
span tables I've consulted, the existing 2x6/24 o.c. rafters are
adequate for the 10' rafter span... especially since they are true
2x6s. I might sister/replace where some have sagged, or where I find
rot. I'll also replace the ceiling framing with 2x8x20s... meets code
for ceiling joists w/ no attic and no drywall, assuming a 10# live
load. And it's easier to do once the roof is gone.
As far as the ridge goes... assuming it is not rotted, will it really
straighten out with support from underneath? It appears to be a true
1x6.
Tony Miklos
JCM wrote:
>
> As far as the ridge goes... assuming it is not rotted, will it really
> straighten out with support from underneath? It appears to be a true
> 1x6.
On a MUCH smaller scale, (a large shed) I had a similar problem. At the
same time I jacked up the ridge, I pulled the walls back in with
cables. I jacked it a little higher than it should be, and pulled the
walls in just a little extra, then used screws and brackets to attach
the things that were comming loose and causing the problems. After
removing the jack and cables, it's still pretty darn straight a few
years later. You can always leave the cables in place too.
My parents old house has a cathedral ceiling almost the entire length of
the house. Through the dining room, living room, bedroom, to the master
bedroom, with no trusses or ceiling joists! Cables run through the
walls that divide the rooms too keep the roof from sagging and the
outside walls from spreading out. It was a very DIFFERENT house built
about 55 years ago. The roof peak is still straight today.
--
Tony