I am building an attached garage to replace an attached carport. The
existing carport had a flat roof. The new garage will tie into the
house's roof with the same slope, 3:12. Although the house has a hip
roof, the roof over the garage will be a gable roof. The garage is
approx. 25' x 31'. The ceiling joist will run perpendicular to the
rafters . The 25' span of the ceiling joist requires either 2 x 10's
or 2 x 12, depending on whats available at the lumber yard. With the
shallow slope of the roof, the first joist will be approx. 4' from the
parallel exterior wall. I plan on adding joists perpendicular to the
ceiling joists to the exterior wall. I will use joist hangers for the
connection at the ceiling joist. My question: Is a 4' perpendicular
joist too long? I assume I will need to add blocking to attach the
sheetrock. Will the above pass an inspection (IRC 2003)? I will be
adding stongbacks at 4' o.c. since the ceiling joists run
perpendicular to the rafters.
How are you planning to hold the outside walls if the clng joists
are not parallel to the roof rafters? The triangle created by
rafters and joists is crucial to the structure.
It is possible to create a structural ridge, but this is not usual
and requires some careful planning.
Keep the whole world singing . . . .
The span is approx. 31' if I run the the joists parallel to the
rafters and the angle cut on the joists would be serve due to the
shallow slope of the roof. I intend to run the strongback from rafter
to rafter 4' o.c. The strongback would be the base of the triangle.
Why not take / fax a drawing to a truss company. At that low a pitch there
isn't going to be any usable "attic" space, and overall manufactured trusses
would probably be more cost effective than the large dimesional joists.
Plus, the truss company will do the engineering for you. Only thing you'd
have to stick would be the hip/gable overbuild ( if I interpreted your
If I understand your description, yes it would work but
with some modifications.
You won't get a ceiling joist 2 x 10 or 2 x 12 within
16" of the wall under a 3/12 roof rafter so I would put
solid bridging every 4' as you want from that joist
that *will* go under the rafter and block in between
the 4' bridging with the extra edge joist of 1 x 4 or 2
x 6. The 4' stiff backs nailed well to the rafter and
bridging would do the job fine. Then double up the
extra loaded joist.
On Jul 20, 6:59 am, email@example.com wrote:
No one can answer that question. Sizing the members is only part of
the solution. The connections are just as important, and your version
has some serious limitations.
I don't understand what you're trying to do with the whole setup. You
should price your idea against trusses. You might be surprised how
little difference there will be in cost and your way is a lot more
I really appreciate the responses. I will check into trusses. One
problem with trusses is access for a crane to lift the trusses. The
power line drop is in the way of the ideal location for the crane. In
fact the electric meter will need to be moved at some point in the
project otherwise the meter will be inside the garage. But I need a
wall and the roof in place before it can be moved.
I can size the members without problem, I have the span tables and
know the loads required by the city. I will try to explain the
question another way assuming trusses do not work out. The house is
basically a rectangle with a hip roof with a 3:12 slope with 4' eave
overhangs. The shallow roof slope means a 2 x 10 joist will be more
than 16" from the exterior wall. Using a 2 x 10, the outside joist
will be a little over 3' from the exterior wall. I will call the 2 x
10 joist a "regular" joist. The plan is to place a "short" joist
perpendicular to the "regular" joist that extends to the exterior
wall. The "short" joists will have blocking between them at the
exterior wall to provide a way to attach the sheetrock ceiling. My
question: The "short" joist will be a little over 3' in length, is
there anything in the framing code placing a limit on the length of a
I will post the difference in cost when I get a price for the
trusses. If it's like everything else in this project, the cost of
trusses will be out of sight. I received two bids on this garage from
remodeling contractors, one for $90,000 and one for $55,000. Doing
the job myself, the cost is about $18,000.
Well, to answer your question, a joist is a joist. If you know the
span, then you can figure out the rest. I would be more concerned
about overloading the joist that the blocking is tying into. You say
you want to span 25'? Are you serious? First of all, where are you
going to get lumber over 25'? If your ceiling joists are only
functioning to hold up a drywall ceiling, I would suggest a suspended
drywall ceiling by USG. That said, you should look into trusses.
Marson, I checked with my lumber yard and 2 x 12 x 26' are available
(Douglas Fir). Normally 2 x 10 x 26' are in stock, but the day I
called they were out. With no attic storage, and a sheetrock ceiling,
either will work according to the span tables. The 2 x 12 can span
31'. I do intend to check on trusses and will go that route if they
are affordable. The 2 x 12s are affordable but are more work as
mentioned by an earlier poster. Walking through a number of houses
under construction in my area, a 25' span or greater is common in the
garage area with some using 2 x 10 , some using 2 x 12 and some using
engineered joists. I have seen several things that I didn't think
were to code (for example a purlin supported by double joist spanning
25' instead of a load bearing wall) but the inspection sticker was
On Jul 20, 8:18 pm, firstname.lastname@example.org wrote:
OK, I didn't know that. Here in the midwest, long lengths like that
are special order. You might want to double the last joist, the one
that has the blocking tied to it, since that joist is carrying more
load than the others.
I of course, meant 2 x 4 and not 1 x 4, either parallel
to the joist or perpendicular like the solid bridging.
I am wasting you 2 joists though by saying double the
joist at the edge with the blocking. It's supported
every 4' with stiff backs bearing directly on the solid
bridging that is in turn bearing on the outside plate
and as such is probably the strongest one in the
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