On 18 May 2007 07:48:26 -0700, marson wrote:
On May 18, 9:24 am, under construction wrote:
On 18 May 2007 04:55:26 -0700, marson wrote:
On May 18, 6:22 am, under construction wrote:
On 17 May 2007 18:18:17 -0700, wrote:
question on trusses. contractor is building a stand-alone garage
24'x30'. 2nd floor is for storage. he's using 2x8 lumber for the floor
joists, mated in the middle with a gusset plate.
is this sufficient for bearing weight on the 2nd floor for storage?
some reason I thought wood-composite i-beams were better. he said the
gusset-type should be fine.
yes? no? opinions?
I'm a bit confused. You say question about trusses but I don't think
you are describing trusses? To me, you are describing a 24' long 2x8
spliced in the center of the span, right? Also, are you building a 2
story garage so there is a floor at the 2nd story or is it just a
normal garage where the ceiling chords are going to be used for
storage above?
Assuming a 2 story garage with a long 2x8 with a splice in the middle
of the span and NO support in the middle (like a column or beam) you
do NOT want this. Not only will it not support a FLOOR load but it
will also DEFLECT too much. And if these members are only ceiling
chords as in a normal garage, I'd still want no splices and at least
2x10 members.
Please do yourself a favor and hire an engineer or architect for
adequate member sizes. It sounds to me like the contractor is not
good or is trying to keep the cost very low by building a subquality
garage. Over the years you will be sorry about this garage.
There are a lot of people posting on this thread that have never seen
a set of attic trusses. If your contractor is using attic roof
trusses, they commonly come with spliced 2x8's for bottom chords.
These will be engineered and gauranteed for a certain load. They do
come with some caveats--usually the specs call for no holes and of
course no alterations. I have installed many sets of these. Again,
they do have splice plates. I have used them in houses as well as
garage storage areas. Trusses usually come with a packet that will
spell out the assumed loads--your contractor should have that. It
does not mean that your contractor is not good. Floor joist can have
splices. You do not have to rip it out and do it the right way. What
you are doing would indeed pass inspection.
First of all, your diagram (other post) is NOT a "floor joist" but
rather a chord member for a truss. That said, floor joists should
not have splices especially in the middle (in commercial structures
they use drop in beams). The reason your chord member (in your
diagram) has a splice in the middle is that it is a tension member.
If you are going to help at least give correct advice.
Here is a link for the engineering of an attic truss. Note the splice
in the bottom chord. Note the bottom chord loading of 40 psf.
http://www.wsitruss.com/Prod_Frame.asp?Truss=A248. Why would you use
an attic truss if you couldn't use the space created for a room?
The OP used the term "floor joist", but I suspect that he is looking
at the bottom chord of an attic truss. He needs to clarify this.
Since most attic trusses will have a spliced bottom chord, I suspect
that is what he has, and his contractor hasn't given him a very good
answer.
Just to clarify, I agree that bottom chords can have bending between
panel points if engineered accordingly but generally they are tension
members. Notice tho even as in floor joists, the splice is not in
the middle to avoid maximum stresses.
I agree w/ your 2nd paragraph.