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Should there have been a beam?

4K views 22 replies 8 participants last post by  Yoyizit 
#1 ·
My garage's attic is 2x10's and they are 27 ft long! with no support in the middle... should the builder have put a beam down the center at least? any problems with how it is? the drywall that is on the ceiling is starting to crack at all the joints and there is no load on it at all right now... but it is an attic space..... so it could potentially have a load
 
#3 ·
They have the boards running 27' unsupported? I'm no expert but that doesn't seem right, especially if it is supposed to be an attic. They aren't trusses?
Rafters.... the only support they have is about half way they have a vertical board from the joist to the roof joists to tie them together in the middle... besides that its only supported on both ends and its a 27 ft span with a 8 / 12 roof pitch
 
#7 ·
I have what is probably called a "common rafter" system.... the ceiling joists are a 27 ft span (no support in the middle) made of 2x10's then I have the rafters going up at a 8/12 pitch with collar ties at the top... but then from the collar tie down on one side they have a piece of 1x4 nailed from the collar tie and then it goes down vertically and attaches to the ceiling joist and that is the only support near the middle there is..
 
#9 ·
How much sag do you have at midspan? L/180 would give you ~4".
not exactly sure how to check the sag, but the measurements from the ground to the ceiling joists there is virtualy no difference in height with no load on the joists
 
#11 ·
I doubt the structure met code when it was built, unless it was pre building code, but that may be of no interest to you. The 2x10 ceiling joists are structurally adequate to hold the walls together, however they are not adequate to support more than a nominal floor load. From your description, there is nothing in the attic, so the joists are unloaded, which is why they have not collapsed or sagged.

I am still unclear what the dimensions are of the rafters. It sounds like you have a 1x4 vertical support part way up the rafters, but a photo would be very nice. As you are in PA, snow load would be an important component of the total load on the roof, and the rafters could be overspanned.
 
#13 ·
nope, just 2x10's horizontal, and a 1x4 vertical to the collar tie
 
#14 ·
here's a photo looking down the center of the garage's attic

after looking again there are no collar ties, was thinking of another attic here.....
 

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#16 ·
I suspect those 2x10 are not single boards that are 27' long. If they were, they would cost hundreds of dollars each! Where those boards break, there will be a wall underneith.

Is the space completely open underneith?
nope those are one complete left to right solid 2x10 board..... the plywood is on there just to walk down, pick it up there is no breaks in the joists under it...

the space under this is completely open, only walls on the 4 sides of the garage
 
#18 ·
If you know the dimensions and the sag you can calc. the E value, the MOE. Then you can work backward as to how strong this is.
The other way is to decode the grading markings on the boards.
What should I be looking for interms of coding on the boards? I have tons of 2x10's in the house exposed in other atic parts, but dont see anything printed on them anywhere
 
#22 ·
yeah, I can't find a stamp on any of the boards or on any of the other 2x10's in the house attic... only have info on the OSB flooring....


but for sag there is virtually no sag when no weight is on it, I think those 1x4's are holding the sag out that go vertical from the ceiling joist to the rafters.... and when stepping on it there is only about an inch of sag in the dead center of the floor...
 
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