Should there have been a beam?

BlueBSH

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

acme54321

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?

BlueBSH

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

Daniel Holzman

Are you talking about joists that span horizontally at floor level between the walls, or the rafters?

tpolk

sounds like ceiling joists

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Scuba_Dave

Picture ?

BlueBSH

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..

Yoyizit

How much sag do you have at midspan? L/180 would give you ~4".

BlueBSH

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

Yoyizit

You could stretch a line. If the line hits each wall 4" below the ceiling at each end while grazing the ceiling at midspan then you have 4" of sag.

Daniel Holzman

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.

RickyBobby

Is there a strongback running down the middle?

Strongback consisting of 2x4 on the horizontal with a 2x4 nailed on the vertical next to it, nailed perpendicular to the joists? I have seen that quite often on longer spans.

BlueBSH

nope, just 2x10's horizontal, and a 1x4 vertical to the collar tie

BlueBSH

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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xxPaulCPxx

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?