How much weight can a truss hold?

[KathyJB]

Or rather my truss'. I currently have a shingle roof that needs replacing. The plywood base was put on wrong. I was told that I could put a tin roof over it and would install a ridge vent also. The contractor told me that I could put some kind of radiant barrier that would go under the tin that would cut the Texas heat pretty good (your opinion?)
Now to the inside, I saw on another post in the heating/cooling section where someone was putting inside white barn tin on their roof along with pink insulation. Can you tell by my pictures if my truss' can handle the weight? I haven't measured them because I don't really know how you would want me to do that. I appreciate your help, kathy

 

[NUTTSGT]

That foil/bubble heat barrier stuff seems to work good acccording to others that have used it.

As long as your trusses are in good shape and haven't been modified (hacked on), they should be able to handle some insulation and metal siding no problem.

 

[Falcon67]

Kinda hard to guess without the original design drawings. Whata you can try is to get the span, the slope of the roof (rise per foot of run) and some measurements of the timbers used. Looks like 2x4s or 2x6? Take that and a good picture or sketch of the truss layout to a lu8mber yard that sells trusses. They could look up a similar design and tell you what the load limits may be.

For inside, if you hold to 5 lbs sq/ft I'd bet you would be safe - that is usually the bottom number on a truss. With 2x6 bottom chords, maybe 10 lbs sq/ft. Sheetrock runs around 2.5 lbs sq/ft. Tin sheets would be a lot less than that.

If you are taking the roof off, you can use radiant barrier OSB over the trusses, with whatever top covering you like. In Texas there is no snow load, so OSB and shingles would be close to 5 lbs sq/ft of roof loading.

 

[Mike in Ohio]

Falcon is right about checking with a lumber yard or truss company.

Your trusses look just like the ones in my shop, 30' span. I called the truss company and asked about the load rating on the bottom cord and told them what I wanted to do. They told me that mine were rated for 11 pounds per square foot. Yours may be different depending on the span.

 

[ephotrod]

As much as it was engineered to!!!! If you need a quantitative figures contact your local structural engineer and have him do load calculations! Please note he may charge you for his services.
Josh

 

[KathyJB]

I haven't the faintest idea who made the trusses. My brother was in charge of that back in the day. I think it was after '98. Anywho, don't think I'll do the "check with an engineer" thing too much $$$. I may ask Franklin, the local builder what he thinks.
Thank you and to all the Veterans here, I thank you Very Much!

 

[DZL JIM]

Your trusss are not 'Attic' or 'Storage' trusses, the design was not meant to hold weight above the bottom cord. In other words, empty the attic space, it's putting stress on the trusses. If you feel it's all 'light-weight' stuff, then make the call yourself. After seeing many ceilings crack from too much 'light' stuff, I only have extra empty boxes in my attic.

They are, however, desinged to hold up a ceiling, typically desinged for Drywall. So if you want to use a metal siding and insulation, that will weigh less than drywall and you'llbe OK.

 

[bigdav160]

Also, some metal roof material (and installation) acts like a radiant barrier. You may not need to add one.

 

[brownbagg]

tin a lot lighter in weight than asphalt shingles

 

[KathyJB]

Your trusss are not 'Attic' or 'Storage' trusses, the design was not meant to hold weight above the bottom cord. In other words, empty the attic space, it's putting stress on the trusses. If you feel it's all 'light-weight' stuff, then make the call yourself. After seeing many ceilings crack from too much 'light' stuff, I only have extra empty boxes in my attic.

They are, however, desinged to hold up a ceiling, typically desinged for Drywall. So if you want to use a metal siding and insulation, that will weigh less than drywall and you'llbe OK.

Jim that explains some things. I'll have the husband unit help me remove some items. There are a few heavy things but for the most part they light. Is there anything you can do to make them stronger for attic type storage?

 

[John in OH]

The contractor told me that I could put some kind of radiant barrier that would go under the tin that would cut the Texas heat pretty good (your opinion?)

There was a recent discussion regarding the radiant barrier at:
http://www.garagejournal.com/forum/showthread.php?t=123367

 

[DZL JIM]

...Is there anything you can do to make them stronger for attic type storage?

Sure, but you're really looking at re-structuring the roof system to do it right. Larger bottom cords, larger rafters, and tie them togther. There's no simple, easy, or cheap way to do it. You're kind of stuck with plain old trusses that are not meant for storing things.

 

[KathyJB]

Bare with me, I don't know what this board would be called. It's the one that spans the whole length of the garage down the middle north and south. It had separated from the North wall and that wall was jutting out. That is what those straps are for from the north wall up to almost 1/2 way to the west and east walls. I was told that there should have been some kind of support there in the first place. Your thoughts on if the support was missing when it was built?
My brother and brother in law basically built the garage. They messed up on the laying of the plywood on the roof, so there may be some other things they either didn't know about or skipped. (I just threw that picture of the ranger in there because it's the only 4 wheeled vehicle in the garage)

 

[Falcon67]

The board down the middle is just a board, probably used to help set the correct truss spacing. It doesn't add anything much to the structure. The metal straps look like corner braces - they add diagonal strength to the corners.

 

[KathyJB]

The board down the middle is just a board, probably used to help set the correct truss spacing. It doesn't add anything much to the structure. The metal straps look like corner braces - they add diagonal strength to the corners.

The board down the middle had come unnailed from the north wall and the north wall was bowing out because of that. The straps were added for strength (just like you posted). They used a come-along to pull it back in and nail that board to it plus the straps. Maybe because of the garage door and the header left for another garage door leaves that north wall weaker? I don't know. It freaked me out to see that wall bowing out like that.
I don't plan on putting in another garage door. I need that wall for stuff.

 

[flingwing1969]

tin a lot lighter in weight than asphalt shingles

Right you are. If you use 1/2 inch osb or 1x3 boards as your deck, a synthetic moisture barrier (as opposed to 30# roofing felt), and 26 ga metal roofing (energy star rated), you will be way lighter than your original roof. You will be surprised at how much that light ga metal roofing stiffens the the bouncy 1/2 inch deck when it is properly screwed down.

 

[bczygan]

A couple of things.
That long board above and perpendicular to the truss bottom chords is a strongback, a type of bridging, used to keep the bottom chords from twisting. Don't remove it.
While your truss may not be designed to carry a heavy load, it has a safety margin that will allow you to store light things above the bottom chord. Put light bulky items in the middle of the span and smaller heavier things near the eaves. Since you are changing to a lighter roof the truss as a whole will support more. Trusses are designed for a certain deflection based on their design loading. If they are designed to have a finished ceiling such as drywall, they will be stronger and stiffer so less deflection and less chance of cracking. If you are not putting a ceiling in, then you don't have anything to worry about. A little extra deflection won't hurt. Just don't go crazy putting heavy things in the middle.
As far as roofing and insulation, rigid insulation is very light. Not a big deal.
If the roofing you are talking about is galvanized steel barn roofing with a white finish inside, it will be heavier than a standing seam metal residential roof, but also cheaper. Look carefully at the profiles and materials before making a decision. Also compare the weights of shingles that are on the roof now and the different metal roofs to see the weight differences.

 

[KathyJB]

Wow, you guys are so smart here. I'm learning a lot. My sister and I were discussing the year the garage was built and we are thinking '89 at the earliest or '92 at the latest so it's time for a new roof anyway. I would like the old shingles removed and also a ridge vent put in.
I measured the distance between the truss' and on the inside of each truss it's 23" and from outside the board to outside it's 26". There are 14 truss'. The garage measures: 24 x 26

I can't wait for the siding to be changed. We are going with a 4x8 hardiplank and the door will be fixed and will open toward the outside making it easier when there is a vehicle parked inside other than the Ranger. Sometimes there are hail warnings and I would rather my Equinox be inside to be safe.