Intro & Roof Truss Question (Long)

[Louis Nigro]

Hello all,

I'm finally getting settled in after a move and getting my shop setup. I'm sharing a three car garage with a Shelby Cobra replica build and my workshop. For now the woodshop is more or less confined to one bay of the garage.

I have installed a subpanel (passed inspection!), a 220V heater, five shop lights, insulation and drywall. I have a Delta contractors TS, Jet Jointer, Delta Portable Planer, and the usual assortment of hand tools. All of the machine tools will be mounted on mobile bases.

Here's my question: I have a 1HP Penn State DC on a mobile base and a Onieda 1.5HP DC. The original plan was to sell the Penn State DC and hang the DC piping for the Onieda on one side of the garage. The collector is already mounted on the wall waiting for the final 220V line.

Then I started looking at what I already had hanging from the ceiling and I became concerned about the weight hanging from the trusses. It's a standard garage roof truss setup (gable, not sure of the pitch, 2x4 truss material). The ceiling is already drywalled and there will be no storage in the attic area.

I have 5 commercial type light fixtures (the kind that mount in a drop ceiling) attached to the bottom cord of the trusses with brackets and lagbolts. I estimate that the fixtures (3 and 4 bulb) weight about 30-35 lbs each. I have the electric heater (30 lbs) and one of those ceiling mounted storage units with a bunch of light weight stuff also mounted to the trusses. Total weight besides the drywall ceiling is maybe 300 lbs spreadout over the entire ceiling.

I realize only a structural engineer can give me a defiitive answer, but I'm just looking for some general opinions at this point; does this soundlike too much weight? I was hoping to finish up by insulating the garage ceiling with blow in insulation and then hang my DC piping, but I became concerned about the weight.

I have my wood rack mouted to one bearing wall and I was planning on placing my air cleaner on a self to to keep that little bit of weight off the trusses. I can shoot some pics if that would help.

I apologize for the long post. Thanks for any suggestions, and may I say that this forum is one of the best I have seen, I throughly enjoy it.

Regards,
Lou Nigro

[Thomas Williams]

I would guess that adding the dust collection ducting would not add enough weight to cause a problem. Not being an engineer or architect I do not really know how much weight a roof truss could carry. However, I have been in some attics where there was way more than 300 pounds sitting on the lower chord. I suppose how the trusses are built would also have a bearing on the amount of weight that could be supported.

[Matt Ocel]

Louis -
I was told by a truss designer that a engineered truss can handle a "good bit" of interior weight. When I asked how much is a "good bit" he wasn't specific, but did say that they are built to have a few guys walking around on individual trusses when setting them during construction. He didn't seam worried about truss failure under when storing items in truss space "not" designed for storage.

From what you described, you should be OK.

[Chase Gregory]

Only the truss manufacturer can tell you what loads they used, but your dc piping isn't going to be an issue.

I wouldn't recommend hanging a chain hoist for working on the Cobra, though...

Chaser

[Louis Nigro]

Thanks guys. I figured I would be ok with the limited load that are up there now, but it never hurts to ask.

Regards,
Lou

[Matt Ocel]

Louis -

I was just thinkin. If you look closely at the trusses you might find that the Truss manufacturer is stamped on a truss somewhere, and the Job # for that set of trusses. If you find that you can call them, and i'm sure they would answer your load questions.

I have found that the Truss manufacturers are usually more than happy to help you out.

[Lee Koepke]

If you were to run some 'cats' ( 2x4s ) across the bottom chord of several trusses to spread the load for heavier items, it would create less of a point load that may not have been designed.

ductwork is pretty lightweight, as are lights. The truss design should have considered loads for lighting.

[Shane Withenshaw]

I used to work at several truss factories and I'm no engineer but it sounds like you will be fine. Even with a 2x4 bottom cord it is partially tied to the top cords by the web components. I would think that the load restrictions would vary according to different web configurations but just a guess. If you measure the span of the truss, grade of lumber (defined bya stamp on the lumber), have available the web config. and size of the top and bottom cords any local truss builder should be able to help you.

[Nathan Conner]

Hey, Louis. When we redid a little pole barn and turned it into a studio, we had 18' 2x6s with no bracing for a ceiling. Before I had the sheetrock hung, I added some purlin braces to make sure they would take the weight of the sheetrock, which is HEAVY, compared to the weight of DC piping.

It took about an hour to do a 500sf room with 2x4 purlins. It may be worth running up there with a handful of them and a hammer and nails. If nothing else, it's peace of mind and will certainly help out with any weight/structural concerns. Of course, without them, I'd be scared to use a ceiling-mounted cherry picker or anything on the Ford, but...honestly, if the ceiling seems stable now, DC won't add enough to make a difference.

Good luck!

[Louis Nigro]

All,

Thank for the additional suggestions. I'm going to get up in the attic later today and look for the info on the truss manufacturer. I'll take some photos too.

Lou

[Leo Zick]

trusses have to be designed to support the wet snow load in your area (assuming).

lights (even your super duper heavy 35 lb ones!! holy mackerel!), and other items are peanuts for them..

[steve reeves]

The load rating will be based upon the size of the timer (2x4) in your case and the unsupported span, the manner in which the joist is connected to the rafter and whether or not the joists have been "bridged" to one another and the size of the bridging coupled with the span of the joists... 24" etc. etc.

The type of lumber used "could" be a factor but nearly 100% of all trusses are made from local softwoods... most engineers are going to figure on fir or pine...

Techno mumbo jumbo aside, I don't see you having any issues with what you have planned. I'd certainly span the joists though... it's cheap and a good insurance policy.