Hanging heaters on lag bolts

[jmarkwolf]

I've perused other threads regarding hanging garage heaters but haven't seen any hard data on strength of lag bolts in wood.

I just hung a 45K BTU Beacon-Morris heater in my new 28ft x 30ft detached garage using 2-1/2in long, 5/16in lag bolts. See pics. The Unistrut is suspending under the 2x8 joists at 5 points.

The heater only weighs 65lbs, so each of the lag bolts only holds up approx. 13lbs, not counting the weight of the unistrut, the stack, and plumbing etc.

I found myself lying in bed last night wondering if the 5/16in lag bolts are sufficiently strong enough considering the wind loading on the stack, walking around in the attic above the heater, wood contraction and expansion, building wracking, etc.

It's easy enough to change out the 5/16in lag bolts for 3/8in or even something bigger, but I imagine there is a point of diminishing returns.

Am I just being paranoid?


Locating heater with a drywall lift from suggestion on Garage Journal!

Hanging from unistrut lagged bolted in to the joists with 5/16" by 2-1/2" long lag bolts.

 

[lametec]

http://www.kineticsnoise.com/seismic/design/a/a7 - seismic design data for lag screws.pdf

I wouldn't worry about it.

 

[Rockhead261]

Why didn't you place the strut on TOP of the joists and hang the unit with longer rod?

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[djjsr]

Why didn't you place the strut on TOP of the joists and hang the unit with longer rod?

I agree.

 

[PugetDude]

5/16" lag bolts are good for ~198 lbs per inch of depth. Here's a link:
http://www.eng-tips.com/viewthread.cfm?qid=335775

 

[jmarkwolf]

Why didn't you place the strut on TOP of the joists and hang the unit with longer rod?

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For optimal placement of the heater, considering the stack and the gas line, the floor above gets in the way of placing the unistrut above the joists.

 

[daveroy]

If placement is right... And stack can be run. I think your more than good.

 

[rlitman]

5/16" lag bolts are good for ~198 lbs per inch of depth. Here's a link:
http://www.eng-tips.com/viewthread.cfm?qid=335775

There's a diminishing return, because it is still limited by the tensile strength of the fastener, but yeah, you have nothing to worry about.

 

[gregtwojeeps]

Should be fine. Anytime I mount supports to a ceiling/wall for an apparatus I always put my "engineered" load test on it . I grab it and just hang on it. If it supports my 210 pounds, it will hold anything up to a 100 pounds.

 

[PugetDude]

There's a diminishing return, because it is still limited by the tensile strength of the fastener, but yeah, you have nothing to worry about.

Ultimate tensile strength of a lag bolt is generally calculated with a thread penetration of 10 to 12 times the bolt diameter in softwood species.

So, in typical framing lumber, you'd be looking at about 3"-3.75" penetration with an ultimate tensile strength of 600-740 LB per bolt- 2400#-2960# for a 4-bolt connection. With a 65 # heater you're looking at a safety factor of 37x-45X; you should be plenty safe.

 

[BD1]

IF, you didn't want the unistrut on top of joists as mentioned, I would have thru bolted angle clips to joists and bolt unistrut to them or drop rods down to the unistrut depend on angle clip dimensions.