How much weight will my trusses hold for installing ceiling and insulation

[dae06]

I've read a lot about people using OSB and plywood as their ceiling in the sheds. My questions is: Is this too much weight for my trusses?

My shed: 36' x 56', 14' walls, trusses centered with 8' spacing.

Trusses:
30 lbs/square foot top chord live load (TCLL)
4 lbs/square foot top chord dead load (TCDL)
0 lbs/square foot bottom chord live load. (BCLL)
1 lb/square foot bottom chord dead load (BCDL)

Plywood and OSB are much heavier than tin, but can my roof handle the weight of wood and insulation? To be honest, I do not know what the truss spec above mean.

Thanks

 

[PWC Repair]

Those specs basically mean you can't even hang a ceiling at all. They weren't designed for any load at all.

 

[n20junkie]

It would be maxed out, and thats before lighting and such.

 

[K'ledgeBldr]

Those were designed for the "roof" only.
Hang some lights- you're done!

 

[dae06]

This is not good. I specifically told the builder to build it for future insulation. He did book shelf the walls

Is there anything I can do to prep these for a ceiling and insulation?

Thanks

 

[dae06]

The trusses are rated at 9' on center, mine are 8' on center:

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I'm assuming the LLBC is where the issue is?

 

[Chris705]

So your specs on the trusses say 1lb/sf dead load...the trusses were designed for an 8'-0" center to center spacing that does give you some ability to insulate and put up a ceiling...However as replies above indicate it can't be much in the way of adding weight. You would have to add strapping to span between trusses (2x6s or 2x8s) metal or osb sheathing plus the insulation you intended to use....And of course the lights. Add the weight of all of these items up cannot total more than 2016lbs. ....or a total of 63lbs for every 4x8 sf of area. It will be tight and possibly the best way to accomplish would be strapping at 24"oc with metal ceiling liner and insulation of an appropriate thickness....maybe cellulose to save on weight? AND maybe best to go back to truss manufacturer to confirm the loads and deem if what I interpret to be accurate?.....each linear foot of truss can support 8lbs of added dead load?

 

[Chris705]

LLBC is live load bottom chord....that means a load which is not constant....snow load is a live load to the top chord. Adding things to an attic space is a live load.....DLBC means dead load bottom chord...the load that gets added to the upper chord would be roof purlins, sheathing etc. Your ceiling, insulation and lighting would be dead loads....

 

[dae06]

LLBC is live load bottom chord....that means a load which is not constant....snow load is a live load to the top chord. Adding things to an attic space is a live load.....DLBC means dead load bottom chord...the load that gets added to the upper chord would be roof purlins, sheathing etc. Your ceiling, insulation and lighting would be dead loads....

If you look at the highlighted area in my picture, at 8' OC, I see 5 lbs. dead load (DLBC). Is this of any help to me?

 

[Chris705]

where did that chart come from ....it doesn't make sense if based upon 9' spacing why doesn't every spacing less than 9' continue to grow in other loading potential?

Maybe the live top cord load is increasing but bottom chord loads are not benefitting....

I think a call to the truss manufacture will easily answer your questions....Yes 5lbs/sf will definitely help with what you want to do?

 

[dae06]

where did that chart come from ....it doesn't make sense if based upon 9' spacing why doesn't every spacing less than 9' continue to grow in other loading potential?

Good point. This is from the truss manufacturer.

https://hw.menardc.com/main/items/media/MWTRU012/Prod_Tech_Spec/1082_001.pdf

 

[dae06]

9' to 8' go from 1 to 5
7' to 6' go from 1 to 5
5' to 4' go from 1 to 5

I must be missing something.?.?

 

[dae06]

The only way to contact them is through an on-line message. We'll see how long it takes for a reply and I'll let you know.

It sure looks like the dead load and OC spacing is related to LLTC.

Thanks for your responses!!

 

[-Brent-]

To be honest, I do not know what the truss spec above mean.

Live Load = loads that can/do change over time, such as people walking around a building or movable objects such as a storage items, furniture, etc. In addition, environmental loads (wind, ice/snow, seismic, etc.) are also considered for live loads.

Dead Load = loads that typically don’t change over time, such as the weight(s) of materials (framing, flooring material, roofing material, ceiling material, etc.) and the weights of fixed/service equipment.

 

[Chris705]

http://www.midwestmanufacturing.com/MidwestManufacturing/help.do

look at the "Truss Store"....they offer live chat.

 

[csp]

Trusses:
30 lbs/square foot top chord live load (TCLL)
4 lbs/square foot top chord dead load (TCDL)
0 lbs/square foot bottom chord live load. (BCLL)
1 lb/square foot bottom chord dead load (BCDL)

Where did these numbers come from? If they are from the spec sheet that came with your trusses then they are specific to your trusses and spacing regardless of what the chart posted says.

 

[dae06]

Where did these numbers come from? If they are from the spec sheet that came with your trusses then they are specific to your trusses and spacing regardless of what the chart posted says.

Menards website.

 

[dae06]

Just got off the chat with them. Here is what I got:

Since I am at 8' OC, I have a 5 DLBC (Dead load) which means: these trusses are designed for 40 lbs./lineal foot which would be 5 lbs./sf.

The live load does factor in the calculations. If I were to space these same trusses at 7' OC and only require a 30# live load, the DLBC would be even larger than 5. I didn't ask him to do the math, but I would guess in the range of 9 or 10?.?.

 

[Jeepster04]

5lbs/sqft is pretty significant. I would imagine thats more than enough for some metal ceiling and blow in insulation. Over a 30x30' building, for example, thats 4500lbs of material.

 

[dae06]

Yes, he basically said 160 pounds per 4' x 8' area (sheet).

 

[Chris705]

Sweet - good news the builder didn't do you wrong....!! I am interested in knowing how you intended to span between the trusses? I assume your roof purlins are held in place with clips or joist hangers? Will you be doing the same for the ceiling supports?

 

[csp]

With 5lbs you could go with as much weight as 5/8" drywall, so steel and insulation won't be an issue at all.

 

[dae06]

Sweet - good news the builder didn't do you wrong....!! I am interested in knowing how you intended to span between the trusses? I assume your roof purlins are held in place with clips or joist hangers? Will you be doing the same for the ceiling supports?

I think I will go with 2" x4" joist hangers.

If I run them 4' apart, will that be sufficient to hold the tin and insulation?

 

[Chris705]

Depends on the weight of insulation you intend to use. I would probably suggest you stay with 24" oc. Possibly go to 32" oc if you run insulation batts parallel to truss orientation.

 

[dae06]

I just got off the phone with Menard's. They said they are rated to span 9' (mine are 8') with 3' OC joists and will hold insulation on top of that. I have also read others that have the 8' span and they say they have been that way for many years with no issues. It does surprise me a bit.

 

[rburke65]

This is why it is always a better idea to NOT go with the bare minimum. Ya nver know what might be in the future. Are you sure a metal ceiling liner is hair than OSB or plywood?

 

[Chris705]

So you imply that you want to use 2x4's to span 8' between trusses. Depending on your choice of insulation & ceiling finish that may or may not work so well. A light metal ceiling & light cellulose insulation will be good with 2x4. 12" of fiberglass and a heavy 5/8" plywood or osb 2x4's probably not adequate.