How do I make my Trusses stronger to support a ceiling

[DekeT]

I dug out my plans today

here what it says

TC LL 30. PSF
TC DL 4.0 PSF
BC DL 1.0 PSF
BC LL 0.0 PSF

Total LD 35 PSF
DUR. FAC. 1.15

I'm assuming the abbreviations are as follows?

TC Top Chord
BC Bottom Chord
LL Load Limit
DL Dead Load

DL = dead load is permanent component of the structure
LL = live load is people, machines, movable objects, snow, rain. all temporary

Bottom chord dead load of 1#/sq ft tells me to put absolutely nothing on the ceiling except a few light fixtures. I would be curious what your engineer says about solving your problem. I predict it won't be cheap and it won't be easy.

 

[manrmark]

I just got a call from my salesman and his engineer told him that I can marry a 2x8 to the bottom cord and I would be ok. I'm not sure how much stronger it would make it and it seam like just adding more weight to the trusses.

What are your thoughts

 

[ez-duzit]

I just got a call from my salesman...

You're talking to the wrong guy.

 

[radrush]

I just got a call from my salesman and his engineer told him that I can marry a 2x8 to the bottom cord and I would be ok. I'm not sure how much stronger it would make it and it seam like just adding more weight to the trusses.

What are your thoughts

My thoughts are if you don't get it in writing than it didn't happen.

I would need the sales guy to provide a signed and stamped letter from an engineer who is licensed as a professional engineer (-important part-) in the state in which the building resides.

Did the sales guy specify what species of wood this 2x8 is to be? How many and what size fastener is required to "marry" this 2x8 to the BC? And what is the placement pattern or the fasteners? One row? Two rows? Two rows alternating top & bottom? Placed at what spacing? Is that one full length 2x8 or a spliced 2x8, and if spliced where/how? The devil is in the details.

 

[manrmark]

My thoughts are if you don't get it in writing than it didn't happen.

I would need the sales guy to provide a signed and stamped letter from an engineer who is licensed as a professional engineer (-important part-) in the state in which the building resides.

Did the sales guy specify what species of wood this 2x8 is to be? How many and what size fastener is required to "marry" this 2x8 to the BC? And what is the placement pattern or the fasteners? One row? Two rows? Two rows alternating top & bottom? Placed at what spacing? Is that one full length 2x8 or a spliced 2x8, and if spliced where/how? The devil is in the details.

I have to agree, I feel like I need something in writing or a set of plans. I think Just marrying a 2x8 to the bottom BC will and extra weight and will possibly sage in the future.

 

[Nekit]

Mark,
Thought I would answer your question here so others could see it.

Your PM:
I ran a crossed a post you made about you using a thicker metal for your ceiling. Can I ask you what is the span between your trusses and what did you use for your ceiling and where did you get. I have 8' span between trusses and would just like to put up the steel siding on the ceiling that Menards sells then insulate but I'm afraid it will sag without reinforcement otherwise ill need to strength the trusses some how and run 2x4s perpendicular to keep the metal from sagging, I would rather just screw up metal and insulate. I started a thread a while back which you can see on my profile which might explain a little more. Thank you Mark

Mark,
I have 8' between my trusses and no 2x4s perpendicular for support, I didn't want to loose the ceiling height in the shop.

What I used was steel siding that is made for ceiling use. The metal itself isn't any thicker in gauge, might even be thinner for weight, it just has bigger bends that make it about 3" thick. I too was worried about bowing once it was insulated. I blew in about 10" of insulation and it didn't bow a bit. It's been up 10 years and still is straight.

I bought most of my steel at Menards, but at the time they didn't have this ceiling steel and I got it from a local company that just sells and installs steel pole barn siding. Not sure if Menards has it now. Sometimes they can special order some odd pieces.

Hope this helps.

 

[theoldwizard1]

I just got a call from my salesman and his engineer told him that I can marry a 2x8 to the bottom cord and I would be ok. I'm not sure how much stronger it would make it and it seam like just adding more weight to the trusses.

This is exactly what I was going to say !

You can't buy a 42' 2x8 and even if you could you would have a hell of a time inserting it. I would use 3 -14' 2x8. They need to be attached to the existing bottom chord with construction adhesive and nails (ring shank or twist) The **** joints should be under the larger plywood gussets.

I would need the sales guy to provide a signed and stamped letter from an engineer who is licensed as a professional engineer (-important part-) in the state in which the building resides.

Sadly even this is not enough ! Besides a stamped engineering letter, you typically need to prove that the work was performed in a "certified" manner. The cost of both could kill you.

You might be better off the just build a "box inside your box". A free standing structure that you can insulate. You can share the outside walls, you just can not add any load to the existing roof trusses.

 

[69gp]

You could use steel hat channel to span between the trusses. If the truss span is to big you can run a channel parallel to the trusses and then support the hat channel of of that.

Couple of links.

http://www.clarkdietrich.com/products/drywall-framing/furring-channel-hat-channel

http://www.clarkdietrich.com/sites/...hannel/CD_FurringChannel-Properties&Spans.pdf

 

[rburke65]

I could be wrong but I do not think that metal barn siding will span 8' with cellulose insulation atop. Even without the insulation. Vertically.....with the Girts every 2'.....not 8' and horizontal.

 

[manrmark]

Mark,
Thought I would answer your question here so others could see it.

Your PM:
I ran a crossed a post you made about you using a thicker metal for your ceiling. Can I ask you what is the span between your trusses and what did you use for your ceiling and where did you get. I have 8' span between trusses and would just like to put up the steel siding on the ceiling that Menards sells then insulate but I'm afraid it will sag without reinforcement otherwise ill need to strength the trusses some how and run 2x4s perpendicular to keep the metal from sagging, I would rather just screw up metal and insulate. I started a thread a while back which you can see on my profile which might explain a little more. Thank you Mark

Mark,
I have 8' between my trusses and no 2x4s perpendicular for support, I didn't want to loose the ceiling height in the shop.

What I used was steel siding that is made for ceiling use. The metal itself isn't any thicker in gauge, might even be thinner for weight, it just has bigger bends that make it about 3" thick. I too was worried about bowing once it was insulated. I blew in about 10" of insulation and it didn't bow a bit. It's been up 10 years and still is straight.

I bought most of my steel at Menards, but at the time they didn't have this ceiling steel and I got it from a local company that just sells and installs steel pole barn siding. Not sure if Menards has it now. Sometimes they can special order some odd pieces.

Hope this helps.

Thank you for your help.

 

[72Anthony]

Thinking outside the box here:

Why not use spray foam on the underside of the roof? Then you wouldn't have to provide ceiling.

 

[manrmark]

Thinking outside the box here:

Why not use spray foam on the underside of the roof? Then you wouldn't have to provide ceiling.

I've considered that but we average a hail storm about every 3-4 years and I just had the roof and 2 sides replaced last fall.

 

[black00lightning]

They can spray the outside of the roof using a special foam then a paint coating. It may offer some hail protection.

 

[PAToyota]

I dug out my plans today

here what it says

TC LL 30. PSF
TC DL 4.0 PSF
BC DL 1.0 PSF
BC LL 0.0 PSF

No extra capacity in those trusses. Heck, at 35 psf they wouldn’t even meet the snow loads around here.