Truss spacing

[strick9995]

I'm planning on building a detached 42' x 30' garage behind my house and had some questions for you all on truss spacing. I plan to frame the exterior walls with 2x4 on 16" spacing. Does anyone see a reason why I can't space the trusses on 32"? I don't want to put them on 2' because i'm cheap, and I don't want to put them on 4' because I don't want my ceiling sheathing to sag. The roof and sidewalls will be sheeted with 29 ga R-panels so i don't believe the roof load will be all that great. I didn't think it would be all that uncommon but i haven't ever seen it done, and cant find anything on the interwebs of anyone else spacing them on 32's.

 

[ixlr8]

Truss spacing is determined by the truss manufacturer.
The trusses for my building were 2' OC so my wall studs were 2' OC. It is recommended that the wall studs line up with the trusses to best support them.

 

[The Cobbler]

as noted above.
and, by time you get a truss spec'd for 32 rather than 24, you're probably at the same cost or higher.. and, have you sat down & figured out how many trusses you save by doing that? plus you probably have to go to thicker sheeting, and all sorts of other issues.

 

[strick9995]

2' spaced trusses can sit on 16" spaced stud walls. This is a similar scenario just slightly larger spacing. Every other truss will land on a stud.

 

[strick9995]

There will not be any roof sub sheeting. It will be 1x's or 2x's with 29ga R-panels on top.

 

[strutaeng]

Truss spacing is typically determined by deck span rating. The truss manufacturer will size the truss based on spacing, of course, to a certain manageable spacing.

Look up span rating for wood panels. For 32" spacing you'll need thicker panels, probably 19/32.

I like the look of trusses at longer spacings. It looks "cleaner," but it is more expensive. 24" o.c. is more economical, so you should stick with that.

I did a project in my house that required 48" o.c. roof deck, and used 23/32 plywood. It actually feels stiffer walking on it than 7/16 @ 24" o.c. used typically around here.

For commercial application with metal deck, 48" o.c. spacing or more is typical.

 

[Leaflessshadetree]

The contractor spaced mine at almost 8 FT "to save cost and labor".
Since I'm doing the interior myself I had to add framing for the ceiling.

 

[strutaeng]

The contractor spaced mine at almost 8 FT "to save cost and labor".
Since I'm doing the interior myself I had to add framing for the ceiling.

What is the roof deck? You'd be into the 3x T&G decking for that span I bet?

 

[Vintage Veloce]

Talk with the truss designer / manufacturer. They can design as you wish. My trusses are actually bizarrely uneven in spacing, by design. Just ask.

 

[mike93lx]

2' spaced trusses can sit on 16" spaced stud walls. This is a similar scenario just slightly larger spacing. Every other truss will land on a stud.

Yep, this is how my house is built.

To the OP, you can do whatever you want, but i personally would do what the trusses are specced for, nothing else.

 

[strick9995]

What is the roof deck? You'd be into the 3x T&G decking for that span I bet?

There will not be a roof deck. It will be 1x's or 2x's perpendicularly fastened across the trusses on 30" centers, and a 29ga R-panels on top of that. so a very light roof load. this is a metal building with a wooden frame.

 

[kasander]

There will not be a roof deck. It will be 1x's or 2x's perpendicularly fastened across the trusses on 30" centers, and a 29ga R-panels on top of that. so a very light roof load. this is a metal building with a wooden frame.

He was asking Leaflessshadetree, not you...

 

[strick9995]

He was asking Leaflessshadetree, not you...

Thank you for your input, I didn't notice. Do you have any comments on truss spacing or just forum etiquette?

 

[ForceFed70]

OP, please update your profile with your approximate location. It makes a big difference with these types of discussions.

For example: I assume you don't have to deal with snow load?

As others have said - ask your truss designer. Generally, they'll ask you what your planned roofing material is and will automatically spec the most economical truss design/spacing. But it can't hurt to ask him/her.

 

[paredown]

OP, please update your profile with your approximate location. It makes a big difference with these types of discussions.

For example: I assume you don't have to deal with snow load?

As others have said - ask your truss designer. Generally, they'll ask you what your planned roofing material is and will automatically spec the most economical truss design/spacing. But it can't hurt to ask him/her.

I just assumed that this was a southern build when I read 2x4 walls. IME, 24" spacing is pretty typical, although in the OP's case, by running purlins across, he doesn't have to worry about sheet spacing as you would with conventional 4x8 ply or OSB sheathing on the roof.

 

[strick9995]

I just assumed that this was a southern build when I read 2x4 walls. IME, 24" spacing is pretty typical, although in the OP's case, by running purlins across, he doesn't have to worry about sheet spacing as you would with conventional 4x8 ply or OSB sheathing on the roof.

South East Kansas. We get snow, but not like up north. 2x4 exterior walls are very common here.

 

[Samh]

It is recommended that the wall studs line up with the trusses to best support them.

Only if you have a single top plate. Double top plate makes that a moot point.

 

[850xpeps]

I did my garage on 32” centres using 2x 4 purlins for the roof tin.

Don’t use 1x.

Just make sure the truss is up to the load. The place selling it can tell you.

And the truss doesn’t have to land on a stud if it’s double top plate. Which it should be anyway to tie the walls together a little better and stiffen the top to help keep roof and walls straight.

 

[spudley]

Just a thread on how loud that type of roof will be when raining.

Looks like you'll "save" 5 trusses @ 32" V 24". Common 4/12 W trusses are less than $100 around here. I'd save money somewhere else.

Good luck, hope you don't have a dog named Toto.

 

[matt_i]

I think its not a great idea because trusses must bear 33% more loading and so must be built stronger out of incrementally heavier material costing more.

But you can find out for sure. Have it quoted both ways. Make sure you get 5 psf BCDL for your ceiling sheathing for both cases.

 

[rburke65]

Do yourself a favor and go with 24” spacing. There is a tim3 to be cheap and this ain’t it.

 

[strick9995]

Just a thread on how loud that type of roof will be when raining.

Looks like you'll "save" 5 trusses @ 32" V 24". Common 4/12 W trusses are less than $100 around here. I'd save money somewhere else.

Good luck, hope you don't have a dog named Toto.

Thank you, Occasional noise in a shop isn't really a concern. Also, This type of roof system is used in shops and barns all over down here. The 2x4 purlin system is not much different than a a pre-engineered metal building pulin system. its probably quieter. Plus the insulation and ceiling sheeting will help absorb the noise.

 

[strick9995]

Do yourself a favor and go with 24” spacing. There is a tim3 to be cheap and this ain’t it.

Nobody has given me a good reason as to why its a bad idea. How do yo feel about builders that put their shop trusses on 4' centers?

 

[mike93lx]

Nobody has given me a good reason as to why its a bad idea. How do yo feel about builders that put their shop trusses on 4' centers?

The difference is they are buying trusses designed for that spacing. You want to take a truss designed for 24 centers and space them wider to save money.

If the spec says 8' centers is ok, go for it. But this isn't a place to make on the fly changes

 

[The Cobbler]

Nobody has given me a good reason as to why its a bad idea. How do yo feel about builders that put their shop trusses on 4' centers?

you have not comprehended this thread then

 

[mike93lx]

Why is it our job to convince you?

Do whatever you want.

 

[jdewitt]

If money's the issue and you're doing it yourself, stick build it with rafters. It's time consuming, especially if you don't know what you're doing.

 

[The Cobbler]

trusses are overrated anyway, they'll hold a lot more than rated for

 

[finn]

trusses are overrated anyway, they'll hold a lot more than rated for

Yup, and we have plenty of collapsed pole barns after last winter to prove it.....

Never mind.

 

[KenC]

I don't think it's a bad idea at all. But, the truss maker is the only opinion that matters. Just ask.

 

[danfromsyr]

shyt,
I'm always of the camp to exceed 'engineering minimums'

I'd go 16oc just to be sure I'm not in a wind issue.

here we have SNOW LOADS and on the occasional winter we hear about those 'minimum engineered' roofs compromised.

adding a couple trusses/joists costs less than worrying about loads.

 

[jetnow1]

Remember the building code is a minimum standard, not a recommended one. If you go with non standard methods be prepared to show the building inspector an engineer's stamp on the plans, and the truss manufacturer sign off on the spacing.

 

[pennsylvaniaboy]

2' on center with a double top plate....or go 4' on center, with 2x4 purlins and tin(if the truss is engineered for it, and you have enough rise/run to not hold snow).....do not go 32" or 48" spacing and expect plywoood and shingles to not be spongey......I have been on a 32" OC plywood/shingle roof.....pretty unnerving...

 

[Milton Shaw]

24" spacing gives 4 trusses per 8 foot. I went with 5 for 20 to 25% more strength, which is a spacing of 19.5 inches, and makes a stronger floor. I would not cheap out on the trusses as they will last the life of the building and spending a little more now will make a stronger floor/ceiling that will last a lifetime. I should have done the same on roof trusses but did not and regret it. Less than $200 or so on the total price. should have spent it. As it is I have some sagging of sheetrock on finished ceiling as 24" spacing was too much for the drywall that was installed.

 

[mike93lx]

24" spacing gives 4 trusses per 8 foot. I went with 5 for 20 to 25% more strength, which is a spacing of 19.5 inches, and makes a stronger floor. I would not cheap out on the trusses as they will last the life of the building and spending a little more now will make a stronger floor/ceiling that will last a lifetime. I should have done the same on roof trusses but did not and regret it. Less than $200 or so on the total price. should have spent it. As it is I have some sagging of sheetrock on finished ceiling as 24" spacing was too much for the drywall that was installed.

Should have just strapped the ceiling. My house has 24" OC trusses and it works fine even with our snow loads

 

[NUTTSGT]

Nobody has given me a good reason as to why its a bad idea. How do yo feel about builders that put their shop trusses on 4' centers?

If the trusses are built and spec'ed for 24" on center, then it is a bad idea. If you have the trusses built for a spacing of 32" on center, you'll be fine.


If you're having it built by reputable contractor and you tell him you want, 24" trusses spaced out to 32", he's either going to laugh at you or just shake his head. Don't expect any call backs from him or him to even give you a quote.

 

[NUTTSGT]

As a matter of fact, reading your profile, I see this.

Your Hobbies
Constrution
Occupation
Municipal Building Inspector

This thread is done.


Better yet, troll someplace else, we don't tolerate this kind of drama here at GJ.