# Trusses on 16 or 24?



## Markil (Oct 11, 2007)

Greetings All. I live within 40 miles of NC beaches. Getting ready to build a 30 x 50 garage with attic trusses -- 10/12 pitch, 2x8 tc, 2x10 bc. The trusses are rated for 130 mph wind. There eventually will be a family room and bedroom in the attic space. I am planning 16 oc for the trusses. I like lining up the trusses over studs to transfer the energy to the slab/foundation. Inspector has said either 16 oc or 24 oc is fine. What do you recommend?


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## send_it_all (Apr 10, 2007)

Definitely 16". If I understood you correctly there is going to be living space above?...So the trusses are floor joists?...16 seems like the only choice.


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## Joe Carola (Jun 15, 2004)

Markil said:


> Greetings All. I live within 40 miles of NC beaches. Getting ready to build a 30 x 50 garage with attic trusses -- 10/12 pitch, 2x8 tc, 2x10 bc. The trusses are rated for 130 mph wind. There eventually will be a family room and bedroom in the attic space. I am planning 16 oc for the trusses. I like lining up the trusses over studs to transfer the energy to the slab/foundation. Inspector has said either 16 oc or 24 oc is fine. What do you recommend?


Whoever designed them has to give you that answer. Since there will be rooms above, 24" centers might not be in the design. You also said, 30x50. Are the trusses running the 30' way with no walls underneath?


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## steves (Feb 8, 2007)

That question can only be answered by the truss designer!
If they work @ 24"oc you could go to 16"oc (not that it makes any sense)
But if they are drawn @ 16"oc don't go 24"oc on my or anyones advice


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## Tmrrptr (Mar 22, 2007)

2 x 8 top chord and 2 x 12 bottom chord is a rather stout truss!

16oc sure is noticeably better than 24oc, though...
r


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## Markil (Oct 11, 2007)

The trusses do run across the 30 width. We priced them at two different truss companies, one said go 16, the other said 24. Both companies aware of the hurricane zone we are in. Contacted an engineer today, but he didnt respond. Hoping to hear from him Monday. 

There are no walls underneath and there will be family room overhead.

Appreciate the replies.


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## Bob Kovacs (May 4, 2005)

Do the truss companies know of your desire to put rooms up there later? They'll need to design the trusses to carry that future load and provide the open space between chords. Though trusses at 24" is typically done, if you're planning on rooms upstairs, I'd go 16"- it'll make for a less bouncy subfloor even with a thinner sheathing.


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## Kgmz (Feb 9, 2007)

With a 2x10 or 2x12 bottom chord and a 2x8 top chord, they were designed as what is called a attic truss.

We have used attic trusses on a lot of houses and have never had a problem with them at 24" O.C., and these were 8/12 pitch 34' to 38' long with a 2x10 bottom chord.


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## Bill (Mar 30, 2006)

truss manufacturers specifications!!


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## Kent Whitten (Mar 24, 2006)

The truss engineer is who you want to listen to, not another engineer. He will tell you exactly what you need and what spacing to put them on. If you desire 16" OC's, then tell him first, then he'll design trusses at 16" OC. He's sitting there with truss engineering software, he plugs in the numbers and out it spits what you need. 

The 16 or 24 is irrelevant to the engineer. He designs what he thinks is normal unless you specify you'd like something different, and that'd be before he designed the truss system.

Personally, I'd want 16" OC for attic trusses. but it'd depend on the usage of the room. Not many times have I seen 16" OC trusses. Almost always 24" OC's


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## neolitic (Apr 20, 2006)

16oc = ¾ sub floor, 24oc = 1½ sub floor right? Just a thought.


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## Teetorbilt (Feb 12, 2004)

16" OC = more tiedowns = lower ins. Everything that we built in the Bahamas and Ft. Laud. was 12" OC. A few $ more but everything that we ever built is still standing. Dad built 2 homes before I was born and they're still up too. His first was 1947. Build to last!


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## Kgmz (Feb 9, 2007)

neolitic said:


> 16oc = ¾ sub floor, 24oc = 1½ sub floor right? Just a thought.


The 1 1/8" subfloor is far cheaper than the extra trusses.

The actual floor space in a attic truss is around half of the span.

Last house we built with attic truss the span was 36' and the length of the portion of house with attic trusses was 46'. So with 24" spacing there were 23 trusses, with a 16" spacing there would have been 34 trusses. There was a space for a stairway that was 3.5' wide and this is why the truss count is off by one.

Attic trusses are not cheap, so figure the cost of 11 extra trusses to the cost of a thicker subfloor.


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## supercrew (May 15, 2006)

like teetorbuilt said..12"oc. more $'s but more sturdy. 30' is a long span, engineered products or not.


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