*
I am going to be building a house this year and am looking for some input on roof truss. Suppliers are telling me that they are enginered for 24 centers but my gut feeling says no. Is it overkill to put them on 16 centers if enginered for 24?
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
The code requires installing an approved material to slow the spread of fire between floors and adjacent vertical and horizontal cavities — here are the allowed materials and required locations.
Featured Video
Highlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Fine Homebuilding Magazine
Fine Home Building
Follow
-
Fine Homebuilding
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial Now -
GBA Prime
Get instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
Replies
*
Put them on 24" centers and use 5/8" plywood.
*I agree as I have built over 400 homes with trusses at 24" O.C. and 5/8 cdx plywood. I suggest you use 4 ply. Follow the engineering and you will be fine
*If your sheetrocking the bottom on 24" centers, you may consider 5/8" thick or texture to keep the wavy ceiling to a minimum. Flat finished 1/2" especially with blown in insulation, years down the road don't look so good.
*I put mine on 24,s. I also thought about 16,s. Well today I started hooking up my woodstove and relize that they would be no way I could of run the pipe if it was on 16,s.
*It's overkill.....if they are engineered right....but no reason why you couldn't. Just make sure the rest of the house/foundation is drawn around that new plan. Jeff
*I think 19.2 is a better compomise
*The problem with engineering (and I am an engineer) is that the allowable error can be reduced to below the skill level of the construction people.I would have them engineer the trusses for 16" spacing.Don't forget to put in all of the braces and such that they show on the drawings.
*16" is overkill. IMHODave
*I get this question a lot, being in the business. Here's my opinion, FWIW. Putting trusses on 16" centers is nuts. The only possible advantage I can see is that you can use thinner plywood on the roof and 1/2" drywall on the ceiling. There is no other benifit that I know of. Contrary to what you might think, it doesn't make your roof stronger. (Except in rare cases, which I'll get to) Let's say your local codes require that your roof be designed for a 50 PSF total load. If the trusses are 2' on center, the trusses are then designed for a load of 100 PLF. If you set the trusses at 16" OC., the designer will only design the trusses for 66.6 PLF. So you've gained virtually nothing. The only case where it makes the roof stronger is if you i designthe trusses for 24" centers, but i installthem on 16" centers. That would make your roof stronger, but why would you want to? If you want it to be stronger, just specify that the trusses be designed for additional loading - Say 60 PSF in this case. Since setting trusses 16" O.C. increases your cost for trusses by about 40%, and has virtually no benefits, I'd say it's a waste of money. Don't forget to allow for the additional labor for installing the extra trusses, and extra money for the added nails in the roof plywood and ceiling drywall.
*24" centers, 5/8" ply on the roof, 5/8" rock on the lid. Your go to GO!! Your Golden!! It's all good!! BAM!!!
*I believe that the 19.2 set would create problems with rolled fiberglass insulation. It was brought up in another discussion by someone else here.
*Boss Hog's got it totally correct in every way.......In addition, if you DID use trusses designed for 16"o.c. , the roof sheeting would have more support/be stiffer, so you could go to 1/2". But it's still moot.........24" o.c. w/ 5/8" sheeting rules. -Ken
*24" oc... 5/8 ply with clips... ceilings furred 16" oc... and 1/2" blueboard...16" is for b FRAMINGnot for roof trusses...
*Hey Mike- Ever go w/2 clips/bay? -Ken
*no.... that wud put 'em 8"oc....do you mean if you're setting a narrow strip ?we've used multi-clips in places like that...
*16 inches on trusses shouldnt even be considered, as mentioned. But 19.2 will hold 1/2 blandex and 1/2 dywall very nicely. This system will render savings.hence: check the cost of 5/8 ply, with 1/2 blandex. 5/8 dw to 1/2dw. The ceiling gets blown insulation anyway.
truss spacing
If you are using the continuous load bearing method of framing where the studs are lined up with the rafters/trusses and you have 2x6 exterior walls as required for the energy code and studs are on 16" centers as required for a two story home...Then you should space the trussses on 16" centers. The cost of the extra trusses (1 more for every 4') will be partially offset by using 1/2" plywood or OSB rather than 5/8" plywood. Do not forget to use clips on the sheathing material edges!
good
you have 2x6 exterior walls as required for the energy code and studs are on 16" centers as required for a two story home
Is this a new code rule you cite?
Do you realize the thread you pulled up and posted in is from 11 years ago?
The original post is eleven years old !
Don't know why, but these things seem to get revived from time to time. The answers are usually the same, unless Code has changed !
Greg
Greg
They're usually drug up by new users and it's understandable why. Sometimes added info is worth the archeology.
Me, I'm still waiting to hear why you can't build a two story with 2x6 studs 2' oc and dbl. plate.
Time machine effect.
People revisit the past in hopes of changing it.
People revisit the past in hope of going back there. Of course, if they actually got there they'd hate it, but they have fond illusions ... I mean memories.
Nostalgia
It's called nostalgia. Remembering things as better than they really were.
16" Spacing on trusses
I realize that this is an old thread. I have a comment based on my current problems.
The builder 40 years ago built the home with trusses on 16" Centers. An owner prior to me installed pull down stairs to the attic and cut a truss to do so. The pull down stairs are designed for 24" centers, I don't think you can get one smaller.
Now, I have resold the home and the home inspector insists on a structual engineer designing a proper correction. The opening was cross braced and the Trusses on either side sistered to take the load.. The home inspector says not good enough.
Just passing on as another reason not to go 16" if you ever want attic access.
Also, any comments on a reasonable charge for a structual engineer to design a resolution and a contractor to complete same.
16" Spacing on trusses
I realize that this is an old thread. I have a comment based on my current problems.
The builder 40 years ago built the home with trusses on 16" Centers. An owner prior to me installed pull down stairs to the attic and cut a truss to do so. The pull down stairs are designed for 24" centers, I don't think you can get one smaller.
Now, I have resold the home and the home inspector insists on a structual engineer designing a proper correction. The opening was cross braced and the Trusses on either side sistered to take the load.. The home inspector says not good enough.
Just passing on as another reason not to go 16" if you ever want attic access.
Also, any comments on a reasonable charge for a structual engineer to design a resolution and a contractor to complete same.
Is the home inspector part of your local code enforcement agency or bulding dept or just a realtor appointed weenie?
If the later, take an egg, put a pinhole in one end, have the weeinie suck the yolk out.
He probably said his brother in law could do the 'structural calculations', huh?
Last house I sold the HI (realtor weenie, buyer paid, not me) had a 15 item list. Simply wrote up a 13 item list showing how HI was FOS, did paint over 2 cosmetic items.