Truss construction

[mbledsoe]

From an engineering perspective this truss system seems less than optimal to me. Other thoughts/obeservations??

[Michael R. Boyett]

IRC 2003 R802.3 says: Rafters shall be framed to ridge board or each other with a gusset plate as a tie. Ridge board shall be at least 1" nominal thickness and not less in depth than the cut end of the rafter. Therefore the left side is fine, the right side sucks. Oh, and I wouldn't call this a 'truss system', that sounds like it's an engineered truss and, in this case, it's not.

[away]

In addition to what M. Boyett pointed out, it looks like the ridge board is pieced together. It looks like there is a butt joint under the third set of rafters.

[rrichards2]

Hard to tell what is going on here. Was there a structural reason for using the larger dimension lumber on on side or did they run out of the smaller dimension material and used the available larger stuff? If the latter is the case, I see no problem with it.

Also, there is no problem with the joint in the ridge board.

[Marcel R. Cyr]

Again, hard to see the whole picture in the right perspective.

It appears that the roof framing is definetly stick built, and one side is roughly a 6/12 pitch and the other side a 12/12 pitch.

The 6/12 pitch would have a plumb cut of 6-1/2" and the ridge board of the picture would indicate it in proportion to be 2x8" and the opposite side of the roof would have a plumb cut of 10-5/8" showing 4-1/2" below the ridge.

Again the picture does no justice to all the relative variable factors of condition.
Based on what I deduce, the ridge board, although called out to be a minumum of 1", should have been a 1"x 12" to accept the proportional values of the plumb cuts.

Variable:

Collar ties
span
rafter size differences
exact pitches
loading by area
wind uplift
amongts others.

Hope this helps.

Marcel

[Michael R. Boyett]

Originally Posted by rrichards2

If the latter is the case, I see no problem with it.

Dang Roy, you must be interpreting that photo under Canadian rules.

[rrichards2]

Originally Posted by mboyett

Dang Roy, you must be interpreting that photo under Canadian rules.

Never mind, Canadian rules don't apply in Georgia.

[rrichards2]

Originally Posted by away

In addition to what M. Boyett pointed out, it looks like the ridge board is pieced together. It looks like there is a butt joint under the third set of rafters.

It's hard to find 40 to 60 foot long boards at the local lumber store.

[Marcel R. Cyr]

[quote=mboyett]Dang Roy, you must be interpreting that photo under Canadian rules.[/quote]

Actually, I was born to throw a rock in Canada, and the ridge boards would have been of a 2"x? in liew of the minumum standard of 1" and the answer is no a ridge board does not have to be in one uninterupted length.

Marcel

[Michael R. Boyett]

Actually, I was referring to the wrong dimension of the ridge board, not necessarily the length.....

[Marcel R. Cyr]

I agree Michael;
Sorry for the confusion in the quotes, I was actually trying to address a question downline from that. Still green with these darn computers ha. ha.


Marcel

[Michael R. Boyett]

da nada, amigo......

[rrichards2]

Originally Posted by mcyr

[quote=mboyett]Dang Roy, you must be interpreting that photo under Canadian rules.

Actually, I was born to throw a rock in Canada, and the ridge boards would have been of a 2"x? in liew of the minumum standard of 1" and the answer is no a ridge board does not have to be in one uninterupted length.

Marcel [/quote]

I know Marcel, I am an Architectural Engineering Tech. and a Licensed Carpenter for almost 20 years.

[mbledsoe]

Thanks, great call on the roof pitch, your right on. I don't have a photo that shows it well, but the area exposed below the ridge seems to begin to split . I wouldn't think the load would be that great. I recommended eval by an SE but wanted to get others opinion. Thanks!

[away]

Ok all you smarty pants, I realize they don't make boards that long. I was referring to it with respect to it being unscabbed, unsupported, etc. I was thinking that the load may not be transferred correctly along the length of the ridge and that maybe it could cause problems at the joint.