Cabin Build/Engineering Question

[TaperPin]

No, not those.

More like these.....

View attachment 831152

Exposed structural timber trusses that have been engineered and built to be self supporting look awesome and no ridge needed. You would have to strip all the old roof off to get them in, and they would be many times the cost of new scissor trusses, and the 2x6 T&G to span between them looks awesome and makes my wallet hurt just looking at it - $2 to $10 a linear foot, then the roof 2x sleepers, insulation, and osb on top of that makes for a spendy roof. If scissor trusses seem expensive, these definitely are not in the budget. If you want a T&G ceiling it’s cheaper to have a ridge beam and apply 1” T&G over the rafters.

 

[Tater86]

In modern residential construction we spend a lot of time talking about the air barrier and the thermal envelope. Osb is a partial air barrier if the joints/seams are taped. It is important for the purpose of eliminating air movement inside your insulation if using batts or blown in batt(BIB) either loose fiberglass or cellulose. The thermal envelope is obviously your insulation. There hasn’t been any discussion of insulation. Your chosen roof structure should include discussions of insulation and ventilation so that the whole assembly works together to be maximally efficient and to preclude issues like moisture and mold caused by condensation within the assembly

All the insulation, vapor barrier, ventilation and crack sealing is all included. I understand that portion and all of that is covered. I'm more concerned about the framing and construction of the ceiling.

 

[Tater86]

Exposed structural timber trusses that have been engineered and built to be self supporting look awesome and no ridge needed. You would have to strip all the old roof off to get them in, and they would be many times the cost of new scissor trusses, and the 2x6 T&G to span between them looks awesome and makes my wallet hurt just looking at it - $2 to $10 a linear foot, then the roof 2x sleepers, insulation, and osb on top of that makes for a speedy roof. If scissor trusses seem expensive, these definitely are not in the budget. If you want a T&G ceiling it’s cheaper to have a ridge beam and apply 1” T&G over the rafters.

So you can't set timber trusses on existing wall structures? The roof would still be OSB, weatherguard, purlins and metal. Good thing about living in Amish country is pricing is lower than other areas. T&G goes as low as $0.60 a foot.

 

[TaperPin]

So you can't set timber trusses on existing wall structures? The roof would still be OSB, weatherguard, purlins and metal. Good thing about living in Amish country is pricing is lower than other areas. T&G goes as low as $0.60 a foot.

I don’t think I mentioned the walls. The existing walls would work, but usually have to have extra studs under each one to transfer the extra weight. I love the look - and if you have a cheap hook up for timber framers, that’s awesome.

 

[WV Mountaineer]

Ok, now I'm scared to go with any contractor. All of them were planning to place a ridge beam and add 2x8 rafters along side the current truss system. That was at least 4 different contractors that quoted this way.

I’m a general contractor and there is zero chance I’d do that. ZERO. Unless you use collar ties. And, as pointed out above, you aren’t gaining much with that effort.


Man, I’d be highly suspect if any contractor talking about splicing dimensional lumber for a ridge pole, for a vaulted ceiling versus a laminated beam. Are these guys licensed?

 

[rogerdoger]

The guy your dealing with sounds like he is not a contractor rather a CONtractor if you get my drift.

 

[Rbehrens26]

What about a 26’ ridge beam that is supported by a transfer beam on the interior side of the cabin? The transfer beam would bring the load to each stud wall and prevent the need to drop a column right in the middle or the floor?

You’d likely have to get a little creative with the transfer beam to support it at each stud wall, but if you’re willing to give up a little head space this could be a good option.

One another note that I don’t think has been mentioned - make sure all elements and supporting column connections have some sort uplift capacity. You’d want to chase these connections all the way down to the footing.

 

[4rcgoat]

This beam went 25' 2 ply 20" lvl with a 1/2" steel splice plate in between, all bolted together.