question about ceiling boards? picture provided

[webby]

I found this picture looking through a log home gallery today. Anyone know how they go about making the celing wood (tongue and groove I'm guessing) stay up on the ceiling? Obviously there is a gap between the log rafters and the ceiling wood I'm talking about. So they aren't nailing the boards to those log rafter beams.

I'm trying to picture how that would all go together in my head, and what actually keeps it suspended above the logs. Do they nail the tongue and groove onto some other rafters above the log rafters? I see no seams in this picture on either side really. Obviously they have to stagger the seams somewhere, or you'd see them all in one spot. I found quite a few that were this way, and it puzzled me as to how they actually construct it.

I've seen other students on this site that nailed the boards to dimentional lumber from up above, but in this picture... there is no dimentional lumber visible from below.

am I dumb on this?


http://www.moosemountain.com/Gallery/Photos/Bushur-Living-800.jpg

[mountainmike]

It looks like they have log posts sitting on the gable end walls and a king post truss in the middle to support the ridgepole. What they probably did was build a rafter system above the roof boards (with either dimensional lumber or TJIs) from the ridgepole to the eave walls and then nailed the roof boards up into the rafters. They could either have nailed though the toungue of each board into the rafter or face nailed them with finish nails and an air compressor which would bury the nails into the boards; you can't tell from the picture.

I don't see any seams but I think some companies make a T&G product which lets you match ends and makes the seam almost invisible. If you want to build your roof below the rafters it is often easier to use purlins because you can hide the seams behind the purlins.

[webby]

so do you think they nailed each one to the dimentional boards BEFORE putting it on the roof, or nailed each one from underneath?

[mountainmike]

No, if you apply the roof boards underneath the rafters you put them up after the rafters are in place and have to work from underneath on scaffolding or ladders. If you put roofing underneath you usually use 1x6 T&G. It is much easier to put roofing on top of your rafters eventhough you use 2x6 T&G which is more expensive.

[ets80]

They built a rafter system above the roof boards with dimensional lumber from the ridgepole to the eave walls and then nailed the roof boards up into the rafters. They then nailed though the tongue of each board into the rafter. The roofing outside is attached to the sheathing/decking on the other side of the rafter system.