FlatPak House ceiling

Anyone have an idea what the material used for the ceiling of the FlatPak House featured on page 137 of the April/May issue is? It appears to be birch plywood, hard to be sure though.

Don't interior walls and ceilings have to meet some fire code?

I think it is painted fibercement boards.

I was guessing MDF

I'm not sure if you are looking at the ground floor ceiling or the second floor ceiling, but the second floor is what caught my attention. I spent a lot of time studying the ceiling as I think this is one of the most interesting parts of this house and really speaks to the method of pulling together components sourced from different suppliers in different materials - this is a real furniture like approach.

Anyway I believe the ceiling is the underside of a metal foam sandwich panel. It has a lightly embossed texture and obvious seams which reminds me of this product. This ceiling also follows the slope of the roof as it pitches from one side to the other and you can see a sub structure that is raising it up above the wood framing. That sub structure appears to consist of a series of short tubular steel posts, and horizontal steel tubes running over them which appear to carry the roof loads to each small post and then down to the major wood beams. What I don't understand is that these horizontal tubes do not appear to be strong enough to support the snow loads they must get in that region. The roof system thickness as you see in the exterior shots also looks much thicker than any of the sandwich panels I have seen. So this suggests to me that there is some other framing support hidden in the middle between two layers, one being the roof and the other the ceiling. Or its a product I am not familiar with. But I can't see it, and hes not telling, and whatever it is it may not even make it into the production models.

There are some steel/EPS/steel SIP panels that are quite thick, upwards of 11.25 inches. I imagine that is what the roof structure is. Something that thick in a stressed-skin panel shouldn't have any problems carrying the loads across that span and evenly distributing it to the intervening structure.

mark

I agree with Mark, Look at IKEA those panels are HUGE. TG!!!! This Old House used 10 in Mass for both roof and floor. Insulspan I think. Plams 4'OC