Vaulted Ceiling Question.

[SirReal63]

I am in the middle of framing out the interior of a 24x24 metal building with 14' walls. This will be our guest house and I am finding difficulty on how to frame the ceiling. There is a 12x24 loft with 7' ceilings underneath. The other 12x24 space will be an open vault. My original plan was a traditional structural ridge with support posts on the walls. Since this is just interior framing with no roof load it only has to support itself and not sag in the middle. I am uncertain I can do this without a support pole in the middle, which I can do as the loft runs right down the middle of the space. I am trying to avoid putting a laminated beam across the ceiling, there are metal collar ties in the way and they really need to stay. The ridge has to work around those collar ties and that is what is stumping me. The collars are the real issue.

Perhaps a few pics will help?

The building itself...

Collar ties, the other brace is no longer there, it was just support while framing. The metal framing is on 48" centers.

Roof joists are to be 2x8's @24" O.C. which should be adequate for the 12' run each one has, since it has no roof load other than it's own weight. Those blasted collar ties are going to be an issue, and according to the metal bldg. installer they need to stay. I have no idea how to create this vault with the ties in place, and not have the roof sag. I would prefer not to drop the ridge below the collar ties as that will cut into head room in the loft. The ceiling is to have 11/32" Ply-Bead and R-30 insulation in it, no drywall or any other load than a ceiling fan. I had originally planned on attaching the 2x8's to the roof framing and eliminating the metal collar ties, but that will negate my warranty on the building.

I wish I had better pics, and will take some this weekend if it helps. The loft is very sturdy with 2x10 floor joists and a 3.75" top plate. The walls are attached to the 2.5" steel framing with plates and spaced 1/4" away. The interior walls will add some structure to the building, but not the roof.


Any suggestions or work arounds?

 

[BHD]

I would most likely consider "beefing up" your, current trusses,

most likely I would get some light gauge metal and screw on strips to the current tube and then on the bottom of that strip another light gauge tube, and if you need wood then bolt or screw on a sleeper or a block to the new tube, basically make a C channel or if wanted block in both sides and make a tube, the sides would not need to be solid or continuous (consider it a web). have a web at the peak that ties the two new tubes together and the tie on the original.

that is most likely what I would do, by making the "web trusses", instead of just a tube, the strength would be greatly increased,

here is a simple tube truss, first post 20 foot diameter removable barrel vault and dome trusses

 

[BHD]

I have seen Quonset buildings build with a rebar truss made form two rebar spaced a few inches apart, and flat plates welded in between, them ever few feet,

 

[SirReal63]

Interesting idea. I think I have two real options to make it work, I can add a structural ridge on each side of the ties, with them tied to each other, like a ladder laying down, supported by two poles on each end. The other option is to have the steel bldg. guys make me a ridge in the same fashion they make the trusses for their larger buildings.

This is what the trusses for the 40x70 look like...

One of these across the 24' span should function as a ridge, not interfere with the ties, give me support for the joists and the height to add add the insulation. None of this will be a problem when I begin framing the 40x70, the construction of the roof is different.

 

[sld]

That is a nice building! Was the cost more than a traditional stick built?

Talk about fire proof....

 

[SirReal63]

We like it, and it was way less than a stick built. 40x70 with 14' walls, it should make a nice house, once we get to that, guest house first.

 

[s219]

Nice building -- who is the manufacturer? It looks like the way they build pre-fab carports out here, with option to close them in, just like what you have.

I would be tempted to put up 2x4 or 2x6 supporting walls at an appropriate height, and then run horizontal joists across, making for a flat ceiling and another loft space up above. There just isn't a lot of meat in the current framing to attach to, and creating another inner vaulted ceiling is a little cooky.

Now, if you're determined to have a vaulted ceiling, I'd say again build your supporting walls and then throw up rafters at a pitch that is a little less than the original roof. That way the inner "roof" has some headroom away from the outer roof as you get near the ridge.

Don't forget some type of venting. Once you have people living in there, you need to make sure the air changes over and that you are not trapping moisture/vapor inside the outer building shell (otherwise you will start to see all sorts of odd moisture issues, some potentially damaging). I bet that current shell is pretty darn tight unless it has some venting already.

Good luck! Looks like a fun project. I actually need to build an inlaw suite like that. Right now, the suggestion to bunk in the barn isn't going over so well.....

 

[SirReal63]

Both buildings will have a full interior framing which will basically be a structure in a structure, the guest house has already been started, which is what led me to my quandary. The idea is both will look like a simple metal building from the outside and a house from the inside.

Here is the layout for the guest house.

This is the actual issue, half of the framing is done, the loft floor is done and I am starting to think about the vaulted ceiling.

The rafters will only be there to allow for R30 insulation and the bead board ceiling. There is a vent on the ridge but it is only minimal effective. Those collar ties are presenting a challenge, and I know I could just frame up the wall on the edge of the loft and run the joists off of it but the goal was to have it open from the loft to aid in heating and cooling.

The full thread on our property if anyone is interested in our little adventure.
http://www.tractorbynet.com/forums/south/313136-small-texas-farm-beginning.html

 

[SirReal63]

Nice building -- who is the manufacturer? It looks like the way they build pre-fab carports out here, with option to close them in, just like what you have.

They are a local manufacturer, Texas Building Center, they weld up the trusses at their shop. Overall I am impressed with the 40x70, even with 14' walls the building is very stable and we have had some decent winds hitting it already.

 

[SPIKER]

I would build a faux.boxed wood beam that appears like a REAL SOLID ridge beam. It can be made to take up light amount of space and even make it well enough to tie the wood roof materials to.

I agree about the building ability to breath so occupants moisture does not build up between the metal and the interior walls. Mold is one possibility if it gets too tight. The other thing is those bead boards don't hold up well on a large span, I have a cabin on 24" and every seam of the "wood look" bead board is sagged after 10 years many of the seams are gaped or well misaligned as nails pulled or popped thru it. It would be much better to use glue or construction adhesive under it and the nails only to hold it in till the adhesive sets.

Mark