20 x 30 with extra tall loft area?

[Steve_B]

Do not have the plans for the 20 x 30 with 1.5 but have a question for who ever may know specifically or in general....

Wanting to go with this plan, but trying to make the loft as livable as possible without adding dormers or such, so is there a way to just increase first floor wall stud height to add it to the loft area, or would I have to stop at a certain point and build a second floor wall for the extra height?

Thinking my build would go bigger to 20 x 40 and maybe increase loft size by those 10 extra feet, so trying to get more of a "room" feel up there and livable space

Any help appreciated...

Steve

[MountainDon]

If you want to make the upper area really livable without dormers, then think about making a full height second story. Make the first floor 8 foot, or 9 or 10 if you like high ceilings. Build the second floor with the first floor ceiling joists doubling as the upper floor joists. Then build the upper floor walls 8 feet tall and put ceiling joists on that. The ceiling joists double as rafter ties. Build a regular rafter gable roof as most do. The 8 foot upper wall height would permit windows in the side walls for more light upstairs. Something like that should be built on a good full perimeter foundation / crawl space.

That's one way to do it and it should pass code anywhere as well as being very livable.

[Steve_B]

Did not want to add a complete 2nd story per say.... I believe the plans call for 10' walls, I was curious to see if maybe just going with 12' or 14' studs would be safe and be up to code??

I would go with a true second story plan if it is not possible?

Could one build 12' or 14' high walls safely with 2x6 or would that have to bump up to 2x8 or 2x10 maybe?

[Davegmc]

if you are thinking of going with with a half loft (and half vaulted ceiling), you might consider 10 ft walls with the loft floor let-in at 8 ft.

[Davegmc]

That would require a ridge beam though.

[Steve_B]

The materials list for the 20 x 30 with 1.5 calls for 2x6x10" studs for the exterior walls....

If I am reading IRC2009 table 602.3.1 the right way.... I would be allowed by code to use either 2x6x12' or 2x6x14' to build a wall of a house supporting two floors and a roof

Would this be correct in code, could someone double check my work?

[MountainDon]

There is more to this answer than may first meet the eye.

Davegmc alluded to this when he mentioned ridge beam... With taller wall studs and a loft floor the assumption is that the side wall studs will be extending up a few feet above the loft floor. Also then the roof will be supported by those extended wall studs. As there will then be no room for a conventional rafter tie, in order to meet code, the would need a ridge beam (not a board) with the appropriate load bearing columns right down to the foundation or manufactured roof trusses.


PS: I think you meant to reference a different table, not 602.3.1, but...
TABLE
Scroll down about 4/5 the way.R602.3(5) SIZE, HEIGHT AND SPACING OF WOOD STUDS

[Steve_B]

There is more to this answer than may first meet the eye.

Davegmc alluded to this when he mentioned ridge beam... With taller wall studs and a loft floor the assumption is that the side wall studs will be extending up a few feet above the loft floor. Also then the roof will be supported by those extended wall studs. As there will then be no room for a conventional rafter tie, in order to meet code, the would need a ridge beam (not a board) with the appropriate load bearing columns right down to the foundation or manufactured roof trusses.


PS: I think you meant to reference a different table, not 602.3.1, but...
TABLE
Scroll down about 4/5 the way.R602.3(5) SIZE, HEIGHT AND SPACING OF WOOD STUDS

Don... My reference was to IRC2009 table 602.3.1 and yours is to the more current IRC2012 which I just looked at


So with the information I have right now, this would be my idea... The exterior studs of the house will be either 2x6x12' or 2x6x14' and the first floor ceiling / second floor floor would be right about 8' high. This would give me either 4 feet or 6 feet side wall height in the loft before the roof begins to angle up for even greater headroom across the planned 20' width of the house. As long as I use engineered trusses, this would be safe and be up to code??

I am planning on a concrete slab as the foundation for this house

Thoughts on this idea??

[MountainDon]

Concrete slabs with a perimeter footing appropriate to climate make great foundations as far as I am concerned, with one possible exception. A part time use structure that is left unheated in winter would have a cold floor that would take a while to warm up if the winter use was weekend only. If building to code there may be an energy code requirement to place a certain amount of rigid sheet foam under the concrete, but then a raised wood floor would have to be insulated too in that case.

Engineered trusses would make a good roof. You could ask the truss manufacturer to incorporate a scissors like design or something else engineered to increase loft headroom. Just ask them for what they can do.

In the case of using roof trusses you could also platform frame the loft floor with std 8 foot studs for the first floor walls and then short walls of whatever length desired for the upper floor.   


FWIW, the IRC maintains section numbering from one edition to the other. If new sections are needed they are added as sub sections to those existing. So a table retains the same numbering as does all the other sections. States and local jurisdictions can make changes to the general IRC code so it may be important to ascertain what your own locality uses. Most basic things remain the same, but some things like residential sprinkler systems for fire suppression may not be adopted by all.