Talk me out of building 12' walls

[hnash53]

I am considering building on to my cabin.  Currently, it has 10' walls.  My land slopes and as a result the end of the cabin where I want to add on is about 5-6' off the ground.  I was thinking that I would build the addition 2' lower than the original cabin (so one would step down into the addition from the original part), but to keep the roof lines inline, I would have to build 12' walls in the addition.  Also, I wanted to have 4' walls in the loft of the addition.

Not that I really want to be talked out of this, but is there an issue with doing this that I haven't thought of?  My cabin is in an area that isn't really subject to strict code.  Although I do want to build a safe, sturdy structure.

So whadda ya think?

Thanks.

Hal

[MountainDon]

My first thought is a question. Why do the roof lines have to be kept on the same plane?

Have to run off to work, maybe more thoughts later.

[John_M]

I have used 12 foot walls in my cabin.  They were 2x6's.  Balloon framing.  I have had no problems with that.  I have a nice roomy loft space because of this!   

You just need to have proper bracing / collar ties or something like that to triangulate things and keep those loft walls from wanting to bend outward.  Many of those discussions can be found on this site.

[glenn kangiser]

Many places in Mexico use 12 foot or so high walls for natural cooling -- some areas of our cabin have 15 foot ceilings - others 11-12.  We like it.

Heating in winter can be assisted by a reversed ceiling fan to bring the heat down -even running on low.

[hnash53]

Thanks for the replies, guys.  I have 10' walls now and have triangulated them with collar ties on every rafter (I think John has said that every other or every third rafter is sufficient), plus I have loft joists which tie the opposite walls together.   I would be doing something similar in the addition.

With sufficient bracing, triangulation, etc., would 2x4 walls be ok to use?  That's what I have with my 10' walls now.

Thanks.

Hal

[John Raabe]

The problem with 2x4 walls is cutting in a ledger for the floor joists. There is room in a 2x6 but not a 2x4 - PEG has a great photo tutorial on how to do this.

[hnash53]

Interesting you should say that, John.  The ledger boards used to support the loft joists in my cabin were not "cut in."  They were attached to the edges of the 2x4s using hefty lag screws.  Then the joists were hung using joist hangers mounted to the ledger boards.  Seems to have held up very well.  I don't have lots of weight in the lofts ... queen bed, oak dresser...not a lot of stuff.

[John Raabe]

Hal:

I'm sure you are fine for a loft in a small cabin such as yours. However there are people on the forum building 20' and 24' wide structures with a full second floor where the joists are hung from a ledger nailed into studs.

Here is an interesting chart of shear values for different fasteners. I don't have all the numbers but you can add up the loads and get a pretty good idea of what is needed from this:



Using these numbers for a 20' wide building with a 30psf live load (10psf dead) in the loft, I get 532 lbs to be supported at each stud on the fasteners if the studs are 16" o/c. Two 1/2" Ø lags would seem to do the trick. However, I don't think you could get enough nails into the stud to safely carry the load.

[MikeT]

I mentioned this in an earlier thread on ledger boards and lofts.  I like what my structural engineer advised me to do:

Instead of a ledger board where you create a hinge point, and instead of hangers on the ends of studs, why not set the loft joists between the stud bays and have them sit on a 2x4 or 2x6 and have both the joist and the support post nailed to the stud right next to it?  You have good, solid bearing of the load.  I suppose the tradeoff is in insulation.

Am I missing something?

mt

[glenn kangiser]

That is right -- you cut down on insulation and add wood that transfers heat or cold faster - lower R value.

The joists fastened to the sides of the studs and sitting on a 2x let into a 2x6 stud has to be about the strongest connection you can make.  There is no hinge point then as the 2x studs continue to the top of the wall past the let in board preventing hinging. 

A short platform framed knee wall on top of the loft or second floor will hinge and try to spread out. 

[MountainDon]

  I suppose the tradeoff is in insulation.

As Glenn said.  I believe that today there should be no trade offs made in the direction of reducing insulation. Possibly a case could be made if you had your own wood yard... but even then someone (you!) has to cut the wood, haul the wood, split the wood and buy the gas for the lumbering tools....

[John Raabe]

If you line up the joists and the studs (both at 16" or 24" o/c) then a very sturdy connection would be to set the ledger below the bottom of the joists, have the joist sit on top of the ledger and be nailed off to the full height stud.

This eliminates the hanger hardware, anchors the joist as a tension member and has a two ways to support the joists.