Framing 2x6 Exterior Corners

[medeek]

I've been struggling with the best way to frame ext. corners on 2x6 walls so I looked through a number of my framing texts and online and put together a small matrix with a number of methods.

A high resolution PDF file is here:

http://design.medeek.com/resources/framing/FRAMING_CORNERS.pdf

I do a lot of designs with hardiplank siding so good backing for the trim and siding is important to me. Up until now I've been specifying Detail 2 a lot, but now I'm looking at Detail 5 and it seems to offer the same advantages and more. Any thoughts?

 

[dik]

I've seen #1 and #8 used often, with #8 more common...

Dik

 

[racookpe1978]

Do you need a 2x4 (or 2x6) behind the lower (horizontal) wall sheetrock on the inside corner as an anchor?

Seems like all of those options require a lot of extra nailing, time, and lumber than the optimum.

 

[msquared48]

Well, you have to think two things, studs for the sheetrock nailing at the inside corner, and a two stud minimum for the holddowns, if required,

So, #1, #3, or a slightly modified #8.

Mike McCann
MMC Engineering

 

[SlideRuleEra]

Option #1 is called a "California Corner". It has the advantages of being simple, easy to build, using minimum material, self supporting, allowing a maximum on insulation for the wall perimeter, and providing a vertical nailing surface for both interior wall surfaces that intersect at the corner. When I designed and (personally) built my own house in the 1980's this option was fairly new and considered the best framing detail for combined structural integrity an energy efficiency.

Google on "California Corner" and you will get hits, including videos, that appear to indicate that it still is considered an excellent detail.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[medeek]

Now assuming I've got an in-wall anchor holdown similar to what is shown in Option #9, is 3" of stud depth typically sufficient or would an HDU11 or HDU14 require 4.5" of of stud depth. It seems to me that 3" should be all that is required since the fasteners don't penetrate into the third stud (2-1/2" or 3" SDS screws). The problem is that there is no room for the gyp. board nailer.

I also don't like Option #1 (california corner) for siding because on the one side there is not much to nail your siding or trim boards into. That is which I'm thinking Option 5# would be a better alternative, giving good insulation into the corner, easy access for electrician, nailing surfaces for both gyp. board and siding and trim.

 

[msquared48]

medeek:

You need to think in three dimensions here to solve the problem.

Remember that in #9, any HD class of hold down will only occupy the bottom foot or so of the corner. There us still room for the corner nailer above that - usually another stud nailed to the other three studs or a 6x6. The sheetrock will span that distance OK.

Mike McCann
MMC Engineering

 

[SLTA]

Some of these make it impossible to get insulation into the corner. Wood also acts as a thermal highway, letting heat in and out, so the better options from an energy-efficiency point of view are the ones with the least wood at the corner and/or allowing max insulation. This is actually in the code in lots of parts of the US, and Canada I think, and the problem comes when structural designers don't remember that.

 

[msquared48]

SLTA:

You are putting the cart before the horse here. Structures do not fail due to a lack of insulation. They fail with inadequate or insufficient hold downs. The energy code does not trump safety.

That being said, I can see the conflict however with what you say here. I think one solution would be to compromise and use an exterior strap rather than an internal rod type hold down if the capacity was sufficient, or choose another location for the shear wall, if one was available. Sometimes there is no other location though.

The fact remains that corner placement of hold downs increases the leverage to resist uplift, and decreases the uplift force that is required to be resisted. The use of the corner location can also decrease the overall number of hold downs in the structure as it can be used to resist uplift in two directions, not just one.

Mike McCann
MMC Engineering

 

[medeek]

I used to go primarily with strap type holdowns (ie. STHD14, STHD10 etc...) however the two problems I have with strap holdowns is spalling and the raised bump on the ext. of the wall that causes problems for siding and trim. It pretty hard to nail a trim board through a STHD10 strap.

 

[msquared48]

There are times in structural engineering where we have to choose the lesser of two weevils. Not a difficult choice here...

Mike McCann
MMC Engineering

 

[msquared48]

https://images.search.yahoo.com/sea...age&fr=yfp-t-901&va=The+lesser+of+two+weevils

Mike McCann
MMC Engineering

 

[jayrod12]

Ours are always 1, 2 or 5. And never 8 unless they have the insulation on site to install before they sheath the outside (which is almost never the case).

 

[KootK]

@Medeek: what software package do you use for your drafting? Sketchup? Your details look slick.

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

 

[medeek]

This detail was drawn in AutoCAD 2006. I do most if not all of my 2D work in AutoCAD. For 3D I've been using Solidworks since my background and experience has been largely mechanical, however I have done some 3D work in AutoCAD, sketchup and Catia.

 

[capeengineerma]

One other consideration for how you frame your corners with regards to hold downs is that if you do a solid corner with proper nailing, one hold down can be used at the corner to resist the uplift for both walls framing into the corner if both of those walls are designed as shearwalls. You would need two hold downs for corners using the California corner or #4, #5, #6, or #8 in the figure.

 

[CBSE]

If you are worried about the hold-down taking away from the insulation of the corner due to the required studs, simply move your hold-down away from the corner approximately 12-18 inches. If you plan to use a single hold-down at the corner for loads in each direction then you don't have much of an option. But if you only need a hold-down for one wall, then move it and retain your energy efficiency. I also like detail #5 simply because of nailing trim.