California Corners: Framing Corners for Remodels (and New Builds)
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Aerial view of a California Corner.
California Corners (also called an insulated three stud corner) are a fantastic advanced framing technique that MAY be mentioned when building a high end or custom home. It is a great way to use less lumber and create a more comfortable, energy efficient home. It also is generally used in conjunction with 2×6 framing. However, the vast majority of us live in a home built out of traditional 2×4 framing.
All is not lost!
First, we’ll define a California Corner. Next, why you want California Corners. Then we’ll go over how you can still have a California Corner in your remodel, even if you live in a traditional 2×4 framed house.
What is a California corner?
A California Corner is a framing corner built with three studs. Two studs are perpendicular, ending two walls, with another stud staggered against the wall ending inside the wall. This allows for insulation to go along the back side of the corner and it also allows for drywall to attach to both sides of the corner.
The obligatory base shot of a 2×6 California Corner.
A rarely seen header shot of a 2×6 California Corner with cabinet blocking.
Diagram of a 2×6 California Corner
Aerial view of a mock-up 2×6 California Corner–very, very rare, indeed.
Compare a California Corner to a traditional four stud corner. In this diagram you can see the overlay of three potential layouts:
Diagram of a traditional 2×6 4-stud corner diagram.
One with full blocking from a 2×4:
Diagram of a traditional 2×6 corner framed with a 2×4 for a full backer for drywall.
Aerial view of a mock-up of traditional 2×6 corner framing with a full backer 2×4 stud.
Another with an additional 2×6 lined up with the other three studs. However, you are only left with 1/2″ for the drywall. Not ideal.
Diagram of a traditional 2×6 corner framed with five studs.
Mock-up of a traditional 2×6 corner framed with five studs.
Or leave it as is and just use drywall clips in the corner.
Diagram of a traditional 2×6 4-stud corner framed with drywall clips.
On the 2×4 side of the framing world, which most of us have in our homes, you’ll see similar structures, just on a smaller scale:
Diagram of a 2×4 California Corner
Mock-up 2×4 California Corner.
Compare a California Corner to traditional four studs…
A traditional 4-stud 2×4 framed corner.
A diagram of a traditional 2×4 framed 4-stud corner.
Mock-up traditional 2×4 framed corner.
Why does it matter how studs are lined up in the corner?
#1. Less thermal bridging (aka more comfort for you).
A regular 2×4 stud only gives you an R-value of 4.38. While the R-value of the insulation is R15.
Even if R-value is a foreign language to you, the basic math between those number says every time there is a stud in wall the cold (or heat) comes in more than three times as fast as in an insulated spot.
On your average 2×4 framed home there is a stud every 16”. That means every 16” inches you have a decrease in the thermal barrier between you and the outside temperature.
This also means the more wood you have in your house, the more heat/cooling is lost. So when you build up a corner, all that translates into a pretty large 4.38 right there.
Worse, if blocking is used instead of a full stud you also have an air gap.
2×4 4-stud corner with blocking along an exterior wall.
This air gap is a problem for three reasons:
- There is absolutely no R-value to air.
- It is impossible to insulate (they might still insulate the blocking easily with Rockwool COMFORTBATT in the picture above, but who wants to put money on it?).
- It is impossible to clean if you have water damage and mold growth in the corner.
2×4 traditional corners versus advanced framing California Corners.
Meanwhile, the configuration of a California corner allows insulation to slide or get blown into the corner cavity.
#2 California Corners use less lumber.
The math is pretty simple: you are going from four to three studs.
A California Corner summary: Less cost (due to less lumber), less labor (due to installing less lumber), and better insulation. What’s not to like?
So you are telling me, I can have it all?!?!
Maybe.
If you are looking at an entire build, labor may or may not be less depending on if your framing crew is familiar with advanced framing techniques.
If you are talking about a remodel with just a little framing it probably does not make much of a difference cost wise. On the other hand, the benefits are limited at this smaller size because comfort (thermal bridging improvement) is limited. Comfort also depends on the rest of the exterior around the room.
How can I use California Corners in a remodel?
If you are about to embark on a remodel you might want to consider how you can integrate this in your plan. However, unless you are opening up exterior walls, this post, while educational, is totally useless to you right now.
I’m not just talking about taking the interior covering off like drywall or a shower wall. You have to consider exterior sheathing is attached to the outside of the corner. We’re talking about a BIG remodel.
If you live in a traditionally framed house 2×4 house and are willing to go all the way into the framing (or discover water damage and unwillingly have to replace some of the framing) during your remodel, it is possible.
Once you are at that open stage, here is how you integrate a California Corner.
If you are replacing the sill plate you can beef up a wall to 2×6 construction. That happened in this post Hurricane Harvey house. One wall was replaced with 2×6 framing, meeting up against another original 2×4” wall.
The original 2×4 wall on the right meets the new 2×6 wall on the left to make a California Corner.
A diagram of the the new 2×6 wall meeting the old 2×4 wall to make the California Corner.
A model of the the new 2×6 wall meeting the old 2×4 wall to make the California Corner.
You can see the California Corner is a mix of the two kinds of lumber.
If you just want to replace the corner studs, you can keep two of the studs and align another 2×4 along the side, just as the 2×6 configuration above. There is less insulation and a lot of work to get it there.
For a whopping 2” x 3.125” section of insulation, is it worth the hassle if you are not forced into repairs? Probably not.
Since we are actively looking for bonuses, you also get an extra half inch to toenail the sheetrock into place.
There are alternative solutions.
Even with repairs you might want to go with an alternate solution of exterior rigid foam insulation, which spans every last thermal break caused by all studs in the wall.
Or it might not even matter…
Do you have any other subpar materials in the rest of the room?
How about a single pane glass window? Or a crappy plastic dome skylight?
A California Corner won’t make a difference until these are upgraded because their thermal loss is so much worse than just a stick of wood in the wall. Get a nice double or triple pane low-E with Argon gas window. And switch out the plastic opaque dome with a stunning Velux skylight. Then, let’s talk about California Corners.
There are probably other reasons my bathroom along an exterior wall is colder. The extra stud in the traditional 2×4 corner is probably not the main contributor as captured in this thermal image.
How do you insulate a California Corner?
Many of us have paper faced batt fiberglass insulation in our walls. It is fairly inexpensive and easy to install, but has its drawbacks.
Fiberglass insulation is difficult to cut, itchy on the skin (older fiberglass insulation has formaldehyde added, thus causing extra itchiness) and not as effective as it should be if you just squish it into the smaller section of a California Corner. It is not an ideal experience.
A poorly insulated 2×4 California Corner due to squished insulation.
The compressed paper faced insulation creates an air gap in the California Corner.
We prefer to use Rockwool COMFORTBATT insulation in our remodels and builds. Easy to cut, it friction fits within a wall.
Rockwool COMFORTBATT cuts like butter. The Cutco knife is overkill, but I needed the length to make straight cuts for this photoshoot.
Simply cut out the 2×4 or 2×6 piece of the California Corner and slide the rest of the batt into place.
Other benefits: it requires no stapling and it is fire resistant.
I will say, the Rockwool COMFORTBATT can suffer from the same problem as the paperfaced fiberglass insulation. No insulation should be squished. Part of the properties of the insulation is the fluffiness. The more solid (squished) it becomes, the easier it is for outside heat or cold to transfer through the material–exactly like the dense wood.
Rockwool insulation is known for it’s cutting property and easy to handle, making it a better choice for this application.
Note #1: On a personal note, yeah, I still think it is fun to cut this kind of insulation and play Tetris in real life. My desire for perfection makes it hard to understand why someone would use the smash method when the product is just asking to fit like a glove. I don’t think I’m the only one, right?
Note #2: In the photos above the COMFORTBATT is sized appropriately. The downside of the aerial shot is the perspective of the “base plates” make them seemingly undersized. However, if you compare the COMFORTBATT to the 2×4 or 2×6 right next to it, it is similar.
Also, there is some expansion over the size of the wood. This compensates for other irregularities in framing/sheathing/drywall, allowing the Rockwool to fill in areas where there is additional gap.
Is a California Corner safe if the home is in a coastal or earthquake zone?
Yes.
The name reflects exactly where this framing technique was pioneered: in California, known for it’s earthquakes.
It is also approved for coastal and inland hurricane zones (with the proper strapping, of course).
All the photos taken of California Corners in this post are during the remodel of a Texas Department of Insurance Windstorm Inland 1 zoned home (we claim nothing other than taking the observational photos on all the other framing pictures).
The metallic boot you see in the photo is a Simpson Strong-tie HDU.
In conclusion…
When used in conjunction with other high quality materials over a large span of your home, California Corners will increase the comfort of your home. It will help create a better thermal envelope and use less lumber.
As always, consult your building code before choosing the right corner for your build or remodel.
Note #1: There is another corner that uses even less lumber: a two stud corner.
Diagram of a 2×6 2-stud corner
2×4 and 2×6 2-stud corner mock-ups
At the same time, you also have to consider installing drywall (or any other kind of material so we aren’t staring at framing and insulation) at the corners. You could use drywall clips. Oftentimes your drywall crew is going to be more appreciative of a full 2” length to toenail the drywall into the corner. However, drywall clips keep the corner floating with only one piece of wood. So cracks are less likely to appear. Also, known as smart.
If possible, don’t just assume. Ask your drywall crew ahead of time what they would rather have.
Let’s remember, this article is supposed to be about California corners. However, if drywall clips are how a crew rolls, they can still use drywall clips with that configuration.
Make sure you don’t create the two stud corner like this unless you have a set plan on insulating:
Two stud corner with a potential massive air gap.
Any bets as to how this corner is going to be insulated?
As a side note to this side note…make sure your backer stud is effective.
Poor stud choice for drywall backer. Exterior sheathing won, interior drywall did not.
What’s the point of this backer stud? It could be switched with any other stud in this corner (other than the other perpendicular stud)–or even used in the same place, if flipped around! You *know* the drywall crew is going to be cursing at the framing crew when they hit this corner…
This is a friendly reminder to choose your backer and drywall facing studs wisely. This goes for all corners–traditional and California Corners can suffer from this problem.
Note #2: Another alternative to address the thermal bridge 100% at the corner is a Massachusetts Corner:
Diagram of Massachusetts Corner Framing
This corner uses two 2×6″ studs on the outside and two 1×4 studs along the inside. The 2×6 is structural and the 1×4 is for drywall installation. There is a 3.5″ gap all the way through allowing insulation throughout the corner.
This is definitely a trickier corner to install.
Also note, you can’t even FIND a photo of a REAL Massachusetts Corner (diagrams don’t count!) on Google images. If it isn’t on Google, it isn’t real…sooo…
The closest thing I’ve seen to real on Google–here is a Massachusetts Corner mock-up.
While optimization is a good thing, you have to balance reality and consider complications for the next trades.
Note #3: While I’m praising one insulation over the other, no insulation is a solution for air sealing. More on that soon!
Note #4: You can read up more on Rockwool COMFORTBATT here. It’s found more readily on the shelf at Lowe’s (like it was when we replaced this ceiling)–back in the day we had to special order it when Rockwool was still Roxsul (Roxsul Safe’N’Sound is hidden behind the shower walls on the interior walls of the house in this post, dampening the sound).
While we use COMFORTBATT in our remodels, the photographed insulation are samples provided by Rockwool as these were not taken on the jobsites.
Note #5: I also had to throw in a fun photo of the aftermath of all these mock-ups. The rest of the driveway was covered in sidewalk chalk so the sidewalk got the photoshoot. And all the people driving down the street got to see this treat:
