Saturday, June 16, 2012

Small Building Construction, Part Three

Dear Preppers and Survivalists,

I figured I should talk about window headers, window sills, and cripples before going on to the roof.

Rough Openings
All windows have a 'rough opening.' This opening is the required opening that needs to be in the wall before the window is mounted in the wall. The rough opening measurements can be found written in the window's installation instructions.

Now, we are going to have eight windows, two on each wall for ventilation.. Two big windows require a ??X?? rough opening and the other windows require a 14 inch by ?? inch rough opening.

Rough Opening
for the
"Big" Window
In this picture, you can see the doubled 2X6s for the window header and the single 2X4 for the window sill. The short pieces of 2X4 studs are called cripples.

So, why do you need a header?

Remember, the top plate (the double 2X4s) acts as support for the roof. When you cut an opening in the wall that spans between studs, you have to replace that missing support. The header acts as that support.

Now, needless to say, the bigger the opening, the bigger the header.

I talked to some former carpenters at work and they said a doubled 2X6 would be fine for this short of a header. Plus, one remarked: "It's a chicken coop. If you really wanted, you could probably use double 2X4s as a header."

Now, if you were putting in a picture window in your home, you would need a much thicker header, maybe a 2X10 or 2X12, maybe even an engineered wooden header or a steel beam header for a really large window.

OK, back to building a small building.

Rough opening
for the
"Small" window
The small window's rough opening is 14 inches wide by ?? inches tall, so I don't need a big header because there is no need to support the roof, since none of the studs were cut.

Wow, what a sentence!

Needless to say, you want to know why I covered up the windows rough openings with the OSB sheathing.

It's a lot easier to cover up the opening, and cut it out later, than cut the sheathing then attach it to the 2X4 wall.

I almost forgot.

The cripples, those short pieces of 2X4 above the headers and below the window sills, act as a place to secure the sheathing to the wall. They basically 'fill in' for the studs that I removed for the window opening.

Just so you know, they're called cripples because they are 'broken' studs.

Making the Headers
Just like I said earlier, we used 2X6s as headers. Since they are going to support some of the weight of the roof, I doubled them.

When I was screwing the studs into the top plate and the sill, I placed one 2X6 between the studs and screwed it into the stud with six screws (three on each side) Next, I placed the other 2X6 even with the top edge of the stud and screwed it in with another six screws (again, three on each side)

The former carpenters said I could place a piece of plywood between the double 2X6s to fill in the gap.


I could nail the two 2X6s together and make sure the header is even with the inside edge of the stud.

I could do it the way I described.

Lastly, one of the guys said that I could also place a cripple between the header and the window sill for added, really added, support for the roof. As you can tell, I didn't do that.

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