Roof rafters??? need to cut some

Question

I am making a dog hose for my dog she is big and expecting pups so the house is 42" wide from the out side of one wall to the outside of the other (not including siding 7/16") i want to cut the rafters at a 45deg angle on both sides and have the pices meet in the center I dont want to make a birds mouth cut just want the 45 to sit on top of the walls top plate so the question is how long dose each rafter need to be?

Answer 1

Let's make it easy.

Take a sheet of the plywood or o.s.b. that you are going to use for the roof. Now just make and end view of your dog house right on the o.s.b.

Draw the bottom, the 2 walls. Find the center of the width and square that center line straight up a couple feet. Now take a speed square or any other square and mark your 45 Degree angle at the top and bottom *leave some overhang on sides to give dog some shade when he/she is laying outside the house.

Cut rafters along your 45 degree lines. *Hint - make 4 extra rafters and you can have overhang on the front and back also.

*Don't forget to subtract half the distance from the top of each rafter (3/4") for a 2" x 4" ridge board.

We layout a lot of things in construction on the floor, and then just cut templates or patterns.

Sometimes electricians will layout lighting locations on the floor and then take a vertical laser and transfer all those locations up to the ceiling. It keeps you off the ladder a lot.

Go to it!!!!

Answer 2

This is simple high-school Trig.

1/2 of 42" is the "opposite", the rafter length is the "hypotenuse".

Cosine = opposite / hypotenuse.

Therefore, Rafter length = 21" / COS(45deg).

The slash meaning "divide by".

29.7"

Answer 3

29.7" is the length along the outside, longest side of the rafters.

Cut one, and then use that one as a template to mark all the others. Either that, or set up your mitre box, radial arm saw or chop saw with some stops so that you can get nice, repeatable cuts to the exact same length.