Saw through both sides. Note the small section left to cut through roof.

Using the saw cuts from the side finish cutting through the roof.

Complition of the first cut.

Measure 5.760" from the other end and mark the top and bottom.

Use a straight edge and scribe a line to follow when sawing.

Using that block of wood with the slot cut in, line up the
slot in the wood with the scribed line and saw though the side.

Once both sides are cut through you will now have two
saw cuts to line up the last cut through the roof.

Line up the saw with the side saw cuts and cut through the roof.