Please help :<O
I have installed copper cap flashing on my window trim. I am now ready to install 6 1/2″ width with 5″ exposure cement fiber board planks. How do I prevent rain from running down the left and right (of the cap flashing) and then running down behind the plank siding?
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you need the flashing on top because it is flat and water will settle there. leave 1/8" between the siding and trim and fill with a good exterior caulk and the water should run off without problems.
Any water that drips off the ends of the drip cap (Not much water, one would hope.) should be handled by the flashing (Usually felt or house wrap) that is between the sheathing and side window casings. The caulking mentioned above would help prevent the water from getting even that far. Some may think that caulking at that joint looks sloppy and will be of limited usefulness in the long run.
Al Mollitor, Sharon MA
The flashing should cover the head lap of one course of siding and then in turn be covered with the next course of siding. The flashing should be installed with the siding instead of before.
I have a slip of metal in under the bottom of the side casing and ear of the sill that cuts just over the top of the last full piece of lap siding just under the sill. Then a slice of tarpaper or Vycor runs verticaly up under that side casing. When the head flashing is installed, the end of it lies over that so that water is always directed down, out, and away. Depending solely on caulk is poor practice. Always look for a way to use flashing to kick that water back out when it leaks in.
Excellence is its own reward!
Piffin...I like your detail at the BOTTOM of the side casings to deflect water out over the siding. I have a funny feeling many, many windows lack this.
Al Mollitor, Sharon MA