How to trim Window / wood siding

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Ashful

Minister of Fire
Mar 7, 2012
20,075
Philadelphia
So, I'm getting to the trim planning stage on my carriage house project. Specifically, now to case out and trim the windows with horizontal 1x6 cedar clapboard siding.

The windows are Andersen 400-series double hung (WDH-2436), and casing trim is to be cedar 1x4 sides with 1x6 header. Still undecided on best way to handle sill & skirt. The Andersen (broken link removed) shows the typical house wrap, cut and folded in, with adhesive flashing in the sill area, nailing flange followed by side flashings, then a drip cap installed on window with bead of caulk, adhesive header flashing, and then fold house wrap down and tape over header flashing. All good, but then they show the trim placed atop all of this.

I assume this might work fine, if you're doing aluminum or Azek trim board, with a J-channel and vinyl siding over the header. But I don't know how you'd do true wood horizontal clapboard siding and trim this way.

Seems to me, the better plan is to cut the house wrap up 6" higher above the window, install the header trim directly over the nailing flange, and then do the drip cap, adhesive flashing, and house wrap fold-down above the header. Following the Andersen install guide seems like a guarantee for water behind the casing header, unless I'm missing some detail on how clapboards are normally trimmed into window and door headers.

Advice, please?
 
follow the Anderson directions for their warranty purpose and add the flashing above the header. Essentially 2 drip caps. Do not cut the house wrap high, leave it as is and add drip cap and tape it.
Make sense?

edit: I would go with 5/4/cedar trim, so after you butt the siding in it leaves a small reveal. will be easier to seal too.
 
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pony, so you want the upper drip cap on top of the wrap? Seems backwards. I'd think it would be better to slit the house wrap, and tuck drip cap behind, with adhesive flashing on top.
 
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pony, so you want the upper drip cap on top of the wrap? Seems backwards. I'd think it would be better to slit the house wrap, and tuck drip cap behind, with adhesive flashing on top.


yes, no voids in the wrap. drip edge, adhesive flashing over it.
 
Another option might be to skip the second drip edge above the casing, which is what I seem to be seeing a lot of. Just have the single drip edge above the window, per Andersen spec's. I could always bevel rip the top edge of the casing at a 5 - 10 degree angle, like a window sill. Sills always have their drip edge below, too!
 
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Thanks, Hogz. Andersen 400 series does spec a drip cap over window top flange, so I guess they probably have mitered corners.
 
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