Trimming windows on existing home

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Old 09-28-15, 02:59 PM
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Trimming windows on existing home

I've installed several new construction windows on my house and now plan to finish the exterior by installing the trim. The windows are flashed per the manufacturers instructions. I have been reading about installing trim, and most of what I read says horizontal trim should be flashed also.

My house currently has beveled cedar siding on it. I plan to cut the siding back more to fit 1x6 cedar trim around the windows. Since the siding is already on the house it doesn't seem possible to flash the trim on the top on the window without removing long pieces of siding.

Is it worth the extra time and effort to flash the trim or can I get away with caulking it up and calling it a day?
 
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Old 09-28-15, 03:01 PM
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You will be able to cut the siding back, pull or clip nails as needed, then slip a z-flashing (drip cap) behind the siding on top. Then apply your trim under the drip cap.
 
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Old 09-28-15, 03:48 PM
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Thanks! If I'm installing a drip cap, it seems to me that caulking the trim anywhere could potentially trap water. Should I be caulking anything?
 
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Old 09-28-15, 03:49 PM
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The only time I'd consider skipping the flashing would be if there was an overhang directly overhead with no expectation of rain hitting the top of the window. Caulking will fail sooner or later
 
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Old 09-28-15, 06:05 PM
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You can caulk the trim to both the window and the siding. You should not caulk the drip cap to the window and you should not caulk the drip cap to the siding.

Personally, I like to bend a 3/8" upturn on the ends of the drip cap. (Put a dab of sealant in each of the upturned corners where the flap is folded). This prevents water from running behind the siding at the drip cap ends. A small 1/8" notch in the siding allows the siding to slip down over these upturned ends, leaving 1/4" between the siding and flashing for drainage.

That is actually a Canadian code, and they specify a 1" upturn. I think that's a bit extreme, but like the idea behind it. 1" is also quite ugly.
 
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Old 09-29-15, 03:47 PM
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I've been buying wood to make the trim and realized that the local box stores don't stock drip edge that would fit very well.

The drip edge I bought for the windows is 1 1/4" and fits exactly. The store only had that and 2" drip edge. The 1x6 boards are just over 3/4" thick. Do I have to live with almost 1/2" of overhang or is there another option?
 
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Old 09-29-15, 04:18 PM
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I spoke too soon. Looks like I just needed to search z flashing.
 
 

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