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Is aluminum drip cap really needed over vinyl window?

This topic can be found at:
http://boards.diynetwork.com/eve/forums/a/tpc/f/1491013504/m/6803982577

Nov 15, 2013, 10:25 PM
SturdyNail
Is aluminum drip cap really needed over vinyl window?
The vertical surface of the drip edge is only about 1.5", which is the same as the flange on the vinyl window.
So, does the drip edge buy me anything?
If so, do I adhere the drip edge to the top of the window or do I leave a 1/8" space?

Thanks in advance.
Nov 16, 2013, 02:50 AM
Jaybee
If your vinyl window is of the type that includes the window trim as a part of the window, then no - you do not need an extra drip edge. If you will be adding separate trim around the vinyl window then you will need a drip cap to go up under the siding and over the top of the top trip piece.

The drip cap flashing is just like step flashing - if you trace a path from top downwards, every edge should overlap the start of the next material below it.


Jaybee
Nov 16, 2013, 07:58 AM
CommonwealthSparky
I agree with Jaybee. If your window units have a factory formed nailing flange in actuality will the water ever get though?
The only reason to install may be to match the look of other windows on your abode. If you are that exact in your detail that is. {Sadly, I'm like that}.


Popeye only reached for the Spinach can as a last resort...
Nov 16, 2013, 09:58 AM
SturdyNail
Thanks Jaybee, that does make sense.
And, thanks CommonwealthSparky. What you said fits for me too. The other windows in my house (original wood) have a drip edge and a wooden drip cap. The drip cap is pretty similar to the Azek Drip Cap (AZM-197), so I think I'll use the Azek Drip Cap only and skip the aluminum drip edge.
So, would I adhere that Azek Drip Cap directly to the top of the vinyl window?

I'm adding a picture of the window.

Thanks again.

Picture of the window

Nov 16, 2013, 12:13 PM
Jaybee
The drip cap goes directly on top of the window but it must overhang. Also, if it's an Azek solid drip edge piece make sure that there is a small notch cut in the underside - this will keep water drops from clinging on the underside and weeping between the drip cap and the window. If the style drip cap doesn't have the notch, it's easy enough to make with a table saw set on a very shallow setting.


Jaybee
Nov 16, 2013, 01:17 PM
SturdyNail
Here's a picture of the profile. It does have the notch.

I'm going to go out and put it on now. We have an unusually mild day for November today (in the 50's). We had near 20 degree F. temps and snow earlier in the week. Turning colder again in a few days. So, gotta "make hay while the sun shines".

Thanks again!

Azek dripcap profile

Nov 16, 2013, 06:01 PM
SturdyNail
Another question came up after I cut the drip-cap to size.

There is a "channel" that runs along the back of the top and sides of the window (similar to the sketch I've attached). I'm thinking it's there to give water a chance to run off the top and down the sides of the window. If that's the case, then I'm likely defeating that design by attaching the drip-cap.
I'd still like to use the drip-cap though. Heck, I paid for the material and now I've cut it.
When I adhere the drip-cap to the top, should I try to fill that channel with adhesive?

Thanks yet again.

Profile of the top of the window

Nov 17, 2013, 08:04 AM
CommonwealthSparky
quote:
Originally posted by Jaybee:
The drip cap goes directly on top of the window but it must overhang. Also, if it's an Azek solid drip edge piece make sure that there is a small notch cut in the underside - this will keep water drops from clinging on the underside and weeping between the drip cap and the window. If the style drip cap doesn't have the notch, it's easy enough to make with a table saw set on a very shallow setting.

Right you are Jaybee, as it certainly would not be a drip cap without that underside kerf. My millworking days of employment we stocked a primed finger-jointed product very similar to the picture provided by Sturdynail. Hardly sold a bundle a month {400'} as I recall buy sent many a stick to New England states. Mostly because of building codes and wood window units methinks.


Popeye only reached for the Spinach can as a last resort...
Nov 17, 2013, 08:07 AM
CommonwealthSparky
I don't think you are defeating the design by adding a drip cap. You actually have less rain water to deal with with that added piece of Azek trim.
Hope you finished the job yesterday {Saturday} as today might be good for football game viewing only.


Popeye only reached for the Spinach can as a last resort...
Nov 17, 2013, 09:42 AM
Jaybee
Go ahead and add the Azek drip edge. don't do anything to the channel - While it will likely not be used now that the other drip edge is over it, it will still be there and will function the same 'just in case' some water gets by other flashings.


Jaybee