There are windows that have the option of a nailing flange and you can get a clip in J-Channel or sill expander that can be made to act as a J-channel.

If you run a flat trim, you should put a drip edge above the window and above the trim.

You will need some sort of j-channel to cover the cut edges on the siding regardless.

The integrated look is a bit better.

No siding system is intended to be the final drainage plane on a house.

The siding is there to protect the actual drainage plane from damage mechanically and from the sun.

Tar paper used to be the drainage plane of choice, but there are plenty of newer materials available.

Though sometimes I have my doubts what the new materials will look like in 60-70-80 years.

Ya, I noticed the snap on trim with built-in J-Channel for the Andersen 400 series. Unfortunately they appear to cost a large amount of $.

So in terms of a casement window, does this sound like proper steps for a good Weather Resistant barrier:

1. Tyvek wrapped / stapled / taped into the window opening
2. Flexwrap the bottom and lower sides of the opening
3. Silicon caulk around the nailing flange
4. Nail in the windows
5. Flash tape the sides
6. Flash tape the top

What do people recommend doing to the window after step 6? I'd like to avoid running straight vinyl j-channel. Any ideas on the azek board? I'm looking for a nice look, but also don't want water easily running under the vinyl siding.

Thanks again!

3. Not a fan of silicon in this application as compared to some other sealants but check the compatibility with the flashing tape manufacturer.

Easy finish trim would be an foam PVC board that could be run or routed for a j-groove. I would bend up an L-piece of coil to go against the wall to provide the proper drainage to outside the siding.

Did you ever get an answer for the question about whether there was a way to avoid the unsightly J channels? We did do Azek trim but it is not rabbeted. Lost sleep over this all night as the first side of the house was done yesterday and I do not like the J channels at all.

What kind of siding are you running?

Georgia Pacific triple 5 cedar shake.

Don't like the J channel around the windows and soffit. Azek was already put up, didn't know about about rabetted azak until I read your post. Trying to figurew out where to go from here.

Unless you want to put Humpty Dumpty back together again, you are pretty much stuck with it. You would need to take it all apart (siding) to get to the nailed leg of the J-channel. Is it that important to you as far as the look goes?

Before installing window Nail a 1x 4 around window opening. set window and seal with 6 inch bara bond flex tape. trim window as normal with 1x6, this leaves 1.5-inch x 3/4 to hide siding ends and eliminates the need for j channel, will this work? inside window to be dry walled.