Hi... Rookie here.

I am going to be installing 1*4 Trim against ny windows. After that I am installing either vertical or horizontal siding. Is it recommended to notch out the trimboard to act as a j channel in place of installing J Channel for the siding, or are the trimboards to be installed with j-channel as well?

I've seen the azek be back cut, but this causes the trim to look like it sticks out a great deal where the siding profile becomes thin.

Any recommendations will be appreciated.

 

Vinyl j channel not only trims out the siding, it provides a water channel to keep water from behind the siding. So unless you can get the Azek to provide what the j channel does, I would install the J.

 

I also would not recommend notching out the Azek trim. Azek is cellular extrueded PVC and notching it would leave a small lip of Azek in front (maybe 1/4 x 3/4?) that would probably warp in the sun, or could break if bumped.

If the trim was to be painted a custom color, you'd need to paint the notch you make in the Azek, and that notch would be impossible to paint in the future without slopping paint all over the siding.

I'd suggest you surround your window trim with the j-channel as Chandler mentioned. If you prefer, you can caulk the gap where the j-channel meets the Azek to make a seamless transition.

 

J channel is cheap. All the time you will spend notching the azek I wouldn't even think twice.

 

Thats what I figured. The houses I saw, I was not that impressed with.
Actually, I've decided to go with Hplank siding so it's not an issue at all.