The intergral j is a real bad idea.
Installing vinyl siding around windows with integrated j channel.
Continue installing courses of siding along the sides of the window leaving 1 4 inch spaces within the j channel at the end of each piece of the siding for expansion.
I only use plywood.
Don t drive them tight.
Drive roofing nails every 8 to 10 in.
It does not drain water off the top of the window but to both sides where some it will end up behind the siding when leaving the bottom of the side j s it s a built in fault with regular and integral j s and the way 99 of people install vinyl and similar sidings.
Position the j channel under the window.
For the window first position the j channel against the window casing.
Install j channel under the window.
Another option is crane board makes an adapter that snaps onto the windows built in j channel that turns it into a 1 1 4 deep j pocket for use with their insulated siding.
Caulk behind the vinyl nailing flange of the window first then install grace strips over the flange and then you can run your siding right into the window j channel.
Alternatively i use vinyl window and door casing which is essentially a 2 1 2 in.
Some modern vinyl windows however incorporate a j channel right into the.
Through the middle of the slots.
No pieces to separate.
Mark cut and notch the top.
Cut and position an undersill trim if necessary see when to use undersill trim.
Lats are ok but they tend to split too easily especially if you are nailing the window every other nail slot.
On the top of the window don t run it to tight leave room for the water to run off.
When i know a house will be sided in vinyl i select windows that have either an integral j channel or a slot to receive an applied cap that creates a receiver channel.
Windows and doors install the j channel vinyl siding around all four sides of a window or three sides of a door.
Nail it to the wall but remember not to nail it tightly.