cimhof

Hello

I am in the middle of a big debate on a job. New garage addition, Homeowner already bought 2 windows for us to use. They are vinyl with J- Channel integrated with the nail flange. Originally they were going to put up vinyl, but instead are using cedar clapboards.

Debate we are having is:

Should we fill the jchannel with a 3/4 strip of wood and install\caulk the cedar up to that or caulk the j channel opening and slide the cedar into the channel.

I am just worried about water getting behind the wood.

Opinions?

mdshunk

Why wouldn't you slide the cedar into the J? At least it'll have a fighting chance, and won't rely on a caulk bead.

Tom R

Personally, - - I'd finish the ends, slide 'em in, and leave a gap.

And I'd use a window-cap up top.

Caulking wood to vinyl is useless.

Jake Stevens

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. On the top of the window don't run it to tight, leave room for the water to run off. Note; Make sure when you caulk the window behind the flange, caulk to the plywood and not the house wrap on the top of the window.

tomstruble

ive had viny siding like monogram wouldnt fitin the j pocket . install reall cedar into a vinyl window j?

tinner666

If you're caulking to the plywood, you must have forgooten to flash the thing, don't you think? Caulk to the aluminum flasing instead!

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Burby

If it is the vinyl window I am thinking of, it has J on all 4 sides. You are unable to flash the top as typical, because of the top J. Idealy if standard windows from Lowe's or homo depot, return and get windows without J.
If insist on using them,

Run your felt or tyvek to 8" above top of the opening.
Install the unit
Use sticky back tape, (I use Vycor) to each side of the unit, starting inside the j as far as possible, a few inches below the bottom to 3" above the top.
Run a pc of 9" tape accross the top of the unit inside the j again to about a 1/2" beyond both sides.
Install pcs of cedar for trim around the unit, apply another bead of NP1on the back of the trim just inside of the j so the trim is sealed
Flash the top pc of trim & apply the tape to the flashing extending the sides to at least beyond the existing pc of tape.
Apply the felt or tyvek above the unit. Just to be certain of no back up, especially if in cold climates I would run a bead of NP1 along the top pc of tape to stick the felt or tyvek to.
When the siding goes into the j at the bottom of the unit I would caulk that as well to prevent water running inside of the J once completed won't run behind that bottom pc, back caulk it as well as caulk the top edge before running the next pc on the sides. This will force the water to run over the outside of the siding as should.

If your customer does not want wood trim around the unit:
If the windows are labled "self flashing" & your inspector will allow it not have flashing using wood siding, install the same as described above just omit the wood.
I would still back caulk each pc of siding installed around the unit to be safe.

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Patrick

Ask for a L fin adapter. It is a piece of vinyl that fits into the J pocket so you can install your siding like normal.

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tomstruble

on my siding jobs i leave the backing on the side flange flashing tape on the last 4'' or so on the bottom then as i work my siding up i like to overlap the tape over the top edge of my last course triming it to the exposure line of the window cut pce to give the water a place to weep out

72chevy4x4

might be too late or not possible, but I've been using J channel patio new contruction doors and cutting off some of the fins for my install w/ a thin cutoff wheel and grinder-it works very well with a steady hand. You could cut off the outter fin of the J, then butt the cedar trim to the thin frame or might look nicer to box the window with cedar then butt the siding up. This should give you the same result as patrick's L fin adapter.