[Cldlhd]

Joes correct on all points.I've installed hundreds of the Anderson windows with the J and never had a problem as long as installed properly and taped.No seams in the J.

Isn't the concern that water will collect in the j-channel along the top and run down the sides and with the necessary gaps with vinyl water will get behind the siding and run between the siding and sheathing? I have these kinds of windows and in lieu of a drip cap I filled the j-channel at the top with clear silicone to cut back on the water getting in. When it warms up I plan on removing the row of vinyl at the bottom of the windows and installing some metal flashing along the bottom of the window to direct any water that gets in to the vinyl siding with the drip/weep holes .BTW the sheathing is Zip so no house wrap.

 

[Cldlhd]

Zip is the drain plane, water proof just like house wrap. As long as you tape it properly on the top and both sides.

That was my thinking originally but by the time I got the siding up the Zip would darken when it got wet which told me it was absorbing water. As it will dry out it's prob not an issue. I did take the top and sides. Thanks