Can flush fin windows be installed along with vinyl siding?

Question

I recently bought some flush fin retrofit windows. They don't have a nailing flange, just the decorative fin. I'm building a shed, and want to put vinyl siding on the shed.

From what I understand, these windows are meant to be installed flush with a flat outer wall surface. Have I made a mistake by buying these windows?

Or how can I install these windows over or under the vinyl siding and somehow make them work with trim?

I just want to try and make them look nice and not leak.

Thanks in advance

(Ps, yes window is upside down in the photo, it is right side up now)

Answer 1

1. Drill slightly oversized nail holes to prevent cracking and mount the window to the wall sheathing. Go easy when driving the nails. Just snug them up lightly.

2. Seal the windows to the wall (ideally to the building wrap you should be using) with purpose-made flashing tape. Lap it properly for drainage.

3. Install vinyl J-channel over the flanges according to best practice for proper drainage.

4. Install siding and be happy.

As with any window, be sure your rough openings are properly sized. They should be no more than 1½" larger than the window dimension (ideally closer to 1").

Low-expansion spray foam will really lock them in place after install, even if you don't need the insulation or wind-stopping features it offers.

Be aware that caulk isn't really a solution with modern window installations and maintenance-free siding. Vinyl needs to move, and the flashing tape handles weather. Don't booger up your nice project with inappropriate goo.