Installing used windows for a shed

[atgcpaul]

I bought 2 used vinyl replacement windows for my shed. There's no nailing flange, just holes in the side to screw into the framing. I'm not going to dress up the interior so I plan to just sit the window in my framing.

--Do I need to use membrane around the frame? Should the membrane wrap around the frame and overlap the siding?
--Do I install the siding (LP Smart Side) flush to the frame, install exterior window trim, then push the window up to the trim and caulk, OR overhang the siding over the opening and push the window up to the siding and caulk? (The former seems better)

What else don't I know?

Thanks
Paul

[Cabinet Monkey]

for a shed, does any of it really matter ?

[Snipe Hunter]

I'd flash (you call it membrane) the openings and then trim out around the windows with 1x4 or 1x6 vinyl board (whatever covers your flashing). The 1x should overlap the vinyl window frames a little. So the window frames would sit flush with the siding so the sit against the 1x. Caulk all the way around the inside and outside of the 1x.

[jteneyck]

I installed house wrap on my shed, then put membrane tape on the sills before setting the windows in place.  After the windows were in, I added more membrane tape over the sides and header of the windows.  I installed PVC trim around the windows set against a bead of caulk, then installed my vinyl siding which slips behind a rabbet I cut in the outside edges of the trim.  I'd do the same with your Smart Side, except I'd install that first, before the trim.  Just stop it a few inches short of the window and the rabbet from the trim will fit over it when that's installed.  Caulk as needed.  

John

Or set your windows proud in the openings by the thickness of the siding.  Then you can run the siding right up against the windows and then simply nail the trim on with no rabbet needed.

[MstrCarpenter]

I've done it several times and repaired other installs more. Last time was upgrading a porch that was "enclosed" to a 3 seasons sunroom. The main point of failure with replacement type windows is at the sill, as in the window sill which is not the bottom of the rough opening (R.O.). The window sill must extend into the framing. I have used 2x6 P.T., PVC sill, and PVC sill nosing with an extension solvent welded on. (That was the porch because full PVC sills would break the budget.) I cut the horns and install casing after the sheathing is properly flashed at the R.O.. Now it is just a simple "replacement window" install. Even though the casing was sealed to the sill as it was installed, I still use flashing tape to seal the stud and sill to the back of the casing. When I install replacements the sides and top are pressed into a bead of silicone or butyl caulk. If the sill expander has weep holes I leave them open; if not, I stop the caulk a little shy of the corners to allow drainage, just in case. Closed cell foam insulation will also help prevent water infiltration, and I always use spacers to keep the jambs from bowing in. (I know there's "low pressure" foams available, but I only use fire rated stuff in guns.)

[atgcpaul]

I'd flash (you call it membrane) the openings and then trim out around the windows with 1x4 or 1x6 vinyl board (whatever covers your flashing). The 1x should overlap the vinyl window frames a little. So the window frames would sit flush with the siding so the sit against the 1x. Caulk all the way around the inside and outside of the 1x.

Or set your windows proud in the openings by the thickness of the siding.  Then you can run the siding right up against the windows and then simply nail the trim on with no rabbet needed.

These things I can and will do for my windows.

Thanks
Paul

[K. L. McReynolds]

I used backer rod plus caulk to seal the gaps. You can install the frames however you want---the trim being the biggest factor.