Can I order/do they sell windows that can accommodate changing the wall thickness at a later date?

I want to replace some windows in my house, but - at some later point - I also want to re-side the exterior. Right now, the house has vinyl over 1" rigid, and I plan to do cedar shakes over 2" rigid. Will I accommodate the windows simply by installing a deeper sill and trim on the exterior? Or do I have to remove the window, install my rigid, install a new nailing flange on the window, and then add a deeper stool and trim on the interior? Is there a particular type of replacement window I need to order? If so, what's the terminology for this type(s) of window?

Yes, I'm quite aware that the easiest thing to do would be to do the siding and the windows at the same time, but that's not an option for my house right now.

3 Answers 3


You don't need to move your windows. What you do need to do is be sure to maintain a proper drain plane. Flashing tape, metal flashings, a deeper sill, and caulk (the latter used sparingly) should handle the situation if done well.

It's a bit difficult to say more without specifics. Post a photo if you like.


If you're replacing windows and siding at a different time, consider installing trim around each window. (Like a picture frame.) This will allow you to remove either / tie into either at a later date.

Also, if you have a narrow window flange and the future siding will be thicker than the window flange, then the trim around the window will protrude out past the window flange, but this is ok. What's not ok is having end grain exposed out beyond the window flange.


If you are buying a "Replacement Window" they usually depend on the existing window jambs, sill, flashing, etc. You tear out the existing sashes and fit your custom measured unit into the existing frame. That keeps you away from worrying (at the time) about your siding issues.

If you are replacing a window by buying a "new construction window" it will come with a new frame, and you have to tear out the window down to the studs, drywall, and sheathing/siding interface. Then you will have to fit that frame in the opening. You'll have to work your way under the siding and properly flash and maintain your drain plane. (as isherwood says).

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