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Exterior Insulation and Window Replacements

user-6978760 | Posted in General Questions on


I am currently working on an exterior renovation of a kitchen addition. The kitchen has a large Bay window that I will be replacing. I am also planning on replacing the existing lap siding and adding 2”of Rockwool insulation to the outside of the sheathing followed by strapping and James Hardie lap siding.

The bay window I have quoted has 6” side jambs which I am told are fairly standard. However, with the addition of the exterior insulation I am worried that 6” jambs will not be deep enough to allow the siding to butt into it correctly (1/2” drywall + 3.5” stud-wall + 1/2” sheathing + 2” Rockwool + 1/2”strapping + 1/2” lap siding = approx. 7.5”).

Should I be ordering a bay window with a deeper jamb? Or is there a good way to detail where the bay window and the siding/insulation meet that I am not thinking of?


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