new construction window install: q. about shims and expansion
I am in the process of installing new construction windows (Andersen 400 Tilt&Wash Double Hung), and have a question about the installation.
The installation instructions say to shim the sides at top, middle and bottom. Fine, I can do this. I believe this is to prevent bowing of the windows. But I wonder, what about expansion/contraction? How will expansion/contraction occur when the sides are shimed in three places? Won't the shim interfere with the normal expansion/contraction of the windows within the rough openning? The windows I am replacing are 30 year old wood windows and they were not shim'ed at all on the sides.
Sorry if this is a silly question. And I have no problem following the recommended install instructions. But I just can't get past the expansion issue when the shims are concerned.