Insulating the cavity around the window with minimal expanding foam is the best method of installation as it creates an airtight barrier when applied properly. Insisting that a contractor use it, when he doesn't regularly do so could be dangerous however. Improperly applied, it could void the window manufacturers warranty and can bow the windows.

The steel lintel should be left uncovered.

+1

I agree 100% with Ultra Windows.

Thanks. I was somewhat suprised when the installer just summarily dismissed using spray foam - almost sounded like it wasnt worth the hassle to them. He said if its insisted on they would probably charge extra per window.

The lintel is left uncivered. Spray foam is a bit more expensive than fiberglass hence the upcharge. However, he doesnt seem as if he uses foam which is why he doesnt want to use it. There is somewhat of a learning curve.

One more follow-up question. One installer says they use PVC Trim Coil for the capping while others just use regular aluminum coil for the capping. Is there any difference or is one preferred? My house is brick with steel lintels above the window if that is relevant. Thanks.

Six of one, half dozen of the other. No difference, just personal preference.

+1

We like the non-PVC for better scratch resistance but it is most personal preference.