Replaced all windows on large home, also replaced all window sills with new stone sills. Also replaced patio door same time. AND We also did the garage doors at same time with Northern (but had new front door done custom elsewhere). All windows are black with triple glass. Garage doors are top of the line (for what Northern offers - there are higher end doors) also in black matching. Patio doors in matching black with between glass blinds. Sills are stone. It was large order to say the least.
Garage Doors were done fairly quickly - the installer was absolutely first rate and very professional, and though not on contract - Northern offered to install new garage door openers I had already ordered from my suppliers. I had them already installed by the time they returned so not necessary. Materials and installation is very good.
Windows -- took a long time to arrive to be sure but windows are great, only time will tell how they hold up. They appear to be well made and operators are very smooth in action. All windows were the right size. I have one window where the interior trim is not level (1/2" over 4') and not the same height as rest of room matching windows - I will probably just fix this myself. The window is level and same height as others - it was just the inside trim somehow.
The Installers are 100% professional and being in the construction business myself, these guys are great. Took a week to install all windows. And another day to install patio doors.
The outside caulking is some of the best I have seen.
Then we waited several weeks for the sills - it was a different specialized crew. Very very good work and looks great. These guys bent over backwards to fix old brickwork as necessary. One set of windows needed new flashing as sills didn't quite meet together with new windows, this took a few days to get resolved but it was done.
Overall everyone was neat and cleaned up well all material and waste.
Other than the few issues I mentioned and a long delivery time (not unusual in construction these days and lots of rain days has slowed down some outside works) I am very pleased and would recommend Northern to my clients and others.