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How to Stop a Bay Window From Sagging

A 5-year-old bay window is sagging so much that the windows won't close properly.


We had a bay window installed about five years ago. Unfortunately it now sags about 1/2 inch, and the double-hung windows on each side don't close properly. What do you suggest?

— Nick Reciniello, Nutley, N.J.


Tom Silva replies: When I hang bay windows, I use a stainless-steel cable support system that's anchored to the wall framing at least 10 inches above the window and then cover it with the bay's roof. You could retrofit this "invisible" system to support your bay if you rip off most of the roof sheathing. Or you can suport it on a couple of structural metal or wood brackets.

Either way, you first have to get the bay back to where it belongs. I'd use two small hydraulic jacks, one under each corner of the bay. Support the jacks on 2x8 planks so they won't sink into the ground when you start to lift. Raise the window slowly and evenly until it's about 1/8 inch above level, then attach the cable supports or the brackets to the house framing. Once the brackets or cables are secure, lower the jacks, and your windows should work again.

The bay's roof protects the cables from the weather. You need to provide the same protection for the brackets. Cover them with sheathing and siding, or with MDO — medium-density overlay — my favorite weather-resistant panel. Enclosing the brackets this way also allows you to thoroughly insulate the underside of the bay.


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