Single Versus Double Glazing

For a wood shop that makes custom windows and doors, insulated glazing is a debatable topic. September 7, 2013

I am considering replacing some replacement windows/tracks that are poorly fitted with sashes I'll make in my shop. Would it be better to use a single pane of glass in conjunction with a storm window, or a double glazed unit? The warranty period of an IGU is part of the calculation; I can't find anyone who has longer than a five year warranty on just the glass. I'd prefer the double glazed, but not if it's going to fail so quickly.

Forum Responses
(Architectural Woodworking Forum)
From contributor A:
They don't fail in five years. They simply warranty it for that long. How long is your warranty?

From contributor T:
In ten years will you be able to repair the sashes you make? (Probably yes). In ten years will you be able to repair an IGU when it fails? (Probably not). Single glaze with storms has energy performance equal to IGUís but is infinitely repairable in your lifetime. Double glazed, single seal IGUís are the norm in plastic/vinyl and most stock wood windows with an average seal life of two to six years according to accelerated testing by the flat glass manufacturer, IG Cardinal.

From contributor G:
All of my glass suppliers in California offer no warranty at all in wood sashes; only vinyl and metal windows. They say that without weep holes IGU is destined to fail. I always suggest to my clients that they avoid IGU whenever possible. It's not a matter of if, but when.

From contributor A:
It's an interesting subject. My old employer made hundreds of 15 light and more individual pane custom doors for decades. I really don't remember any recalls. These were all small individual panes in SA mahogany doors no weep holes.

From contributor D:
We've made numerous front entry doors over the years. Actually we are doing a 1/4 sawn white oak one now and would only use insulated glass panels. You would be surprised at the cost - itís well worth it.

From Contributor J:
If for some reason you need to use silicone sealant, be sure the double glazed is silicone compatible because I've been told it breaks down the usual sealant. I specify silicone compatible when I order, and the glass people know just what it means. I always use it with wood and no weep holes. I havenít had any problems.