What is clear glass?

Mike Jackson
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Joined: August 30th, 2011, 4:58 pm
Full Name: Mike Jackson
Location: Springfield IL
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What is clear glass?

Postby Mike Jackson » August 30th, 2011, 5:27 pm

What is clear glass?

The use of replacement glass when the original glass is broken or missing leads to the rather vexing question of “match existing?” How close does new glass have to be to old glass to be a good match? Can the new glass utilize new technologies such as low-E coatings or lamination and still match traditional clear glass? A technical standard that addresses light transmission, transparency and reflectivity is needed for both single and insulated glass units. So far, this has proved to be a difficult item to pin down, and the changing glass technologies related to tinting and low-E coatings are making this even more complicated.

This insulated glass standard is needed for several reasons. Insulated glass storm windows are a new product that shows great promise in improving energy efficiency. There are also quite a few historic buildings that don’t have any original sash, and therefore replacement sash with insulated units is an acceptable option. Thirdly, we are beginning to review historic building from the mid-century that originally had insulated glass units.

sschoberg
Posts: 49
Joined: June 9th, 2011, 9:43 pm

Re: What is clear glass?

Postby sschoberg » December 24th, 2011, 9:26 am

I'm surprised this didn't draw any comments sooner. Should have unless I'm missing it elswhere.

My first response would be don't rush into replacing old glass with glass that is tinted or has a LowE coating unless it is specified. If it is specified to change the original glass to one of these types than I would and I have done so. I would not though, replace original glass with IGU's (there is discussion on this here at the forum)

As far as IGU's in general-----I do not like them. They don't last long at all. I've seen them break seal and fog up as soon as 8 years. And the replacement IGU's usually only have a warrantee for five years. Even using IGU's in a custom wood replacement sash comes up short. You cannot duplicate an original wood sash with a new one with an IGU installed. Profile will be different, if any and they will not have the strength needed to last much more than 20 years. Not to mention using an IGU in a wood sash will not allow use of a glazing putty. You would need to use thin pieces of wood to hold the IGU in place and this wouldn't last very long at all. They use use glue to not only hold IGU's in place in newere modern winows but also to give strength to a weak built sash. In other words they are using the strength of the glass to help the weak wood sash.

Lots of people are trying to redesign storm windows and thus converting them to another prime window by incorporating IGU's in them and sealling them to the max with everything they can think of. The whole purpose of a storm window is to take the brunt of weather, to help the prime windows cope. Being simple and lite and having this single purpose allows them to be lighter in weight and easier to open or take down to enjoy the more desirable weather. When you seal them up and make them heavy and tight you take away from their intended function and you may very well be causing harm to the original prime windows by not allowing moisture and humility to escape to the outside.

Once our window comparison results are published, you will see that storm windows need to be kept to their original functions, which will help the prime windows to perform as good as modern, non-lasting and single-feature high-maintenance windows.

sschoberg
Posts: 49
Joined: June 9th, 2011, 9:43 pm

Re: What is clear glass?

Postby sschoberg » April 3rd, 2012, 8:01 am

I say just ban the use of IGU's all together in original wood sashes!


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