Help with requirements for butt glass

Darrel Hood · 09-28-2011, 02:26 PM

I have been asked by a client to examine an installation of a butt glass window. It is a $3,000 installation of 5 panes to form a bay window. He says the joints are too wide and that he has pictures of a man's little finger through the joints before they were sealed. He wants an inspection opinion, if possible, with supporting references. He has not paid the withheld portion of the price. Oh yeah, he is an attorney.

In my experience, if I can put my little finger through the unsealed joints, that is much wider than I usually see and it will not be attractive. However, I am unsure where to find requirements or standards for butt glass windows. Can anybody help point me in the right direction for my research? Thanks in advance.

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**Jerry Peck** · 09-28-2011, 03:10 PM

Originally Posted by Darrel Hood

I have been asked by a client to examine an installation of a butt glass window. It is a $3,000 installation of 5 panes to form a bay window. He says the joints are too wide and that he has pictures of a man's little finger through the joints before they were sealed. He wants an inspection opinion, if possible, with supporting references. He has not paid the withheld portion of the price. Oh yeah, he is an attorney.

In my experience, if I can put my little finger through the unsealed joints, that is much wider than I usually see and it will not be attractive. However, I am unsure where to find requirements or standards for butt glass windows. Can anybody help point me in the right direction for my research? Thanks in advance.

I would stay as far away from making any comments about "In my experience, if I can put my little finger through the unsealed joints, that is much wider than I usually see and it will not be attractive." as that will get you in territory where you have no substantiation backup.

Before you can answer his question you will need know the manufacturer of the sealant and the specific type/number/model/style of the sealant.

*Only with that information* will you be able to make a statement which can be backed up.

An example is the sealant used to seal storefront type windows in high rise building, Dow, 795 I think it was, had a minimum sealant width and depth (1/4" x 1/4") and a maximum sealant width and depth (2" x 1/2" as the center of the hourglass profile), as well as a minimum maximum width to depth ratio, along with a specifically required profile (hourglass shaped) of the sealant, additionally, the sealant will typically specify a minimum bite (surface contact on each of the two surfaces, typically 1/4") for the sealant to adhere to the surfaces.

Typically, the minimum gap you will find specified on any sealant is going to be 1/4". The maximum gap will depend on the sealant.

I would dare say that *most* butt glass installations *do not meet* the minimum sealant width as they try to butt the glass together so close that the butt joint is not as visible as it would be with a wider joint.

Darrel Hood · 09-28-2011, 03:45 PM

Thanks Jerry. I never would have thought of going at this from the sealant side. You may be right that the common "attractive" joint is not compliant with sealant requirements.

**Gunnar Alquist** · 09-28-2011, 04:37 PM

Originally Posted by Darrel Hood

You may be right...

Uh-Oh. Take cover everyone!

**Billy Stephens** · 09-28-2011, 04:39 PM

Originally Posted by Darrel Hood

. However, I am unsure where to find requirements or standards for butt glass windows. Can anybody help point me in the right direction for my research? Thanks in advance.

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Two other things come to mind, Wind Load and U Factor.
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**Jerry Peck** · 09-28-2011, 05:27 PM

Originally Posted by Billy Stephens

Two other things come to mind, Wind Load and U Factor.

If the sealant is suitable for that use, then it should have joint width, depth, and adhesion ability to resist the wind load.

Now, regarding U Factor ... I have no friggin' idea!

BUT ... "If the sealant is suitable for that use," ... then being "suitable for that use" 'should' include U Factor as well as wind load.

**Billy Stephens** · 09-28-2011, 06:32 PM

Originally Posted by Jerry Peck

If the sealant is suitable for that use, then it should have joint width, depth, and adhesion ability to resist the wind load.

Now, regarding U Factor ... I have no friggin' idea!

BUT ... "If the sealant is suitable for that use," ... then being "suitable for that use" 'should' include U Factor as well as wind load.

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Well Thanks,

* For Clearing that up?

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