The Building Envelope

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Over eighteen years of work experience in the forensic investigation, design, analysis, consulting and inspections of residential, commercial and retail building envelope components. 

Wednesday, November 25, 2009

Impact Resistant System vs Non-Impact System w/Shutters

Impact resistant exterior envelope products (windows, doors, storefronts) are more expensive then non-impact products but, in South Florida, if you specify a non-impact product you are required to install shutters to protect it from wind borne debris, so the short term cost is not that different. However, in some parts of North Florida, there is no requirement for impact protection.

There is a mis-conception that impact glass will not break during a storm. That is not entirely true. Impact glass is very resistant to wind loads and should not break due to wind load during a storm but may break when hit by wind borne debris.
Should the impact glass break, you now have to replace the impact glass therefore adding a long term cost.

By Code, the impact glass is allowed to break so long as it does not allow wind, water or debris to enter the space. This is possible because impact glass is laminated (similar to a cars windshield) and will remain in place while broken.

Which brings us to the point about convenience. With Impact systems you do not have to run around and hang/close shutters every time there is a storm warning.


It's cost or convenience, barring locations that don't allow shutters or where impact systems are not required, if you choose cost, go with a non-impact system and shutters, if you favor convenience, go with the impact glass.

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