This came up today. The MLS listing stated…”full impact windows and doors” but when the inspector got there he said that he could not give the house a mitigation credit for hurricane protection because the glass block needed panels over it. Does it?

First, if the house (and presumably the glass block in question) was built after the 2001 Florida Building code (POST March 2002 permit) was adopted then the house is assumed to be code compliant in terms of the wind storm protection. If there are no shutters there then the glass block should NOT require them ASSUMING that all the other windows and doors DID require some form of impact protection, given the location of the house.

Next, if the glass block itself, lets say in a bathroom remodel, was installed with a building permit issued under the 2001 (or later) FBC then you can assume that, as above, if there are no shutters in place then no shutters are required as, similar to above, if they were required then the building inspector would have seen to it that they were installed.

Finally, it IS possible to use glass block to fill in an opening in a wall and IF (that’s the BIG if) it was properly constructed (as in with an FBC approved block and detailed just like it is shown on the FBC Notice of Approval) then one would NOT need to have hurricane panels to protect it. The block itself must be approved for use in either the High Velocity Hurricane Zone (Miami-Dade and Broward counties) or with a Florida Building Code Notice of Acceptance for use elsewhere in Florida. THE BIG QUESTION IN THIS IS: THE BLOCK MUST HAVE BEEN INSTALLED IN ACCORDANCE WITH THE APPLICABLE NOTICE OF APPROVAL. It’s not just that the right block was used but that it was properly installed. And Without a permit it can be difficult to know that IF right block was used and/or that it was properly installed. I will note here that as a practical matter I checked the glass block sold at the Home Depot near me which is made by a company called Seves and their Nubio, Clarity and Endura product lines are approved for “Miami Dade” or High Velocity Hurricane Zone use and these require a label. The others lines are NOT rated for small or large impact but are FBC approved for the wind loads. Thus, for the latter, the block would again need to be properly installed to take the prescribed wind load and these WOULD require an approved shutter to take the prescribed impact loading.

If you are reading this trying to decide if you need to put plywood up over glass block then I would advise that if you are not certain and the time and material allows for it then better safe than sorry.

For those in cyber space who say glass block is the same as block, Concrete Masonry Unit (CMU) please read:

FBC 1626.1

All parts or systems of a building or structure envelope such as, but not limited, to exterior walls, roof, outside doors, skylights, glazing and glass block shall meet impact test criteria or be protected with an external protection device that meets the impact test criteria. Test procedures to determine resistance to wind-borne debris of wall cladding, outside doors, skylights, glazing, glass block, shutters and any other external protection devices shall be performed in accordance with this section.