Thread: 4-hour CMU demising walls with masonry foam insulation

Florida code requires 4-hours separation between dwellings that share a common wall and/or commercial uses that share a common wall.

Some propose to achieve 4-hours by injecting foamed-in-place masonry foam insulation to fill the core spaces of 2-hour 8" CMU walls.

Has anyone seen this? If so, what are your thoughts?

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Originally Posted by Bob Sullivan

Florida code requires 4-hours separation between dwellings that share a common wall and/or commercial uses that share a common wall.

Bob,

You need to re-read the Florida Building Code, Building as your above statement is incorrect.

Some propose to achieve 4-hours by injecting foamed-in-place masonry foam insulation to fill the core spaces of 2-hour 8" CMU walls.

Has anyone seen this? If so, what are your thoughts?

If there is no UL design for what is being proposed, then it does nothing.

One must construct the walls specifically as stated in the UL design, but first you must figure out what hour rating is required for your specific use - and your first statement is incorrect.

Jack,

SECTION 705.1 General and 705.1.1 Party Walls seem to clearly call for party walls between buildings to provide a 4-hour fire-resistance rating.

What do I not understand?

Bob

That some of the walls you included in your post are under 708 Fire Partitions.

You need to more clearly define what walls located between what occupancies and if they are or are not 'the same structure' or 'different structures'.

There are several options for time rating based upon your answer.

Jack,

I need to be more specific. My inquiry refers is specific to 705, so you're correct.

Thanks.

Bob