We have a project that is Type III-A, wood frame construction, with an NFPA 13 sprinkler system.
The client is weighing options of filling floor truss cavities with non-combustible insulation versus adding sprinkler coverage within these floor-ceiling cavities.
Does anyone have recent experience to know the relative cost impact of adding sprinklers within these floor cavities?
Thanks in advance.
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3/16/2022 07:28:53 am
No one is really going to be able to answer that without knowing the square footage of the structure.
3/16/2022 08:09:40 am
Its really difficult to answer that. The combustible concealed space is a volume of space. If these cavities between the ceiling and floor are 1-ft high, the cost of insulation will be substantially less than if they are 4-ft.
3/16/2022 08:56:50 am
Generally its fairly easy to get a price for insulation. So start there and work that against a sq ft number for the rest of your building's sprinkler cost that should be a decent ballpark number.
3/16/2022 11:11:13 am
I agree with Anthony here. You also need to be careful when your cavity size gets large. The code outlines limits on amount of insulation that can be installed.
3/16/2022 11:07:38 am
Coming at this from the architectural side, contractors we've worked with have always preferred the "fill voids with insulation" solution, but that's for voids that are generally no deeper than 24" or so. Note that some floor/ceiling or roof/ceiling assemblies have limits on amount and type of insulation that can be added, and/or require an additional layer of gyp if fiberglass insulation is used, so check Gypsum Association or UL assembly notes before proceeding.
3/16/2022 07:52:33 pm
I think you also have to consider that if you are already running branch lines the additional heads are a cost but significantly less than a new system
3/17/2022 09:34:12 am
Be sure to loop in your AHJ. The AHJ may require a third party inspection of the insulation in the interstitial space due to the difficulty of completely filling the cavity from the underside.
3/17/2022 04:21:38 pm
Insulation filling a void, locally when this is done it is blown in above chicken wire to maintain a filled void. I would think that when the void is over 24" deep, I would think sprinkler protection would start to be competitive with insulation. In most cases where this takes place you have a branch line within the cavity anyway, so you are talking the cost of a weld-o-let a sprig and sprinkler head.
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