NFPA 1142 - Rural Water Supply

[Charlesm]

We are having an discussion in my area with the Fire inspector. It is not really pertinent here to get into what that is because my question came up as a side note to it.

We have areas with a lot of Agricultural construction and no municipal water supply available. Fire uses the standard calculation for on site water storage based on NFPA 1142. As part of that calculation you must use the volume of the structure. What I am having trouble understanding is when they do the calculation and come up with a 10,000 gallon water storage requirement on a metal shade structure that has no walls. I understand that it may be used for covering wood or hay products, but it seems as though not having any walls would make calculating the structures volume kind of arbitrary. There would be too many ways of arguing what the volume is, i.e. total volume of the building materials, volume of the area under the roof from the lowest roof point to the highest, etc.

Has anyone else with this type of construction and rural setting come across this situation? If so, what was the decision made in regards to calculating water storage?

Thanks.

[Jerry Peck - Codeman]

Has anyone else with this type of construction and rural setting come across this situation? If so, what was the decision made in regards to calculating water storage?

To me, the easiest way to calculate the volume contained within the structure would be to take the perimeter around the exterior supports for the structure and its roof, then multiply by mean roof height.

I am not aware of other disputes on this, but the above would be the logical method for the measurement and calculation of the volume contained within the structure.

An open structure could have excess storage in it which could extend outward beyond the structure's supports.

From the example you gave possibly storing hay, that would make the Occupancy Hazard Classification a Number 3. The Type of Construction would be Type V as you described. Is the structure in question a structure with an exposure hazard (is it within 50 feet of another structure or building? I presume it is 100 sf or larger in area.

I will also presume that you did the calculations correctly based on the occupancy classification, type of construction and whether or not the structure has an exposure hazard or not.