Sprinkler coverage in storage attic

[Brookhaven 58]

I have a walk up attic of non combustible construction that will be used for storage thus requiring a fire sprinkler system. Due to water supply issue and being a dry system the spacing between heads can not exceed 12.2' in order to achieve the required density. Therefore the distance to the eave or soffit can not exceed 6.1'. The question is where does the measurement end at the exterior wall or at the end of the roof sheathing which extends approximately 2' past the exterior wall creating the soffit or overhang. NFPA is presently OOS. It is a sloped roof.

 

[cda]

how many sq ft is this area??

where are you getting the density and spacing???

I normaly end it at where the roof line meets the exterior wall, as in all floor area has to be covered.

I take it the rest of the building is sprinkled??

 

[FyrBldgGuy]

If the interior of the soffit is part of the attic it has to be included in the space. If the soffit is a concealed space you have another issue.

 

[Brookhaven 58]

In response to cda the area is 2037 sq ft with light hazard density .1 gpm, spacing is required due to area increase for dry system. Yes the building is fully sprinklered. The situation is similar to figure 8.6.4.1.4 of NFPA 13 2010 ed.. The 12" wide rafters rest on the top plate of the exterior providing continuity to the soffit area for the attic space.

 

[Brookhaven 58]

Just to close the loop on this issue. I spoke to NFPA tech services today and per the engineer coverage is based on floor area and thus ends at the exterior wall. I Thank all for their input and Wish all a great and safe holiday season.