the BB head itself can cover three feet on each side and up to 60 foot span:::Builder Bob said:I also believe the sprinkler head spacing in the 62 foot wide building exceeds the allowable coverage area of one sprinkler head of 250 SQ Ft... thiis equates to about 15 ft. by 15 ft. area....
http://www.tyco-fire.com/TFP_common/TFBP_Attic_ProdSlick.pdf