Calculating the Volume

Saturday September 3, 2005


Mr Pest Control


How much Premise 75 would I use to cover 14,820 sq. ft. with a .05 solution?

Mr Pest Control


Sometimes doing the math for these things can be kind of fun, if you break it down into bite-sized chunks. Let's do the two easy things first, and then we'll toss in some variables that are meant just to confuse you. For a 0.05% solution you would mix 4 packets of Premise 75WP into each 100 gallons of water. For the rest of this I am assuming that you are referring to a pre-treat application, and for that area presumably a concrete slab is going onto it. Assuming a normal soil type your application rate would be 1 gallon of solution over each 10 square feet of soil, so for a 14,820 square foot area you have 14,820 divided by 10 square feet = 1,482 gallons used on the surface of the soil.

Now comes the trickier part. The Premise label calls for treating by rodding or trenching on a pretreat as well, around the foundation (inside and outside) as well as around construction elements that might penetrate the slab, such as bath traps, plumbing entries, utility entries, etc. So, you need to know in advance what the design is for this building, and all those elements need to be in place prior to your pretreat application. You don't want any disturbance of the soil after you have applied the protective termiticide. It is those interior elements that will be unknown to me in this equation.

However, we can calculate the volume needed for treating around the inside and outside perimeter of the foundation. We calculate overall area of a flat surface by multiplying length times width, so in reverse we can just find the square root of 14,820 to determine the length of the perimeter. The square root (easy on a calculator) is just under 122 feet, which means you average 122 feet on each side of the building, or a total linear feet around the foundation of 4 times 122 = 488 linear feet. On the INSIDE of the foundation the Premise label calls for treating with 4 gallons of solution for each 10 linear feet. Since you have a total linear feet of 488, divided by 10 = 49 (to round off) increments times 4 gallons per increment of 10 feet = 490 gallons used along the interior of the foundation.

So far so good - 490 gallons along the interior foundation plus 1,482 gallons over the soil surface = 1972 gallons. This is, as a reminder, excluding whatever spray solution you needed for the various areas that would penetrate the slab. Those also are treated at 4 gallons per 10 linear feet. What's left is the exterior of the foundation, and here the Label states that you use that same 4 gallons of solution for each 10 linear feet, but for each FOOT OF DEPTH OF THE FOUNDATION. So, if you have a foundation that extends 2 feet into the soil you would need to use 8 gallons for each 10 linear feet. For the sake of this exercise let's assume it will be a 2 foot deep foundation, meaning your total chemical solution used around the 488 linear feet (49 increments) is double that used on the inside of the foundation, or 980 gallons.

Now, our total chemical is 1,482 (soil surface), 490 (inside foundation), plus 980 (outside foundation), for a total of 2,952 gallons needed. Again, you would need to add in that amount needed for the odd-ball places under the slab where additional rodding or trenching is needed. Since we needed 4 packets of Premise for each 100 gallons our final math is to divide 2,952 by 100 = 29.5, and multiply this by 4 packets which leaves your absolutely final total as 118 packets of Premise 75W.

Mr. Pest Control

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Please note, Mr. Pest Control is answering questions supplied by PMP customers across North America. His answers are generated from industry and manufacturer-provided information. The answer may not be specific to the laws and regulations for your State, Province, Territory or Country. In addition, products mentioned may not be registered and or available in all areas. Always check with your local Univar office for specific information to your area. Always read and follow label directions.