I have a 27 x 36 foot rectangular crawlspace that has bare dirt floor. It reads around 30 when I conduct tests for 48 hours.

I want to place 191′ of 2″ ID ABS irrigation pipe in crawlspace in a grid pattern with 4 cross laterals. I was going to run a 5″ solid ABS plastic pipe from CS floor to most top place on roof, that’s 22′ of vertical rise of a 5″ plastic pipe.

Temperature under the membrane is 42 deg F coldest Winter (frequently around 50), and about 50-55 deg F at hottest in Summer.

I’m not sure how close/size I should drill the drain-sunction holes in the horizontal pipes on the ground. I was considering every 1 to 2′, in a spiral type pattern, so that water (if ever) can always escape nearby. And 1/2″ dia holes. Any ideas?

Does anyone know a formula or other means to calculate what size and length horizontal pipe is required for enough suction from the soil, based perhaps on sq footage?

And size/frequency of drilled holes?

I’m planning to install a 5″ Vertical black or white ABS/PVC pipe 21′ up side of house to make natural flow better.

How do I figure the math to plan and lay horizontal/vertical pipes to provide enough draft to vent the radon trapped under the vaper barrier on floor send it up the radon roof pipe?