View Full Version : Base prep for patio

09-18-2008, 08:14 AM
I have a somewhat unique patio project coming up soon and I was looking for a little insight on how you guys might approach the base prep. The patio will be using Techo econo slabs, 12"x24" in a herringbone pattern. The house is new construction, built on a slab with 4' frost walls. It sits atop a fairly good size slope. The driveway to the house is probably a 30 to 35 degree slope. The sight was a lightly wooded area with trees all under 2" diameter. Site work included light grading of the house site and driveway construction, then approximately 2' of sand used to create the finished grade. Then entire hill side is sand underneath whatever top layer the trees are growing in. So essentially, a soil profile of the site is 24" of sand, 6" to 8" forest soil, then sand.... Also of note, the builders installed 2" foam board, 6" deep and extending 4' from the foundation, laying flat. We get cold winters in these parts, with much snow cover. The entire area is obviously very well drained.

what would you guys use for a base? Dig down the two feet to the original soil line and build up a gravel base from there? Dig further? Or just the normal 6" to 8" base with geofabric? Also, how would you deal with the foamboard insulation?

09-20-2008, 09:50 PM
no weigh-ins?

09-20-2008, 09:55 PM
I don't understand the 2' of sand for grade? Your in the NE not Florida?

09-21-2008, 08:30 AM
Yes, New England. The house lot is in a river valley with A LOT of sand. Just behind the house lot, maybe 300 yards is the entrance to an old sand pit. So, using materials on site, sand was used as a cushion for the cement slab, frost walls poured (the trench for the walls was dug below the existing grade to some extent) and then sand was used as fill around the foundation/slab.

09-23-2008, 09:07 PM
Jimmy...how big is the patio going to be?

09-24-2008, 10:35 PM
The plan, as it is right now, is to build 4 patios around the house that range from about 120 sq. ft. to about 400 sq. ft.

09-25-2008, 12:03 AM
If i were in your situation i'd go all the way down until i hit dirt, even if it means going down 2 feet or more. You'll need to charge for your time to excavate down that far, as well as to haul the sand away, plus dump fee. Example: the 120 sf patio will need (if you really need to go 2 feet down) around 14 tons or 10.5 yards of 3/4" crush. As for the foam board, anything other than what is attached (glued) to the foundation should go straight to the dumpster.