Permeable Patios

What is a Permeable Paver Patio and what is with all the Ps?    

Permeable pavers and driveways are the now and the future!  Introduced first in about 1991, permeable pavers and permeable paver driveways have a different base than traditional paver patios are ECO friendly by Helping with reducing Water Run Off  The are also required for some projects or municipalities based on a % of a customers existing property run off.  

As an example, In Town and Country, MO, depending on how much sf of normal pavement you already have, you may have to have Xsf of areas around your pool as permeable surfaces.   

Unilock, who manufactures high end pavers, recommends sometimes using permeable base for non permeable paver patios.  

After you build a permeable paver driveway or patio, you can plan to Redirect water here so more water can be slowly infiltrated rather than run off like normal into store sewers.    

How Far Do You Excavate for a Permeable Paver Patio?

Depth of excavation depends on expected usage, slope and site soil conditions, the depth for commercial and residential permeable paver patios may vary.   

Should Be even and smooth fashion without rutting or compacting the soil  -for bigger driveway jobs, each tier can be dug to 21” to 36” and dug and sloped slightly backwards   Need to consider soil type -Sandy soil = 100% infiltration 

Clay soil = need drain tile! (Like in West County, MO)  

-Possible contact local watershed district to engineer paver system based on soil ties   

-Excavate to at least 1” or so below the base of the street curbs to prevent water build up and freezing near this frost line  -ok to lightly compact loose sub soil but do not want to over compact     

Geotextile   

-use polyeurothean construction adhesive sealer to put the apx 45mil liner GEO in place (near foundation)   

-45mil used in MN Video  

-Plan to overextend all borders for double insurance so water doesn’t go back into the foundation    

Geosynthetic  Fabrics 

-needs to be highly permeable and very strong  

-Geo Grid installed underneath first course will help prevent settlement underneath in the middle of patio   

Sub-Base Stone   

-First stone in the base (coarser stones)  Minimum 12” deep,  1.5” to 2” thick or 150MM thick clean or clear rock (with no fines in it) so water can go through.  In the voids, the water pools and slowly infiltrates into native soils  

-need only made of crushed angular rock and not round rock that will roll when compacted  -Also Needs to be properly compacted   

Exfiltration Drain Tile  Needed with holes to help direct water away from property and may be used if needed to act as discharge for excess water in the reservoir under the pavers.   

Edging Restraint   

(Needed either stamped concrete or full brick row of pavers)  

-Recommended a spike every 12” or so  

-critical for the system to not fail!  The edging should hold the pavers in place  

-full size paver for the boarder corse   

Open-Graded Base Stone  

-4” thick layer of 3/4” clean to 1.5” or clear rock

-This layer provides stability for cars to drive on or people to walk 

-averaging 3/4” In Size  

-Needs to be properly compacted   

Bedding Course 3rd Base Stone  

-Minimum 1” to 2” of apx 3/8” or 1/8” minimum to 1/2” thick or 40-50mm thick clean or clear rock ASTM 8’s or 9’s stone (From Unilock video)   

-plan to use 3/8” traps rock

-This course Does NOT need to be compacted! 

1" of 3/8” Trap Rock or Clean Stone swept into joints  

-Allows water to flow through and also acts as a filter to trap sediment that may clog the system  -planing to use 3/8” trap rock for this step and for top   

-2nd compaction needed on top of pavers after pavers set in place (with paver protector on compactor needed)  

Compacting Permeable Pavers Notes  

-compacted to seep pavers into the bed