Base For Turf System

1 . A turf underlayment layer configured to support an artificial turf assembly, the turf underlayment layer having panels, each panel including a core, a top side having a plurality of top projections disposed across the top side, and a bottom side having a plurality of bottom projections disposed across the bottom side, the top projections forming top side water drainage channels and the bottom projections forming bottom side water drainage channels, the top side water drainage channels being in fluid communication with the bottom side drainage channels, the top projections and bottom projections terminating in generally flat support surfaces, with the flat support surfaces of the top projections having smaller support surface areas than the flat support surfaces of the bottom projections, and the core presenting a dynamic response to an axially applied compressive load, with the response being an initial compression of the top projections at a first spring rate, followed by a subsequent compression of the core at a second, higher spring rate.

2 . The turf underlayment layer of claim 1 in which the top projections have tapered sides extending from the flat support surface outwardly to the top side of the core.

3 . The turf underlayment layer of claim 1 in which the material density is within the range of from about 45 grams per liter to about 70 grams per liter.

4 . The turf underlayment layer of claim 3 in which the material density is within the range of from about 50 grams per liter to about 60 grams per liter.

5 . The turf underlayment layer of claim 1 in which the top side water drainage channels are in fluid communication with the bottom side water drainage channels via drainage holes, with the drainage holes intersecting top side water drainage channels and bottom side water drainage channels.

6 . The turf underlayment layer of claim 1 in which the top projections are truncated cones, and the support surfaces of the top projections have a friction enhancing surface configured as one of bumps, raised nibs, ribs, and dots.

7 . A turf underlayment layer configured to support an artificial turf assembly, the turf underlayment layer having panels, each panel including a core, a top side having a plurality of top projections disposed across the top side, and a bottom side having bottom side water drainage channels, the top projections forming top side water drainage channels, the top side water drainage channels being in fluid communication with the bottom side water drainage channels, with the top side water drainage channels being spaced in a different arrangement relative to the arrangement of the bottom side water drainage channels so that the there is substantial non-alignment of the bottom side water drainage channels relative to the top side water drainage channels.

8 . The turf underlayment layer of claim 7 in which the top side water drainage channels are in fluid communication with the bottom side water drainage channels by means of drain holes, with the drain holes intersecting both the top side water drainage channels and the bottom side water drainage channels.

9 . The turf underlayment layer of claim 7 in which the bottom side water drainage channels are formed by a plurality of bottom projections disposed across the bottom side of the panel.

10 . The turf underlayment layer of claim 7 in which the top projections and bottom projections terminate in generally flat support surfaces, with the flat support surfaces of the top projections having smaller support surface areas than the flat support surfaces of the bottom projections.

11 . The turf underlayment layer of claim 7 in which the top projections have tapered sides extending from the flat support surface outwardly to the top side of the core.

12 . The turf underlayment layer of claim 7 in which the material density is within the range of from about 45 grams per liter to about 70 grams per liter.

13 . The turf underlayment layer of claim 12 in which the material density is within the range of from about 50 grams per liter to about 60 grams per liter.

14 . A turf underlayment layer configured to support an artificial turf assembly, the turf underlayment layer having panels, each panel including a core, a top side having a plurality of top projections disposed across the top side, the top projections defining top side water drainage channels, and a bottom side having a plurality of bottom side water drainage channels, the top side water drainage channels being in fluid communication with the bottom side drainage channels, with the top projections being integrally molded with the core, and being solid, so that when the top projections are subjected to an axial vertical load, they expand laterally.

15 . The turf underlayment layer of claim 14 in which the panels are made from a plurality of polyolefin beads, the plurality of polyolefin beads bonded together by at least one of pressure and heat to produce a substantially water-impervious surface.

16 . The turf underlayment layer of claim 14 in which the top projections have tapered sides extending from a flat support surface outwardly to the top side of the core.

17 . The turf underlayment layer of claim 16 in which the material density is within the range of from about 45 grams per liter to about 70 grams per liter.

18 . The turf underlayment layer of claim 17 in which the material density is within the range of from about 50 grams per liter to about 60 grams per liter.

19 . A turf underlayment layer configured to support an artificial turf assembly, the turf underlayment layer having panels, each panel including a core, a top side having a plurality of top projections and top side water drainage channels disposed across the top side, and a bottom side having a plurality of bottom side water drainage channels, the top side water drainage channels being in fluid communication with the bottom side water drainage channels through drainage holes, the panels being formed from an expanded, closed-cell, foam-bead material having a density within a range of from about 45 grams per liter to about 70 grams per liter.

20 . The turf underlayment layer of claim 19 in which the top side water drainage channels are arranged in substantial non-alignment with the bottom side water drainage channels along a length of the panel.

21 . The turf underlayment layer of claim 20 in which the top side water drainage channels are spaced in a different arrangement relative to the arrangement of the bottom side water drainage channels, and in which the drainage holes extend between the top and bottom water drainage channels.

22 . The turf underlayment layer of claim 21 in which the material density is within the range of from about 50 grams per liter to about 60 grams per liter.

23 . The turf underlayment layer of claim 19 in which the panels are made from a plurality of polyolefin beads, the plurality of polyolefin beads bonded together by at least one of pressure and heat to produce a substantially water-impervious surface.

24 . The turf underlayment layer of claim 21 in which the material is a closed-cell polyethylene foamed bead material.

25 . The turf underlayment layer of claim 19 in which the top projections have a height in the range of about 0.5 millimeters to about 6 millimeters.

26 . The turf underlayment layer of claim 25 in which the top projection height is in the range of about 1.5 millimeters to about 4 millimeters.

27 . The turf underlayment layer of claim 25 in which the top projections include a friction enhancing surface configured to increase frictional engagement between an artificial turf backing layer and the underlayment layer.

28 . The turf underlayment layer of claim 27 in which the friction enhancing surface is one of bumps, ribs, and dots that are integrally molded onto an upper surface of the top projections.

29 . The turf underlayment layer of claim 19 in which the bottom side has a contact area configured to contact a substrate layer, the bottom side contact area being greater than an upper surface of the top projections.

30 . The turf underlayment layer of claim 19 in which the top side water drainage channels are in fluid communication with the bottom side water drainage channels by means of drain holes, with the drain holes being spaced apart from the top side projections and intersecting both the top side water drainage channels and the bottom side water drainage channels, the panels being formed from a closed-cell, foamed bead, polyolefin material having a density in a range of from about 50 grams per liter to about 60 grams per liter; the top projections having a height in the range of about 1.5 millimeters to about 4.0 millimeters, and at least one of the top projections including a friction enhancing surface configured to increase frictional engagement between an artificial turf backing layer and the underlayment layer.