Housewrap with drainage channels

A housewrap for controlling moisture in the walls of a building, comprising:

• a moisture vapor permeable, water impermeable composite sheet material having opposite surfaces, said composite sheet material comprising:
• a nonwoven substrate comprising polymeric fibers randomly disposed and bonded to one another to form a nonwoven web having a grab tensile strength of at least about 40 pounds in at least one of the machine direction (MD) and the cross-machine direction (CD);
• and an extrusion coated polyolefin film layer overlying one surface of said substrate and intimately bonded thereto, said film layer comprising a polyolefin polymer and at least 40% by weight inorganic filler;
• said film layer having micropores formed therein,
• a plurality of drainage channels formed in said composite sheet material for directing the flow of liquid therealong, said drainage channels imparting to the composite sheet material a three-dimensional configuration, and said composite sheet material having a crush resistance under a load of about 2.65 psi of at least 50%.

A housewrap comprising

• a composite sheet material including a spunbonded nonwoven fabric formed of randomly disposed substantially continuous filaments bonded to one another throughout the fabric to form a nonwoven web having a grab tensile strength of at least 40 pounds in at least one of the machine direction (MD) or the cross-machine direction (CD), and an extrusion coated polyolefin film layer overlying one surface of said substrate and intimately bonded thereto, said film layer comprising a polyolefin polymer and at least 40% by weight inorganic filler;
• said film layer having micropores formed therein by stretching;
• a plurality of drainage channels formed in said composite sheet material for directing the flow of liquid therealong, said drainage channels imparting to the sheet material a three-dimensional configuration,
• the sheet material having a moisture vapor transmission rate (MVTR) of at least 135 g/m2/24 hr. @50% RH and 23° C., a Gurley porosity of at least 400 sec/100 cc, a hydrostatic head of at least 55 cm