Waterproofing specification for concrete curbs, Sept 1998

NYC 9/11 Public Portal Document

NO'J 13 ’98 1'5:04 PR ftMBPSSftOOR CONSTR. .C0212 949 9762 TO 6191196 P.02/05 SWANKB HAroEN CO/WBLL 0002/005

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KBIMm SI Via Fax (212) 219-0059 & Regular Mail

Septombtr 12,1998

Mr. Juan M. Mejia, AlA Swankc Hayden Connell & Partners LLP 295 Lafayette Street New York, NY 10012

Re; OEM Radio Equipment Room 7 World Trade Center, NY, NY

Dear Jaun;

As discussed, the new concrete curbs for the above project may be poured directly on the existing Kemperol membrane. Before pouring the new concrete, the existing mambrane must be protected from alkalinity in the cement by applying two (2) coats of Primer D (@ 0.0-1.0 gaIZlOO SF) and broadcasting kiln-dried silica sand into second wet coat of primer. The above protective measures are mandatory in ail areas where concrete is to be placed over Kemperol waterproofing membrane. In addition, care should be taken to clean adjacent areas of Kemperol with continuous water and brush (high-pressure water if necessary) to eliminate settlement of concrete residues on membrane. Once installed, the new concrete curbs may be flashed with one of the attached details. Detail "0-1" shows a metal/Kemperol membrane composite flashing used to flash the new concrete curbs while the concrete is still green Detail ''D-2" would be used to flash the curbs after the concrete has completely cured As discussed, detail "D-2" would require a bead of polyurethane sealant applied between the bottom edge of the concrete curb and existing Kemperol membrane to form a temporary water seal. Then, after the new concrete cures (with a maximum 5% moisture content), the Kemperol membrane fleshing could be installed.

Both flashing details require a tie-in of the naw Kemperol membrane onto the existing Kemperol field membrane. To accomplish this, the sand aggregate surfacing must be completely removed from the surface of the existing in-place membrane. The area of sand aggregate removed should be approximately 6" wide to accommodate the new flashing. After removing the aggregate, the top surface of the mambrane must be thoroughly cleaned with toluene or acetone. After the solvent has been allowed time to

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