While choosing the correct waterproofing/vaporproofing membrane is important to achieve a successful barrier in any underslab or blindside application, proper installation is imperative to avoid costly and time-consuming repairs if failures occur. W. R. MEADOWS recommends using PRECON pre-applied underslab/blindside waterproofing membrane for vertical and horizontal applications when access to the positive side of the concrete is restricted.
Prior to applying PRECON, proper surface preparation is necessary to ensure the surface is structurally sound and all objects are removed that may cause damage to the membrane. Use of MEL-DRAIN is recommended to be used with PRECON to assure proper site drainage. Removal of a drainage board is up to the discretion of the engineer if site conditions hinder use. If MEL-DRAIN is not being used, any gaps larger than 1” (25 mm) need to be grouted prior to installing PRECON. Gaps larger than 2” (50.8 mm) need to be grouted if MEL-DRAIN is used.
PRECON can be applied at temperatures down to 40° F (5° C). PRECON LOW TEMP is recommended when temperatures will be between 60° F (16° C) and 25° F (-4° C). MEL-PRIME should be used on the selvedge edge to enhance the bond when weather conditions warrant.
In vertical applications, PRECON should be mechanically fastened within ½” (13 mm) of the top of the membrane every 12” (304.8 mm). Install PRECON with the fabric side facing toward the concrete pour. Adjacent PRECON rolls should be attached by removing the 6” release paper and overlapping that distance. End laps should also be overlapped by 6” (152.4 mm) and sandwiched between an initial layer of BEM, HYDRALASTIC 836, or MEL-ROL LIQUID MEMBRANE and 12” (304.8 mm) of the same product centered over the termination. DETAIL FABRIC should be placed over the HYDRALASTIC 836 or MEL-ROL LIQUID MEMBRANE with 6” (152.4 mm) on each side of the PRECON lap edge. An additional layer of HYDRALASTIC 836 should be applied to cover the DETAIL FABRIC.
Penetrations and protrusions should be addressed and properly detailed. Any damages that occur during installation require patching. Concrete should be poured within 60 days of PRECON installation. Contact W. R. MEADOWS technical services with questions.