Page 415 - Construction Waterproofing Handbook

THE BUILDING ENVELOPE: PUTTING IT ALL TOGETHER 10.17
systems are applicable over slightly damp or uncured concrete, allowing for immediate
dampproofing after concrete placement.
Emulsion systems should not be used in any below-grade applications or above-grade
locations where sufficient amounts of water are present that can actually wash away the
dampproofing material from a substrate. In addition, emulsion-based systems must be pro-
tected from rain immediately after installation. This protection must be adequate to keep
installations protected until primary envelope materials are in place and backfill operations
are complete.

Dampproofing Installation
Dampproofing applied to concrete or masonry substrates requires surfaces to be clean, cured,
and free of all honeycomb, fins, and protrusions. Some emulsion systems allow application
over uncured or slightly damp concrete. Sheet materials applied directly over soil should be
placed on compacted and level granular soils that do not promote capillary action.
Negative applications are used when only vapor transmission is expected through pri-
mary envelope waterproofing systems. If water is expected to enter through the primary
envelope components, negative systems should not be used. Negative systems provide no
means to collect and redirect this water to the exterior.
Positive systems are used in conjunction with flashing and weeps to redirect entering
water to the exterior. Water-based systems should not be used where substantial amounts
of water are expected to enter and collect on the dampproofing, as this can wash the water-
based material off the wall, particularly in below-grade construction.
Mastic applications are applied in thicknesses ranging from 30 to 35 mil. Sheet systems
are generally 10–20 mil thick. Cementitious systems are trowel-applied to thicknesses of
approximately 8 in. Millage applications should be checked regularly to ensure that proper
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thicknesses are being applied.
When applying dampproofing to inner wythes of masonry veneer walls incorporating
brick ties, a spray application of mastic is most suitable. Spraying allows for a uniform
coverage around the ties, which is difficult using a trowel.
Dampproofing used in conjunction with flashing systems should be installed after flash-
ings are adhered to the substrate. Applying dampproofing after the flashing fasteners are in
place is preferable to having the dampproofing punctured during flashing application.
The dampproofing used should be compatible with flashing materials. Some solvent
materials can damage sheet-flashing systems. Dampproofing should extend over the flash-
ing and attachments to allow adequate transition detailing and ensure proper drainage of
water onto the flashing where it can be redirected to the exterior. Refer to Fig. 10.17 for a
typical flashing and dampproofing transition.
For negative installation, first, furring strips should be installed; then dampproofing
materials should be installed. This prevents damage of the dampproofing continuity by fas-
teners used for attaching the furring strips. With cementitious negative systems, furring
strips can be directly applied with adhesives to the dampproofing to prevent damage.

Sealant Joints
Sealant materials are frequently useful in providing transitions between dissimilar materi-
als or systems in a building envelope. They also provide watertight allowances for thermal