Page 242 - Construction Waterproofing Handbook

CHAPTER 5

SEALANTS

INTRODUCTION

Sealants are not only the most widely used waterproofing materials, but also the most
incorrectly used. Although sealants are a relatively minor cost item, they constitute a major
function in a building’s life cycle. Applied from below grade to roof areas, and used as
components of complete waterproofing systems and for detailing junctures and termina-
tions, sealants act as direct waterproofing barriers. As such, sealants are important in con-
structing successful watertight building envelopes. Sealants are also used to prevent air
from infiltrating in or out of a building. Sealants thus have a dual weatherproofing role,
with waterproofing as the primary role and environmental control as the secondary role.
Practically every building’s exterior skin requires sealants for weathertightness.
Junctures of dissimilar materials or joints installed to allow for structural or thermal move-
ment require sealants to maintain envelope effectiveness. Below grade, sealants are used
for sealing expansion joints, junctures, or terminations of waterproofing compounds and
protrusions. Above-grade applications include sealing joints between changes in building
facade materials, window and door perimeters, and expansion and control joints. Sealants
are also used to detail numerous joints, including flashings and copings that act as termi-
nation or transition details.
Since sealants are a minor portion of overall construction scope, they receive a compa-
rable amount of effort in their design and installation. Yet because they are a first-line
defense against water infiltration, sealant failures can cause an unequal proportion of prob-
lems and resulting damage (Fig. 5.1).

SEALANT/CAULKING/GLAZING

Technologically, sealants have advanced dramatically from the white stuff in a tube, and a
clear differential should be made between caulking, sealants, and glazing materials.
Caulking refers to interior applications, to products manufactured for interior use and
installed by paint contractors. These materials are usually painted after installation.
Caulking is installed as a filler between dissimilar materials in an interior controlled envi-
ronment not subject to thermal or structural movement. Therefore, caulking does not
require the performance materials that exterior high-movement joints do. Sealants are
exterior applications using high-performance materials (e.g., silicones), which are typically
colored rather than painted and are applied by waterproofing contractors.

5.1
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