Q:
What’s the difference between asphalt and coal tar?
A: Asphalt is
derived from crude petroleum. It’s an aliphatic or
‘straight-chain’ hydrocarbon resin. Coal tar is derived from the
destructive distillation or coal. It is an aromatic ‘ring shaped’
hydrocarbon resin. The two are different and generally incompatible.
Asphalt is normally lower in cost and is the most common bitumen used
for dampproofing and waterproofing. Coal tar is less permeable
than unmodified asphalt and has much higher resistance to biological
degradation over time. Coal tar is often used to protect
underground pipelines and certain types of waste treatment facilities.
Q:
What allows solvent based coatings & cements to adhere to wet or
under water surfaces?
A: An oil
soluble ‘surfactant’ or soap is added to the mastic. The surfactant
lowers the surface tension of the mastic and allow the moisture present
on the surface to be displaced. Pressure will be necessary to aid in
adhesion of the mastic to wet surfaces. These surfactants also promote
penetration of, and adhesion to, polyester reinforcing fabrics.
Q:
What is the difference between ‘waterproofing’ and ‘damproofing'?
A: Damproofing
will resist penetration of moisture through a foundation into the
interior under normal conditions. Waterproofing will do the same even in
the presence of hydrostatic pressure.
Q:
What are the advantages and disadvantages of applying coatings by brush,
roller and spray?
A: Brush
application allows the coating to be ‘worked in’ to the surface.
This will ensure an adequate bond, particularly if the surface is less
than ideally clean and smooth. Brush application is the most time
consuming method and will often result in visible brush marks.
Rollers are
faster than brushes and still allow a measure of mechanical assistance
in adhesion to the surface. Rollers also eliminate brush marks but may
still leave a textured surface. Applicators should be aware that rollers
will lower the natural rate of coverage below that which is recommended.
Spray
application is the fastest method of coatings application and generally
leaves the smoothest surface. Total lack of mechanical assistance in
adhesion, difficulty in assessing coverage rates and the danger of
‘over-spray’ limit the suitability spray applications.
Q:
What is the difference between silanes, siloxanes and silicone?
A: All three
are silicon based molecules that have masonry waterproofing
applications. Silanes are monomers, the smallest and most simple
of the three molecules. Silanes are best suited for dense surfaces like
concrete and cultured stone. High concentrations of about 40% are
necessary because of silane's volatility.
Siloxanes
oligomers are larger and more complex molecules than silanes. At
lower concentrations they provide excellent moisture protection to more
porous surfaces like split face concrete block. Siloxanes can be blended
with silanes to produce a treatment with the advantages of both
materials.
Silicone
polymers are large functional molecules that are used in caulks and
sealants. Silicones can be useful for protecting porous
natural stone that has a neutral ph. For concrete and masonry
applications, silanes and siloxanes penetrate farther and preserve the
surface's original appearance.
Q:
What type of insulation is suitable for below grade foundation walls.
A: Extruded
polystyrene and rigid fiberglass are the two most suitable types of
insulation. Polystyrene is inexpensive and widely available.
However, polystyrene does not allow water to drain down to the drain
tile, is incompatible with solvent based systems and is not recommended
for use in areas where termites are found because it provides a
protected rout from the earth to the wooden structure.
Rigid
fiberglass is the most suitable type of insulation for below grade
foundations. It is resistant to decay, will not harbor pests and
sheds water efficiently to the drain tile.
Q:
Is an ICC Evaluation report required for polymer modified asphalt
waterproofing.
A: No, a
research report is not required for polymer modified asphalt
waterproofing provided it is applied at a minimum thickness of 40 dry
mils. 40 mils of polymer modified asphalt is an ICC "approved
method" for complying with IRC 406.2. Only unapproved methods
require a research report.
Q:
What is the difference between a "masonry paint" and a
"waterproof maronry coating"
A: Masonry
"paints" are intended as decorative finishes for masonry
walls. Waterproof masonry coatings are performance coating systems
that offer breathable moisture protection and crack bridging abilities
in addition to decoration.
