Wall Waterproofing/damp Proofing With Transparent Penetrating Resins
Posted: Saturday, February 28, 2009
by Christos Strogilis
http://www.macon.gr
There is a vast range of clear water repellents for wall waterproofing (The term waterproofing is used here somehow catachrestically).
Generally these products are only suitable for uncracked surfaces although some of them can seal hairline cracks.
In terms of substrate consolidation: there are some products with a consolidating effect.
1. Penetrants: Products that penetrate deeply in the structure of the walls and work with intermolecular phenomena. They are invisible and leave walls water-vapor permeable.
2. Pore blocking, wall waterproofing products: These products penetrate only marginally. They form a thin, resin based membrane and for this reason are succeptible to UV degradation. They usually have a mid-sheen or a glossy finish.
Pore blockers are chemically based usually on acrylic or polyurethane resins, silicones of high molecular weight, stearates, paraffine etc.
Pore blockers will not be further discussed in this entry. We don't like and thus don't adopt these products because of major aesthetical problems.
Our main interest here is in...
Penetrating, clear water repellents.
These products that are non consolidating and non film forming come mainly under the following sub-categories:
a) silane based
b) siloxane based
c) combinations of the above: silane - siloxane based
d) polysiloxane based.
It's out of the scope of this entry to delve into dark chemistry paths.
What we can say is that silanes have the smallest particles so they can penetrate deeper in the substrates and are more appropriate for denser substrates.
Siloxanes' particles are somewhat bigger and finally polysiloxanes have the biggest particles.
SOLVENT OR WATER BASED REPELLENT?
Undoubtedly the future belongs to water based products. They are more user end environment friendly. They are very easy to clean and they are doing a fine job.
On the other hand solvent based products:
- have a proven track record of success
- can be used in lower temperatures.
Both types can be deeply penetrating and non yellowing.
WHY SO MANY FORMULAE?
The number of variations in water repellent formulae brings confusion. Check what better suits to your needs. There are products e.g.:
- better suited for trafficable substrates.
- That possess oleophobic or antigraffiti properties
- completely invisible of slightly reviving the substrate colours
- better suited for alkaline substrates etc.
Examine data sheets carefully.
We have found water-based silane-siloxane combinations to give the best results in most cases.
WHAT SHOULD WE EXPECT FROM A GOOD WATER REPELLENT?
1. Deep penetration: Well protected from UV, deeply in the substrate pores, water repellents can last for up to 10 years.
2. An effective waterproofing mechanism: Penetrants work with their hydrophobic properties. They reduce or suspend capillary phenomena by lining capillary pores reducing thus adhesion forces with water.
3. A non yellowing behaviour.
4. Protection from frost. Vapor permeability of substrate should stay intact. Outwards water vapor diffusion shouldn't be allowed to produce condensates and eventually ice. Vapor pressure should be relieved through vapor permeable pores. Frost protection will greatly reduce spalling or flaking.
5. Protection from efflorescence. Not from efflorescence due to rising damp. This needs special treatment. Here we consider the efflorescence due to water penetration - water evaporation cycles.
6. Protection from dirt. Dirt cannot adhere but superficially on treated substrates.
APPLICATION CONSIDERATIONS
- Substrates should be relatively dry. Efflorescence, mold and mildew should be removed with appropriate cleaners and/or gentle scrubbing.
- Respect consumption rates, number of layers, time between layers.
- Always make a test. There are hundreds of different substrates.
- Check climatic conditions and decide if you can go on.
Chris Strogilis
http://maconwaterproofing.blogspot.com
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