The art of waterproofing started 13,000 years ago, developed to become the third trade after carpentry and masonry. As we became an agrarian society, farmers had to protect their grain from moisture and rotting during the cold months to prevent starvation. This Neolithic Era also brought boat-building and sea voyages into play to foment trading, so they devised a bitumen made from the surface of peat bogs, which wasn’t unlike the asphalt we use today. And then there were the Egyptians, whose Pyramids of Giza tombs were pristine despite the flooding of the nearby Nile River, so even in 3600 B.C., they were already waterproofing their basements.
When you construct any building, the foundation will always have contact with its surrounding soil. In most cases, you can interpret this as constant contact with groundwater moisture. Hydrostatic pressure, or the pressure of water pushing against your foundation, causes moisture problems if it is not mitigated. This is especially true if you’re building in an area with high water tables or an area with surrounding soils that drain slower than Internet Explorer after 7 p.m. Your building has to live with the terminal threat of moisture intrusion.
What Do Cold Fluid-Applied Waterproofing and Dampproofing Share in Common?
While both methods are designed to keep moisture out of your home or commercial property, and we often hear people using these two terms interchangeably, they’re very different in terms of the end results.
The confusion is understandable because both methods are performed below grade (or below ground level). However, waterproofing is the only method that will protect your building from the force of hydrostatic pressure water passing through your walls. Dampproofing, on the other hand, merely retards the moisture from being absorbed in buildings where you don’t have the worry about hydrostatic pressure. In short:
- Dampproofing keeps soil moisture out.
- Waterproofing keeps all moisture and liquids out.
Does Every Building Need Dampproofing?
The International Residential Code (IRC) Section 406 states that any concrete or masonry foundation walls “that retain earth and enclose interior spaces and floors below grade shall be dampproofed from the top of the footing to the finished grade.” The IRC then provides a list of the permissible materials, which include bituminous coating and acrylic-modified cement.
Dampproofing cannot resist water under pressure. However, it can help walls resist moisture penetration. If you’re constructing a single-story, above-grade building, the area that transitions from the slab edge to the footing can be treated with dampproofing material to save your client costs, since there is no below-grade finished, occupied space like a basement. If your external ground level is lower than the floor level inside of the building, then your risk of pressurized water ingress is less and damp-proofing would make sense.
Does Dampproofing Have Any Drawbacks?
Aside from the fact that dampproofing doesn’t totally shield your interior from water, there are a few drawbacks. If your foundation has formed ties holes or larger cracks, dampproofing cannot seal those chasms. Coarse, careless backfilling can easily damage your dampproofing application. Normally 10 mils in thickness, the damp-proofing material sets and cures quickly, leaving a coating that provides moisture resistance, but unfortunately is very limited in its resistance to any movement, or cracking of concrete.
- Can’t seal cracks and holes
- Not sturdy in varying temperatures
Materials Used for Dampproofing
Dampproofing mostly focuses on the exterior surface of a building. Dampproofing compounds are usually asphalt-based, water-repellent (a.k.a. hydrophobic) coatings that are applied in liquid form by brushing, rolling, or spraying to any foundation or basement wall surfaces that have direct contact with the earth.
These materials are designed to prevent water from absorbing and wicking through damp or wet concrete, but they will not resist pressurized water.
Does Every Building Need Cold Fluid-Applied Waterproofing?
The International Residential Code (IRC) 406 states that waterproofing is only required by the IRC “in areas where a high water table or other severe soil-water conditions are known to exist.”
While waterproofing typically accounts for 1.8% of any building’s construction costs, it represents 83% of all building defect complaints. The good news is, this is totally preventable. When you waterproof a building exposed to water under hydrostatic pressure it will prevent water from entering concrete, even with high-head pressure.
While dampproofing requires 10 mil materials, waterproofing materials are normally 40 mil materials or more, retain elasticity and flexibility at low temperatures (unlike damp-proofing), and can bridge cracks up to 1/16 of an inch.
There Are 3 Types of Cold Fluid-Applied Waterproofing
- Positive-Side Waterproofing: This is when you apply waterproofing material to the side of the structure that meets the source of the water. This is designed to stop the water before it can enter your structure and cause damage.
- Negative-Side Waterproofing: This is when you waterproof the interior side opposite of the hydrostatic pressure, such as elevator pits, tank liners, or remediation work.
- Blind-Side Waterproofing: This is a version of positive-side waterproofing where the waterproofing system is installed prior to the structural walls or slabs.
The 5 Most Common Waterproofing Materials
- Not easy to use at first
- Great adhesion to all substrates
- Consistent 60-mil coverage
- Excellent elasticity
- Higher in-place cost
Cold Liquid Membranes
- Fast application
- Low in-place cost
- Varying thicknesses based on chemistry
- Excellent flexibility
- Coverage is dependent on the installer
- Good strength
- Poor elasticity
- Easiest to use and apply
- Depending on formulation may be Intolerant of joint/crack movement
- Can absorb 15 x its volume to fill cracks and voids
- Extended post-backfill seal time means no contractor visibility
- Can be applied at low temperatures
Cost Comparisons: Dampproofing vs. Waterproofing
For a residence, damp-proofing costs $3 to $6 per square foot, and waterproofing is $5 to $10 cost per square foot1. There are many factors that can affect this cost, but most quality waterproofing membranes will far outperform all damp-proofing materials, in both performance and long-term durability. So, despite the higher up-front cost, it’s a stronger investment.
If you still have unanswered questions about dampproofing vs. waterproofing, please give us a call at 1–800-342-5976. To see W. R. MEADOWS dampproofing products, please click here. To see our waterproofing products, please click here.
- Source: Home Advisor