Basement Waterproofing basics

Examples of Waterproofing a Foundation

1. Liquid Rubber Foundation Waterproofing Membranes

are elastomeric polymerized coatings made from liquid rubber – the same quality material your car tires are made from.

Advantages: They are easy to apply, quick to dry, cold applied. You can do it by yourself, by using sprayer, roller or trowel. The liquid cures into an elastic rubber coating, able to fill up current small holes and bridge possible future cracks in foundation wall as the building settles down. Rubber is flexible. They also usually come with a long warranty, and many are environmentally friendly with low solvent content, or solvent free. Very economical.

Disadvantages: Possibility of inconsistency in coverage, but the newest products will help you to determine the “right” thickness by the intensity of color, i.e. if you apply the product and you see any lighter patches, you just add more liquid. Additional surface preparation and curing may be required. If there are bigger cracks or holes in the structure you have to fill in with cement or other trowel-grade material before applying the overall coating. Also some of the liquid membranes require longer curing times for the concrete before they can be applied to insure proper bonding.
2. Hot applied Liquid Rubber Foundation Waterproofing:

It’s a rubberized asphalt compound that forms a strong, flexible monolithic waterproofing membrane. Can be also applied on roofs.

Advantages: Adheres to virtually any structural surface. Ideal for rough uneven surfaces. Monolithic, free of seams, watertight, eliminates water migration and buildup of moisture. Offers strong protection because of the way it has to be applied.

Disadvantages: The surface has to be primed by primer first. The cost is higher because the product has to be applied in layers – basically you apply first coat of hot liquid rubberized asphalt, then you have to quickly firmly press on the fabric reinforced sheet into that hot layer, then apply a second coat of hot liquid waterproofing. Also, depending on the local building code you may have to apply 2 or 3 of these sheet layers. Because of this, the elasticity is low. And because it is Hot you have to be very careful – the best is to have it applied by a certified specialist.
3. Sheet membranes

The most common are self-adhering rubberized asphalt membranes composed of rubberized asphalt laminated to a waterproof polyethylene film.

Advantages: The biggest one is the consistent thickness because they are “pre-made” to a required standard. Mechanically strong, and resistant to hydrostatic pressure. Cover even the bigger holes or damaged areas.
They can be applied to concrete, metal, wood or masonry surfaces.

Disadvantages: Harder to apply because of their very high “stickiness”, also the cost for in-place is higher. Application requires at least 2 people to put in on properly. Requires lots of additional work = additional cost. If there are irregularities on the surface you want to put a sheet on they have to be smoothed first with some coat to make the surface even. You also would need to learn of joint treatment, lap joints, corners, penetration, priming, patching etc. And once the piece is down you won’t get it back up in reusable condition.
4. Cementitious Waterproofing

Is a cement based flexible waterproofing membrane? It can consist of Portland cement, sand, acrylic mixture, plasticizer and other active waterproofing chemicals to increase its durability and effectiveness.

Advantages: Very easy to use, just mix the powder with water according to manufacturer’s recommendation, and apply with brush or trowel. Very accessible - available from suppliers of masonry products, or specialized dealers. Paintable. Also comes in a variety of colors. In most cases one coat is sufficient, although some areas may be needing a use of the reinforcing mesh. Low cost. Corrosion and weather resistant. Can be applied as a positive or negative side waterproofing.

Disadvantages: No flexibility – cement does not stretch, so as the structure settles down there are the possibilities of the future cracks. Before applying the surface has to be free from protrusions, gaping cracks, oils, paints, water repellents and any other foreign material that could act as a bond breaker. Holes must be filled with approved block filler.
5. Bentonite Waterproofing

is a Bentonite clay below-grade foundation waterproofing product which consists of sodium Bentonite clay sandwiched between 2 layers of woven and no-woven puncture resistant polypropylene fabric. Comes as a clay panels and sheets.

Advantages: Can absorb tremendous amount of water. And as it takes the water in the clay swells and pushes itself into cracks and voids where it stays permanently as a barrier against the water. It is flexible and resistant to most chemicals. Non-toxic, non-polluting. No fumes. Can be applied in cold weather.

Disadvantages: Because of the way the clay works the seal does not form until the foundation is backfilled and the water reaches the Bentonite material, which means you cannot confirm the integrity of the seal.

Damp proofing is the traditional method of protecting a foundation. Sealer is a damp proofing membrane that stops water vapor from passing through a foundation wall and into the basement area. It can be used on either poured concrete or masonry block construction and forms a smooth continuous barrier.

**If such a basement is constructed of masonry block or concrete and not reinforced properly, such a damp proofing might not be the best product to protect you against water infiltration when cracks come about due to stress, movement or just plain fatigue from hydrostatic pressures, poor drainage and poor backfill. **

When plans call for dry basement living space, a membrane or liquid can do the job if it’s installed right

Sheet Membranes

The most commonly specified sheet materials are self-adhering rubberized asphalt membranes. These 60-mil-thick membranes are composed of rubberized asphalt laminated to a waterproof polyethylene film. The asphalt side is incredibly sticky but is covered by a release paper, which you remove during application.

The first time you work with this material, it’ll drive you crazy because it sticks to everything. But you’ll be surprised how fast you can move with it once you develop a rhythm. It takes two people, one on top to smooth it out and stick it down, the other on the bottom to pull off the paper. You’ll have many details to learn about surface preparation, priming, patching, joint treatment, terminations, lap joints, penetrations, and corners.

Because they’re so sticky, these membranes can be pretty unforgiving. Once a piece is down, you won’t get it back up again at least not in reusable condition. However, the system allows easy repairs of holes, fish mouths, puckers, and wrinkles. You’ll patch holes or damaged areas with a piece of membrane placed right over the first layer. With a fish-mouth or wrinkle, all you do is slit the raised area, press it down flat, and cover it with a patch.
A chief advantage of sheet membranes is their consistent thickness. Because they’re manufactured to exacting tolerances, you can be sure of the 60-mil coverage. These membranes also have good elongation.

A higher in-place cost is one of the main disadvantages of sheets. The cost of the material itself is likely to be greater on a square-foot basis than the liquid membranes. Labor cost is also higher, because of the entire cutting, handling, reinforcing, and detailing you have to go through during installation.

Not everyone agrees, however, that sheet membranes lessen the quality-control risk. A rubberized liquid forms a continuous, seamless coating, whereas a sheet membrane results in many seams, with the potential for a poor seal. If you’re applying these materials, make sure your lap joints are tight and properly detailed. Make correct use of the manufacturers mastic or other accessories. For example, one manufacturer requires you to apply a bead of mastic to every lap joint within 12 inches of a corner when using its product.

Hope this might help to understand some basement water proofing basics.
This does not even touch the parameters of the waterproofing technology.

Marcel :slight_smile: :slight_smile: :smiley:

Very nice!

Thanks Marcel

*** Thanks Marcel***

The full article, with some pictures, is at:

Thanks Marcel, you filling in for Bubber. Got Mold?

Not actually Ken, just trying to point out as many point of interest as possible to reinforce what John says.

I like to prevent and recognize what John has to repair everyday.

Between recognizing the waterproofing systems, reinforcement required in a concrete wall and block wall and especially the backfill of any foundation wall, are all critical points as to why John is so busy, the proper way just is not done in some of these residential markets.

Since reinforcement of foundation walls is not possible to verify on an inspection, the waterproofing can be by digging down about 4" which is where it should start.

Visible cracks on the interior and exterior is also an indicator that something is moving and will let water in.
The type of waterproofing used might be able to withstand some of the leakage issues while not addressing the structural part of it.
It is at that point that some of these cracks in the foundation wall and/or block wall be reported and deferred to a foundation specialize for further review. I dose not have to leak at the time of the Inspection to be referred for further evaluations.

Identification of further evaluation is based on recognition of the facts and possibilities that it probably will leak and structural problems may occur.

Marcel :slight_smile: :smiley:

Just thought I would add a couple of pics to show the system and especially the stone backfill that John likes and so do I.

System Bituthene 4000 by Grace Products, 2" styrofoam protection board, and Hydroduct 220 for a drainage board.

Yeah, send that water down to that underdrain. Hydrostatic pressure, does not exist here.

Marcel :slight_smile: :slight_smile:


I guess a couple of pics would help, huh

This might help a little, ha. ha.

Marcel :slight_smile:

There are two primary categories of waterproofing: proactive and reactive. If you are building a home, waterproofing your foundation during the construction phase can save you a lot of time and money. There were several examples you mentioned, and a long list of other solutions you didn’t. How you waterproof your foundation should be dependent on your need, your climate, and the condition of the soil surrounding the foundation.

Now, if your foundation has already been poured and you haven’t had a need to waterproof for the past 20 years, it may come to a surprise to you when suddenly you have moisture problems in your basement. As concrete ages, the pores get larger and the larger the pores the more water, moisture, vapors, and air the basement takes in. For many homeowners, digging you the soil around the home simply is not an option. Here are a few other solutions (which solution is best for you depends on how severe your water or moisture problem is, and what the climate is like in your area).

First, you want to repair all concrete cracks. You want to repair wall and floor cracks, coveseam cracks, cracks in the mortar (if you have cinderblock), gaps, pipe penetrations, etc. Consider using a hydrophobic polyurethane for wet cracks, a rigid polyurethane flor floor cracks, and a flexible polyurethane for joint cracks.

Once the cracks are repaired you want to seal the entire basement, from the inside, with a penetrating, waterproofing concrete sealer. If you want to put a waterproofing coating on the surface after it has been sealed with a waterproofing sealer, that is fine - but don’t use a coating alone, it won’t last. Foundation Armor manufactures sealers that are guaranteed for life and approved by the U.S. Military as water and vapor barriers.

In some cases, you may have to install a Radon mitigation system, french drain, or sump pump.

good post

Thank you so much for this article about basement waterproofing!
I learnt the hard way about the importance of using basement waterproofing. My basement flooded and I lost about 100,000 worth of stuff in my place. Luckily a friend told me about City Wide Group and they ended up being an excellent Toronto basement waterproofing contractor.

I found that there were many benefits to it that I did not know about:
Improved Structural integrity – Waterproofing your basement will provide you with structural soundness and the assurance that your family and your possessions will be protected.

Updating plumbing, electrical fixtures and insulation – By waterproofing your basement I was able to inspect and determine if you need to update or improve outdated plumbing, wiring, and insulation.

I appreciate that you have posted information about basement waterproofing! It is very helpful!

Found a website that says: All waterproofing coatings gradually break down or separate, even flexible elastomeric liquid membranes. Elastomeric sheet membranes separate as the alkalis attack the primer and taped joints - they are guaranteed for only 5 to 10 years.

My application is a 10 year old house with basement built with cement blocks and coated with tar. The useful life of the tar has expired and water is beginning to penetrate the basement walls. I have read online about many systems that are supposed to be the best. After removing all the dirt and cleaning the outside walls, it would be good to redo it correctly. After removing everything including the old tar, thinking about using Quikwall or similar product to fill in the porous blocks and mortar joints. Then applying the best sealant. After this Dimpled Foundation Membrane, make sure the French drain system is clean and installed correctly, then back-filling with wash gravel all the way to ground level. Is this one correct way?

My home inspector said: Virtually all basements exhibit signs of water penetration and virtually all basements will leak at some point in time.

I believe, if done correctly, the basement will remain dry for most people’s lifetime. Of course, many are not done correctly, in my experience.

Good post!

This is way too expensive and scary. Just bring in some dirt and extend the downspouts, and your basement will be bone dry. :cool:

how NOT to waterproof a basement, err umm what is NOT waterproofing

as usual, the water is first entering through exterior cracks in the block foundation walls and some openings into the home above grade, these interior systems do not fix/repair/waterproof any of the exterior cracks n other openings hence will not stop/prevent mold, efflorescence

another interior basement system installed, pffftt

This is waterproofing, homeowner was getting water in basement in this area THREE different ways, 1) through cracks/openings on the exterior of the foundation wall… 2) through the old basement window that was replaced … 3) through openings ABOVE grade, rotted wood siding etc… No interior basement water-diverting system and sump pump would have stopped further water from entering any of the ways hence would not have stopped further mold, efflorescence, wood rotting etc
… hydraulic cement in/over all exterior cracks and other openings in the foundation wall, thick mastic/roofing cement over the entire area of foundation wall and visqueen and then backfill 99% of the trench with gravel.

Hope all is well Mr Cyr

Hi Bubb!
I’m disclosing your secret weapon & your brother in-law is Phil Swift! :mrgreen:

nooo Mr G, loooooollllll nooooo dammmmit

Hey Bubba!, keeping your head above the dirt?
Keep on digging, lot of people need your help out there. :):wink: