Concrete Waterproofing Sealer For Basements
Why Basements Start Leaking Water
There are many factors involved in why basements start leaking water. This can come in the form of heavy rainstorms or melting snow. These two can raise the level of groundwater around your significantly. An inch of rain on a roof area equal to 1,500 sq. ft. can yield a thousand gallons of water. This can result to clogging up rain gutters and downspouts especially if there is any debris present on the roof area.
New houses also face the problem of “reverse grading” occurring years after the initial construction of the structure is done. Another issue is fill dirt settling and directing all of the water directly on to the foundation.
When all of this water build up seeps into the topsoil, it can result into excessive amounts of water and debris pushing against all the walls of your building structure. This only stops right beneath the footings.
As the house settles, the footing drains you’ve installed could also break or silt up. The worst thing that could happen is if you have clay in your soil which essentially traps the water and pushes it up through the soil around your foundation.
All of these can have a disastrous effect to your basement.
Before moving on, let’s define a few technical terms that is going to prove crucial for you to know.
Hydrostatic Pressure – this happens the water around a foundation accumulates. As the water pressure builds, leaking in the basement is going to happen next. This is what we call hydrostatic pressure. This happens a lot if there is a lot of clay present in the soil around the foundation walls. Clay, does not drain well and it has the tendency to hold in rain water. Water then pushes its way through any weaknesses like cracks, joints or even exposed pores in the concrete. Rising groundwater or an underground spring can also cause this to happen. Lastly, when a house settles in, hydrostatic pressure can also build up from this.
Settling Cracks – Concrete develops stress cracks from too much exposure to water. This can also happen when a house settles over time. Alkali attack is also an issue that leads to settling cracks as it accelerates the disintegration of exterior waterproofing. Lastly, when water is trapped inside the concrete, it can affect the embedded steel and cause it to rust or expand which leads to cracking.
Concrete Efflorescence Signifies Water Seepage – water has a way of finding its way into any exposed weaknesses in concrete. Pores, cracks and joints are especially vulnerable to water damage. It’s also a known fact that as the concrete ages it becomes more porous. These pores are prime areas where surface salts and lime are deposited after the water that seeped in evaporates. You’ll know efflorescence has happened simply by looking for the white deposits left by the water seepage.
Plastic Barriers Do Not Last – Let’s face it, plastic barriers do not last. They’re not meant to. The plastic “vapor barrier” that you have on concrete slabs eventually disintegrates. This is because of lime build up over time. Once that’s gone, the concrete will start absorbing water leading to damage over time.
Why Exterior Foundation Waterproofing Does Not Last
Tar Waterproofing Is Brittle
Tar waterproofing is a popular option to protect walls. Sadly, this doesn’t last as long as most homeowners would want it to. You see, tar waterproofing does not expand and contract with the concrete as it settles. The same is true for tar paper or pargeting which is the process of laying mortar directly on concrete. All of these are inelastic making them brittle overtime.
Concrete has a ph level above 9. This makes it very strongly alkaline. This is why saponification or alkali attack happens very commonly on its surface. Alkaline soils in some regions can also accelerate this process which eventually eats away at the concrete in a few years.
With that said, it is a guarantee that all waterproofing coatings eventually break down or separate from the concrete. Even flexible elastomeric liquid membranes lose their hold on the concrete after 5 to 10 years.
In conclusion, your concrete needs better protection. And tar waterproofing isn’t the solution you’re looking for especially if you live in an area that receives a fair amount of rain.
So think about this for a second: wouldn’t you want to have concrete that is resistant to all of the factors leading to alkali attack? There should be a way to protect your concrete surface better right? We’re going to look into more solutions as we continue with this discussion.
How Water Gets Through Concrete
To arrive at a final solution, you will need to get the root cause of the issue at hand. You can only do this by knowing all the facts and then work towards a suitable resolution by addressing each of the factors causing the issues you are facing.
We already know that concrete is naturally porous. It has 10 to 18 percent air in it and this can vary from 2 to 60% presence within the concrete structure. But why is there air present within the concrete?
This is because when you work with concrete, you have to make a good water to cement ratio in your mix. A good ratio is 0.45 to 0.50. As the cement cures, the excess water within the structure escapes leading to the creation of capillary holes inside.
We don’t really see these pores but they are there. There is no size uniformity for these pores. They can be as small as 3nm to 0.1mm. and they’re all over the place! By all accounts, concrete leaks like a sieve.
But what stops your concrete structure from leaking constantly? You can attribute this to surface tension and the lack of external pressure to push water out constantly.
Lastly, concrete has hygroscopic qualities. What this means is that it attracts water and absorbs water constantly. And it takes years for the water to seep through the concrete!
Ok, now that we’ve got that squared away, let’s move on to resolving your water leakage issues.
How to Check for Concrete Moisture Transmission
You’ll need to be your own building inspector to check for moisture within your building. You can do a quick visual check and look out for visible cracks or leaks in the concrete. You should also do the same to the joints (floor to wall and expansion control joints) as well as other points of penetration in your basement.
You can also do a moisture transmission test by placing a square foot of plastic or aluminum on the affected areas and check for any signs of water after a couple of days.
To help you on your path to becoming an efficient building inspector, here are some tips you need to know.
What do building inspectors look for?
- Dampness – Residual dampness usually occurs at the base of walls. This is one of the first and most obvious signs you are looking for.
- Rust – when water, metal and air meet, oxidation happens. A byproduct of oxidation is rust. So, if there’s rust, you can be sure that there’s water there!
- Rust Stains – rust stain happens a lot if a rusted object is placed too long on a surface.
- Efflorescence – look for “white powder” on the concrete structure. This is a clear sign of efflorescence.
- Peeling – Peeling happens to the paint you used on your concrete structure. This is an obvious sign of separation as water escapes from the concrete into the air. This can also happen to floor tiles and carpets.
- Mildew Stains – wonder why people hate mildew? Mildew leaves stains!
- Damp Smell – if an objected is subjected to long periods of water immersion, they eventually develop a smell. That damp smell is a good indicator of leakage.
- Musty Odors – another reason why people hate mildew is because it smells.
- Condensation – condensation on your windows and surface of your concrete structure can also be a good indicator of where the excess moisture is coming from.
- Rain Gutters – clean your rain gutters regularly. Plugged or damaged rain gutters can lead to water not being drained properly.
- Grading – Improper grading, puddling of water, and the growth of moss.
Alternative Concrete Waterproofing Techniques for Basements
INTERIOR DRAINAGE GUTTERS ($3,000–$5,000) – This method requires a “dam and channel” technique. What you basically do is create a channel system by gluing a plastic system around the entirety of your perimeter.
Not a good option if you’re constantly remodeling your basement though.
INSTALL A SUMP PUMP ($800–$1,250) – Installing a sump pump can be a good solution if your water issue is serious. If you have a high water table issue inside your basement, you’ll need a good sump pump to drain it quickly!
Sump pumps drain excess by draining the gravel bed. To do this, you’ll need at least 2 main sump pumps and a battery-powered or water-powered back up sump pump.
EXTERIOR SOLUTION ($13,000+) – This requires some excavation and landscaping next to your foundation. After that, you’ll need to lay the gravel, install the perimeter drains, remove all of the old tar from your foundation walls before applying the penetrating concrete sealer. After that you still have to apply the polymer waterproofing membrane, backfill, and finally, fix the landscaping for aesthetic value. It’s a long process but it is also a good option to consider!
FLOATING SLAB DESIGN – The floating slab design allows water to trickle down the foundation walls, into the perimeter drainage gaps and finally, below the basement floor.
This design can help solve your issues but there is also the gas and moisture buildup present that you’ll have to consider.
FRENCH DRAIN ($6,000) – The French drain requires the use of a jackhammer to form a trench along the perimeter of your slab. This effectively creates a trench. The trench then directs the water down into a sump basin.
This method also leaves a gap that can easily allow water to flown down the wall. This efficiently creates a trench that efficiently directs water away from your concrete structure.