Sheet membranes vs liquid membranes

Frequently our technicians at Mar Flex find ourselves in discussions with customers, resellers,  designers, and specifiers. And a question that arises is whether sheet membranes or liquid membranes are better.

This is a hard question to answer definitively, except to say, it depends a great deal on the situation.

Sheet membranes

Sheet membranes are part of systems that are becoming more and more popular in the marketplace. Most membranes bond really well to substrates. This allows the flooring systems to be bonded over so that there’s no adhesion issues at all.

Well, one advantage of a sheet membrane is that you have a uniform shape. It’s  factory made, and you’ve got uniform thickness, so you don’t have any risk that there could be any differences between the film thickness of the membrane.

Secondly, it’s not as elastic as a liquid membrane, but it’s far higher strength. So when you have a concrete bit or concrete slab with hairline cracks, a sheet system makes sure that you’ve taken care of those cracks. So that sheet is an anti-fracture system as well as a waterproof membrane.

Third, installation of sheet systems is far quicker because there’s no coming back to the second coat or the third coat.

Liquid membranes

If sheets are so great, then when would you use a liquid over the sheet?

Sometimes it comes down to cost

Liquid membranes can be used in the place of a sheet, and can be effective when properly installed. This means that applicators will be asked to work harder because they’re concerned with a liquid membrane reinforcing cracks in the concrete.

Sometimes certain joints on the substrata need to be reinforced with a sheeting system. This happens a lot with timber flooring, where installers are putting additional reinforcement over all the joints. They put an extra layer of of liquid membrane down.

From a customer standpoint this will work just fine, but as an installer, when you actually analyze all of that, you could have done it a lot quicker with a sheet, and at a much better quality.

Contractors value time over material cost

There are many situations where a sheet is far quicker than a liquid, AND it is far more effective. However, it will be more expensive.

As a contractor, your time is more important than the cost of materials. Using high quality systems helps your company build a strong reputation for building quality, durable projects.

Photo by Ricardo Gomez Angel on Unsplash

Contractors often leave the work of waterproofing to companies that specialize in that work. This is because the application and selection of materials is so important, and keeping the home waterproof is a primary indication of a quality build.

When the waterproofing experts show up, they work in the trench around the foundation.

First they chalk out the foundation line. This is all done in preparation for the waterproofing work.

Spraying the membrane…

The first step of actual waterproofing is when they spray the walls with a waterproofing membrane. In this case, they are using a black asphalt based waterproofing membrane.

The footings on the foundation wall are sprayed first, and then the technician sprays on up to the grade line. After they spray the wall with the membrane, they will double check to make sure there are no visible cracks and there is a definitive layer visible around the entire exterior.

Once the membrane is applied, the weeping tile system should be put in place, prior to the application of the membrane.

Applying the drainage board

Next the technicians put the selected drainage board on top of the tar around the foundation. They will wrap it like a coozie on a beer can.

The board acts as an additional water barrier. It creates an barrier between the dirt and the wall. If any moisture or water gets behind it, this moisture allows the water to drop right down to the footing.

The membrane is actually doing the the waterproofing on the foundation.

The board is then applied using physical fasteners.  It goes all the way around the perimeter and they just roll it out like sheets of paper towels, only far more durable!

If you were to look closely, you would see a sort of dimple on it. It creates airspace behind the dirt. So when it’s backfilled with rock and soil, if any water or moisture gets in behind the wall, it allows the moisture to drop in a private river, right down to the footing into the weeping tile.

The weeping tile directs that moisture away from the house via the stormwater or wastewater system.

After the tech is done putting on the board around the perimeter, the stone “slinger” or stone truck comes by to put stone all around the perimeter along the base of the trench.

Once he’s done that, we call the inspector to come in and inspect the foundation to make sure the steps have been followed according to the local codes.

But you don’t have to know or do all of this yourself. Mar-Flex has been installing, waterproofing, and providing materials to waterproofers for years.

Photo by František G. on Unsplash

When contractors are waterproofing commercial, or industrial spaces, they often rely on sheet membranes to offer the best possible protection against water. In concrete waterproofing, sheet membranes are applied to either external surfaces. Together the concrete and membrane form a nearly impenetrable barrier.

Despite the double barrier, waterproofing membranes can still fail. Here are some common reasons why.

A failure of skilled application

The application of waterproofing sheet membranes is a very labor intensive task. The workers who apply it need training and experience to do the job well under the best circumstances. However, because it is so dependent on labor, this is where the failures occur. Some estimates suggest that poor workmanship alone accounts for 90% of all waterproofing membrane failures.

Debonding can be caused by several factors, including application to an uneven surface or to a wet surface. Application to contaminated surface, lack of primer, or insufficient priming of the surface prior to installation of the waterproofing sheet membrane can lead to debonding.

Further, insufficient coverage or uneven application of a membrane prevents establishing a uniform thickness of the waterproofing layer. This can result in the failure of the application as thinner parts of the membrane get damaged quicker, not fully bonding overlaps pose potential breach of the waterproofing layer. Membranes can then come apart at the seams  and allow water to penetrate.

Companies can overcome this with training, experience, and teamwork. Everyone needs to do this the first time, so experience alone isn’t the answer. But careful oversight can prevent catastrophe.

Choosing the wrong components

Choosing the wrong membrane, using the wrong items for the intended application, or matching the membrane with the wrong substrate can lead to the failure of the waterproofing application.

In matching the selected membrane with primers, it is important to select complementary products. Failure to do so can lead to an unbonding of the membrane and failure of the waterproofing. Unbonding is when the sheet membrane no longer forms a watertight seal with the concrete, allows water migration between the membrane layer and the concrete.

To mitigate this problem, sheet membranes for underground waterproofing applications must meet international standards. Choosing from EPDM, TPO, or PVC membrane types is important, but selecting the right primers allows the sheet membrane to be fully mechanically adhered to the substrate, however these might not be the right combination for below grade applications.

Another common problem is blister. Blister is caused by insufficient prime at the surface. As a result, trapped air builds up under the membrane causing debonding and blistering. These blisters are prone to puncture and then result in a breach of the waterproofing layer allowing water to pass through to the concrete. Waterproofing sheet membranes are exposed to a high risk of damage.

Often this damage occurs in the subsequent stages of the construction schedule. Both puncturing and tearing represent a breach of the waterproofing layer and thoughts of failure.

The effects of time

Many waterproofing membranes deteriorate over time, due to exposure to UV rays, harsh environments, aggressive groundwater, or permanent ponding leading to the disintegration of the waterproofing layer. Ultimately this leads to the failure of the membrane.

In conclusion, membranes are not recommended for certain types of projects. Efficient and long lasting waterproofing solutions require newer technologies that permanently reduce permeability and improve concrete properties and durability.

Photo by Holly Obermiller on Unsplash

Technically speaking, hydrostatic pressure is

“The pressure exerted by a fluid at equilibrium at a given point within the fluid, due to the force of gravity. Hydrostatic pressure increases in proportion to depth measured from the surface because of the increasing weight of fluid exerting downward force from above.” – Dictionary.com

But what does this mean for someone doing a construction project? What forces does a construction manager (or industrious home do-it-yourselfer) have to consider when waterproofing below-grade or even below-water walls and foundations?

This means, in part, that a product simply being water-repellant or even waterproof in common testing in a laboratory is not the same as that product keeping out water in a wall or foundation that will be exposed to water.

How does hydrostatic pressure impact waterproof surfaces?

Hydrostatic pressure is not constant in a given spot over time. This is because the nature of hydrostatic pressure means that it changes based on the depth of the water.

Why? There are two variables at work. First is the water itself. Second is the depth of the water or, more precisely, the pressure exerted by the weight of all the water above it.

You have experienced this pressure before if you have ever dived into deep water, like the deep end of a pool, or if you have gone a few body lengths below the surface when snorkeling or scuba diving.

If you have done those things, you have felt hydrostatic pressure against your eardrums. The additional pressure of the weight of the water above compressed your ear drum. At first it just muffled the sounds, but then, if you dove deep enough, the pressure even may have caused some pain.

This increased pressure works against your waterproof eardrum membrane in much the same way as it works against a waterproof wall membrane.

Eventually, if the water gets deep enough and the pressure gets high enough, the pressure causes a fissure or rupture.

Or, even if there is not a large leak, water can still be forced through the tiny pores and pockets that are part of a concrete pour. Over time, this water gets forced in and adds to the degradation of the wall and the foundation.

This is why your building project must account for water around the foundation. And it must take into account the effects of hydrostatic pressure.

Photo by David Bartus from Pexels

For your next construction project, you want to select adhesive products that are up to the task. That is, they need to be able to withstand the forces they are going to face over the lifetime of the finished product.

They will also need to bond well with the materials being used in the project.

Your favorite adhesive from your favorite company or supplier is unlikely to be the best solution for every project. And if the contractor you use seems to have a “one adhesive” approach to all of their work, it might be wise to look around for a company that approaches each project with the best possible tools and resources.

Your professional Mar-Flex supplies will include or suggest the right waterproof construction adhesive for the project.

What to consider when choosing construction adhesive

1. Surface type. Construction materials differ from one another on a molecular level, and thus different adhesives will work better with different materials. The best construction adhesive will be formulated to work well with both sides of your project. For instance, if you are adhering glass to metal, you will use a different adhesive than when waterproofing stone against concrete.
2. Drying time. Often waterproof construction adhesive instructions include two times: a drying time and a curing time. The drying time is the time it takes for the chemicals that make the adhesive pliable to evaporate. This is simply when the product becomes unable to move or ben, but it is NOT when it is fully set. The curing time is the time it takes for the remaining ingredients to crystallize and become fully active in waterproofing and bonding. Only after a product has cured is it ready to do be exposed to the elements and daily use.
3. Strength and longevity. Strength of an adhesive is scientifically measured by two different measures, based on the two ways an adhesive might be stressed. One is lap shear, or how the waterproof adhesive holds up when the materials around them want to move laterally against the glue and/or the other surface. This is extremely important if the waterproofing adhesive is being applied to vertical surfaces. (Note: when possible, adhesives should not be the ONLY thing holding up vertical building materials.) The second measure of strength is peel strength, or how the adhesive holds up against perpendicular stress, as if someone is pulling the two surfaces apart.

Cleaning up and following directions

A good construction project is only as solid as its weakest link, material, or construction shortcut. So reading the instructions and getting the right material for your waterproofing project is important. Work with an expert supplier to make sure your products match the results you want.

Every builder and owner dreams of a dry foundation, with water effectively repelled from the outside, and no seepage, dampness, or water intrusion for the history of the project.

In reality, this is a very challenging standard to try and meet. A construction manager faces multiple obstacles in defeating his nemesis: water.

Fortunately, through a combination of construction techniques, approaches, and materials, we know there are a lot of avoidable mistakes. One such obstacle is backfill saturation. If backfill is poorly done, and the foundation incorrectly prepared, backfill saturation can defeat even the stoutest of waterproofing materials.

What is backfill?

When builders dig the hole for a building project, they are often disturbing soil that has sat and compacted in one place for decades or maybe even centuries. The impact of time, the elements, and pressure has often compacted the soil into almost unworkable solid clay.  This clay is hard for water to get through, because time and pressure have closed all the small crack, while the water itself carried away the loose soil and gravel.

Clay repels water.

However, when the hole is dug for the new home, this clay and other materials are set aside to use later to fill in the hole around the completed foundation. This fill-in material is called “backfill.” It is the “fill” you put “back” in around your completed foundation.

Why is backfill saturation a problem?

This backfill might include the same clay that was originally in the foundation space, but there is now a key difference. It has been dug up and moved multiple times. Instead of being a solid, water-repelling block of clay, it is now filled with holes, channels, and cracks through which water can run.

No matter how you pound it down, it won’t be as waterproof as the clay around it that was not disturbed in the building process.

Water will naturally run to this new basin, and saturate it. This is backfill saturation.

This water, if not appropriately accounted for, will then sit against the new foundation of your building project. The lower it is, the more pressure it will exert, and over time it will seep through the tiniest cracks and airholes into your structure.

Make sure you or your construction manager account for backfill saturation in the plans for your next project.

Every day, hidden from view, your foundation is doing battle. It is fighting the hidden forces of water, pressure, and time.

If you were a general, you would not send your troops into battle without equipping them with sufficient armor to protect them. Why would you do that to your foundation?

At Mar-Flex, we know the forces your foundation is up against. And, more importantly, we know the right equipment and materials to use to help your foundation win the battle every time.

With our Armor series of waterproofing resources, you can be sure that your basement and foundation remain dry.

Armor Air Barrier

The Mar-flex ArmorAir Barrier permeable air barrier system is designed to stop air infiltration and exfiltration in the building envelope. It also allows the transmission of water vapor, preventing condensation in the wall assembly.

ArmorFlash Transition Strips

Transition strips create impermeable barriers which protect vulnerable areas like joints, edges, and corners between barrier materials from the water.

Armor Foundation Membranes

Water-based and solvent-based membranes help keep your foundation protected from both dampness in the ground and from running or standing water against your foundation. Pick from a range of options to fit your needs to your solution.

ArmorClay Bentonite

Bentonite clay expands when wet, absorbing several times its weight in water and makes for a very stable, below-grade solution. The Mar-Flex Bentonite clay membrane uses nature’s own waterproofing techniques against it, protecting your project from damage.

Armor drainage board and tile

With a wide range of drainage board and tile options, Mar-Flex offers your project increasing damp-proofing and waterproofing options. Additionally, our products might help you achieve your desired LEED status.

Look through the options and talk with one of our knowledgeable staff members today.

When you are at war with water, you want to make sure you have taken every possible precaution in order to triumph. The Mar-Flex Armor Series of solutions can help make that happen. With solutions that undergird, surround, and line your building project, you can be sure to create a dry, sound foundation that lasts for years to come.

You can trust that with our expert installers and full warranty, we will not only do the work, but we will also stand behind it. That is the level of service and commitment to quality you can trust.