Concrete Foundation

Should I seal my concrete foundation?

Concrete walls sometimes only leak periodically, such as after a hard rain or during snow melts. However, some walls gush water through openings in the concrete. Most leaks occur in walls built below grade, or below ground, such as those used in the home’s foundation. The correct patch or sealant depends on the type of leak.

How to seal cracks in concrete floors, foundations, walls, or another masonry: this article how to seal and repair cracks in poured concrete slabs, floors, or walls.

We list all of the current methods used to seal control joints or cracks that occur in those building surfaces, giving the properties, general procedure, and pros and cons of each method: control joint inserts, masonry caulks, radon crack sealants, and semi-rigid epoxy resin crack fillers, special polyurea caulk designed as a joint filler – polyurethane foam injection to seal cracks, grouts including portland cement, latex-modified, epoxy, modified epoxy-supported, and furan grouts or other products used to fill or seal cracks in concrete or other masonry surfaces & structures.

At Hitch Property Constructions, we offer the best range waterproofing services to rectify your water issues. 

What’s the difference between dampproofing and waterproofing?

Yes, your builder has already or plans to spray a black liquid on your foundation. He may even call it waterproofing. But the fact is this product may be just damp proofing. There is a significant difference between dampproofing and waterproofing. Because the buzzword mould is now as loud as the steel-against-steel clash of wheels on the rails of the L, you need to make sure the moisture from the soil can’t possibly invade your new basement walls.

Concrete Foundation

What causes that mouldy smell in an old basement?

Perhaps the best way to start is to go back in time to a basement in an old home. Surely you can recall that smell, that dank mouldy smell of an old basement. You were smelling mould, and its growth was fueled by the constant stream of moisture from the soil through both the unprotected walls and through the concrete slab you walked across. Years ago, builders didn’t regularly apply even a simple tar coating to foundations. They did not have access to large sheets of plastic that help retard the transfer of water vapour from the soil through concrete slabs.

Black Goo Doesn’t Cut It.

In the old days, the go-to foundation waterproofing was an asphalt-based, black, nasty goo. That material is a byproduct of oil refining and is not considered “waterproofing” but only “dampproofing.” Asphalt goo can’t block bulk water that builds up against a foundation; it can only prevent the moisture from damp soil from seeping into the concrete. As soon as that moisture accumulates and saturates the soil, it builds hydrostatic pressure that can drive the water right through asphalt dampproofing.

Effective foundation waterproofing is more than just one product; it’s a system with three critical components: a membrane to protect the concrete; a drainage mat to relieve hydrostatic pressure and allow water to drain down, instead of in; and a French drain at the footing level to carry water to a daylight drain or a sump pump.

First Line of Defense

In the order of building, the first component in the system is a true waterproofing material applied to the surface of the foundation walls. This can be a liquid-applied coating or a peel-and-stick membrane.

Liquid-applied membrane. Newer-generation liquid-applied materials that use SBR (styrene-butadiene rubber) are specifically designed for waterproofing concrete. They function as true waterproofing because they are completely insoluble in water and can resist hydrostatic pressure (although we do want to limit this pressure, as I’ll explain further on). The material is spray-applied as a liquid, so it goes on as a continuous, monolithic membrane. At critical areas—transitions between the footer and the foundation wall, inside corners, or pipe penetrations—a liquid material perfectly conforms to surface variations without a lot of fancy origami.

Peel-and-stick membranes offer an excellent waterproofing alternative. For best results, I start with a 40-mil-thick membrane applied to the horizontal ledge of the footing and up the wall for about afoot to protect that critical footing joint. The vertical leg of this cold-joint barrier should be overlapped by a 40-mil-thick peel-and-stick product that’s about 3 feet wide. We typically run the membrane vertically. Most peel-and-stick products made to be applied over concrete require a primer. Once the primer is rolled on, we pull the backing off the membrane to apply it, creating an adhesive-to-adhesive bond that holds tenaciously.

Over the waterproofing membrane, we add an insulation layer. Here in Austin, we need only one inch of foam; in northern regions, you’d need more, of course. We’ve had good luck with plastic stab anchors for installing the insulation. The anchors have a peel-and-stick adhesive that bonds to the surface of the wall membrane. With these in place, all we have to do is push the insulation on to hold it in place. We can use the same anchors to install the drainage mat. Most important is that we end up with no penetrations through the waterproofing membrane.

Drain Down

After applying waterproofing to the foundation, a lot of builders think the job is done and move directly to backfilling. But by doing so, you are allowing water to back up directly against the membrane, where it might find an imperfection and create a leak.

The ideal way to solve this is to put a drainboard over the membrane. The primary purpose of this drainboard is to provide an air gap so that water running towards the foundation hits that gap and flows down to the footing drains. Think of the gap as a pressure relief valve. If there is an open gap, water pressure can’t easily build up against the foundation.

Secondarily, the drainboard protects the waterproofing membrane against rocks or road base or whatever you are using as a backfill material.

Drain Out

Any foundation waterproofing system that protects the foundation from water and relieves hydrostatic pressure needs a third critical component: a way to drain out. We always install a traditional French drain system—a standard that Americans have been using for generations on houses. This consists of a drain pipe that is run in a bed of rock. We typically use 4-inch Schedule 40. We have found that Schedule 20 can collapse (and the black corrugated pipe seems essentially worthless), so it’s worth going with the thicker-walled PVC pipe. The holes are pre-drilled and always face downward. The perimeter pipe is covered with a coarse gravel or septic rock that must be separated from the surrounding soil with filter fabric to prevent soil from clogging the rock.

Do you need to check local building codes?

And while we are speaking of the code, here is one of the traps. Every local building code can be different, but most state that unfinished basement living spaces have to be damp proofed. But what happens if you know you are going to finish your basement a year or so after you move in? The answer is to waterproof the foundation now for that possibility and to ensure your basement will indeed stay dry even if it remains unfinished.

What is a good waterproofing method?

The waterproofing method I used on my own home is still available.

It was called Tuff-n-Dri at the time, and Owens-Corning pioneered it. They subsequently sold off this business segment to Tremco.

It’s a mixture of hot asphalt and rubber. The coating ends up being about one-eighth inch thick or even thicker. A special insulating panel is placed in the hot liquid that helps protect the coating from damage during backfilling, and it acts as both an insulator and a drainage plane. The rubber in the mixture imparts elasticity to the coating so if the foundation cracks, the coating stretches over the crack to provide protection.

Damp Proofing compounds can’t do this. If the foundation wall cracks and most develop tiny shrinkage cracks over time, water can readily pass through to your basement. It is also better to waterproof from the outside rather than try to stop water once it is already into your basement space. Spend the money now and waterproof before the builder backfills.

How to Seal a Leaking Concrete Wall

What Causes the Leaks

Reinforcing rods installed into concrete walls are potential sources of leaks. The rods help hold the concrete steady as it cures during the home’s construction. Eventually, builders remove the rods but leave the holes behind. Cracks and voids also appear in concrete as the building settles over time. Some of these may even be small enough that you cannot easily detect them. Any of these openings are potential sources of water entry.

Looking for the best waterproofing company? Look no further! Hitch Property Constructions has you covered. 

Patching Holes

You can patch any obvious holes or cracks with hydraulic cement. This product is typically sold as a powder that you must mix with water before applying, although some brands come in a putty-like form that is ready to plug into place. You can even apply hydraulic cement as the concrete wall leaks, which allows you to treat the problem while it happens. Enlarge the opening slightly by removing any loose concrete material. Then mix a batch of hydraulic cement as directed on the package and work it into place. Hydraulic cement cures quickly. Only mix what you can apply in three minutes or less.

Masonry Waterproofing

Concrete is a porous material when fully cured. It can also develop small, pinhole openings that act as capillaries for water transmission. Seal the entire concrete wall with a waterproof masonry product. Paint a generous coating of this material onto the wall, working the product in all directions to completely seal any pinholes. The material is thick, much thicker than latex paint, but it brushes on with ordinary paintbrushes. Once dried, waterproof masonry products form a watertight membrane that prevents water from leaking through the wall.

Attacking the Source

Look for the source of the water penetrating the concrete wall. Check whether a gutter or downspout is leaking into an above-grade wall. Make sure the ground around the building slopes away from the structure so that water can run downhill, away from the foundation. Install gutters, or make sure gutters already in place are clean and not causing water backups. Install downspouts that take water several feet away from the foundation.

Why Sealing a Foundation isn’t a DIY Project.

When most people refer to “sealing a foundation,” they are talking about applying an exterior waterproofing membrane, which is a thick coating of asphalt-modified polyurethane applied to foundation walls to keep out water. Exterior waterproofing membranes are very effective on both poured concrete and masonry foundations, and installing one to stop seepage is usually a great idea.

However, there are several reasons why it’s best to rely on a professional when sealing a foundation:

Sealing a foundation is very labour-intensive.  

Do you like to dig? Like to dig? You’d better if you’re considering a DIY membrane project. The process begins by removing anything next to the house in the affected area, including decks, patios, sidewalks and planters – and then the real work starts.

In order to install the membrane, the entire foundation wall must be dug out to a depth of as much as eight feet, and the trench should be wide enough to work in. Oh, and because it’s right next to the house, all the digging has to be by hand.

The right materials can’t be found at the hardware store.  

There are horror stories on the internet about people using roofing tar and plastic sheeting to “seal” their basements below ground, and the ending is always pretty gruesome. The polyurethane used by professionals is a specialized material meant for soil contact, and it won’t erode over time as consumer materials will. Heavy-duty drainage board and insulating material may also be used, depending on the situation, and a roll of Visqueen doesn’t measure up.

Drain tile may be needed.  

A professional will be able to assess the groundwater situation and recommend whether the foundation would benefit from installing exterior drain tile when applying the waterproofing membrane. A homeowner probably couldn’t and would be hard-pressed to install it correctly anyway, even if he or she did guess correctly.

Got a lot of spare time?  

Even if you’re willing to take on the job, it requires a huge commitment of time. Even with a few non-disabled helpers, the excavation alone can take days to complete. Then the wall has to be cleaned thoroughly, the membrane applied and allowed to cure, drainage board or insulation installed and the excavation backfilled. That’s not even counting removing outside structures.

How to seal control joint & expansion joint cracks in concrete slabs

Photograph of a sketch of typical crack patterns in a poured concrete slab here we discuss how to choose among and apply the alternative methods for repairing or sealing cracks in masonry surfaces such as poured concrete floor slabs, concrete foundation walls, or brick or masonry block foundation walls. We describe the use of epoxy sealants, polyurethane foam sealants, and hydraulic cement crack repair sealants.

This article series describes how to recognize and diagnose various types of foundation failure or damage, such as foundation cracks, masonry foundation crack patterns, and moving, leaning, bulging, or bowing building foundation walls.

Types of foundation cracks, crack patterns, differences in the meaning of cracks in different foundation materials, site conditions, building history, and other evidence of building movement and damage are described to assist in recognizing foundation defects and to help the inspector separate cosmetic or low-risk conditions from those likely to be important and potentially costly to repair.

Types of Sealant Repairs in Concrete & Concrete Structures

Control joint sealant

Control joints, designed to control where cracks appear in concrete placed horizontally or vertically, are themselves sealed against water, frost, debris and to handle recurrent movement (listed below) using a flexible sealant.

Recurrent movement

Seal and repair cracks in concrete using an injection of either epoxy resin or polyurethane where recurrent movement is expected (in my opinion a flexible sealant is what’s called for here) when the movement is considered normal, perhaps caused by traffic vibration or temperature swings, and where the movement is not threatening structural damage.

Stop a water leak

Seal and repair cracks in concrete when it is important to quickly stop water leaking through a crack, seal those cracks in concrete using an injection of either epoxy resin or polyurethane sealant.

Structural repair

Seal and repair structural cracks: for some situations (usually where an engineer, expert in masonry repair has made an assessment), actual structural repairs are made using injectable epoxy resin and possibly in some (probably low-load) cases by using injectable polyurethane sealant.

In my opinion (I’m not a P.E.) this application of injected epoxy resin is probably most-appropriate when cracks have appeared due to non-recurrent stresses. When we epoxy cracked structural concrete or a concrete slab that was broken by an initial installation error or by a subsequent event, we expect the repaired area to be as strong or stronger than if no crack were present.

Structural reinforcement

Some sealant manufacturers such as Sika provide a seal or wrap-and-seal systems that provide additional strength to existing concrete structures such as concrete columns.

Structural reinforcing wrap systems may include the use of synthetic fabrics, carbon fibre fabrics, and other wraps. These products might also be used on steel or concrete that has been damaged by weather, frost, corrosion.

Surface repair

For working surfaces such as industrial work floors or parking decks cracked by spider-webbed shrinkage cracks that are non-structural, special “healer-sealer” crack sealants may be applied.

We have a huge range of waterproofing services Melbourne at Hitch Property Constructions that offers stress-free services for any water problem you got! 

Who are you gonna call?  

So, after all that work, your basement still leaks. Are you going to call yourself up and complain? A professional will provide a warranty.

DIY is a great thing and an admirable pursuit for homeowners, and it can even work for keeping your basement dry. Clean your gutters and make sure your downspouts and sump pump discharge more than 10 feet from the house – don’t take on jobs that are best left to the pros.

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