Waterproofing Archives - Avenue Road Masonry

Many clients inquire about the process involved to complete foundation waterproofing.

The first step is to define what the purpose of the activity is. Simply put; foundation waterproofing involves the prevention of groundwater/moisture, penetrating through a building’s foundation walls, which can result in damage to interior spaces below grade (such as basements), and preventing the avoidable deterioration of the foundation structure itself.

Further consequences of water ingress through foundation walls can result in mould, mildew, efflorescence and damage to interior finishes. The items noted can also serve as clues to the fact that foundation waterproofing is a required action.

In eastern Canada and the U.S., most homes and commercial structures are constructed with basement areas, defined by poured concrete walls, or masonry block walls. In some instances, the foundation walls protrude above grade from six inches to three feet, depending on the structure; with a minimum of eight feet below grade.

Many older homes constructed in the eighteen hundreds and earlier parts of the nineteen hundreds may have shallow basement heights. Such older structures may also have rubble stone basement foundation walls or fieldstone basement walls.

As a result, there can be varied techniques required to achieve sound basement waterproofing based on the foundation circumstances of a particular structure. To add further complexity; in many downtown urban areas, homes have been constructed in very close proximity to one another, which can serve to make digging or excavating foundation walls difficult between neighbouring buildings.

While the majority of suburban homes have relatively good access to complete foundation waterproofing from the exterior, some urban homes have no choice but to complete waterproofing techniques from the interior of the basement area.

The process of waterproofing begins with the action of obtaining service locates involving gas, water hydro or cable, which has been located below grade. Failing this step can have dangerous consequences particularly where hidden gas lines may be concerned.

Once the utility locates are completed by the utility provider’s designate company, removal of dirt and or clay against the foundation walls can begin. In tight locations; the ground dirt may have to be stored in disposal containers or elsewhere at the site if there is limited room to store such material.

Trenches adjacent to the foundation walls are usually dug out to be about four feet wide, and dug down to the footing level of the structure. If only waterproofing one side of a particular structure, it is typically necessary to dig somewhat around each opposing corner in order to make a proper weeping tile connection to such sides.

When trenching, it is important to insure that proper shoring of the trench is completed to insure workers are not injured due to caving in of the trench.

Once the exposed exterior surface of the foundation wall is revealed, the next steps involve cleaning and properly preparing the surface.

Cleaning involves wire brushing down the foundation wall surface and may require power washing to remove all loose debris and dirt. Repairs, as required to the surface of walls, can now be completed.

In the case of a block wall foundation, tuck-pointing of deficient mortar joints may be required, where voids in the mortar may need to be repacked with fresh mortar. Poured concrete walls which exhibit cracks or divets in the surface, must also receive remedial cement repairs to insure the structure is sound. Hydraulic cement is typically used to fill cracks and voids.

Installation of a trowel applied cement parging serves to create a clean and smooth surface to accept future waterproofing materials. Such cement parging mix will contain a liquid concrete bonding agent to help achieve superior adhesion to the existing block or poured concrete surface.

Once allowed to properly dry and cure, the application of waterproofing materials can begin. There is an array of products available on the market which can be used as waterproofing agents.

Popular are liquid applied foundation coatings having an asphalt base. Other options include bituminous coatings. Such materials are commonly trowel applied with some versions being sprayer applied.

Common practice involves applying a poly sheeting over the liquid applied waterproofing materials. Alternative upgrades include the use of self adhering membranes, which provide enhanced waterproofing characteristics.

There are dimpled plastic sheets which can be mechanically attached over the waterproofing membrane(s), which serve to supply further protection and isolation of exterior earth from the foundation wall.

At the footing level, new plastic weeper pipe, covered in a filter cloth sheathing, is connected from corner to corner of the foundation and is set in crushed gravel, to a prescribed depth, before being filled back in with the former soil.

It is often necessary to add more soil and compact the area. Final grading involves shedding the dirt away from the foundation wall at grade; in order to promote positive drainage.

Where recessed window wells may be present below grade; such areas also should be comprehensively waterproofed, as they represent a common failure point. Installing a shedding plastic cover over such window wells also helps to divert water away from the area.

Other considerations of the project may involve the re-routing of downpipes away from the foundation wall at least five feet at ground level or re-connecting downpipes into below grade pipes where applicable.

Further cost considerations of engaging in such a project can include the restoration of sod, shrubbery, and landscaping, or hardscaping materials such as stone or concrete walkways.

A well done exterior waterproofing project should provide at least twenty years of life, and likely beyond. Costs involved to complete such work can vary greatly depending on the terrain, accessibility, and methodology required.

Where interior waterproofing of foundation walls is required; it is typically necessary to break the concrete basement floor adjacent to the wall and install weeper drainage pipes leading to the main drain in order to divert groundwater. Interior wall surfaces would require waterproofing to prevent water from leaching through. Such work can be unique to each particular home’s circumstance.

In some instances, the interior basement walls may require pinning from the interior if there is evidence of shifting.

Other methodology involves having an internal weeper tile system directed to a sump pump and sump pit located in the basement floor to direct water back out of the house.

It is best to have a professional waterproofing contractor survey the situation and in some instances, retaining an engineer is advisable to develop a strategy for interior basement waterproofing. The reason is that considerations involving electrical, plumbing, and internal furnace locations can add complexity on what specifically may be required in the overall scope of work.

Where stone basement foundations are concerned, it is important to note that stone can be porous, and often the integrity of such foundations is reliant on the integrity of the cement holding the stones together. When the concrete mortar breaks down, water can easily enter.

Some solutions involve repairing deficient mortar, and parging exterior and or interior surfaces, before applying waterproofing materials. Other solutions can involve pouring new exterior footings and forming a new exterior foundation wall; particularly if the existing stone foundation has shifted or exhibits any lack of structural integrity.

Commensurate with certain newer construction methodology, many homes are built using insulated concrete forms where concrete is poured into the forms (similar in nature to building blocks). Such methods provide higher thermal efficiency, and as such require alternative products to be used to waterproof the exterior foundation. Frequently specified is some form of membranes or liquid applied rubber coatings.

To learn more about foundation waterproofing, masonry, stonework, or other related services, visit www.avenueroadmasonry.com or see us on Youtube™.

Most people understand the necessity of having a structurally sound and damp-proof basement foundation.

What many people don’t immediately recognize, are the signs which signal the need for proper concrete foundation waterproofing. This can result because of finished interior basement walls, or simply the fact that many people don’t spend a great deal of time in an unfinished basement environment.

As a result; it becomes a good idea to incorporate into one’s regimen of maintenance inspection; checking the basement floor, interior basement walls, exterior foundation walls, and associated downpipes, which exit into the in-ground drains near, or at foundation walls.

In some areas of Toronto, homes are located in very close proximity to one another or are virtually touching one another. Such design configurations can be difficult to inspect, and even more difficult to perform concrete foundation waterproofing.

Under such circumstances, it can be possible to waterproof from the inside of the building. For most homeowners with conventional construction homes, exterior waterproofing is the desired course of action.

Enlisting the services of a professional masonry and waterproofing contractor is the best course of action, to receive an accurate appraisal of the scope of work necessary to correct any such concrete foundation deficiencies.

Signs that you require waterproofing assistance include; the appearance of efflorescence (white chalky marks on interior concrete basement walls), visible internal cracks, damp or wet areas visible on basement walls or wall to floor junctions, dampness or musty smells, or evidence of mould on finished basement wall surfaces.

What is required to complete comprehensive concrete foundation waterproofing?

The first step is to determine how extensive an area requires waterproofing. It is often possible to do one side of a home if the budget is a consideration, and carry on with other perimeter sides when a homeowner’s budget would permit. This approach assumes that there is no visible evidence of leaks found on adjacent foundation walls.

If undergoing a strategic concrete foundation waterproofing repair; it is advised to go from one exterior corner to another as a minimum, and to wrap around the opposing corners, even if only one or two feet.

Most typically; concrete foundations are more vulnerable to leaks after twenty years, but some newer construction builds have exhibited problems in less than ten years if the workmanship has not been of the best initial quality.

Other common sources of leaks around concrete foundations can be traced to sumped, basement window wells, and in-ground drains which have become corroded over time. Many older homes have clay tile pipes below grade as an example; which can break down over decades.

It is also important to maintain grading away from the foundation, so that groundwater has a path to shed away from the home’s concrete foundation. Cracks and shifts in the structure of the concrete foundation are obvious vulnerable points for water ingress. Such repairs can be made using hydraulic cement, and or injecting epoxy if the cracks are small enough.

In severe circumstances where concrete block foundations have shifted over time; strategic concrete block replacement may form part of the remedial strategy before actual waterproofing can begin.

Excavation of a trench around the specified concrete foundation wall must be completed to reach the footings of the foundation. Part of the excavation can include carefully removing finished hard surfaces such as poured concrete walkways or interlock paver walkways. The easiest excavation involves the removal of sod and related earth.

Also to be considered in this step of construction is where removed materials can be placed. If there is only three feet between houses; materials have to be transported and located temporarily elsewhere.

Under such circumstances; one must also consider the integrity of a neighbour’s foundation located in close relationship to the one being worked on. Many neighbours will consider completing their respective sides in tandem; which can serve to help both parties reduce some costs associated with excavation.

It is important for a neighbour undergoing such work to be cautious that the adjacent neighbour does not assign blame for concrete foundation leaks that they may have, as a pre-existing condition. And particularly after their own waterproofing has been completed. Therefore; it is advised to extend the courtesy to one’s neighbour by a), advising them well in advance that such work may be undertaken, and b), that they may wish to have their basement /concrete foundation, pre-inspected to identify any issues for which they may take advantage of better pricing, or to exonerate the professional contractor doing such work, and minimizing any potential blame for themselves from that neighbour in the future.

Excavation work is often accomplished using machinery, but in some instances requires hand digging. Soils such as clay can be slow and difficult to extricate. Once the excavation is complete; the next step involves wire brushing and or power washing the exterior concrete foundation surface. This reveals cracks, or structural deficiencies that need attention, and permits a clean wall surface for eventual application of waterproofing materials.

Once strategic structural repairs (if required), are completed; the actual waterproofing may begin.

It is often best to apply a new parged coating of concrete over the existing concrete wall surface. This is particularly suggested if the wall is constructed of concrete blocks. A bonding agent is used to provide for proper adhesion. This must-have time to cure properly. This process is not always required, but under some circumstances can be a must-do step.

A bituminous liquid coating, specifically designed for concrete foundation waterproofing, is then liberally applied. It is most often trowel-applied, but can also be spray applied in multiple coats until the desired thickness of the coating is achieved. A polyethylene barrier is then applied to the wall surface, and recoating of the wall takes place. The waterproofing should extend above the finished grade.

The next process involves the application of a dimpled plastic membrane which acts as a secondary waterproofing barrier and protects the coating beneath. This product is mechanically attached and extends downward to the level of the foundation footing.

At the base of the foundation, a new weeper (plastic corrugated drainage pipe) is installed in an initial bed of aggregate to facilitate drainage. The weeper pipe is covered in a filter sock, which helps prevent debris from entering the pipe and creating future clogs. The characteristic of the weeper pipe is that it has small perforations that allow accumulated groundwater to escape into the surrounding aggregate materials. The weeper is adjoined to an adjacent pipe on connecting foundation sections or terminated away from the foundation under particular circumstances.

An additional volume of aggregate is then applied over the weeper and further compacted to six inches. Previously removed soil can then be restored into the trench and should be re-compacted. Often there is a need for new earth to be added to allow for the result of compaction, and to permit proper grading away from the concrete foundation wall.

Where possible; downpipes exiting from the gutters should be re-directed away from a home’s foundation by at least five feet where possible. Older in-ground drains designed for downpipes should be capped off. Another option for the drainage of roof-related water, can include rain barrels and or pop up diverters embedded in one’s lawn, well away from the home’s foundation.

As foundation leaks are typically at their worst during winter melt periods, spring runoffs, and prolonged periods of rainfall, it is best to schedule such work in advance of the winter season before the ground becomes frozen.

To learn more about concrete foundation waterproofing, or other masonry services, visit; www.avenueroadmasonry.com

Tag: Waterproofing

What Is Foundation Waterproofing?

The Importance of Waterproofing Your Concrete Foundation for Winter

About

SERVICES

Service Areas

Our Office