Services

Leaking Basements and Retaining Walls

Most external and integral basement waterproofing systems have an expected build life of 10-15 years. This means that in the lifetime of any basement structure, failure of the system – to some extent – is to be expected.

These failures often present as:

• Leaks through basement and retaining walls
• Leaks through basement floors and basement ceilings (podium slab)
• Leaks around pipe, conduit and other penetrations

Leaks through basement walls

This occurs when external groundwater penetrates through the external basement and earth retaining walls and is typically caused by poor waterproofing design and specification, compromised membrane installation or failure of the external/integral membrane, or simply the age of the waterproofing system. They are sometimes incorrectly referred to as ‘wet walls’.

The most common point of failure in the basement waterproofing system is the wall/floor and wall/wall junctions. Movement in the structure can cause premature failure of any waterproofing membrane that has been applied.

Leaks can often start as rising or penetrating damp, showing as damp patches on walls, before progressing into active water leaks that require more substantial repair methods.

Groundwater through basement floors and basement ceilings (podium slab)

This often occurs through cracks in the slab or moisture rising through the slab. It typically happens when there has been no waterproofing installed under the basement slab during original construction, allowing groundwater to penetrate. Additionally, movement in the structure can cause premature failure of any waterproofing membrane that has been applied, particularly if the incorrect waterproofing system has been specified to begin with.

Leaks around pipe, conduit and other penetrations

Any penetration of a basement or inground waterproofing system can cause a water leak if not detailed correctly. These penetrations can be for pipes, electrical conduits, drains and other services. Unfortunately, many basement waterproofing systems fail prematurely because proper care and consideration has not been taken to detail these penetrations. It literally only takes a ‘pinhole’ for a water leak to occur.

Repairing basement and retaining wall leaks from the inside

Historically, the best means of repair was to excavate and re-waterproof from the external side, thereby extending the service life another 10-15 year. Wherever feasible, repairs from the external side are still recommended, however, repairs of this manner can have a significant impact, on the ‘landscape’ of the property, especially those properties with hard landscaping in place. Access can often be a problem, with the only way to address the issue is to apply systems to the basement and retaining walls internally.

Dryspace Solutions employs many different internally applied systems and methods to repair groundwater ingress to repair these leaking areas from the inside, including:

• Cavity Drain membrane systems
• Negative hydrostatic coatings
• Crack and grout injection
• Specialist water stoppage solutions

Penetrating and Rising Damp

Penetrating Damp

The cause of penetrating damp is almost identical to that of water leaks however the signs and symptoms are slower to appear, with damp patches on walls typically the first sign. This gradually worsens over time and left untreated will turn into active water leaks. These patches can appear as a discolouration of the wall, or the areas being damp and cold to touch.

Penetrating damp is a sure sign that there is water trapped inside the substrate wall, with it’s source either being from higher up within the wall, or more likely, coming through the wall from the external ground as groundwater penetration.

The great news is that penetrating damp can be repaired easily from the internal side, should external access be a problem.

Rising Damp

Rising damp occurs when ground water travels up through the bottom part of a wall or floor that is in contact with the ground and occurs when the dampcourse has failed. In Australia, a damp-course (DPC – Damp-Proof-Course) barrier is installed during construction to prevent rising damp, however it can be damaged during construction, placed incorrectly, compromised or bridged during or after construction. This damp course will be installed between a layer of bricks or blocks above the external ground height.

People often confuse rising damp with penetrating damp and it is important to engage a specialist to help identify what type you have as the repair methods are different for both.

Moisture and Condensation Management

Condensation on Internal Walls

Condensation occurs when moisture vapour is unable to dry as readily as it forms, causing it to accumulate on surfaces. The management of internal to external temperatures within a building also cause condensation to form on the surfaces of the structure.

Condensation appears as small water droplets on the surfaces of buildings, on either the internal or external side of the structure. It is most commonly seen in basements where ventilation is poor, and the external ground temperature is cooler than the internal temperature of the room.

Interstitial Condensation

This occurs when condensation forms between two or more layers of a building or structure. For example, between an external basement block retaining wall, and the internal plaster wall linings. It will create an environment a damp environment, ideal for mould and mildew if not treated with appropriate waterproofing solutions such as a cavity drain system, or adequate ventilation.

Moisture Vapour Transmission

Moisture vapour is water in a gaseous state that can pass through substrates and then condense into a liquid form. Some waterproofing membranes allow moisture vapour transmission, which means they stop active water and damp, but still allow moisture vapour to pass through. This becomes an issue when the moisture vapour is ‘trapped’, particularly for Grade 3 habitable spaces.

Moisture vapour cannot be seen, however it creates the perfect environment for efflorescence, mould and mildew to thrive.

Critical Dry Rooms

Similarly, critical services rooms in commercial buildings in particular present a challenge when the external waterproofing membrane fails. Critical rooms such as server rooms and Medical backup UPS rooms are a prime example of where an internally applied waterproofing solution such as a cavity drain system is the most ideal way to repair any water, condensation and moisture that could affect and potentially destroy the housed equipment.

This equipment is typically sensitive to dust as well as moisture, which makes many alternative systems unusable for such projects.

Sloping Blocks and Zero Boundary

Sloping Blocks

Structures built on sloping blocks are a common occurrence within Australia, most commonly as what’s referred to as a ‘Walk Out Basement’. i.e. where at least one side of the basement structure is at ground level – for example the below ground garage of a home where three sides are earth retaining and the garage door is the ‘walk out’ part.

These areas are typically waterproofed from the external side during construction unless they are ‘zero boundary’ construction. When the original waterproofing membrane is compromised or eventually fails, often a repair from the internal side is the only feasible option. Limited access, existing landscaping and often cost, are the main factors to consider when considering repair options.

Zero Boundary

Zero boundary construction refers to a structure being built up to, or very close to the edge of the property’s boundary line. This is done to maximise the useable space of the building and is particularly popular in high density areas. There are many benefits to zero boundary design, however it makes the design an installation of a suitable waterproofing system a vital part of the project.

In these types of construction there usually is not enough access space to apply a suitable waterproofing system to the external side of the structure. Other options such as concrete additives, sandwich membrane installations, negative hydrostatic coatings and cavity drain membrane systems must all be assessed as to suitability for the design and end use of the space. I.e. is the below ground space required to be a Grade 1, 2 or 3?

The good news is that there are guaranteed, internally applied waterproofing solutions suitable for these types of projects that provide at least the same, if not better warranties when applied by a suitably qualified technician.

New Basement Construction

The inclusion of basements and other habitable below ground spaces is quickly becoming commonplace in the Australian Building and Construction Industry, as the utilization of the entire building envelope becomes more important. As a result, there is an increasing need for guaranteed waterproofing design and installation solutions that can deliver on these types of projects with confidence.

Dryspace Solutions are experts in the design and installation of basement waterproofing systems, specializing in internally applied waterproofing systems such as cavity drain membranes or negative hydrostatic coatings. For new basement construction projects we recommend the design and installation of ‘Combination Waterproofing Systems Specification’ using internal, external and integral waterproofing specifications to provide a bullet-proof, 100% dry basement, now and in the future.

Our resident CSSW – Certificated Surveyor of Structural Waterproofing – can assist you with the specification of a suitable waterproofing system for your basement project.