Dealing with Concrete Slab Edge Dampness in Australia: Causes, Effects, and Effective Solutions.

INTRODUCTION:

Concrete slab edge dampness is a prevalent issue faced by homeowners and builders in Australia. It can cause various problems such as mould and mildew growth, damage to flooring and finishes, decreased energy efficiency, and even structural damage. In this article, we will delve into the causes, effects, and effective solutions for concrete slab edge dampness in Australia, providing valuable insights for those seeking to tackle this issue…

CAUSES OF CONCRETE SLAB EDGE DAMPNESS IN AUSTRALIA:

There are several causes of concrete slab edge dampness in Australia. Poor waterproofing during the construction process is a common culprit. If moisture barriers, sealants, or coatings are not properly applied, water can penetrate the concrete slab’s edge, leading to dampness. Additionally, improper site preparation, such as inadequate drainage or poor grading, can also contribute to concrete slab edge dampness. Groundwater or rainwater seeping into the soil can accumulate and find its way into the slab’s edge, causing dampness issues.

EFFECTS OF CONCRETE SLAB EDGE DAMPNESS:

Concrete slab edge dampness can have detrimental effects on the integrity and functionality of a building. Efflorescence or ‘salting’ to slabs edges as pictured above is one of the most common signs of slab edge dampness. Mould and mildew growth are also common consequences of dampness, which can lead to possible health hazards. Dampness can also cause damage to flooring and finishes, leading to costly repairs or replacements. Additionally, over an extended time, dampness can cause structural damage to the concrete slab, compromising its longevity and strength.

SOLUTIONS FOR CONCRETE SLAB EDGE DAMPNESS:

Rectification works relating to buildings with slab edge dampness problems are typically undertaken on a trial-and-error (iterative) basis with attempts to rectify obvious poor site features first, followed by more comprehensive and costly rectification techniques. Typical rectification methods are aimed at water-proofing the edge of the slab and reducing the moisture content of the surrounding soils. Proper site preparation, such as ensuring proper grading and drainage, can also help prevent water from accumulating around the slab edge. Additionally, implementing effective moisture management strategies, such as installing gutters, downpipes, and proper landscaping, can help divert water away from the slab edge. Ongoing monitoring must then be undertaken to verify the results.

Regular inspections and maintenance of the building envelope can also help identify and address any potential dampness issues early on. This includes checking for signs of water intrusion, such as damp spots, mould or mildew growth, and musty odours, and taking prompt action to rectify any issues.

CONCLUSION:

Concrete slab edge dampness is a common issue in Australia that can have detrimental effects on buildings if not addressed properly. By understanding the causes, effects, and solutions for concrete slab edge dampness, homeowners and builders can take effective measures to prevent and mitigate this problem. Proper waterproofing, site preparation, moisture management, and regular inspections and maintenance are key to tackling concrete slab edge dampness and ensuring a dry and healthy living environment. Our skilled team can help prepare a rectification strategy for your property.

We recommend you contact Booth Engineers and Associates or another suitably qualified professional engineer with experience in assessing and rectifying damaged structures to evaluate your property today.

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For more information, or to get a quote , please contact our team.

Water Ingress to Basements and Podium Slabs

Basements are extensively adopted in multi-residential and commercial construction to provide sufficient spaces for parking and services. However, structures partial or fully underground can be challenging to achieve adequate long-term waterproofing, with items such as garden beds and construction joints typically being the most problematic. Long-term rectifications relating to moisture ingress issues typically involve an iterative solution, whereby the most likely causes and rectification strategies would be considered first. With the understanding that other additional rectifications would likely be subject to ongoing monitoring and the success of any previous measures taken. Rectification works are typically a combination of limiting water build up against the building and (positive and/or negative) waterproofing of existing building components.

Booth Engineers can be contacted to assess and investigate any water ingress and associated problems (efflorescence, cracking, concrete cancer/spalling) currently experienced around your property.

COMMON DEFECTS RELATED TO WATER INGRESS ARE:

• Efflorescence (white staining on the surface of concrete/masonry)
• Rust stains
• Concrete cancer/spalling
• Mould and algae

COMMON RECTIFICATION METHODS:

• Positive / negative waterproofing of walls and slabs
• Crack injection
• Additional drainage (grated drains, perimeter drains, sump drains, etc…)
• Removal of garden beds
• Re-profiling or topping of slabs to achieve falls
• Larger or additional sump pumps in basement floor
• Repair and upgrade plumbing

We recommend you contact Booth Engineers and Associates or another suitably qualified professional engineer with experience in assessing and rectifying damaged structures to evaluate your property today.

Talk to an Engineer Today

For more information, or to get a quote , please contact our team.

Project Assistance – We Help You Get the Job Done

Our Project Assistance service is aimed at assisting our clients through the construction process from start to finish; obtaining relevant quotes from suitable contractors, making sure that quotes have reasonable allowances and expected contingencies, and that all relevant paperwork, inspections and approvals have been catered for during the construction process. A fee proposal for Project Assistance can be provided once a suitable engineering design/scope has been developed for the rectification work that you require (e.g. footing system movement, cracking, underpinning, concrete repair, rusting steel, other damaged structural components, etc…)

The Process

The typical process to completing your structural rectifications is as follows:

How We Help With Project Assist

Once you have contacted Booth Engineers about assisting with your project, we can proceed to carry out our ‘Project Assist’ package and the works for your property.

1. Tender Documentation Prep & Approval

We will prepare the “Invitation to Tender” documents and all the tender conditions, which outline the process of the job. You have the opportunity to review tender documents with the option of seeking legal advice. “Invitation to Tender” will be sent to professional and capable contractors who will provide us with their tenders for evaluation.

2. Evaluation Of Tenders

Once the tender period closes we will prepare an evaluation report for all the tenders documents provided. The evaluation report will be sent to you with our recommendations and you will make the final decision of which contractor to proceed with. Once the decision is made, unsuccessful contractors will be notified and the successful contractor will proceed with the job.

3. Project Begins

We organize a pre-start site meeting so you can meet with us and your selected contractor to clarify any questions you have regarding the project. Inspections are carried out throughout the rectification works to ensure construction complies with the intent of the design/scope. If unforeseen conditions are encountered during the works, you have the experience and knowledge of this office to guide you. We also ensure all relevant certificates of approvals have been finalized before the completion of the project.

4. Project Completion & Handover

We attend a progress meeting/s during construction to ensure the works meet the design/scope intent. Once the work is completed we assist in the site handover process and liaise with you to make payment to the contractor based upon certifications of works carried out. We also provide a final report advising on practical completion and receiving of certification.

Contact Booth Engineers & Associates Pty Ltd today to discuss your project and see how we can assist with your structural rectifications.

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For more information, or to get a quote, please contact our team.

Expert Witness and Causation Reports

Expert Witness and Causation Reports


Booth Engineers and Associates inspects and reports on hundreds of distressed structures each year. Ranging from small retaining walls and residential dwellings, up to large commercial and multi-residential buildings. Booth Engineers and Associates can inspect and provide succinct written structural engineering reports and advice on your specific structure. In particular, common requests for causation reports include:

• – Damage to building / residence from trees, retaining walls and excavations;
• – Insurance claims and associated causation reports;
• – Expert Witneess / reports relating to injury or damage;
• – QBCC decision reviews for builders and owners;

The Director and Principal for Booth Engineers, Stephane is involved in the preparation of expert investigations and reports for numerous legal forums every year, with regular court attendances. Typically engaged by clients such as the Queensland Building and Construction Commission (QBCC), Law Firms, and private parties – Stephane’s expert professional skills, in-depth knowledge of the industry, and necessary verbal clarity allow for comprehensive expert witness services to all clients across various forums.

Some noteworthy cases we have worked on:

Queensland Civil and Administrative Tribunal (QCAT)

• – Hall and Agoston v Queensland Building and Construction Commission (2020)
  Expert witness for QBCC (2016 to 2020)
• – Dixon Homes v Queensland Building and Construction Commission / QBCC (2018)
  Expert witness for Dixon Homes / CDI Lawyers (2018)
• – Correnti v Queensland Building and Construction Commission (QBCC) (2014)
  Expert witness for QBCC / Holding Redlich Lawyers (2011 to 2014)
• – Imperial Homes Pty Ltd v QBCC (2014)
  Expert witness for QBCC / K Henwood Lawyer (2012 to 2014)

District Court (QDC)

• – Haggar v Qld Metal Recyclers Pty Ltd (2019)
  Expert witness for Haggar / PHV Lawyers (2018 to 2019)
• – Greatorex Industries Pty Ltd v Suncoast Property Developments Pty Ltd (2016)
  Expert witness for Suncoast / Romans & Romans Lawyers (2012 to 2016)
• – Gratrax Pty Ltd v TD & C Pty Ltd (2013)
  Expert witness for Gratrax / Crouch & Lyndon Lawyers (2009 to 2013)

Supreme Court (QSC)

• – Bigby v Kondra (2017)
  Expert witness for Bigby / Carter Newell Lawyers (2014 to 2017)
• – Jackson v Redcliffe City Council (2010)
  Expert witness for Jackson (2008 to 2010)

We recommend you contact Booth Engineers and Associates Pty Ltd today to discuss your structural engineer expert witness and causation report needs.

Talk to an Engineer Today

For more information, or to get a quote, please contact our team.

Corrosion and Rust to Permanent Steel Formwork (Bondek, Condeck, etc.)

Permanent steel formwork (generally known as “Bondek” or “Condeck” in Australia) is commonly employed to construct suspended slabs in both residential and commercial structures. The permanent steel formwork can provide some economic benefit at the time of construction by reducing the volume of propping and eliminating the need for contractors to remove formwork after construction.

Although this steel sheeting is a means of formwork it is also regularly acting as a bottom layer of reinforcement within the slab, therefore making it an integral part of the suspended structure. Consequently, if the condition of this steel sheeting has too deteriorated the suspended slab can fail or collapse. Significant engineering investigations including concrete scans (GPR / X-ray) or destructive testing is generally required to confirm the construction details of the slab and to assess if the steel sheeting is just formwork or an integral part of the slab. We recommend a suitably qualified engineer always be contacted to investigate your specific slab.

Rectification of the rusting steel formwork can be as simple as removing surface rust and treating sections with appropriate rust treatment products, or where rusting is severe and has been allowed to spread throughout the structure, complete demolition and replacement of sections may be required. Early intervention and rectification can be the difference between simple repairs or complete demolition. A suitably qualified engineer will have to be contacted to consider the specific suspended slab’s construction, location, and possibly service conditions to determine an appropriate rectification procedure.

We recommend you contact Booth Engineers and Associates Pty Ltd to evaluate your rusting steel formwork today.

Talk to an Engineer Today

For more information, or to get a quote, please contact our team.

Movement, Cracking and Underpinning

Over the years, this office has been involved in the investigation and rectification of thousands of structures and we have noticed that much of the available literature available can appear overwhelming, ambiguous and even confusing to many building owners and managers. When confronted with damage to your main asset or investment, who do you trust and what should you do or expect? It can be tempting to believe and expect that a quick and cheap fix ‘will do the trick’ or that one solution exists over all others, however as in all walks of life, this is rarely the case and as a company, our reports, investigations and engineering services have evolved over the decades to provide quality professional engineering which take into account your economic concerns and the range of construction methods and techniques made available by contractors today.WHY IS YOUR HOUSE MOVING AND CRACKING?

Footing system movement is often the major factor influencing cracking in South East Queensland in particular. The South-East area of Queensland has had substantial fluctuations of weather conditions for many years. This causes the clay soils to a depth of 1.5 to 2.5 metres to undergo significant reduction in volume in prolonged dry conditions followed by expansion as the moisture content of the soils increase. This process is naturally occurring and would continue in the future as weather conditions change.

Another significant factor is the presence of any fill material on the site. Fill material is commonly introduced on to sites to create a level building platform. This fill material may compress over time subsequently causing the footing system to move and subside.

In many cases underpinning can be implemented to minimise the above effects.

We recommend you contact Booth Engineers and Associates or another suitably qualified professional engineer with experience in assessing and rectifying damaged structures to evaluate your property today.

WHAT IS UNDERPINNING?

In South-East Queensland deep pier underpinning remains the most common method used for long term rectification of failed foundations and footings – particularly for most residential sized structures. It should be recognised that if the damage to a building is severe enough to warrant underpinning, it can be typically assumed that the existing footing system is inadequate or has at least failed to adequately cope with the site conditions.

The installation of underpins, is used to bridge the existing footing system and transfer the building loads well below ground level. The recognised depth of moisture changes in reactive clay in South East Queensland is 1.5 metres to 2.5 metres. Generally, the underpins are installed to depths exceeding these moisture changes in the soil and as such any future footing movement should be minimal – although it cannot be eliminated. Any underpinned section of a building should only undergo nominal amounts of movement, however sections of the building that are not underpinned will continue to undergo varying amounts of movement as the reactive clays are influenced by environmental conditions.

Full underpinning of external walls and internal walls and floors would be required to prevent any significant movement of the footing system in the future, however due to budget constraints partial underpinning is often undertaken. Underpinning will improve the performance of the footing system, however depending on the inadequacy of the existing footing system there is no guarantee that some degree of additional rectification work will not be required in the future as the performance of underpinned footings can vary significantly from site to site.

WHAT TO EXPECT FROM JACKING:

Jacking, or the process of ‘lifting / raising’ the foundations following underpinning can in many cases be undertaken with relative success. Depending on the depth and stiffness of the existing footing system, jacking of the footing system off the newly installed underpins may be possible. The success of the jacking process is influenced by the stiffness and integrity of the existing footing system and an acceptable amount of damage to internal and external fabric resulting from the jacking process – it is simply not possible to jack the foundations without expecting some form of movement and reaction to the structure above. Full rectification of the floor levels is not very common. In most cases there is a compromise between partial and complete rectification of the levels.

Building owners should not carry out underpinning where the primary aim is to jack and rectify level differences, as jacking results are largely unpredictable and in some cases jacking is not possible. This office would typically expect that jacking should be viewed as a windfall or bonus following underpinning stabilisation works rather than be the primary aim of such a rectification.

SITE FEATURES AND INFLUENCING FACTORS:

The amount of future footing movement may be reduced if the external areas of the building are maintained in accordance with the CSIRO publication `Foundation Maintenance and Footing Performance: A Homeowner’s Guide’ and available online – QBCC. These documents outline the problems associated with trees and poor site drainage, leaking services for buildings that are constructed on reactive clay sites as described previously. Whilst it may be possible to limit and even reverse some observed movement by modifying site features (removal of trees and improvements to drainage and repair of any plumbing leaks in particular) it would take time to assess any recovery (approximately 8-12 months and the owners may elect to consider this option first) and results vary significantly from site to site.

WILL MY HOUSE OR BUILDING MOVE & CRACK AGAIN:

The use of underpinning and other stabilisation works would rarely be expected to completely and totally eliminate all future movement and cracking in most buildings. Some amount of movement and cracking should be expected in almost all buildings and structures – even if underpinned – and whilst undesirable, this does not imply structural failure. In many cases it is inevitable and for this reason Australian Standards as well as numerous other industry guidelines such as the QBCC Standards and Tolerance Guide confirm that some amount of movement and cracking is to be expected.

Typically, modern buildings on continuous rafts with flexible wall fabrics which have undergone minor localised movement and deformations will react better to rectifications. Conversely, to older buildings with more brittle and disjointed wall fabrics on irregular footing systems which have undergone more distinct movement and damage – rectification and reconstruction work will need to be more extensive.

We recommend you contact Booth Engineers and Associates or another suitably qualified professional engineer with experience in assessing and rectifying damaged structures to evaluate your property today.

Talk to an Engineer Today

For more information, or to get a quote, please contact our team.

Cracking and Spalling Concrete

Concrete spalling, commonly referred to as concrete “cancer” is typically caused by low cover (reinforcement too close to concrete surface), poor quality concrete, moisture ingress, chemical attack (salt, chlorine, etc..), poor fixing details, or a combination of all these items. The cracking, drumming and delaminating concrete is caused by the rusting steel reinforcement expanding forcing the concrete outwards.
 
While at first concrete “cancer” appears cosmetic it is a potentially serious structural issue that requires rectification. If left untreated it will spread and propagate over the structure and may lead to failure or even collapse.

How to repair concrete “cancer”

Concrete “cancer” is most commonly rectified in the following way:

1. Remove all broken, damaged and unsound concrete.
2. Clean all exposed reinforcement to ‘bright steel’. While replacing any significantly damaged steel reinforcement like for like.
3. Reinstate the removed concrete with an appropriate repair product.

Our office can be engaged to investigate and prepare a detailed repair scope for your structure and assist through to the completion of the rectifications.

Concrete Repair Project – Newmarket (Brisbane), Queensland

Booth Engineers inspected the structure and site to investigate water ingress noted to basement and carpark. During our inspection we identified significant drumming / spalling concrete to an external suspended slab. This office further investigated the drumming / spalling concrete in-conjunction with a concrete ultrasound to identify the severity of the damage to the suspended slab.

Talk to an Engineer Today

For more information, or to get a quote, please contact our team.