These photos show the current stage of a marine project at the Cowell Marina designed by Magryn Engineering
Currently, the marina basin is being excavated to a suitable depth and constructing breakwaters around it, then rock armouring them.
The marina is sized for about 28 vessels on floating pontoon berths with a wharf area, vessel sewerage pump-out and other services.
Stunning drone photos of the Whyalla Jetty project nearing completion provided by SA Drone Services
Read more about the Whyalla Jetty Project:
Cracking Houses – Its an epidemic!
The recent article by ABC News of January 10, 2020 “Houses are cracking in dry, hot weather, but when should you start to worry?” discussed the rising occurrence of cracking in houses across Australia due to the recent drought and lack of rain generally.
The article discussed that the lack of rainfall around Australia generally is causing the soil under and around many houses to dry and shrink, leading to cracking of the houses. The article is mostly informative and correct, but it doesn’t actually give you much information on when you should start to worry.
Cracking can be hairline width (less than 1mm wide) to 5mm or wider. Any wall cracking 5mm or wider is classified by the Australian Standard AS2870 “Residential Slabs and Footings” as severe.
Any cracking is a concern, but the rapidity with which it appears and develops is a larger cause for worry. Some cracking is slight and only shows minor seasonal change (getting wider over summer and then closing up over winter). It tends to remain generally constant over the years. Other cracking however may be rapid and severe, going from no cracking to cracks 10mm and wider in the order of 3 months. This may indicate a severe and worsening problem with the underfloor plumbing, or another cause. This type of rapid appearance of cracking should be investigated urgently.
With any cracking, investigation to find the cause and remedial works undertaken in a timely manner are likely to result in a cheaper overall cost, rather than putting the problem off by ignoring the issue for several years.
It is always cheaper to resolve a smaller problem earlier rather than wait until the problem is larger, requiring more extensive and expensive works to remediate it.
Hence, if cracking:
Magryn strongly recommends that you seek professional advice from a suitably qualified and experienced engineer.
We are here to help. Just give us a call on 8295 8677, or email admin@magryn.com.au.
Retaining wall engineering involves the assessment and design to create a wall to retain a height of material. In some situations, an engineering design is legally required to satisfy local council requirements.
Retaining walls come in all sizes from 0.2m to 10m high and many different styles. There are moss rock walls, steel post/concrete sleeper walls, stacked block walls, steel-reinforced concrete-filled block walls and many more.
And of course, retaining walls come with many different prices. They are generally expensive, and the longer and taller they are, the more costly the total price.
But what type of retaining wall is best for you?
The most common type of wall used in residential cases is the post and sleeper wall. This can either be:
These walls can have metal sheet fences installed over.
The timber sleepers come in many different colours and textures and don’t have to be concrete grey and flat.
These tend to be the cheapest type of retaining wall and are very versatile.
As the wall is supported by a concrete pier in the ground, these walls may not be suitable for sites with shallow rock, as the cost of boring into rock is high. If rock is suspected or known to be shallow in the area, it is best to take some soil logs to determine upfront if this type of wall is the best option or not.
This type of wall is suitable for wall heights of 200mm to 5m. Obviously, the greater the level change, the greater the cost of the wall.
This type of wall is suited to placing a retaining wall across an easement, where it may be necessary to excavate and replace a pipe sometime in the future. In this case, the sleepers in one bay can be removed, giving easier access to the pipe under that area. The general requirements are for the in-ground concrete piers to be at least 1m away from the pipe.
This type of wall is basically a battered earth slope with large rocks stacked over it, in an engineered layout.
This type of wall does not extend far below ground level and hence is suitable for sites with shallow rock, but it has a very wide footprint due to the batter slope and the size of the rocks. This width is typically as wide as the wall is high, or wider.
These walls have a very natural look compared to other types of retaining walls.
These retaining walls are made from concrete besser block (or similar) and contain steel reinforcement. Cavities in the blocks are concrete filled. They are narrow (about 200mm wide generally) and can be several metres high.
They must be founded on either:
The concrete slab footing makes these walls suitable for sites with shallow rock. However, the concrete slab will extend out some distance in front of the wall.
If the wall is to be installed on a site which is to be filled, the slab footing can extend back under the fill, which makes the wall more efficient and the slab footing narrower.
As the walls are blockwork, they are often finished by render and/or paint to improve their appearance.
These walls tend to be more expensive than post and sleeper walls, as they require several trades:
These are walls constructed of special proprietary engineered blocks, such as keystone or AB blocks.
They are suitable for lower height garden walls (up to 1m, depending on the type of block) and they are:
Walls higher than 800mm (depending on the block type) may be engineered by including geotechnical tie backs to tie the wall to the soil mass behind.
All the different types of retaining walls discussed above require structural engineering design to ensure they are suitable for their intended application.
An engineer should be engaged to design your wall for your particular situation.
We would be happy to assist with your selection of retaining wall type and the design of it to ensure your wall is cost-efficient and long-lasting.
Give us a call today to discuss your retaining wall requirements
Underpinning is the process of lifting or supporting the footing of a building or structure, so as to provide a more stable foundation.
Underpinning is commonly used to stabilise houses when they experience severe cracking.
There are several different types and methods of underpinning. Two of the most common are:
These methods are quite different and are best used in different situations, the choice dependent on the cause of the cracking.
Traditional concrete underpins used to be dug by hand and were typically 1m cubes of concrete placed under a footing beam. The footing beam could then be jacked up, using the concrete underpin as a stable base.
However, the cracking in some houses is related to seasonal moisture variation in the soil which can extend down to over 3m in depth. This seasonal moisture variation is the drying/shrinkage of the clay soils over summer and the wetting/expanding of the clay soils over winter. Hence, due to the depth of soil moisture variation, the 1m cube concrete block also experiences some lift and settlement over the seasons. Hence, a 1m cube underpin may not be a stable foundation.
It is better practice to install a concrete underpin as a concrete-filled bored pier to a depth of at least 4m, founding the pier in soils which are stable over the seasons. Please note that this depth may vary due to other considerations, such as the permanent water table depth, soil conditions or shallow rock, proximity of trees, etc.
The footing under the building may then be jacked off the underpin if jacking is viable.
The location of underpins will affect the decision to use traditional concrete underpins or another method, as it is preferable to use a machine such as a small excavator to auger or dig the underpin. It may not always be possible or practical to position an excavator where required to dig the underpin – you don’t want an excavator in your hallway!
Underpins are often installed as a stable base so that the footings of the building can be jacked up and re-levelled. This can only be done using traditional concrete underpins.
However, there are many limitations to this jacking, which include:
Chemical underpinning is undertaken by injecting an expanding urethane foam (or similar) into the soil at selected locations under the footing. This creates a pier of foam in the soil to lift and support the footing over. This type of underpinning incorporates jacking.
Chemical underpinning has some advantages and some disadvantages when compared to traditional concrete underpins. These are discussed below.
The advantages of Chemical Under-pinning are:
The disadvantages of chemical underpinning are:
The decision whether to use traditional concrete underpins or chemical underpins should depend on the reason for the movement and cracking occurring, and location of the cracking.
If the movement is due to seasonal wetting and drying of soils around the exterior of a house, traditional concrete underpins are better as they are founded at a deeper depth.
If the movement is in the centre of a house and is not related to seasonal wetting and drying of the soils, chemical underpins may be a better option.
Magryn recommends both types of underpinning, with the choice depending on the details and requirements of the individual project.
We recommend that you engage a structural engineer to review any project which may require underpinning, to ensure that:
Magryn would be pleased to assist you by providing an underpin report and design for your house. We can even recommend quality, reliable contractors to undertake the work. Our preferred underpinner is Complete Underpinning (contact Grant on 0423 305 078)
Give us a call on 8295 8677 and discuss your problem and requirements with us.
The relative cost of chemical underpinning vs traditional concrete underpins is variable and depends on many factors, but the order of magnitude of both options is similar. The exact relative costs are best explored with individual contractors.
Magryn recommends both types of underpinning, with the choice depending on the details and requirements of the individual project. We recommend that you engage a structural engineer to review any project which may require underpinning, to ensure that:
Magryn would be pleased to assist you by providing an underpin report and design for your house. We can even recommend quality, reliable contractors to undertake the work.
Give us a call on 8295 8677 and discuss your problem and requirements with us.
Houses are a rigid structure, built on top of a footing, which in turn rests on the soil under the house.
When the soil moves, the footing over can bend and this causes the house structure over to move and crack.
Many things can cause the soil to move. For clay type soils this generally involves a change in moisture content. As clay soils dry, and shrink, or when they get wetter and swell. This change in moisture content can be due to many different reasons, including:
Some clay soils are more “reactive” than others, meaning they shrink and swell more for the same moisture content change.
Sand soils on the other hand, are not reactive, and don’t change volume with a change in moisture content. However, sandy soils have other problems. Sandy soils, particularly in Adelaide are along a coastal strip and are generally old sand dunes. These dunes were placed by wind action and the sand is poorly compacted. Hence when you build a house on top of them, they can compact and settle, which may cause the house to crack.
The extent a house may crack will depend to some extent on three factors:
The more rigid the house structure, the more it will tend to crack.
It is better to have a house that has no cracks rather than a cracked house. However, most houses (particularly in Adelaide) show some cracking.
Cracking can be divided based on its severity:
If a crack is causing you concern, then it should be looked at and reviewed by an experienced structural engineer.
Generally, cracks in houses are not dangerous, but there are exceptions in severe cases.
Of course, the appearance of cracks in your house can reduce its potential sale value, should you wish to sell it.
If you are concerned, you should get your house reviewed by an experienced structural engineer.
Most cracks have some seasonal influence, meaning that they change with the seasons. Generally, they get wider over winter and tend to close up over summer.
Hence they open and close over the year, and tend to grow in width and length over the years, getting worse.
If you do nothing, they will tend to grow until they become a structural problem, and ultimately compromise the structural integrity of the house.
So the sooner you do something to control them the better.
The exception to the above is cracks which appear suddenly and grow very quickly (eg they appear and grow to 20mm wide over six months). These are often due to another external cause and require urgent attention.
There are many things that you can do to repair a house that is showing movement and cracking – some are expensive and some are not.
It is important that any action you take is targeted towards what is causing the cracking, so that you reduce the cracking and don’t waste your money.
It is important to realise that it is unlikely that you will eliminate all future cracking and your aim should be to reduce it to a maintenance level, where regular patching and painting is all that is required.
Some of the work that can be done to control cracking in a house can include:
We recommend that you seek and receive professional advice in regards what is required in your particular case in regards remedial work to reduce and limit future cracking.
We have years of experience in building movement assessment and recommending appropriate remedial works.
We will get one of our experienced engineers to visit and inspect your house internally and externally. We may also:
We then write you an engineering report which notes:
Our fees for the above are time-based, and dependent on how much time we spend on your job.
If you would like to book in for an engineer to attend and inspect your house, or just talk to us regarding your house, please give us a call on 8295 8677 or contact us here.
“Concrete Cancer” a generic term often used to describe cracking and spalling concrete in buildings. Concrete cancer indicates a severe problem which requires remediation.
Concrete in buildings is often concrete with steel bars inside it to act as reinforcement in the tension zones of the concrete.
The “cancer” term is often used as this is a problem which once it starts, tends to grow and spread until eventually, it will affect the structural integrity of the building. This type of deterioration is a problem best attended to in the early stages when it has not spread. Addressing this issue as soon as possible is likely to minimize the extent of damage, which in turn reduces the remediation costs.
The problem occurs in steel-reinforced concrete elements, such as balconies, edges of floor slabs and concrete wall panels.
Over time moisture and salts permeate into and move through the concrete. This moisture will eventually encounter the steel reinforcement bars, causing the steel to rust. As the steel bars rust, they expand causing the concrete around them to crack and spall.
This cracking, along with the associated rust staining on the concrete, are the typical telltale signs of concrete cancer.
As the concrete cracks, it then allows easier water penetration to the steel bars, accelerating the process.
There are several important factors which will determine how quickly concrete cancer is likely to occur. These are:
The steel reinforcement bars in the concrete act as tension tie rods and are vital for the performance of the concrete element.
If concrete cancer occurs, it will:
Hence, the concrete element becomes more and more ineffective and unable to do its job.
It should be noted that concrete cancer deterioration in one part of a concrete element may render the entire member ineffective.
It is important to treat the concrete cancer as early as possible. Leaving it untreated may lead to the spreading of the rusting along the steel bars, or extensive loss of cross-section of the steel bar, which affects its ability to perform.
If the rusting of the reinforcement is allowed to spread along the reinforcement bars it means that a much greater area needs to be treated, rather than a small area. This increases the cost of the remedial work.
If the rusting of the steel reinforcement is allowed to continue unabated, the cross-sectional area of the bar may reduce or the bar may break. This then means that the remedial work will need to include replacement of the steel reinforcing bar, at a much higher cost than treating the bar when only slightly rusted.
We have had several cases where steel-reinforced concrete balconies have had to be cut off the building and completely rebuilt, as the concrete cancer was so severe that they could not be saved. Don’t leave your concrete cancer untreated until it is too late!
We can specify many ways to treat and remediate the concrete cancer.
In the early stages, treatment can be as simple as cleaning and painting with specialised products. However this may still be expensive, depending on the extent of damage and ease of access to the affected areas.
In later stages of concrete cancer, the repair work is much more involved and may include replacement of steel reinforcement and extensive patching.
Other remedial work may be specified, depending on site conditions, such as the installation of galvanic anodes to slow future corrosion.
The above advice is generic only and cannot be taken as site-specific for a particular case.
Each case needs to be assessed and reported on individually by an experienced structural engineer, who will specify particular remedial work for that building and site.
For more information on Concrete Cancer Treatment please contact Magryn.
The historical timber main wharf at Pt Augusta was built in 1870 and has seen irregular and adhoc maintenance over the years.
In 2018, Magryn undertook a comprehensive assessment of the whole of the wharf, including timber decking, wharf substructure and timber support piles, both above and below water level.
This assessment showed that the wharf is in poor condition and urgently in need of maintenance and structural repair. A plan was formulated by Magryn to allow this project to be tackled over several years, with the most urgent areas of concern address first.
If these works are carried out it is anticipated that the historical wharf can be retained and used for recreational purposes of the community into the future.
Magryn celebrated 25 years in business this year, growing slowly but steadily over that time to a current staff of 14.
Celebrations were recently held at Jolly’s Boathouse on the Torrens River, with staff and partners, clients, past staff members, service providers and friends enjoying a cocktail party.
The food, wine and night was enjoyed by all.
Magryn Engineering
We have undertaken several upgrade designs to the original ramp which unfortunately was very limited and inadequate.
Kangaroo Island Council and Team Civil are now involved in the rebuilding of the ramp to provide a better facility including:
The ramp is located in an exposed location, and floating pontoons were not feasible for this site.
