Cobblestone paving picture from Wix
Paving, according to Merriam- Webster online dictionary, is defined as the "artificially covered surface of a public thoroughfare" which refers to our public roads, including our driveways and patios in the garden. It adds aesthetic value to the landscape and it also provides other services such as water redirection and more space for us to utilize (e.g. easier transport of heavy objects from outside to inside the house).
On this blog, I would talk about safety and precautions taken before starting a paving job, types of pavers and the common bonds used, how to measure falls, and the methods of paving.
For landscape construction, constructing pavements can be hazardous due to the possibility of penetrating underground and overhead services with your digging equipment. It is, therefore important to take precautions before starting a paving job.
Precautions when carrying out a paving job
Ensuring a safe working environment is important in any job specially when it requires operating machineries and handling of weights. Everyone should always make sure these precautionary measures are taken to ensure everyone's safety. Some of the safety precautions that should be taken when working on a paving job are listed below.
Locate all service line before starting any excavation jobs. I think it is important to start by knowing where it is safe to dig and where you should not dig. Service lines can be located using detectors (e.g. hum detectors for detecting live electricity cables) or by contacting local service units, such as the ESB for electricity in Ireland.
Wear PPE. Personal protective equipment (PPE) should always be worn in a construction site. In a paving job, steel-toe boots with anti-penetration midsole is very important due to probabilities of stepping on sharp objects and chemical reactions (with wet cement) which can burn normal shoes. Gloves and masks should also be worn specially when in contact with smaller particles, for example, wood dust and cement dust. Eye googles should also be worn when using saw and drills to cut pavers to prevent damaging the eyes. Lastly, refrain from using loose clothing and jewelleries that might get entangled with machineries.
There are hundreds of ways to ensure safety in the workplace but the two mentioned above are the main ones that everyone should comply with, in my opinion.
Types of Pavers
Cobblestone pavement picture from Wix
There are 4 paving types that can be use to add colour and pattern on our pavements. Their qualities and simple description are listed below:
Brick pavers
- Its usage dates back to Roman times were clay were used as brick pavers, nowadays, it is made up of concrete with coloured pigments.
Clay brick paver from New England Silica
Concrete slabs
- The cheapest option among the 4 pavers. It can be reinforced (with wire and fiber mesh and is stronger) or non-reinforced (weaker concrete slab).
Concrete slab from Maxi Ready Mix Concrete
Stone slabs or flagstones
- It comes in various colours and shapes and is joined by mortar with split or sawn surface.
Flagstone pavement from WordPress
Cobble or stone blocks
- It is made out of natural stones such as granite and had been widely used as roads since pre-Roman times specially in Europe. It is built on top of mortar beds and mortar joints. The cobble-block is cheap to purchase.
Cobblestone driveway from Whoseview
The types of pavers discussed above can be joined together in certain bonds or designs. The most common bonds used in paving are:
Herringbone
The herringbone can be arranged in a 45-degree angle (as seen on the picture on the right) or a 90-degree angle. Between the two, the 45-degree is a harder technique that requires more expertise. Both patterns are very popular for driveways, as the interlocking design means it can handle significant weight and won’t become displaced when vehicles brake or turn on them. 45-degree herringbone paving from Friendlyshade
Basketweave
The most common alternative to the regular block paving. It resembles the patterns on a basket, hence the the name 'basket weave'. Different colours can be used to make the weaving effect more visible.
Basketweave pavement from WordPress
Running bond
This type of paving is usually used with cobble-bock pavers. It is also the most commonly used paving pattern specially in walls and buildings.
Cobble-block running bond from Pinterest
Stretcher bond
It is also one of the most commonly used pattern in paving. The joints of the paver is connected halfway from the pavers above and below.
Stretcher bond pattern from Pinterest
After deciding what type of paver and what bonding pattern suits your needs, the next step is to consider the need for surface water drainage. To be able to direct water towards drainage holes, a gradient needs to be applied on the pavement.
Gradient is a specified fall which is needed to prevent accumulation of surface water. The recommended gradient for a brick paved driveway is 1/80 and the lesser the number the steeper the fall. For example, 1/40 is steeper than 1/80. The formula used to calculate for the fall is written below.
Falls = Distance / Gradient
To explain further, let's take this example:
Distance/length of driveway: 6 meters
Gradient: 1/80
Falls = 6 meters / 1/80
= 6 m / 80
= 0.075 meters or 75 mm
This means that the height of the end of the driveway closer to the building is 75 mm higher than the end of the driveway closer to the drainage holes near the footpath.
After calculating the fall, we can set up the perimeter of the area using string lines and pegs. This can help prevent any bystander from stepping into the workspace.
Next, is to remove the top 200mm -300mm of topsoil. For every 1 square meter of soil dugged out, there will be 1.3 cubic meter of soil for disposal. Excavated materials bulks up by 20%- 30%.
Before excavating, we need to determine the datum level and level the paving against it. The datum level is the basic level in which all the measurement for the building can be taken. It is usually the same level as the finished floor level of the building. The datum level is based from the fixed mean sea level in the tide gauge Malin Head in Co. Donegal.
The DPC level or the damp proof course level is composed of a strip connected to the damp proof membrane and forms a seal that absorbs the moisture from the outdoor environment and the ground that can affect the brick work and the stability of the building. According to Paving Experts, in buildings less than 30 years old, a polyethylene or bitumen-polymer is used in a bedding joint between two courses of bricks. The "ground-level DPC" is actually required to be at least 150mm above the ground level (See Building Regulations for England & Wales - Part C, Section 5.5 ). The DPC is used as a fixed point of a paving project and the footpath outside can be the other end point.
DPC level from Paving Experts
There are 3 methods on how we can level the pavement and transfer the level on the other end of the paving job.
Methods of transferring levels
Leveling board with spirit level
It is a straight board with a spirit level on top it is usually used in small projects because of the short distance that can guarantee its accuracy.
Leveling board with spirit level from Pavingexperts.com
Boring rods
The boring rods are one of the oldest leveling materials used. It uses 3 identical rods to set the level. According to Paving expert, the boing rod is secured against a fixed surface or a peg. The next one is then set on the same level as the first rod and the cross-pieces of the two rods should be perfectly horizontal. It can be checked using a spirit level. The third one is known as the 'Traveller' can be put on any point between the two established rods. Boring rods can be used in longer distances.
Water Level
This method is the most accurate and it can be used not just in longer distances but also in between walls. It is composed of a rubber hose with a glass tube attached on each end. The level of water on both tubes should be the same. The problem with this method is it tends to freeze but anti-freeze chemicals can be mixed with water if needed.
Water level from Foam Sandwich Construction
After excavating, we need to set out the falls by applying restrainers bedded on concrete foundation. Restrainers prevent the paving from spreading and causing accidents from indents. It helps even out the paving and prevent grass or weeds growing in loose joints. Lastly, it also helps define the edge of the paving and mark out the perimeter. Below is a picture of a restrainer applied on top of concrete foundation.
Picture from External Works UK
Before proceeding to the next step, we need to learn some terms used in paving.
Expansion joints are used to separate the driveway or patio from walls, columns and piers. It prevents cracking by allowing space for any temperature-related changes to concrete (i.e. expansion due to moisture). It is only used in rigid paving.
Rigid paving vs. Flexible paving
Rigid paving requires a concrete base slab 100mm thick to be laid on top of the 150mm of compacted hardcore, usually used in areas of heavy traffic while flexible paving is most commonly used because it is cheaper in total because it dispenses the need for a concrete base slab and bedding mortar. It only uses 150mm hardcore with 50mm of grit sand.
The diagram below shows the layers of a pavement using concrete slabs with the hardcore at the bottom unlabelled.
Picture from City of Playford, Australia website
After haunching the restrainers, the next step is to apply 150mm of hardcore. Hardcore is a layer of mass, solid, not easily degraded materials such as limestones to strengthen the foundation of a paved driveway or patio. The average depth of hardcore required for a domestic paved driveway is 150mm. Next is to screed 50mm of compacted grit sand.
Once the grit sand is compacted, we can now lay our bricks. The method of laying blocks depends on the design pattern desired or bonding type. For example, a 90-degree herringbone would start at the main edge of the building. This is a corner that is 90-degree as shown in the picture below from Paving Experts.
The 45-degree herringbone, starts by setting out a line and then laying blocks on both side in a 45-degree angle as shown on the diagram below from Paving Experts.
After laying down the bricks, we need to set out the edging or kerbs. This can be done by just laying them directly on top of a 100-150mm thick fresh concrete or to lay it on top of a 100-150mm thick hard foundation with a 20mm mortar bed underneath.
When laying bricks and edging, there are pavers bound to get cut to fit the pattern or design of the paving job. To address this without compromising the aesthetics of the project, we can use radius units (smaller pavers) which is expensive but gives us an excellent appearance or we can just cut the length of the regular pavers using power tools.
There are several power tools available in the market for cutting pavers such as a con-saw and a guillotine.
Con saw from Macroom Tool Hire Ireland
Manually-operated guillotine from Express Tools UK
Always remember to check the machines before using specially when it was last inspected. Never use a machine that was not regularly inspected or maintained. Furthermore, wear appropriate PPE and never operate a machine that you haven't used unless someone experienced is supervising your work.
After laying the bricks, we can now add sealants like fine sand or mortar depending on the design and the paving method used. The last step is to compact them using a compacter equipment.
After working on a paving job, it is important to clean the area and make sure the equipment used are cleaned and put in place and not laying around.
References include:
Paving experts
You never know, we might get into the workshop before the summer🤞
Thank you Robbie and yes I enjoyed making this so far this is my favourite. I'd like to be able to make the patterns in real life like the herringbone and mix colours that would be fun.
Hi Anne, another fabulous blog post and what wonderful images you have included. These really make the posts come alive. You have clearly spent considerable time and effort reading, researching and composing this blog post. You have not only hit all of the major points but extended your research beyond, so well done. Keep up the great work Anne, and I hope you are enjoying and learning from these blog posts.
Thanks
Robbie