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Grass is one of the most common garden surfaces for good reason. Grass lawns are lush and multifunctional hosting a wide range of activities outdoor activities.
However, there are also some serious disadvantages to lawns especially during wet weather. Therefore it is often sought to lay paving slabs onto grass. Replacing lawn with paving can provide a more maintenance free and practical outdoor surface. In this article I will explain how to replace grass with paving slabs correctly. I will include some considerations of replacing grass with paving such as installing correct drainage, sub-base and jointing. Can you lay paving slabs straight on grass?
It is never advised to lay paving slabs straight onto grass for a few reasons I will discuss this below. Firstly it is very rare lawns are flat enough to lay slabs consistently level. Furthermore, seasonal variations in ground moisture can lead to paving shifting and moving. In order to lay paving slabs on grass you will need to remove the soft topsoil and install a robust sub-base. You will then need to lay your paving on a 30-40mm layer of cement based mortar to stick them into position. Perhaps the only acceptable scenario where you would put paving slabs directly onto grass is stepping stones.
At the very least it is best to base these upon a level bed of compacted sharp sand.
However, if you laid multiple slabs together this way as a patio they would move and displace too much! Any jointing or pointing material would deteriorate between the gaps and weeds would become established. Eventually your paving slabs would sink and become overgrown with a layer of weeds and grass. Planning your paving
If you are planning to replace a grass lawn with paving it is important to plan correctly. Do you want the whole area to be paving? What shape patio do you want? What is your budget? Planning your project correctly will enable you to get a good idea of what it will involve and cost. It is more efficient to get your project right first time with no cutting corners. Below I will break down and explain the considerations and stages of replacing grass with paving slabs. Implement a drainage strategy
Drainage is a very important consideration when replacing grass with paving slabs. As grass grows upon natural topsoil it naturally absorbs rainwater like a big sponge. However, when you replace grass with paving the water has fewer places to permeate to. This can lead to flash flooding and boggy gardens. If you are installing a paved surface where it was once grass you need to implement a drainage strategy.
This could involve gently sloping the paving to a channel drain or a large flower bed. The most typical patio drainage systems are plumbed into a soak-away system.
For more information about implementingpatio drainage visit our article on the subject here. Excavation
One of the most common pitfalls of replacing grass with paving is not removing the soft topsoil. This top layer of soil is full of organic matter or ‘humus’ which can move and displace when wet. If this soil is not removed before the paving is laid the surface will shift and crack. Consequently all areas of grass should be excavated to a minimum depth of 150mm. The soil should then be removed leaving no loose particles in the base. You will then need to spread a compactable sub-base to the area. Laying your sub-base
A paving sub-base is typically a compactable aggregate such as Mot type 1 or crushed concrete. This is spread to a depth of around 100mm or 150mm for vehicular traffic and compacted. This sub-base will then allow you a strong and stable base to lay your paving slabs. Laying your paving
Once you have laid and compacted your sub-base you are ready to lay your paving. You will need to mix a 1:4 sharp sand to cement mortar mix using a cement mixer. Add plasticiser and water until your mix reaches the consistency of bricklayer’s mortar. Bed down your paving slabs onto the mix so there are no voids under the paving. You want your paving to be as flush and level as possible. Use a long spirit level to level your paving as your work. Jointing your paving
When you’re paving is set after 24 hours you can joint the gaps in between the pavers. This is best done using a 1:3 plastering sand and cement mortar mix. For our full guide on how to grout paving slabs visit our article here. FAQ'SHow do you build a cheap patio on grass?
Probably the cheapest way to build a seating area on grass would be using gravel. Gravel is generally cheaper than paving slabs and faster to lay. However, just because you are using gravel it doesn’t mean you should not add a sub-base. You should still remove the topsoil and spread a minimum sub-base of 60mm. Alternatively you can use cheaper paving slabs. However, it is never advised to lay less base to save money, this normally results in spending more in the long run. Can you lay pavers without a base?
If you lay pavers without a base they will move and shift over time. Tables and chairs will not sit firmly upon the surface and will rock. Eventually soil will rise up in between the gaps leading to weed establishment. The result will be a messy surface with loose pavers which is not suited for purpose.
Thank you for reading our article on how to lay paving slabs on grass. If you require garden patio or paving services do not hesitate to contact us. Based in Amersham, Buckinghamshire we provide a wide range of landscaping services I will link to other relevant articles below you may also find useful.
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Sloping gardens are a very typical in hilly areas and regions of topographical undulation.
Although there are some advantages of having a sloping garden there are also many disadvantages. This can be particularly so when it comes to landscape drainage. Garden hydrology in hilly regions can be complex with slopes distorting both catchment and surface run-off acceleration. On slopes it is very typical for your gardens drainage to be affected by surrounding properties. The most problematic garden drainage on slopes is when water flows towards the home. In this article I will provide a summary of typical garden drainage problems on slopes and how they can be resolved. Why do you need to install drainage on slopes?Sloping ground can greatly accelerate the velocity of storm water runoff in times of heavy rain. This can lead to flooding events which in extreme cases can cause damage and financial loss. Land on a gradient is also much more susceptible to movement and subsidence. Seasonal moisture changes on such sites can help contribute to such movements. Consequently, providing adequate landscape drainage to sloping gardens is always advised. This is particularly the case on sites with extreme bogginess and moisture fluctuations throughout the year. How do you drain a sloping garden?
To drain a sloping garden effectively you will firstly need to diagnose the source of your particular issue. Most drainage problems on sloping sites are due to topographical funnel points. This is where surrounding landform channels and directs run-off into a specific area. These wet zones can become particularly boggy and saturated.
Landscape features such tree lines, boundary walls and buildings can also act as a barrier to water travelling downhill.
In such cases horizontal drainage channels must be installed to collect water and direct it away in an orderly fashion. These can include, French drains, channel drains, swales and other landscape drainage installations. I will describe these in more detail below: 6 Drainage installations for sloping gardens
Channel drainsChannel drains are linear drainage channels which slot together to form a continuous surface collection drain. These channels are typically topped with a robust drainage grill which allows water into the drain. Channel drains are typically installed into paved surfaces where surface water can be captured. On sloping sites these drains can be installed along garden edging, retaining walls and patios. The water can then be piped downhill to a collection vessel or drainage network. French drains
French drains are long trenches filled with free draining gravel encasing a perforated drainage pipe. These drainage channels can not only direct water flows but draw water from the surrounding ground. In sloping gardens French drains are laid along the width of a slope to collect all downward moving water. French drains are very effective at draining lawns and low lying boggy areas. These drainage channels can be plumbed into soak-aways. Garden levelling
One of the most effective ways to mitigate drainage problems on sloping sites is by levelling. Levelling upon slopes is almost always the most expensive option, especially where terracing is involved. However terracing a whole slope is not necessary to improve its drainage. Simply by flushing up the levels to the existing ground will make a significant improvement. Scraping off high areas into low areas can create a more consistent slope which allows water to escape evenly. Retaining walls
Retaining walls are almost always associated with raised beds, and terracing slopes. However retaining walls can also be utilised strategically for garden drainage on gradients. Walls can be positioned to make changes within the slopes gradient. Subsequent gradient manipulation can help funnel surface water where it is less likely to affect lawns and flower borders. Grated channel drains can also be installed to the top and base of retaining walls to capture storm water. Mounds
Mounded soil can create linear bunds of ground which help to redirect surface water on slopes. Mounds can be particularly effective at steering water around a property or away from a specific area. These types of damming mounds are very effective combined with French drains. French drains can be installed along the line of the mound to collect excess surface water. The water can then be directed away or to a soak-away system. Moats & Swales
Moats and swales are shallow ditches and landscape depressions which collect water during heavy rain. Traditionally moats would be larger and hold standing water where swales would normally only fill during wet weather. Nonetheless moats and swales can be excavated along sloping ground to help channel and redirect water. Contouring such channels can help to reduce flash flooding and garden drainage problems on slopes.
Thank you for reading our article on garden drainage for slopes. If you require garden drainage services do not hesitate to contact us.
Based in Amersham we cover Buckinghamshire and neighbouring counties. We have also just opened a new office in Norfolk. Below I will link to some of my other landscape drainage articles you may find useful.
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Driveways are one of the most convenient and practical surfaces around your home. They provide fast and safe access to your front door with a clean and level surface to load necessities.
Like all hard surfaces however, driveways can accelerate surface run off whilst contributing to flooding and pollution. Consequently, driveways should always have a suitable drainage strategy which mitigates the effects of water runoff. One of the most effective ways of doing this is by collecting water in drainage channels. Drainage channels for driveways come in a wide variety of different products and installations. In this article I will explain everything you need to know about drainage channels for driveways. I will summarise the various types as well answer some common questions regarding driveway drainage channel installation. Why have drainage channels for driveways?
Drainage channels collect vigorous flows of surface water in times of heavy rainfall. This is particularly important for properties where drives slope down towards the home. A well installed driveway drainage channel will collect excess water and direct it to a drainage feature. Driveway surface water drainage is particularly important as it contains toxic particles.
Tyre rubber, break pad dust, oil spills and metal particles all wash off our driveways and access roads.
If allowed to drain into drainage networks these lead to the toxification of natural watercourses and aquatic ecosystems. Such pollution can intern effect our drinking water, food sources and health. Therefore drainage channels play a critical role in collecting and draining driveway runoff away safely.
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