This article was first published on Natural Paving
Landscaping projects involving natural stone are high on the wish list for many homeowners and often represent a significant investment, so getting the installation right is extremely important. Here Malcolm Gough, Group Sales and Marketing Director at Natural Paving Products (UK) Ltd explains what to look out for in the best installation products and how to protect natural stone installations effectively from the most common problems they face.
At the installation stage preparation is key. All paving should be laid to a level that is at least 150mm below the Damp Proof Course (DPC) of any adjacent buildings and flagstones must always be laid on a full bed of mortar that supports the whole flag and not just the corners. This bedding layer should be roughly 50mm thick and flags should be carefully laid leaving a 15 to 20mm gap between each flag – for square edged or more modern flags this joint width can be reduced to suit the preferred style. For adequate drainage, flags should be laid with a fall of 15mm per metre of paving.
Once the paving has been laid, installers will need to joint the paving using a jointing mortar or compound. The crucial things to look out for when choosing a jointing product are:
- Binding strength to ensure longevity and durability
- Minimal mixing requirements makes use easier
- Setting periods – the shorter the better (some compounds can be walked on within 24 hours and some mortars in as little as four hours)
- The ability to be used in all weather conditions – a particularly useful attribute when British weather is taken into consideration
- Desired colour choice
Note: because of their rapid setting times and composition, jointing mortars are very much a trade rated product that require two people to apply effectively.
With a secure installation in place, the next step is to protect the stone. There are a number of coatings and sealants on the market and it’s important to know the difference between the various types. Some simply provide protection from marks and stains, while others add a subtle sheen that enhances the natural colours of the stone.
It’s important to understand that coatings and sealants are in themselves two quite different things. Coatings will sit on the surface of the substrate, while sealants are designed to penetrate deep into the stone itself – offering longer lasting protection.
When choosing a sealant, look for one that these will provide protection against both water and oil based contaminants. Landscaped areas treated with high quality sealants like this actually become self-cleaning to an extent, as rainwater can wash away most materials that cannot penetrate into the stone and are left on the surface.
The timing of applying this protection could not be more crucial. Many manufacturers recommend allowing stone to weather for several months before applying any protective sealants, so that any efflorescence (calcium carbonate that has risen to sit on the surface) is able to appear and then be worn or washed off. The problem with this is that it leaves the installation vulnerable to the elements and discolouration from vegetation, birds, pets and spillages. It is therefore worth choosing a breathable sealant that can be applied immediately and that will allow the efflorescence to rise through it and sit on the surface. The Pavetuf range from Natural Paving Products, for example, is fully breathable and can be applied as soon as the paving has been laid, giving instant protection.
Efflorescence is a common problem, but it can be made worse if a poor quality, non-breathable sealant or coating has been applied immediately after installation. These types of sealants will lock in the calcium carbonate and make it very difficult to get rid of. Providing a breathable sealant has been used, a salt neutralising solution is the most effective method. The Pavetuf range includes a premium Salt Eraser that is capable of penetrating deep into the stone without harming the substrate for comprehensive treatment. Unfortunately, many people try to power wash it off and use abrasive brushing but this will only cause more damage and staining as it can unblock the pores within the stone.
When it comes to on-going care and maintenance, one of the more common problems can be rust marks from patio furniture that’s been left out in wet weather. In these instances, the best protection against rust is to remove and store furniture when it’s not being used, but understandably this is not always possible. Covering barbeques and furniture when not in use is the next best thing but will not guarantee that no staining will occur.
In the event that staining does occur, the quicker the response the better. The best rust removers are those that are specially formulated to convert rust compounds into a water-soluble solution. These types of remover actually pull out the rust that has penetrated the surface of the stone allowing it to be simply washed away.
Natural stone is extremely hard wearing and is a relatively low maintenance landscaping choice. To ensure peak performance and to keep it looking its best however, it’s worth using quality products and planning ahead. Natural Paving Products offers a comprehensive range of top quality installation, care and maintenance products that are specifically designed to offer lasting protection and be easily used.