How To Grout Paving Slabs?

Step 1) Select Your Paving Grout

When determining how to grout paving slabs, there are various grouting option to choose from, we are often asked ‘how to grout paving slabs’ and ‘which paving grout should I use for my patio?’ and without following knowledgeable advice, an easy grouting project can become a complicated and time consuming task, costing additional funds. When it comes to installing your patio, there is a wide range of jointing compounds and paving grouts available for filling the gaps between your paving slabs. These products vary in price and possess distinct characteristics that should be taken into consideration when selecting the appropriate patio grout for your project – for example, some grouting options are precisely formulated for porcelain paving while others cater to natural stone paving.

Four Primary Types of Grout:

Single Part Polymeric Jointing-Compounds (DIY Project) 

It’s a highly versatile grouting solution, which can be used for most types of paving – these products can be easily applied by simply wetting the paved area first, then introducing the dry compound; you can then spread this compound into the joints (between slabs) using a brush or sponge. The benefits include easily application of the compound and it’s designed to be left as it is, no further instruction to follow. This type of grout is what we recommend alongside the modern innovative grouting method, in order to achieve a professional, lasting finish. To achieve your desired outcome, we would encourage you to use our Single Part Polymeric Jointing-Compounds such as the Pointfix Resin Jointing Compound for all natural stone patios, supplied in either a 12KG or 20KG tub with 4 available colours to suit your design requirements and match your natural stone paving: Grey, Charcoal, Mushroom and Buff.

Example: Pointfix Jointing Compound Mortar (Single Part Polymeric Jointing-Compound)

Some grouting options are precisely formulated for porcelain paving, for example our Projoint RapidFlow Brush-In Porcelain Grout, supplied in a 12.5KG tub and available in various colours to suit your design requirements and match your porcelain paving: Black, Mid Grey, Light Grey, Basalt and Buff. Its supplied as a pre-mixed formula, making it an ideal option for DIY projects.

Example: Projoint RapidFlow Brush In Porcelain Grout (Single Part Polymeric Jointing-Compound)

Two-Part Epoxy Resins

Two-Part Epoxy Resins such as our ProJoint Titan High Strength Epoxy Paving Grout, which consists of a sand-based aggregate and a resin, mixed professionally on site – this is less of a DIY project and would require professional assistance to ensure good and lasting results, therefore not recommended to apply with no experience. Once mixed, spread out the slurry and apply directly to the paving joints (space between slabs) using a brush or sponge, just like you would when applying single-part polymeric jointing-compounds.

It is important to remember that during the application of this slurry grout, the paving must remain wet at all times. The resin inside the mixture helps to strengthen the aggregate, ensuring its more resilient to high foot traffic and weight bearing activities. Overall, epoxy resins may be the more expensive option, however these grouting solutions are designed to last for many years to come with little maintenance. This is more suitable for tradesman with experience in grouting.

More information can be found online at:
www.nexuspavingsystems.co.uk/products/titan

Example: Projoint Titan High Strength Epoxy Grout (Two-Part Polymeric Jointing-Compound)

Cementitious-Based Slurry Grouts

These are pre-mixed paving grouts, such as our highly versatile Ultra Scape Flowpoint Fine Rapid Set Flowable Grout, available in a 20KG tub; which only requires the addition of water, making this grouting solution ideal for home DIY projects. Once mixed, spread this grouting slurry into the joints (gaps between slaps) using a sponge or brush and clean off after 30 minutes, ensuring you dont miss any as this can dry and cause unwanted marks on your paving project.

The advantage of using this option over single part polymeric jointing-compounds is that this mixture will actually form a stronger bond and is also suitable for both permeable and non-permeable paving. The negatives of using this cementous-based slurry grouts is that you need to ensure during the application, there is a run off to allow the excess to disperse as this mixture cannot go down a drain; it can causes blockages other issues.

Example: UltraScape Flowpoint Fine Flowable Grout  (Cementitious-Based Slurry Grouts)

Traditional Mortar (Traditional Method)

This traditional method uses a sand and cement mixture. The grouting mixture is applied by hand between the paving slabs (joints) with the use of a jointing tool.

The benefits of using a sand and cement mixture is that it matches traditional paving like natural stone, granite and all concrete slabs. This is a cheaper alternative to more expensive grouting options like Single Part Polymeric Jointing-Compounds. The negative of using a sand and cement mixture is that there are very limited colour options so its difficult to match with design requirements, it can also be time consuming to apply. Further to this, avoid applying in wet, cold or extremely hot conditions which can cause issues and increase paving project costs.

Step 2) Prepare Your Area For Grouting

To achieve your desired outcome and the appearance of your paved area, we recommend you clean your paving slabs; removing any moss or unwanted materials from the surface of your paving slabs before grouting begins. In addition, eliminate any weeds and excess dirt from the joints (between the slabs) to ensure a debris-free environment.

Prepare Your Area For Grouting (Remove Excess Dirt)

Once you have cleaned your patio area, to ensure a smooth grouting process, you should wet the surface of your patio area with water. However, you should try to prevent surface water from building up on the slabs as this creates issues during the process.

Prepare Your Area For Grouting (Wet Patio Surface)

Step 3) Create The Grouting Mix – Product Specific Instructions

To begin the grout mixing process, first determine the grout you are going to use from point 1. You need to mix your preferred patio/paving grout slowly in a bucket, ensuring to adjust the consistency as and when needed based on product specifications.

If you are working with a flowable slurry grout like our professional grade Flowpoint Fine Rapid Set Flowable Grout, its advised to strive for a batter-like texture when mixing.

For sweep-in or brush-in grouting products like our Projoint RapidFlow Brush-In Porcelain Grout, this comes as a pre-mixed mixture for immediate use; making it ideal for home DIY projects.

This grout mixing process is specific to the product that you choose, please always refer to your chosen products specifications.

Step 4) Apply Grouting Mix

Wet the patio area before applying the grouting mixture. Now start to pour the grouting mix over the paving slabs, its advised to work in small sections to ensure the slabs remain damp and further ensures consistency throughout the grouting process. The negative of grouting dry slabs is that it can create staining and other issues, its important to avoid this to prolong the appearance of your outdoor patio area.

A sponge or brush can be used to spread/push the grout into the joints (space between slabs) where needed. Its vital to ensure an even spread, further compacting the grout into the joints to prolong the lifespan of the patio area and prevent future cracking.

Application Video: Projoint Rapid Flow Brush-In Porcelain Grout

Its important to consider that when applying a brush-in grout like our Nexus Projoint RapidFlow Brush-In Porcelain Grout, once evenly spread using a brush, tightly compact the joints using a specific jointing tool to provide an even finish – now leave to cure. Further, clean off any residue left behind from the grouting process with a sponge to ensure a professional finish.

Application Video: UltraScape Flowpoint Fine 

When using slurry grout like our UltraScape Flowpoint Fine Rapid Set Flowable Grout, the joints will start to become solid after roughly 15 minutes cure time, you can now carefully wash off any excess grout from the surface of your slabs, using the sponge to loosen the material. After around 30/45 minutes, all dependent on outside temperatures, you’ll be able to give the area a good wash and clean.

Traditional Grouting Vs. Modern Solutions

Traditional Paving Slab Grouting with Sand and Cement

Historically, sand and cement have been the go-to materials for grouting a patio area and pavement grouting. This traditional method of how to grout paving slabs, offers excellent durability and strength when mixed and applied correctly. The sand cement mix for paving joints creates a stable bond between the paving stones, ensuring a secure and long-lasting patio surface.

This method works and has done for centuries, but is not one we would recommended to our customers who are looking to complete a simple DIY grouting project. As without proper training or experience, the project may go wrong and create further problems and/or increase project costs compared with the new innovative grouting solutions, tailored more to beginners.

We highly recommend following the modern (innovative method) for grouting patio slabs; polymer-based grouts have superior benefits compared with a traditional sand and cement mix. 

Innovative Grouting Modern Solutions

While traditional sand and cement grouting remains popular, innovative solutions have emerged to offer enhanced performance and convenience such as Single Part Polymeric Jointing-Compounds. As listed above, polymer-based grouts, such as resin or epoxy, provide superior flexibility, strength, and resistance to natural weathering and staining. These modern alternatives offer numerous benefits compared with traditional methods for example; faster curing times and are available in a range of colours to complement your patio design.

When applying modern grouting solutions, follow the manufacturer’s instructions carefully to ensure optimal results. Typically, these products come in pre-mixed formulas, requiring minimal preparation, prefect for home DIY projects. Use a sponge or brush to apply the material evenly between the paving slabs, smoothing out any excess to create a neat finish. Allow sufficient curing time as specified by the manufacturer before subjecting the patio to foot traffic or other loads.

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