Patio Grout

Preparation

Paved domestic patios, pathways, and terraces should have permeable support structures for drainage and load-bearing capacity. 'Bound' paving is set in mortar, while 'unbound' paving is laid on sand, like in supermarket car parks. In the UK, it’s recommended that 'bound' paving use a permeable mortar on a concrete bed over compacted fill, such as MOT Type 1 or 2, which provide strength and drainage. A simple water test can check permeability. The British Standard BS 7533 Part 101 focuses on heavy-duty paved surfaces but only covers cement-based jointing materials, which can be difficult to apply in British weather and are often unsuitable. As a result, high-quality domestic paving in the UK typically avoids cement-based jointing, favoring polymeric sand or advanced epoxy resin-based products like GftK’s solutions, which provide superior durability and performance for both residential and commercial paving.

Limitations

Patio Grout is a permeable jointing solution for domestic patios, pathways, and terraces, suitable for natural stone and concrete paving but not for impermeable concrete beds, vehicular areas, or swimming pool surrounds. It complies with German water protection regulations and requires proper structural movement joints. Application should occur between 5°C and 25°C, with precautions in extreme temperatures. Before repointing, old jointing material must be removed, and surfaces should be cleaned, ideally with NCC’s cleaning solutions. Wet-slurry application requires specific tools like a squeegee and a soft brush, with proper joint sealing and protection of adjacent areas. For porous stones and porcelain paving, pre-sealing is advised to prevent staining. A test area is recommended, as some natural stones may darken temporarily. Further guidance, including jointing for porcelain paving, is available on NCC’s website.

Application - The Installation Process (Condensed)

Pre-wetting: Thoroughly saturate the paved surface with clean tap water before applying Patio Grout, avoiding puddles.

Wet-slurry application: Work with one pail at a time, ideally with two people. Apply the grout using a controlled water jet and a hard rubber squeegee, moving it diagonally across joints to ensure full compaction. Keep the surface wet throughout, using the hose nozzle to prevent mortar buildup on tools and shoes. Avoid overfilling joints and use a damp coconut-fibre brush to remove excess grout after the water drains.

Working time & tooling: The grout remains workable for about 45 minutes at 20°C. No additional tooling is required, but if a special finish is needed, it should be tested in an inconspicuous area. Chamfered edges must be cleaned while still wet to ensure correct joint performance.

Curing: At 20°C and 65% RH, the area can handle light foot traffic after 24 hours and normal use after about 7 days. Protect the freshly grouted area from people, animals, sun, and rain during this period. If prolonged damp conditions occur, curing may be delayed, and poor drainage may impair strength.

Pouring & application tips: Open the vacuum-sealed bag, cut a small corner, and pour small piles (~200mm Ø) onto the wet surface. Work in areas of 4-5m² at a time, keeping the grout wet with the hose to prevent premature drying. Avoid pouring out the entire pail at once to maintain ease of application.

Prolonged damp weather during curing may cause some delay in hardening. If the joints are waterlogged in this period, this may impair ultimate strengths and indicates that there is inadequate drainage.

Maintenance – After care in service

Paving Cleaning:

All external paving requires regular cleaning to keep it in good condition and generally this now includes frequent jet-washing along with suitable paving cleaning detergents and clean water. The use of bleach and industrial style cleaners containing sodium hypochlorite is not recommended. This is because these may damage natural stone as well as affecting Patio Grout joint colours. For safer and more efficient cleaning we recommend using NCC’s Specialist Paving Cleaning Solutions to facilitate the removal of dirt and stains, as well as eliminating, or significantly reducing the need for high pressure water jetting.

Jet wash cleaning: As with all air-drying, polymeric sand paving jointing mortars, Patio Grout filled joints should not be cleaned directly with high-pressure water jetting equipment, such as Karcher, Bosch or similar Patio Grout filled joints should not be cleaned directly with a high-pressure water jet, despite having higher strengths and better strength correlation than any other 1-part paving joint compound. However, it is not easy to clean paved surfaces without jet-washing the joints, so there are several recommendations and suggestions given in the industry to help with this dilemma, including:

‘Only use a domestic power washer’….?
‘Only pressure wash lightly’ …..?
‘Keep the nozzle 300 / 200 / 150mm (12 / 8 / 6”) away from the joint’ ….?
‘Pressure wash the joints at an angle of more than 45° to the surface’ ….?
‘Pressure wash the joints with a low-pressure wide fan jet’ ….?

On reading these, if you are an experienced paving contractor you might well think: ‘Have they ever used a Karcher / Nilfisk / Bosch jet wash and held a lance before…?’

However, notwithstanding this, all these suggestions are intended to assist, and they give a very good hint that 1-component paving joint compounds are not designed to be high pressure jet washed.

All this advice should help formulate a plan for cleaning and maintaining the appearance of your paving, whatever your level of experience with such machines. Clearly, it is better to try and minimise any water jetting / jet washing and not jet wash the joints directly, as whatever way you do it, the pressure washing will usually lead to some jointing material being displaced, particularly when the operator gets distracted or bored. The clear message is to avoid jet washing if you can, and if you do, then take it ‘slow and easy’ on and around the joints.

Keeping the original pristine appearance of external paving will always require frequent cleaning to prevent staining and the build-up of dirt and grime. Fortunately, this can be achieved without, or at least with minimal high pressure water jetting, by using NCC’s Specialist Paving Cleaning Solutions. These are very effective treatments that can help you quickly and easily remove algae and grass stains, green growths, rust stains etc., as well as to remove general dirt and grime more easily. This is often with just a garden brush and a nozzle on a garden hose – Problem solved. One very important caution, no pressure or chemical cleaning solutions should be applied within 4 weeks of the joints being grouted. There is a lot more paving cleaning information and advice on the Paving Cleaning Solutions on our website here: https://nccstreetscape.co.uk/paving-cleaning.

Paving Sealing:

Another way to reduce the need for high pressure water jet cleaning and prevent damage to your patio paving joints, is to use one of NCC’s Specialist Paving Sealing Solutions.

Using an appropriate sealing system for your patio paving, can prevent and or significantly reduce staining and dirt pick-up, which then also reduces the cleaning requirements, and/or makes the paving cleaning process, including the joints, much easier and faster, as well as being less frequently required. Although we strongly recommend that any spillages are always removed and cleaned away as soon as possible.

Depending on the type of paving and sealer, frequently the sealer can also be applied before grouting is carried out, which has several advantages, firstly in preventing, or greatly reducing any possibility of staining by the grout, plus pre-sealing also makes the grouting process easier and faster as the surface pores are filled and suction is greatly reduced.

Note: : For any sealer application after jointing is completed, it is important to wait at least 4 weeks before applying any chemical sealing solutions over freshly applied Patio Grout.

There are many different types of paving and different types of sealers, all of which have different characteristics and advantages, as well as limitations. Therefore, this is also a big subject, but fortunately we have provided extensive information and advice on our website, and we developed a complete range of paving sealers for all types of paving and exposure requirements. Find out more on our website here: https://nccstreetscape.co.uk/paving-sealing.

Weathering Exposure: As with all materials used externally and exposed to natural weathering, the Patio Grout mortar will age over time and some discoloration can be expected.