Norwegian Flagstone is well suited for installation on an unbound base in pedestrian areas. The open construction allows water to drain through the joints and into the ground. A fall is therefore not normally required solely for surface drainage, provided the complete construction is permeable and the ground conditions allow the water to drain away. The supporting base must be stable, properly compacted and suitable for the local ground and climate conditions. This is part of the preparatory groundwork and must be completed before installation begins. Areas exposed to vehicles require a separately engineered construction and are not covered by this installation method.

Before installation begins, the underlying construction must be checked. The sub-base must be stable, properly compacted and capable of carrying the intended loads without settlement or movement. The required depth and construction will depend on the existing ground, local climate, drainage conditions and intended use of the area. The surface should be even and prepared to receive the final bedding layer.

Apply a bedding layer of clean crushed aggregate, typically 2–5 mm, or a comparable material without fines or stone dust. A layer of approximately one inch, around 25 mm, is normally sufficient when placed on a correctly prepared and compacted sub-base. The bedding material makes it possible to adjust each flagstone and create stable, continuous support beneath the complete stone. Use a straightedge and spirit level to level the bedding layer before and during installation.

Use the project drawing to identify the correct starting point, installation direction and section references. Installation normally begins in a corner. From this point, it can be useful to work in more than one direction. This makes it easier to maintain an even joint width and avoid accumulating deviations across the surface. Check the stone number, arrows and alignment marks before positioning the first flagstone.

Place the first flagstone in the prepared bedding layer and adjust it to the correct height. The stone must have stable support across its entire underside. Adjust the bedding material as required until the flagstone remains firm and does not rock. Complete and stabilise one stone before positioning the next. Follow the numbering, arrows and alignment marks established during production. Check joint widths, levels and the relationship between neighbouring stones continuously.

When all stones have been positioned, inspect the complete surface. Minor joint adjustments can be made carefully using a pry bar. Work gradually and distribute the adjustment across several joints rather than forcing a single stone. Protect the slate edges and avoid direct pressure that could chip or damage them. After adjustment, check that every stone remains stable and correctly supported.

Wash the completed surface using clean water from a hose and a suitable brush. Chalk numbers, arrows and alignment marks are removed by gently scrubbing the surface. Clean the stone thoroughly before the jointing material is applied. Avoid aggressive cleaning methods or products that could damage or discolour the slate.

A surface installed on an unbound base must have permeable joints. A suitable permeable jointing compound, such as Rompox Ecofine or a comparable product, is recommended. Always follow the jointing-product manufacturer’s instructions regarding joint dimensions, preparation, application and curing. Fine decorative aggregate may also be used together with a suitable stabilising binder, such as Rompox Decofix or a comparable product. Loose 2–5 mm crushed aggregate is not suitable as a finished joint material on its own. It will remain loose and is likely to be carried onto the surface during use. Fine compactable aggregate may be an alternative in some constructions, but it will not provide the same stability or performance as a purpose-designed permeable jointing system.

Impregnation is not normally necessary for outdoor areas. Outdoor exposure, sunlight and weather will gradually reduce the effect of many impregnating products. For most paths and patios, regular cleaning is normally sufficient. Impregnation may be useful in areas exposed to oil, grease or food stains, such as around grills, outdoor kitchens and dining areas. Always test the product on a small, inconspicuous piece of slate before treating the complete surface. Use a breathable product suitable for natural stone and outdoor use.

The numbered surface has been reconstructed. Every stone is stable and fully supported. Joint widths and levels have been checked. Production markings have been removed. The joints remain permeable and allow water to drain through the construction. The Norwegian Flagstone surface is ready for use.

On a solid base, the flagstones are bonded to the supporting surface using a suitable natural-stone adhesive. The numbered surface is first laid out without adhesive. This makes it possible to check the complete arrangement, adjust the joints and confirm the alignment marks before permanent installation begins. The stones are then lifted section by section and bonded from the defined starting point.

Clear and clean the entire installation area before laying out the stones. The supporting surface must be stable, sufficiently cured, clean and free from dust, oil, loose material and other contamination that could reduce adhesion. Concrete surfaces will normally require a suitable primer. The required preparation, moisture condition and primer must be determined according to the substrate, adhesive system and product manufacturer’s instructions.

Lay out all the numbered flagstones on the solid base before applying adhesive. Follow the project drawing, numbering, arrows and alignment marks. Adjust the stones until the joint widths are even and the alignment marks connect correctly. The dry layout provides a final opportunity to confirm the complete composition and its position within the project area.

Divide the dry-laid surface into manageable working sections. Lift one section at a time, keeping the numbered stones in the correct order. Begin in the corner or at the starting point defined on the project drawing. Continue systematically from the starting point towards the opposite end of the area. Avoid creating isolated sections that are difficult to connect accurately later.

Use a high-quality adhesive suitable for natural stone, the supporting base and the intended environment. Although the flagstones are thickness-adjusted, the natural surface will still vary. Thickness adjustment establishes a maximum thickness, but some stones may require more adhesive beneath them to achieve the correct finished level. Apply sufficient adhesive to achieve the coverage required for the installation. Each stone must be properly supported without voids that could lead to movement, water accumulation or breakage. Check the finished height, stability and relationship to adjoining stones continuously.

Remove adhesive from the slate surfaces and joints continuously during installation. Do not allow adhesive residue to harden on the natural stone. Keep the joint spaces sufficiently clean and open for the selected grout. Use clean water and suitable tools, following the adhesive manufacturer’s instructions.

The adhesive must be allowed to cure before jointing begins. Protect the installed surface from traffic, movement, water, frost and other loads during the curing period. Required curing time will depend on the adhesive, temperature, humidity, substrate and installation conditions. Follow the product manufacturer’s instructions.

Use a jointing mortar with a texture and appearance suited to the natural character of the slate. The clipped edge slopes inward beneath the upper edge of the stone. The joint is therefore wider below the surface than it appears from above. It is important that the jointing mortar fills the complete joint without leaving voids. Work the mortar thoroughly into the joints using a rubber squeegee or another suitable jointing tool. Clean the slate continuously as the work progresses. Grout residue, chalk numbers and alignment marks can normally be removed during the same cleaning process.

Impregnation is recommended for indoor installations and may also be beneficial in shaded or stain-exposed outdoor areas. Always test the product on a small, inconspicuous piece of slate before treating the complete surface. Some impregnating products can deepen or alter the colour of the stone. Use a breathable impregnation suitable for natural stone and the intended environment. The slate and joints must be sufficiently clean, dry and cured before treatment.

On request, the flagstones can be impregnated before delivery. Factory impregnation reduces the risk of staining during transport, handling and the construction period. It also makes the slate easier to clean during installation and jointing. The joints are not treated at the factory. After the adhesive and jointing mortar have fully cured, the joints must be impregnated separately where complete surface protection is required. Use a breathable product compatible with both the slate and the jointing material.