UltraScape Pro-Prime 20KG | High-Performance Polymer-Modified Slurry Paving Primer

'One of the Best Paving Primers on the Market — Independently Tested to >2.20 N/mm² Bond Strength, and Proven on Some of the UK’s Most Demanding Projects'

UltraScape Pro-Prime is one of the best slurry paving primers on the market — an excellent example of a product that does exactly what it promises. It creates an exceptionally strong bond between paving and bedding mortar, dramatically reduces the risk of slabs becoming loose or debonding over time, and helps prevent efflorescence and staining appearing on the surface of your paving. It’s a product our customers consistently come back to tell us they’re delighted with: straightforward to mix, easy to apply, and genuinely effective.

Polymer-modified cementitious slurry primer, independently tested to >2.20 N/mm² adhesion at 28 days, suitable for natural stone, concrete flags, clay pavers and 20mm porcelain — UltraScape Pro-Prime is the professional’s choice for patios, pathways, driveways, town centre pedestrian schemes and carriageways.

We’re a small, family-run business — I’m Cleo, the owner, with over 25 years in the construction industry working with businesses including Tarmac and Instarmac. I work alongside a team of incredibly knowledgeable and caring individuals, and between us we’ve seen a lot of paving primers come and go. Pro-Prime is the one we reach for when a customer needs a reliable, high-performance bond — whether they’re laying a domestic patio or working on a major public realm scheme.

If you’re laying natural stone, concrete, clay pavers or porcelain paving and want a primer that’s been independently tested and proven on some of the UK’s most high-profile projects — Pro-Prime is the product we’d confidently recommend. Highly recommended for porcelain in particular, where the non-porous surface means paving will not bond reliably to the mortar bed without a primer. If you’re unsure whether you need a primer or which product is right for your project, give us a call.

UltraScape Pro-Prime is a polymer-modified cementitious bonding mortar and slurry primer, specifically formulated to provide exceptional bond between all types of stone surfaces, 20mm porcelain tiles, and UltraScape bedding mortars. Used in conjunction with UltraScape Pro-Bed HS or Eco-Bed, it ensures full and even contact with aggregate particles, promoting adhesion to greater than 2 N/mm² — as required by BS 7533, the industry standard that sets out how paving should be properly installed to last. It is suitable for domestic patios, pathways and driveways, as well as town centre pedestrian schemes, carriageways and large-scale public realm projects.

Pro-Prime has been independently tested to achieve a 28-day adhesion strength of more than 2.20 N/mm² — a figure that reflects genuine, measurable performance rather than a marketing claim. It has been proven on major projects including Grand Central Birmingham, MediaCityUK, Granary Square King’s Cross, St Albans Cathedral, and projects for councils including Scarborough, Wakefield and Durham.

Do You Really Need a Primer? Yes — and Here’s Why

This is something we feel strongly about, and it’s worth explaining in plain terms — whether you’re a professional contractor or a homeowner laying your own patio.

Paving slabs are not what they used to be. The market is flooded with thinner slabs and cheaper imports, and those slabs are at significantly greater risk of two problems:

• Salt and mineral migration — salts and minerals from the bedding mortar can be drawn up through thinner or more porous slabs, causing efflorescence (white staining) and surface discolouration
• Debonding — without a proper primer coat, slabs can become loose, wobbly and unstable over time. What the industry calls ‘debonding’, the rest of us call a crooked, rocking, dangerous patio

A primer is also essential for porcelain and dense stone — because these materials are non-porous, standard mortar simply can’t grip them reliably on its own. The primer creates the chemical and mechanical bond that holds everything together.

The industry guidance (BS 7533) specifies applying primer at 1–2mm across the full back of each slab. Based on our experience, we’d suggest going to 3mm where you can, and trowelling it on rather than rolling or painting — you get better coverage, better thickness, and a stronger key into the mortar. It’s a small extra step that makes a real difference, especially with today’s thinner slabs.

We’d always rather tell you this upfront than have you dealing with a failed patio six months down the line.

Why Choose UltraScape Pro-Prime?

• Exceptional bond strength — independently tested to >2.20 N/mm² adhesion at 28 days, meeting BS 7533 requirements
• Full and even contact — ensures complete coverage with aggregate particles in the bedding mortar for a stronger, more reliable bond
• Meets industry standards — part of UltraScape’s BS 7533-compliant system, the benchmark for professional paving in the UK
• Versatile — suitable for all types of natural stone, concrete flags, clay pavers and 20mm porcelain
• Essential for porcelain and dense stone — non-porous materials won’t bond reliably to mortar without a primer
• Protects against salt and mineral migration — helps prevent efflorescence and surface staining, particularly important with thinner or imported slabs
• Prevents debonding — reduces the risk of slabs becoming loose, wobbly and unstable over time
• Proven on major projects — Grand Central Birmingham, MediaCityUK, Granary Square King’s Cross, St Albans Cathedral and more
• Just add water — supplied pre-blended; simply mix with water on site to create a smooth, workable slurry
• Quick and easy to apply — brush, roller or trowel; workability of 1 hour at 20°C
• NBS Plus registered — for ease of specification by architects and specifiers
• Coverage: approximately 15m² per 20kg bag at 1–2mm thickness (allow for more if applying at 3mm)

Key Product Information

• Pack size: 20kg reinforced paper bag (pre-blended, just add water)
• Colour: Grey
• Coverage: Approx. 15m² per 20kg bag at 1–2mm thickness
• Yield: 16.9 litres
• Water required: 7 litres per 20kg bag
• Workability: 1 hour at 20°C
• 28-day adhesion strength: >2.20 N/mm² (independently tested)
• Compliance: BS 7533-compliant system | NBS Plus registered
• Storage: Cool, dry, frost-free area between 5°C and 30°C
• Shelf life: 8 months from date of manufacture (unopened)

Preparation

Correct surface preparation is critical to guarantee successful application and durable performance. Remove all debris, ponded water and loose material from the supporting structure or roadbase. Both the roadbase and the paving elements should be cleaned by brushing or washing with water to remove dust, loose material, packaging and any production aids prior to application. All surfaces should be pre-soaked with clean water immediately before applying Pro-Prime.

Mixing

Place 7 litres of clean water in a suitable container. Add the Pro-Prime powder slowly and mix for 3–5 minutes to create a smooth, lump-free slurry. Use immediately — do not allow the mixed slurry to stand before application.

Application

Apply the freshly mixed slurry to the supporting layer or roadbase at 1–2mm thickness immediately before laying the bedding mortar (UltraScape Pro-Bed HS or Eco-Bed). Then apply Pro-Prime to the underside of each paving element at 1–2mm thickness immediately before placing onto the wet mortar bed — or at 3mm if following our recommendation for added protection with thinner or imported slabs. Trowelling gives better coverage and a stronger key than rolling or painting.

Important: the slurry must be fresh and wet when the bedding mortar is laid. Lay the paving while the primer is still active — wet-on-wet placement is essential for a proper bond. Do not allow the primer to dry before placing the slab.

Note: coverage of 15m² per bag is based on 1–2mm. At 3mm you’ll use more — factor this into your order.

What Products Make Up the UltraScape Mortar Paving System?

Pro-Prime works as part of UltraScape’s complete paving system, which meets BS 7533 — the industry standard for professional paving installation:

• Pro-Prime — this product: slurry primer for bonding paving to the bed
• Eco-Bed / Pro-Bed HS — rapid-strength fine bedding concrete
• Flowpoint — cement-based paving grout applied as a wet slurry. Rapid-set: clean down after 15–30 minutes, walkable after 1 hour, vehicle-ready after 4 hours

Need Some Help?

Download the Pro-Prime technical datasheet (PDF) or see our primer FAQs and article on slurry primers. Or get in touch — we’re always happy to help. Call us on 0330 122 1025.

UltraScape Pro-Prime — Technical Information

UltraScape Pro-Prime is supplied pre-blended in 20kg reinforced paper bags. With the simple addition of water on site, it creates a smooth liquid slurry paste that can be applied to the underside of all paving elements and to the supporting layer or roadbase, immediately prior to placement on the bedding mortar. It promotes adhesion to greater than 2 N/mm² as required by BS 7533, and ensures full and even contact with aggregate particles in the bedding mortar for a stronger, more reliable bond.

Suitable substrates: all types of natural stone, concrete flags, clay pavers and 20mm porcelain.

For use with: UltraScape Pro-Bed HS and Eco-Bed bedding mortars.

Full Safety Data Sheet and Technical Datasheet available on request. Download the Technical Datasheet (PDF).