Microcement (also called micro topping, micro screed, or thin cementitious overlay) is one of the most visually striking decorative concrete finishes available, but it’s also one of the most misunderstood. Homeowners see it in magazine spreads and Instagram interiors, smooth, seamless, mineral-textured surfaces that flow from indoors to outdoors, and want it for everything. The reality is more nuanced: microcement is genuinely excellent in the right application, but it performs poorly when used outside its design parameters.
This guide explains what microcement is, where it works well, where it doesn’t, and what it costs on the Central Coast.
What Is Microcement?
Microcement is a thin cementitious overlay, typically 2-3 mm total thickness applied in 2-3 thin coats, based on a blend of Portland cement, fine aggregate (under 1 mm particle size), acrylic polymers, and pigment. The polymer content gives it flexibility and adhesion that thin pure cement products lack.
The key characteristics:
- Very thin, 2-3 mm total, so thresholds and height changes are minimised
- Seamless, no joints, grout lines, or pattern breaks
- Trowel applied, creates a distinctive hand-worked surface with subtle variation
- Colour throughout, pigment is in the material, not just on the surface
- Requires sealing, must be sealed with a penetrating and/or topical sealer to be stain-resistant and durable
Microcement is not the same as:
- Polished concrete (mechanically ground concrete slab, the concrete itself)
- Spray-on concrete (thicker polymer-modified overlay applied by hopper gun)
- Cement render (thicker wall render mix not suitable for floors)
Where Microcement Excels
Covered Alfrescos and Outdoor Rooms
The most popular application on the Central Coast. Microcement on a covered alfresco (fully protected from rain) creates a contemporary outdoor floor that visually extends from an interior polished concrete or tiled floor. The seamless aesthetic and slim floor-level transition between indoor and outdoor is particularly effective on glass-backed extension homes popular in Terrigal, Avoca Beach, and Gosford’s more contemporary residential areas.
Requirement: The alfresco must be fully covered, microcement in exposed outdoor conditions (UV, rain) deteriorates faster than protected applications and requires more frequent sealer maintenance.
Interior Concrete Floors
Microcement over existing concrete, tiles, or wood subfloors for interior applications (open plan living areas, kitchens, bathrooms) is a major growth area in premium residential renovations. It can go over tiles without removing them, which avoids the cost and disruption of tile removal.
Note: This is an interior renovation application, not a driveway or outdoor resurfacing application.
Bathroom and Wet Area Floors and Walls
Microcement waterproofed with the appropriate sealer is used in premium bathroom renovations for seamless, grout-free surfaces. This requires specific waterproofing compliance under the NCC and should only be done by applicators familiar with wet area requirements.
Feature Walls
Microcement is applied to internal and covered external walls for a contemporary raw concrete aesthetic. This is typically a thinner application (1-2 mm) than floor applications.
Where Microcement Should NOT Be Used
Open Outdoor Driveways
Microcement on a standard driveway (exposed to sun, rain, vehicle loads) is not appropriate. Reasons:
- Vehicle weight causes stress fractures in the thin overlay
- UV exposure degrades the sealer rapidly
- Rain wets and re-wets the surface repeatedly, causing sealer degradation
- Temperature cycling creates dimensional movement that the thin overlay cannot fully accommodate
If you want a seamless, contemporary look for a driveway, an exposed aggregate or a spray-on concrete overlay in a fine grey tone is more appropriate.
Areas with Active Cracks
At 2-3 mm thickness, microcement has essentially no structural contribution. An active crack in the substrate will crack the microcement overlay almost immediately. Unlike thicker overlays where a control joint in the overlay can manage a substrate crack, microcement’s thinness makes this essentially impossible.
Substrates That Are Wet or Have Moisture Issues
Microcement requires a very dry substrate. On-ground slabs with moisture vapour emission rates above 3 kg/m²/24hr will cause microcement to delaminate as moisture migrates upward. The Central Coast’s coastal humidity makes this a significant risk for on-ground applications, moisture testing is essential.
High-Traffic Commercial Floors
The thin film of microcement is not appropriate for high foot traffic commercial environments without specifying a very robust topcoat system and accepting more frequent maintenance.
The Application Process
Microcement application is a multi-stage process that typically takes 2-4 days:
Day 1:
- Diamond grind existing concrete to open pores and level any high spots
- Repair cracks and imperfections with flexible filler
- Apply primer coat, critical for adhesion of subsequent layers
- Apply first microcement basecoat (1-1.5 mm)
Day 2: 5. Allow basecoat to cure overnight 6. Apply second microcement coat (1-1.5 mm), trowelling technique determines final texture 7. Sand lightly to even the surface 8. Apply penetrating sealer, allows the surface to breathe while providing initial protection
Day 3-4: 9. Apply 2-3 coats of topical polyurethane sealer 10. Cure for 72 hours before foot traffic; 7 days for full cure
The quality of the application, particularly the trowelling technique, determines the aesthetic. Microcement shows the applicator’s hand; inconsistent technique creates visible variation (which can be a design feature or a defect, depending on expectations). Experienced applicators can control the degree of variation.
Colour and Texture Options
Microcement comes in a wide range of pigmented shades, though the aesthetic is most associated with neutral, mineral tones:
| Colour Category | Examples |
|---|---|
| Cool greys | Dove, ash, slate, graphite |
| Warm greys/whites | Oyster, bone, ivory, sand |
| Earth tones | Raw sienna, terracotta, caramel |
| Dark tones | Charcoal, anthracite, black |
Texture options range from very smooth (float trowelled to a glass-like finish before sealing) to slightly textured (a more rustic, hand-crafted feel with subtle ridges). For outdoor applications, a more textured finish is preferred for slip resistance.
Sealing Microcement
Sealing is not optional, it’s the critical performance layer. Unsealed microcement stains immediately and permanently. The sealer system typically includes:
- Penetrating impregnating sealer: Applied first, penetrates the microcement matrix to bind and protect
- Water-based polyurethane topcoat (2-3 coats): Provides stain resistance, wear resistance, and sheen control
- Optional matt finish: A final matting coat can reduce the sheen to near-zero for a more natural, dry-stone look
For outdoor and wet area applications, topcoat durability and UV stability are critical. For covered alfrescos on the Central Coast, a UV-stable polyurethane with low-sheen finish is the standard specification.
Resealing: Every 3-7 years for interior; every 2-4 years for covered outdoor applications.
Cost Guide, Microcement on the Central Coast
| Application | Cost Range |
|---|---|
| Interior floor (per m²) | $90 to $150 |
| Covered alfresco floor (per m²) | $90 to $150 |
| Feature wall/surface (per m²) | $70 to $120 |
| Bathroom floor (per m², inc waterproofing) | $120 to $200 |
| Sealer reapplication (per m²) | $20 to $45 |
Note: Minimum charges apply for small areas. A typical covered alfresco project of 25 m² starts at approximately $2,500 to $3,800 fully installed.
Comparing Microcement to Alternatives
| Feature | Microcement | Spray-On Overlay | Polished Concrete | Tiles |
|---|---|---|---|---|
| Seamless | Yes | Yes | Yes | No (grout lines) |
| Thickness | 2-3 mm | 3-5 mm | N/A (in slab) | 8-12 mm + adhesive |
| Indoor-outdoor continuity | Excellent | Good | Excellent | Good if same tile |
| Cost | High | Moderate | Moderate-High | Moderate-High |
| Stain resistance (sealed) | Good | Very Good | Good | Excellent |
| Outdoor durability | Moderate | Very Good | Excellent | Very Good |
| Repair visibility | High | Moderate | High | Low (tile replacement) |
Frequently Asked Questions
Can microcement go over tiles without removing them? Yes, this is one of microcement’s most useful features for renovations. The tiles must be well-adhered (no hollow tiles), the grout lines must be filled to create a level substrate, and a fibre-reinforced primer is used to bridge the grout pattern. This avoids the cost and mess of tile removal.
How does microcement feel underfoot? Smooth, with the texture of very fine stone. When sealed with a satin or semi-gloss polyurethane, it feels slightly warmer than tiles and has less of the coldness associated with large porcelain formats. Bare feet on a well-sealed microcement floor is a pleasant tactile experience.
Is microcement appropriate for the Central Coast’s humid climate? In covered applications, yes, with the appropriate sealer system. For any application where the surface gets regularly wet from rain, heavy humidity, or morning dew, the sealer maintenance interval shortens and the surface requires more frequent inspection. Not suitable for fully exposed outdoor applications.
Can microcement be repaired if it’s chipped or cracked? Patch repairs in microcement are visible, the repair area will be distinguishable from the surrounding surface because the hand-trowel texture is difficult to replicate exactly over a small area. For small chips, an experienced applicator can minimise but not eliminate visibility. For larger damage, refinishing the full surface is often the better outcome.
Can I use microcement on my pool surround? Not recommended. The chemical environment (chlorine, pH-adjusted water), UV exposure, and constant wet-dry cycling are beyond the performance envelope of microcement. Pool surrounds require a purpose-designed non-slip coating, see our pool surround resurfacing service.
Interested in microcement for your Central Coast home? Request a free consultation, an independent contractor assesses your surfaces, discusses finish options, and gives you a clear price and realistic expectations for your project.