Self Levelling Compound Calculator
Calculate Your Requirements
Enter your floor dimensions and depth requirements to calculate the exact amount of self levelling compound needed for your project.
- Tiles: 5mm minimum
- LVT, Carpet, Linoleum: 10mm minimum
- Laminate/Hardwood: 3mm minimum
How Self Levelling Compound Works
Self levelling compound is a cement-based product designed to create a perfectly smooth, level surface over uneven subfloors. When mixed with water, it forms a liquid consistency that flows across the surface, automatically finding and filling low spots whilst creating a flat finish ideal for floor coverings.
Key Benefits
- Automatically levels itself when poured
- Fills gaps and imperfections
- Creates smooth surface for flooring
- Fast drying properties
- Suitable for most subfloor types
Application Areas
- Concrete floors
- Timber subfloors
- Screeded surfaces
- Over underfloor heating
- Commercial and domestic projects
Coverage Calculation Method
The standard formula used in the UK for calculating self levelling compound requirements is based on the weight per square metre at a given depth. Most compounds use approximately 1.66kg per square metre per millimetre of depth.
Calculation Formula
Total Weight (kg) = Area (m²) × Depth (mm) × 1.66
Number of 20kg Bags = Total Weight ÷ 20
Example Calculation
For a 10m² room requiring 5mm depth:
- Total weight: 10 × 5 × 1.66 = 83kg
- Bags needed: 83 ÷ 20 = 4.15 bags (round up to 5 bags)
Thickness Requirements by Floor Type
| Floor Covering Type | Minimum Thickness | Reason |
|---|---|---|
| Ceramic/Porcelain Tiles | 5mm | Provides stable base for tile adhesive |
| LVT/Luxury Vinyl | 10mm | Prevents telegraphing of subfloor imperfections |
| Carpet | 10mm | Smooths surface for proper carpet installation |
| Laminate Flooring | 3mm | Eliminates minor undulations |
| Hardwood/Engineered | 3mm | Creates flat surface for proper installation |
| Linoleum | 10mm | Prevents visible subfloor irregularities |
Step-by-Step Application Guide
Preparation
- Clean the subfloor thoroughly, removing all dirt, dust, and debris
- Check for loose boards or damaged areas and repair as necessary
- Apply appropriate primer to prevent excessive absorption
- Seal any gaps around the room perimeter with flexible sealant
Mixing and Application
- Follow manufacturer’s water-to-powder ratios precisely
- Mix thoroughly for 2-3 minutes to achieve smooth consistency
- Pour mixture starting from the furthest corner of the room
- Allow the compound to flow naturally across the surface
- Use a steel float or trowel to guide flow if necessary
- Work quickly as most compounds have limited working time
Drying and Curing
- Allow initial set time as specified by manufacturer (typically 1-4 hours)
- Avoid foot traffic during initial curing period
- Most compounds achieve full cure within 24-48 hours
- Check surface is completely dry before installing floor coverings
Common Problems and Solutions
Uneven Surface After Application
Causes: Inadequate mixing, incorrect water ratio, or subfloor contamination
Solution: Sand high spots and apply additional thin layer if necessary
Slow Drying
Causes: High humidity, low temperature, or excess water in mix
Solution: Improve ventilation and maintain room temperature above 10°C
Cracking
Causes: Rapid drying, movement in subfloor, or application too thick
Solution: Apply in thinner layers and allow proper curing time
Poor Adhesion
Causes: Dusty or contaminated subfloor, lack of primer
Solution: Always clean thoroughly and apply appropriate primer
Frequently Asked Questions
Most self levelling compounds allow light foot traffic after 2-4 hours, but avoid heavy traffic for at least 24 hours. Always check the manufacturer’s specific recommendations as curing times can vary significantly between products.
Yes, but proper preparation is essential. Clean tiles thoroughly, remove any loose tiles, and apply a suitable bonding agent or primer. The tile surface should be scored or roughened to improve adhesion.
Primer is highly recommended, especially on porous surfaces like concrete or timber. Primer prevents the subfloor from absorbing water from the compound too quickly, which can lead to poor levelling and weak adhesion.
Most standard self levelling compounds can be applied up to 10-15mm in a single application. For greater depths, use a deep pour compound or apply in multiple layers. Always check product specifications for maximum single-pour thickness.
Order 10-15% extra material to account for mixing waste, spillage, and minor measurement errors. For irregular rooms or first-time users, consider ordering up to 20% extra to ensure project completion.
Standard interior compounds are not suitable for outdoor use. For exterior applications, specify exterior-grade or weather-resistant compounds designed to withstand freeze-thaw cycles and moisture exposure.
Product Selection Guide
| Product Type | Thickness Range | Drying Time | Best For |
|---|---|---|---|
| Standard Self Levelling | 2-10mm | 24-48 hours | General floor preparation |
| Rapid Set Formula | 2-8mm | 2-4 hours | Quick turnaround projects |
| Deep Pour Compound | 5-50mm | 24-72 hours | Severe undulation correction |
| Flexible Compound | 3-15mm | 12-24 hours | Timber subfloors |
| Exterior Grade | 3-20mm | 24-48 hours | External applications |
Cost Considerations
Self levelling compound costs in the UK typically range from £8-15 per 20kg bag, depending on the product quality and specific properties. Labour costs for professional installation range from £15-25 per square metre.
Material Costs
- Standard compound: £8-12 per 20kg bag
- Rapid-set formula: £12-18 per 20kg bag
- Flexible compound: £10-15 per 20kg bag
- Primer: £20-30 per 5-litre container
Additional Costs
- Professional installation: £15-25/m²
- Surface preparation: £5-10/m²
- Primer application: £3-5/m²
- Equipment hire: £30-50/day
Health and Safety
- Wear protective clothing, gloves, and eye protection
- Work in well-ventilated areas
- Avoid skin contact with wet compound
- Keep away from children and pets during application
- Follow COSHH guidelines for handling cement-based products
Self levelling compounds contain cement and other materials that can cause skin and eye irritation. Always read the safety data sheet before use and follow proper handling procedures. In case of contact with eyes, rinse immediately with clean water and seek medical attention if irritation persists.