Screed Quantity Calculator
About This Calculator
This screed calculator helps you determine the quantity of floor screed needed for your construction project. Screed provides a smooth, level surface for floor finishes and can also accommodate underfloor heating pipes.
The calculator covers traditional sand and cement screed, liquid screed, fast-drying formulations, and fibre-reinforced options.
Screed Types
Traditional Sand & Cement
The standard choice, typically 50-75mm thick. Can be mixed on-site or delivered as ready-mix. Traditional drying time: 1 day per mm thickness.
Liquid / Flowing Screed
Self-levelling screed that flows into place. Ideal for underfloor heating. Can be thinner (25-40mm) and dries faster.
Fast-Drying Screed
Modified screed that dries in 3-7 days instead of weeks. More expensive but ideal for tight schedules.
Fibre-Reinforced
Contains polypropylene fibres to improve strength and reduce cracking. Good for larger areas.
Recommended Thickness
| Application | Min. Thickness | Notes |
|---|---|---|
| Floating Screed | 65mm | On insulation |
| With Underfloor Heating | 75mm | Min. 25mm above pipes |
| Liquid Screed | 25-40mm | Self-levelling |
| Bonded Screed | 25mm | Bonded to concrete |
| Unbonded Screed | 50mm | On DPM/slip membrane |
Example Calculations
Room Screed (Traditional)
A room 5m × 4m at 65mm thickness:
- Area: 20 m²
- Volume: 1.3 m³
- Bags required (10% wastage): ~127 bags
- Drying time: ~65 days
Liquid Screed with UFH
Ground floor 10m × 6m at 40mm thickness:
- Area: 60 m²
- Volume: 2.4 m³
- Ready-mix: ~5.8 tonnes
- Drying time: 24-48 hours walkable
Fast-Drying for Project
Multiple rooms 8m × 5m at 50mm thickness:
- Area: 40 m²
- Volume: 2.0 m³
- Fast-drying screed ready-mix: ~4.8 tonnes
- Drying time: 3-7 days
Important Notes
- Allow 10% wastage for traditional screed, 5-10% for liquid
- Ensure substrate is properly prepared and dampened
- Protect screed from rapid drying — cover with polythene if necessary
- Do not overload screed during curing — follow manufacturer guidance
- Test moisture content before applying floor finishes
Ready to Calculate?
Enter your floor dimensions and get instant screed quantity calculations.
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References & Sources
Standards Cited
- ACI 302.1R — Guide for Concrete Floor and Slab Construction
Defines screed/topping types, thickness requirements, and drying time guidance - ASTM C150 — Standard Specification for Portland Cement
Specification for cement used in screed materials
Formulas Used
- Screed volume:
volumeM3 = length x width x (thickness / 1000)
Source: Basic geometry - Weight and bags:
bagsRequired = ceil((volumeM3 x (1 + wastage/100) x density) / 25)
Source: ACI 302.1R — Densities: traditional 2200, liquid 2100, fast-drying 2200, fibre-reinforced 2200 kg/m3 - Ready-mix tonnes:
readyMixTonnes = wetVolumeM3 x 2.2
Source: ACI 302.1R — Average screed density of 2200 kg/m3 for ready-mix estimation - Bag coverage:
coverage = bags x 0.4 / thicknessMm
Source: ACI 302.1R — ~0.4 m2 per mm thickness per 25kg bag
Key Assumptions
- Screed densities: traditional 2200 kg/m3, liquid 2100 kg/m3, fast-drying 2200 kg/m3, fibre-reinforced 2200 kg/m3 — ACI 302.1R
- Drying time: traditional 1 day per mm, liquid 24-48 hours walkable, fast-drying 3-7 days, extended 1.5-2 days per mm for >50mm — ACI 302.1R
- Typical wastage allowance of 10% for screed — Industry standard practice