Rock Salt (Grit Salt) — The Complete Guide
Rock salt is the essential material for keeping roads, paths, and car parks safe in winter. Getting the right grade and knowing how much to apply can save significantly on costs.
What is Rock Salt (Grit Salt)?
Rock salt (also called grit salt or de-icing salt) is mined salt — typically sodium chloride (NaCl) — crushed and graded for use as a de-icing agent on roads and surfaces. It works by lowering the freezing point of water, preventing ice from forming and breaking up existing ice. UK road-grade rock salt is typically brown due to mineral impurities. White salt is a purer grade used in food processing and water treatment.
Common uses
- Highway and road gritting by councils
- Car park and private road de-icing
- Footpath and pedestrian area treatment
- Airport and logistics hub de-icing
- Industrial site winter maintenance
- Farm tracks and rural road treatment
Sizes & grades
6mm (fine — spreads easily, good for pedestrian areas and smaller spreaders). 10–14mm (standard road grade — for vehicle-mounted spreaders and bulk road treatment). White salt (fine) — for food-grade applications and where aesthetics matter.
How much do you need?
For pre-treatment (before frost): apply 10–15g per m². For ice treatment: 20–30g per m². A 25kg bag treats approximately 1,600–2,500m² for pre-gritting. Estimate seasonal requirement based on your site area and local average frost days (typically 30–50 days per year in northern England).
Pro tip
Pre-treat before frost rather than reacting to ice. Rock salt takes 20–30 minutes to work. Pre-gritting at 10g/m² uses half the salt of reactive treatment and is far more effective.
Suppliers of Rock Salt (Grit Salt) near you
3 suppliers in our directory stock this material.
Heidelberg Materials Aggregates Wigan Depot
Greater Manchester
Manchester Grab Hire
Greater Manchester
Border Aggregates
Lancashire