With such a vast choice of aggregates available it can be difficult to decide which one is best for your needs.  Whether you are creating a path, an area to sit in, a garden feature or a driveway, this helpful guide should provide you with enough information to help you choose which aggregate is best for your project and how much you will need.

What Is Aggregate?

Aggregate is the general term for particulate materials often used in building and construction projects including foundations and paving.  Aggregates are mainly used as a bulking agent for making mortar, asphalt and concrete.  They provide not only mass but strength and durability as well.  When mixed with water and a binding agent such as cement, it cures over time to produce a good solid base or foundation for a wide range of applications.

The Main Types Of Aggregate

Aggregates with particles smaller than 10mm diameter are considered fine aggregates, and anything bigger is known as coarse aggregate.

Fine Aggregates

Fine aggregates are often used to create thin concrete bases, slabs, mortar, and plaster and are used for general repairs.  The small particles are ideal for filling cracks and voids resulting in a smooth finish.  Fine aggregates make a concrete mix more workable.

Coarse Aggregates

The large particles of a coarse aggregate provides strength, durability and offers a high level of load-bearing capability.  Coarse aggregates are the main choice for concrete, foundations, laying roads, paving and drainage.  It is worth bearing in mind that larger particles aggregates make concrete mixes much more difficult to work with.


Gravel consists of graded stone fragments and is widely used in concrete, as a surface material for paths and driveways, or to aerate soils and increase drainage.  Gravel is quick and easy to use and looks attractive thanks to its wide range of colours and shapes.  It’s a great choice for landscaping, quick fix paving and for those on a budget.


Often a popular choice for garden paths, Sandstone is a hard-wearing material that is often a more affordable solution compared to granite.  It is easier to produce and offers great variations in colour including blues, greys, reds and tans.  Something to consider when choosing the right one for your project.


A popular choice for those looking for strength and durability, Granite offers elegance when used as a paving material.  It is available in a range of colours but can be a little more expensive due to the labour involved with quarrying it and the hardness of the stone.  Due to its price tag, it is often used to accent or as decoration over the top of a filler aggregate.


Ballast is a little different to other aggregates in that it combines a mixture of fine aggregate, coarse gravel and larger stones.  It’s predominantly used for general concrete tasks, filling in gaps in hardcore or creating concrete paths. 


Sand is a natural substance that is versatile, cost effective and found through many forms of construction.  Sharp sand is very coarse and has quite large particles.  It is most commonly used to make hard, durable mortar and is a key component in concrete mixes.  Building sand is extremely fine textured and is mostly used in mixes for brick and block laying.    

Type 1 MOT

A granular aggregate typically used as a sub-base for trenches, paths, driveways, patios and more. MOT stands for Ministry of Transport and it defines that the aggregate meets the standards required by the MOT.  This credential indicates that you can depend on this aggregate’s strength, composition and ability to support other aggregates.  Type 1 is constructed from a variety of different stones and sometimes other inert substances.  Most commonly it includes crushed concrete, granite, granite dust, limestone, gritstone and crushed hardcore.

How Much Aggregate Will I Need?

In order to work out the amount of aggregate you need, you will need to measure the size of the area you plan to cover.  You will also need to take into consideration the depth required.  Most 10mm aggregates will need to be laid at a depth of 30-40mm, but if used to create a driveway this would need to be at least 50mm. A 20mm aggregate would need to be at a depth of at least 40-50mm and at least 50-60mm on driveways.  A larger aggregate will settle and bond together better than smaller ones.

The table below may help you work out a rough estimate, but remember it’s always better to buy too much than too little.

Coverage Area
30mm Depth40mm Depth50mm Depth
1m25 Poly Bags (100kg)
5 Poly Bags (100kg)5 Poly Bags (100kg)
5m21 Bulk Bag / 15 Poly Bags (850kg / 0.3t)1 Bulk Bag/ 25Poly Bags (850kg / 0.5t)1 Bulk Bag/ 25Poly Bags (850kg / 0.5t)
10m21 Bulk Bag (850kg / 0.85t)
1 Bulk Bags (850kg / 0.85t)2 Bulk Bags (1700kg / 1.7t)
25m22 Bulk Bags (1700kg / 1.7t)
3 Bulk Bags (2550kg 2.55t)3 Bulk Bags (2550kg)

Here at KPT Timber, we stock a great range of aggregates available in a choice of bag sizes.  Ideal for a variety of building and landscaping projects including DIY, landscaping and critical foundation work.  To browse our full range of building supplies click here.  Please do not hesitate to contact us if you require more information or advice, our knowledgeable and friendly staff are always available to help.