Subbase is the layer of aggregate material that lies directly below a construction base and usually consists of crushed aggregate, gravel or recycled materials.
There are many options when choosing Subbase, typically we use type 1 & type 2 which are the most common materials used in construction projects.
What is the difference between Type 1 and Type 2 subbase?
Type 1 Subbase is generally graded from 40mm to dust. This material can be laid and compacted to form a level stable construction platform for asphalt or concrete work. It is typically used in the construction of roads & highways, car parks, footpaths and high footfall areas.
Type 2 Subbase usually contains finer material than type 1, type 2 contains fewer angular aggregate sizes also known as scalpings it is a crushed aggregate containing extra dust and fines, which makes this the perfect sub base for a wide array of domestic and commercial projects. Type 2 can be used for driveway construction, backfill, paths and patio areas and to fill in divots and compacts extremely well to provide a solid base.
How deep should I make my Subbase?
The thickness of the subbase can range from 75 to 100 mm (3” - 4”) for garden paths which help avoid weeds from penetrating through. 100 to 150 mm (4” - 6 in”) for driveways and public footpaths. 150 to 225 mm (6” - 9”) for roads with high traffic.
What is the purpose of a Subbase and do I really need one?
The purpose of a subbase is to create a well compacted base that evenly bears the load of the subgrade. Can you get away without a Sub-base? Again, this is a question often asked. Depending on who you ask, The short answer is: If it is going to be a walkway with high foot-traffic or a high amount of vehicle traffic then yes, but if it will just be for light foot-traffic only, then not necessarily. The type of paving or surfacing that will be used is one of the key factors in determining whether a sub-base will be required.