How thick should my sub-base be?

The entire subbase and base system should be at least 4 inches thick—thicker if the engineer feels it is needed for proper support.
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How thick does a sub-base need to be?

The subbase should be laid to a minimum of 75mm on a area which will be having foot traffic, 100mm - 125mm thick for domestic driveways. The subbase will need to compact using a vibrating drum or a "waker plate". The finished surface for the sub-base should not deviate by more then +/- 10mm.
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How thick should a patio sub-base be?

The depth of the mortar bed should be approximately 35-40mm deep. Ideally starting from a right angle or straight edge, place the slab down. Gently tap with a rubber mallet or press down with your hands and use a spirit level to ensure to make sure the slab is level and in line with your proposed design.
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How thick should a slab base be?

Slabs intended for commercial use should be at least 175mm thick and reinforced. Make sure you remove all plant matter, rocks and debris and compact the area before adding the hardcore sub base and compacting again.
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Is 50mm sub-base enough for patio?

If the patio is for light use, then I would use a 50mm thick sub base layer over a suitable weed control membrane. Ensure you also build in any falls to surface drains if applicable.
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PATIO SUB-BASE - Last few bits of prep are done!



Is 50mm sub-base OK?

How deep should my sub-base be? Generally, a flexible sub-base of unbound material needs to be at least 100mm deep, as does a bound sub-base of CBM/HBM. For bitumen-bound material, then 50mm is a typical minimum thickness.
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Can I use 20mm gravel as a sub-base?

20mm screened ballast is versatile and can be used on driveways, footpaths, oversite fill as well as sub-bases.
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What is the best sub-base for concrete?

The best sub-base for a concrete slab is gravel. The soil has to be prepped first before the gravel can be laid down; pouring concrete directly onto rock is not considered a best practice. You can use different kinds of gravel for the subbase as long as it is clean and uniform in shape and size.
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Can you use broken concrete as sub-base?

It will be fine.
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How much subbase do I need?

Measure the length and width in metres of the area you wish to fill with a sub base aggregate e.g. 20m x 10m. Multiply the length and width to find the area in square metres. Multiply by the depth e.g. 150mm. Multiply by 2 to get the tonnage required.
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Do you wet sub-base before compacting?

You'll want to ensure that the water penetrates the entire depth of the sub-base material from top to bottom, but you'll want to avoid flooding the surface. If the base is too wet, you'll find that your plate compactor sinks too deep into surface. If this is case, allow the aggregate to dry out.
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How deep should a sub-base be for a concrete slab?

Preparing the concrete base

As a rule; your base must be 75mm larger that the finished slab to allow for formwork. Clear the area of stones and plants and excavate to a minimum depth of 100mm (deeper for soft ground).
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What sub-base do I need for a patio?

The depth at which you will need your base will depend on where you are laying your paving and whether you want this paving raised or at ground level. The Typical measurements are a depth of 150mm. This includes a 75mm sub base, 50mm of a mortar mix or sharp sand and then the paving on top of this.
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Can you use gravel as sub-base?

If your builder uses the gravel he may find it will dissipate too easily into the ground and will spend more time and money to get the levels needed. I would not advise using the gravel. A well constructed base means your drive will never get sink holes.
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Do you need a compactor for sub-base?

As this sub-base is intended to carry the weight of a vehicle, it is essential that compaction is thorough. It is money well-spent to hire a plate compactor or roller to eliminate the chance of future settlement. The finished surface of the sub-base should be 'tight' i.e. not open textured or with surface voids.
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How thick should type 1 be?

A minimum thickness of 100mm MOT type 1 crushed stone should be compacted and regulated with local deviations no greater than 10mm under a 3 meter straight edge. The stone levels may range between 100mm and 300mm depending on site conditions. A perimeter edging is required to retain the surface.
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What happens if you dont compact sub-base?

Each time a vehicle pulls into a garage and stops, that action creates a plate compactor effect. If the backfill under the slab has not been properly compacted, the structural fill will eventually settle, leaving voids.
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Can I pour concrete directly on dirt?

Long story short, yes you can pour concrete over dirt.
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What happens if you don't put gravel under concrete?

Because concrete is a very porous material, it will absorb any moisture that it contacts. This can cause pooling. Without crushed stone, pooling water will settle under it and erode your slab. Adding a layer of crushed stone will add proper drainage, as well as create a barrier between your slab and the ground.
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Can I pour concrete over gravel?

Cement mix might work in some cases over an existing gravel driveway. Laying a concrete driveway over an existing gravel one is possible, but it is not generally recommended. The kind of gravel that is intended to go under cement is typically a smaller grade than what is used for gravel driveways.
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Can I use old gravel as hardcore?

Gravel can be used to make up a hardcore level. For more information see: Hardcore. Aggregate is a material used in construction as a means of stabilising and reinforcement, included, for example as a component of concrete and cement.
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What is mot sub-base?

SKU: AGSTB020. MOT Type 1 is a crushed material, 0-40mm in size and usually made from granite or limestone. This makes it an extremely strong and hardwearing material once it has been compacted. Due to its strength, MOT Type 1 is usually used as a sub-base creating a stable surface for roads and pathways.
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What is Type 2 sub-base?

Our Type 2 is a crushed aggregate with extra dusts and fines, which makes the perfect sub base for a range of domestic and commercial construction projects. Graded to 50mm down to dust and fines no specified grading, it is finer than our MOT Type 1 sub base, as it is composed of fewer larger angular scalpings.
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