Oak setts installation guide
Natural Oak Setts Installation Guide
Natural Oak Setts are cut from 100% hardwood timber from sustainably managed forests. As with any type of paving there are specific instructions that should be followed in order to make sure that the paving will remain stable, provide slip resistance and maximize the life span.
Base Preparation
When creating the base fore the instillation of the oak setts, it is worth remembering that the quality of the base preparation largely determines the quality of the final result. Base requirements depend on the type of traffic the paving will be exposed to, for example a garden path will have different base requirements to a vehicular driveway where the base sand will be exposed to a greater load-bearing capacity. The sub-base layers, when installed correctly, will spread and transfer the traffic load equally resulting in a long-lasting paving surface.
Category 1 – Pedestrian and Light Traffic
This category includes non-load bearing paving such as garden paths and domestic terraces which only receive foot traffic.
A total excavation depth of 120mm is required to allow for the following base material build-up:
Oak Sett – 70mm depth
Coarse sand/fine grit (compacted) – 40mm
MOT type 1 sub-base (compacted) – 100mm
Sub-base geotextile fabric
Category 2 – Light Vehicular Traffic
This category includes light vehicular traffic such as cars and medium sized vans for access to roadways and driveways.
A total excavation depth of 300mm is required to allow for the following base material build-up:
Oak Sett – 100mm depth
Coarse sand/fine grit (compacted) – 50mm
MOT type 1 sub-base (compacted) – 150mm
Sub-base geotextile fabric
Stabilizing
The sand base layer can be stabilised if the final surface is required to be finished as a gradient. Sufficient drainage must be allowed for if stabilizing is required as this will make the base layer less permeable. The sand base can be mixed with hydraulic additives such as cement or hydraulic lime. As a general guide, 125-150kg of additives should be added to every m3 of sand.
Edge Restraints
Under the traffic load, the paving is pushed sideways and requires an edge restraint to retain it to avoid loss of shape and load bearing capacity. There are numerous edge restraint methods and some of these are as follows:
Heavy Duty steel edging with fixed stakes
Bricks/Stone cobble setts
Oak Landscape sleepers
Stone/Concrete kerb
Drainage
Where possible, rain water should be drained across the surface of the paving. To promote this and to avoid traffic hindrance from a layer of water on the surface of the paving, the paving should be installed on a gradient to shed water. Generally, paving is installed with a gradient sloping sideways so that the water will drain to and off the side as quickly as possible. For larger areas, such as square terraces, gullies should be installed. The surrounding paving should then slope towards the gullies or drainage channels that will then transfer the water into the drainage system.
Weathering
Oak Setts are naturally frost resistant but if the sand base does not drain properly, there is a risk that there will be insufficient expansion space between the joints, therefore causing the sand base to swell or rise, purchasing the paving upwards. This phenomenon is known as frost heaving. Poor permeability of the sand base may also cause thawing issue resulting in water collecting in the sand layer and creating 'swamping' or quick sand.
Pointing
Oak Setts should be installed with a minimum of 5mm and a maximum of 10mm joints. Once the Oak Setts have been installed, all left over material should be removed from the surface and the kiln-dried sand, stone dust or 1-3mm washed grit swept into the joints before use. Do not use a hardening or curing pointing product with Oak Setts as this will not allow the natural weathering process of fine timber. It is important that a loose and free drainage substrate is used to allow maximum permeability and the normal movement of timber throughout its lifespan. A periodic top up of the pointing substrate will be required as necessary.
Finishing
Oak Setts do not require treatment and are extremely durable. In the natural weathering process, the Oak Setts will change colour from pale yellow/honey to a light grey. If a warm colour is preferred, you can dress the Oak Setts with a natural oil, such as Danish oil, which will darken the appearance. If you are unsure, please request images or samples of freshly cut and weathered material to determine the desired finish. Oak Setts are a natural hardwood and will vary in appearance. Splits and cracks may occur and this is a normal weathering process. Staining or marking as a result of contact with steel can be removed by the application of oxalic acid. Consult a specialist timber coating stockist for more details.