Kerbs
On no certain terms should you alter or amend an existing line of road kerbs forming part of a public highway without the consent and approval of the local authority highways department.
A. Retaining the carriageway edge to prevent 'spreading' and loss of structural integrity
B. Acting as a barrier or demarcation between road traffic and pedestrians or verges
C. Providing physical 'check' to prevent vehicles leaving the carriageway
D. Forming a channel along which surface water can be drained
Precast Concrete
Precast concrete units are now the most popular choice for kerbing. Hydraulically-pressed kerbs are strong, durable, cheap and can be manufactured to strict tolerances.
There are some special shapes,internal and external radius, quadrants and some droppers, standard straight kerbs and all have a pimpled finish and come in a standard shade of concrete grey. More decorative (and therefore more expensive) kerbs are becoming popular on prestige schemes, with features such as exposed aggregates and textured finishes, commonly known as Countryside kerb stones.
Traditionally, most straight kerbs are 915mm in length, although some of the kerb-units developed to match block-paving are only 100mm or 200mm long. Radius kerbs, IE those designed to form curves of less than 10m radius, are shorter than the equivalent straight units and the most modern ranges.
All kerbs, other than those with a square profile, have what is known as a 'watermark' or a 'waterline'. This is a line on the face above which surfacing (and therefore surface water) is not normally expected to extend. In many cases, the surfacing level is kept 25mm or more below the watermark.
The watermark is not a physical mark but generally coincides with a change in angle of the kerb face.
Radius Kerbs and Channels
A 'bend' in a kerb line is more correctly known as a 'radius'.While it is possible to create a radius by using straight kerbs, there are both road kerbs and block-paving kerb units that are specially shaped to create true, accurate curves, either internal (concave) or external (convex).
In the landscaping trade, a radius or arc is often described as 'fast' or 'slow'. A fast arc has a shorter radius than a slow arc, so, for example, a 3m radius is said to be faster than a 4.5m radius, which is, in turn, faster than a 6m radius. There is no threshold beyond which all arcs are fast or slow - fast and slow are comparative, subjective terms. A 4.5m arc is slower than a 3m arc, but is faster than a 6m arc.
Quadrants and Angles
As well as the straight and radius kerbs, the manufacturers also supply units with complementary profiles specifically to form right-angles.
Straight standard kerbs can also be cut to mitres to create the more intricate angles, a practice which requires a good eye, steady hand and years of experience, Shaun has this technique off to a tee, fair play mate.
Quadrant Block, sometimes known as a 'cheese'.
The Quadrant Block can be cut with a Stihl saw and a lot of skill to create angles of less than 90°
Drop Kerbs
Dropper kerbs are primarily used to reduce the amount of check on a kerb face to allow easy access for foot and vehicular traffic at access points, such as private driveway crossings or pedestrian crossings. They are manufactured as either a right-handed or a left handed dropper, when viewed from the carriageway.
Drops kerbs are also manufactured to numerous radial sizes, the area around the drop kerbs will always accommodate the Tactile paving units laid at 90° to help the visually impaired.
Bedding material
The bedding concrete should be laid out, approx 100-150mm thick before compacting, along where the edging is required. The kerbs should be strung out using 360° excavator, D shackle and a set of gravity fed kerb lifters. Prepare the bed with a shovel so that it is approximately 20mm proud . Then lay the edging as shown on a level bed making sure to leave a 10mm gap between each unit before continuing with the next section of concrete bedding, rack unit will be butt together when plumb, using a boat level and level to the string line.
NOTE
It is imperative to remove concrete at the end base of each laid unit before continuing to install the next unit, believe me you really dont want to lay and level any unit to find you cant close the unit together just because of a small stone, preparation is key for All procedures.
Kerb Laying
All kerbs should be laid on a concrete bed of at least 100mm thickness, and haunched with concrete to thickness of at least 150mm. A full-sized pavior's mall is preferred for tapping the kerbs down to the correct level, some installers use lump hammers and 4x2 off cuts, whilst others the base of a pick axe.
It is usual to remove any concrete bedding from the front of the kerb, as this is said to prevent 'differential settlement' in subsequent paving. The joints are often not mortared, but are laid with butt joints with out chipping the tops of each unit. The seated edging/kerb should never be more than 3mm above or below the line, use your Stabila spirit level to check the tolerances of each unit.
It is usual to leave 100-125mm of 'check',on the 250mm high units, and 25-40mm on the smaller, 150mm high domestic units, the surfacing level never exceeds the watermark of the kerb, and is usually kept 25mm or even more below it. This is sometimes done to accommodate future re-surfacing of the carriageway, so that, for example, the top 25mm of an asphalt pavement can be planed off, and then overlaid with 50mm of new material, without breaching the kerb watermark.
NOTE
The engineer will mark the levels on pins with insulating tape, ALWAYS place your string line to the top of tape, this simple task will save thousands of pounds.
Haunching
Concrete haunching should be undertaken once the laying process is completed, and the edgings have been checked for alignment both along the face and over the top surface. Make any adjustments to the alignment before placing the haunching.
While the bedding concrete holds the edging firmly at the correct level, the haunching concrete holds the edgings in the lateral plane, and prevents them being 'pushed' out of alignment by the weight of the contained pavement and its traffic. The concrete mixed for bedding is ideal for haunching garden edgings, or you may add a little more water, to aid final smoothing-off of the haunching. Road kerbs and other heavy applications should use a concrete of at least C20 strength for the haunching.
NOTE
Think about the surface thickness that require installing to meet the kerb tops at a later date, If you know the block paving is 60mm thick then the haunching must be kept at least 80-90mm below, Cost a lot of money to reduce the haunching heights.
CLEAN YOURSELF, KERBS AND TOOLS.
Our prices
My prices shown are 'supply and fix' throughout the UK, Price includes 30 linear metres of kerb unit as stated, 100mm concrete bed, 150mm concrete haunching and labour. No allowance has been made for travel, subsidiaries, engineer, any excavation work or the controlled removal of spoil.
Straight Road Kerbs
150x300x915mm Half battered - £430
125x250x915mm Half-battered - £390
125x150x915mm Bull-nosed - £320
Radius kerbs and transitions approximately £1.25 per metre extra.
Should you require advice or a fully written quotation for the installation of all kerbs then please do not hesitate to contact me.
We look forward to working with you.
And remember CLEAN DOWN
(A huge thanks to Auberry MD for Newton Developments, Vic, Foreman, and his lads for allowing me to work with them and collect these images.)



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