Butt Jointing – Non-Concrete Products
Whilst many products may have straight square uniform edges, which may lend themselves to being laid neighbour against neighbour – or butt jointed – it is generally considered not a good idea, due to various factors.
A butt jointed/unpointed slab will still allow moisture to enter the micro-joint between the materials, as they are unsealed. In some slabs, this may manifest in a darker colour shade around the exteriors, where the product remains damp longer than the remainder of the surface.
This is not so much of a problem with a small element paver e.g. brick laid flat and butt jointed, although such a technique may well cause spalling or chipping to the edges, or where any temperature change may cause micro-variations in movement between the units, thus causing micro-chipping to the edges, there being no capacity for movement.
Butt jointing in porcelain paving should be avoided at all times. All porcelain paving must have a joint of at least 5mm, preferably 6mm to prevent spalling. If they have been laid correctly i.e. over a full mortar bed and fully applied with bonding mortar, the slabs will not be able to delaminate or become de-bonded from their laying bed. Any extreme changes in temperature – which in a garden may be variable according to light/shade and aspect – the result may be badly chipped edges if they are laid butt jointed. Note; paving laid apparently butt jointed in a kitchen or conservatory will not suffer the temperature changes that occur outdoors, and therefore cannot be replicated externally to match internal lines.
