Cyril Williams of Woodlink UK
– main UK importer and distributor of the sustainable
hardwood decking range, hosts a question and answer session on the
key considerations when installing decking products.
Decking continues to be a popular addition to any exterior environment,
offering a visually striking and cost effective method of extending
living space, creating a focal point for a garden or simply surrounding
a pool or hot tub. When working with sloped sites, decking also offers
an ideal solution for making the most of the space and importantly from
an installation perspective, can easily accommodate applications where
the door sill to ground level is at too steep a height.
While the flexibility of decking is widely documented, the key to
ensuring a quality installation lies in detailed planning, as decking
design will ultimately dictate the necessary sub-frame and associated
However, when it comes to the detail of the installation, the following
are all key points of which to be aware:
What should I consider as part of the
With a retrospective installation, or if the decking was not included as
part of the original plans, one of the main considerations is the size
of the deck in proportion to the house and garden. This is because new
planning rules now apply (in England) to the size of decks in relation
to the property or garden, which legislate that the decking cannot cover
more than 50% of the garden.
Planning permission is also specifically required where a deck platform
is more than 300mm (1ft) off the ground. However, best practice is to
prepare the design and then cross check against planning regulations to
confirm whether it requires consent.
How do I know what type of sub-frame to
The type of sub-frame will be determined by where the deck will be
installed. A patio style deck, which is a raft construction, is most
common and installed on a garden area that drains well. For sloping
sites or multi-tier applications an elevated deck (post and beam) would
Which direction should I lay the joists?
The direction you wish to lay the deck boards will establish joist
direction, whether parallel, chevron, herringbone, checkaboard or
quadrant. An important point to note is that laying deck boards in
checkaboard and quadrant can hinder drainage and will require more
How do I create a free draining
As part of planning the deck should be designed with a free draining
structure. For adequate ‘run off’, decks should be laid on a slight
gradient (at least 1 in 100). Grooved decking should be laid down the
fall to enable water ‘run off’ and ensure the groove ends can drain
freely, i.e. pack out fascia if required.
What gap should I leave between deck
Deck boards should be surface dry and laid with no less than a 6mm gap
between boards to allow for seasonal shrinkage or swelling. When
installing hardwood such as
decking, you should allow 8mm gaps as the product is kiln dried
hardwood and requires room for expansion in the wetter seasons.
Why is it advisable to loose-lay
components before securing them?
The longer the components, particularly deck boards, are left to become
surface dry the less the effects of shrinkage will be apparent after
fixing them. The timber can also be cut and sanded more easily when dry.
If the boards are allowed to fully dry out prior to fitting, the gap
between boards should be increased by 2-3mm to allow subsequent
expansion in the wetter seasons.
What type of fixings should I use?
For the very best results stainless steel screws should be used at 2 ½
times the thickness of the deck board. To avoid splitting it is
advisable to pre-drill pilot holes near the end of the boards.
Where can I obtain more detailed
The Timber Decking Association is an excellent source of information –
There are also a lot of installation guides available on social
networking sites such as You Tube, or on decking suppliers’ websites