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ultimate guide to garden decking

Timber decking is increasingly the material of choice for stylish or contemporary gardens.   Timber has inherent warmth and beauty which enhances its surroundings; making the atmosphere somehow softer, calmer.  Harmonious to plants with which timber has a natural synergy, timber decking also works well alongside other materials and offers huge scope and design flexibility.   It allows you to create unique and captivating spaces and is ideal for both private and public areas.

Decking is a particularly good product for sloping sites providing an easy and effective transition between the different levels.  It’s perfect alongside bi-fold doors, helping to connect outdoor and indoor living areas and increasing the feeling of space in both.  It’s also great for a quiet corner, a secret garden tucked out of the way, on rooftops or alongside waterways.  Its credentials also make timber garden decking a superb partner to pools or spas which are synonymous with relaxation.

This section of our website is where we house timber decking related guidance.  It covers projects from concept through to installation and aftercare.

IN THIS GUIDE I WILL COVER THE FOLLOWING ASPECTS ABOUT GARDEN DECKING:

So lets start with the design

Decks look good anywhere and can be either contemporary or traditional in design.
Some of the factors that need to be considered at the deck design stage include:

  • Is the site flat, sloping or difficult terrain – can changes of level be built in to add interest?
  • Is the garden decking to be wholly in the sun or a shaded area or need to combine elements of both; either naturally or by including features like an arbour or screening for protection against a prevailing wind?
  • Is the deck intended to be a private space or on public view. Will trees, shrubs, boundaries and buildings provide privacy?
  • Will the deck’s location interfere with services, like drains and manholes – access to these may need to be built in to the design.
  • Is the deck primarily for adults, for entertaining or for family use with a children’s play area – swing/sandpit included?
  • What features will be incorporated into the deck design eg planter boxes, seats, trellis, arbours, pergolas, storage boxes, sandpits, ponds – almost anything is possible.
  • Is a hot-tub spa, out of ground swimming pool, garden pavilion, shed, conservatory or other heavy structures going to be added at a later date? If so you will need to make sure that the structural specification of your deck is beefed-up significantly to take the loads that may be placed upon it.
  • What style of handrail and balustrades will I need to build in?
  • What type of timber do I need to use for the frame. Timber comes in various strength grades and for raised level decks you will need to use the appropriate structural grade eg (C16 or C24 grade).
  • If your frame is in contact with the ground then the timber needs to be suitable for ground contact use.
  • What type of board will be used for the surface of the deck? There are a wide range of species and styles available providing variations in grain pattern and colour. There is also a choice of plain, grooved or ribbed finishes to enable different effects to be created.
  • Is planning or building regulation approval required?

Planning and Building Regulations for Garden Decking

Garden decking are often considered to be exempt from planning regulations. This is not always the case. There are a number of specific instances where consent is required prior to building a patio, terrace or deck and these are set out below:

Situations Requiring Planning Permission (effective 1 October 2008).

  • Where the deck platform is more than 300mm (~1 ft) from the ground
  • Where together with other extensions, outbuildings etc, the garden decking or platforms cover more than 50 per cent of the garden area

In addition to the situations set out above, other restrictions have been known to apply:-

  • Where the deck is situated within 20 metres of a highway.
  • If the structure would affect the amenity value or privacy of neighbouring properties.
  • If the deck is attached to a listed building or situated in a conservation area or National Park.

Building regulations

Building regulations should be assumed to apply to every structure that requires planning permission.

With the exception of ground level outdoor decks, property owners should always check that planning regulations do not apply to their proposed structure.

In addition to contacting the Local Authority, neighbours who may be affected by the structure should also be informed. Neighbour objections are the most usual reason for planning refusal or restrictions.

Hardwood vs Softwood

Timber is broadly classified into two groups – softwoods and hardwoods. This can be confusing because the terms do not relate to the relative hardness of the wood but to the type of tree from which it comes. Softwood species come from evergreen coniferous trees, hardwoods from broadleaved trees. Within each group there are many different species of wood. Some are suitable for decking, some are not.

The key factor in selecting wood for use out-of-doors is durability – its ability to resist the conditions that give rise to decay (i.e. wood will start to decay when its moisture content is persistently above 22%).

Some species of wood have a natural ability to resist decay completely; others have varying degrees of natural durability and may require treatment.

 

It’s recommended that only timber capable of providing a minimum service life of fifteen years should be used. This means selecting:

  1. a hardwood species that is classified as being naturally “very durable” or “durable” or in some cases ‘moderately durable’; or
  2. a softwood species that has been industrially pressure treated with a wood preservative approved under UK Government regulations to the correct standard for its end use
  3. a low durability softwood or hardwood species that has been modified with heat (thermal) or chemical treatment to improve its durability

Softwood is used a lot more for garden decking because it tends to be less costly and easier to work with than hardwoods. However the rich attractive colours of some hardwoods add greatly to their appeal. Naturally durable hardwoods are usually higher in density than softwood and their impact and abrasion resistant properties are reasons why they are used on commercial projects that have a lot of heavy use.

Properly constructed garden decking using naturally durable species or appropriately treated low durability species can provide an equivalent performance.

Deck board options

Deck boards come in various sizes from 75mm to 150mm wide and are plain / smooth, ribbed or grooved in appearance.

To enable fast drainage and reduce the effects of movement caused by the moisture content the it’s not recommend using any board wider than 150mm. 

The wood should be straight grained and have a moisture content no greater than 20%. This will reduce the risk of distortion caused when timber with higher moisture levels dries to suit the local conditions.

No matter what type of deck board is chosen the edges of each board should have a machine chamfer or radius to aid drainage and prevent damage if boards do move in service.

As a further aid to drainage a slight fall, 1 in 100, should be built into the deck structure. If the deck is attached to a property then the fall should be away from the building.

Grooved boards were designed to facilitate draining of the surface and should always be installed with the grooves in the direction of the fall. The grooves should be swept clean of any debris or dirt to prevent the boards from becoming saturated in wet weather by utlizing a cleaning service, which is the principal cause of slipperiness.

A gap of no less than 4mm and no more than 8mm should be left between boards to allow for the natural movement of timber over the seasons and help surface drainage and ventilation of the entire structure. Leave a gap of 4mm where a deckboard abuts a post and no more than 2mm where deckboards abut one another lengthways.

Enhanced grip boards are available with inserts of non-slip material for use in areas where improved grip is required e.g. steps, ramps and key areas of decks and walkways for public access. DeckMark® Plus is a quality and performance rating scheme for these type of boards. It identifies enhanced grip boards that have been independently tested for slip resistance to a UK Slip Resistance Group guidelines and British Standard BS 7976-3:2002+A1: 2013.

Decking finishes

Staining is a highly effective way of decorating and personalising a garden decking.

Water repellent coatings can be used to improve the water repellency of timber. This is suitable for both hardwoods and softwoods. These coatings help to prevent water absorption and improve the weathering properties of your deck.

Some suppliers offer preservative treated timber with water repellent or colour already built into the decking. This might be expensive but this supplier gives you one year interest free financing, Green Touch does the same thing for its customers.

If you want to paint your deck with a natural wood shade or fashion colour, here are a few points to bear in mind:

  1. Make sure your choose a product designed for outdoor use on a decking surface.
  2. Use a penetrating product rather than a film former. Film formers can be problematic on an outdoor horizontal surface leading to cracking and flaking of the paint film.
  3. Always follow the manufacturers’ recommendations when applying and maintaining the coating
  4. You will need to re-coat at certain intervals as recommended by the manufacturer to keep the finish in good condition.