To Deck or Not to Deck

 In Garden Design, News

Gareth and I met through our mutual friend Rae Wilkinson. Gareth got in touch with me on Instagram and we started chatting. We first met at the Chelsea Flower Show in 2021. By this time, it felt that we already new each other. Since then, we have become very good friends and often discuss the good and the bad of landscaping. I invited Gareth as a guest blogger to write about decking.

My Background

With over 30 years’ experience building landscaping projects for domestic clients, I have built more decking areas than I care to mention! I have also taken part in many manufacturers’ courses and training days.

Down the years, my clients have asked for their decking areas to be built in a range of materials including hardwood, softwood, and composite. Today, however, the overriding trend is for the latter of these. Composite decking has several advantages to other materials, but there are some drawbacks too.

I will set out the pros and cons of different types of decking and touch on some installation tips too if you are a DIY fan!

RHS Chatsworth. The Mindfulness Garden
Designer: Rae Wilkinson
Contractor: GKWilson Garden & Landscape Consultancy Ltd.

The decking used on this show garden is a composite decking called Design Board by Londonstone. The composite contains rice husks.

Why Choose Decking?

Decking is a great alternative to paving, providing a somewhat warmer feel and texture to your outdoor space. It has been a popular alternative to paving for almost 25 years.

Decks are very versatile and can be used in a wide variety of situations including balcony gardens, roof terraces, elevated wetland pathways, floating steps and raised decks to maximise garden views (with planning consent of course).

Acacia hardwood decking is very durable and long lasting with a beautiful warm brown colouration. By using planks at different angles, decks can be made to look really interesting.

Types Of Decking

Decking options fall into three main product categories: softwood decking, hardwood decking (which range from English oak to tropical hardwoods) and of course the market leader – composite. You could add aluminium decking too but that is more of a commercial product and rarely found in domestic gardens.

What To Consider With Decking

Softwood decking boards should be slow grown in cold climates such as Sweden. The colder the climate the closer together the growth rings are and, as a result, more resistant to rot. Softwood decking boards now come with anti-slip grip pads attached to the boards to give extra grip.

Hardwood decking should come from approved managed forests and should carry the Forest Stewardship Council (FSC) logo, ensuring it is from an environmentally sustainable source. To maintain the colour of hardwood decking you will need to treat the decking on a regular basis.

Composite decking comprises a mix of materials including plastic and hardwood, making the boards very durable and weather resistance. When using composite decking boards, you are always better off with a solid deck board as opposed to hollow deck boards. Hollow boards are usually poorer quality and can be prone to splitting. Solid deck boards provide a guarantee of 15 years upwards when obtained from a reputable supplier. Most composite decking manufacturers use recycled plastics and tropical hardwoods but be sure to buy from a responsible supplier or manufacturer.

What are the pros and cons of decking?

– A well-built and designed deck can add value to your property and is a great selling point when mentioned on your listing.
– Decks make a great place for entertaining friends and family.
– Decks can also provide a great place to sit and relax at the end of a tiring day or week.
– A carefully placed deck can frame the perfect view and provide hours of relaxation.
– It’s quite simple to add on pergolas and other structures later to a deck.
– Composite decking and some tropical hardwoods are guaranteed for up to 25 years, therefore getting good value for money.
– Composite deck boards come in wide variety of colours and textures.
– Composite decks require a lot less maintenance.

– Decking requires planning permission if you want your deck raising above 300mm.
– Timber decks are high maintenance and if left unmaintained can become very slippery and look shabby.
– High end composite and hardwood decking boards are expensive.
– With the likes of Millboard decking, hardwood decking and Trex decking you will need a highly competent landscaper to build a good deck that will last. Some composite decking manufacturers will train installers.

The most popular hardwood decks are constructed from Ipe or Balau. It is important to maintain your timber deck. Do not let it dry out. Best to oil it with Osmo oil.

Decking Sub-Frame Construction Top Tips:

A decking sub-frame is the framework upon which the decking boards are laid. This is in many ways the most important part of a deck.
– I often see landscapers, when building decks, using a class 1 or 2 treated timber which is only standard treatment. If a timber sub-frame is your choice, ensure a class 4 (UC4) treated timber is used to give your sub-frame maximum longevity.
– You might also use composite joists and noggins for your sub-frame which will give a lot more longevity to your deck.
– Use decking tape on top of the joists and noggins on the sub-frame for additional protection.
– A very important tip is to treat any cut ends of timber when building the sub-frame as these ends are untreated, they could rot quickly if not sealed or painted.
– To give your sub-frame more longevity always use composite support posts which won’t deteriorate for at least 25 years.
– To prevent weed growth coming through the decking, install a non-woven geotextile weed suppressant membrane on top of the ground under the deck and lay 50mm of gravel on top

Here the sub-frame has rotted away causing the deck boards to sink. This clearly shows poor sub-frame construction.

Photo credit: The Decking Network.

General Decking Top Tips:

Whenever using hardwood decking you must use stainless steel screws or the oils in the timber will react with the zinc coating in standard screws and you will get black staining.

When using screws on timber decks make sure the screws finish flush with the surface of the decking boards otherwise if the screws are set too deep into the decking boards the holes will hold water and cause early decay.

All decks should have a fall/gradient to displace water off the surface of the deck so water cannot settle on the surface. A 1-80 gradient or fall is preferred.
If using a timber sub-frame always ensure there is a minimum of a 60mm clearance between the ground and the sub-frame to allow for airflow and prevent possible dry rot issues.

This image shows screws that have been set too deep. They are beginning to show signs of rust but also causing the deck to start rotting. Screws should always finish flush on timber decks

Photo credit: The Decking Network

When using clips systems to secure composite decking boards down to the sub-frame, don’t over tighten the boards or they will dip and hold water.

As a rule, composite deck boards should have a 6mm contraction and expansion gap on mitred corners and where boards may meet a picture frame border or where two boards meet in the middle of a deck.

Decking can be used not simply for the floor surface but in other innovative ways to create in-built furniture or containers for planting. Containers would need to be made waterproof internally.

Decking remains one of the most popular choices for today’s garden. It provides additional outdoor living space to be enjoyed when the weather allows! Finally, you can inject plenty of colourful plant life to your decked area by adding pots, planting and raised planters, creating your own personal oasis.

Gareth Wilson MCIHort, FPGCA, BALI Judge
GKWilson Garden & Landscape Consultancy LTD
Independent Expert Witness & Garden Consultant.
Tel: 01457 868933 / 07753 283878

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