Why substructure is so essential for safe decking

Installing a sub-structure is imperative when you are building decking. This is because it is the foundation of your deck. It might not be the part that everyone sees but it is certainly the most important part.

As with building any solid structure from a house to a shed, getting your foundations right is key to ensure the longevity of the build. While nailing the appearance of your deck is key, firstly you need to know that you are working on solid ground, i.e., that your substructure is strong and safe.

This is why we have put together our thoughts on why substructures are so essential for constructing safe decking and how you can go about building a resilient and long-lasting deck.

A deck’s substructure is made up of footings, posts, bearers and joists. Whether you are building your deck yourself, or getting the work done for you, the project starts by digging deep into the ground, way below the frost line. Then concrete is poured into the hole, before posts are installed to create a firm basis on which your deck can be built.

Bearers  must then be fitted to the posts. They are large, thick sections of timber (or even steel if the project is a large public area) and help to create a solid, immovable structure – usually two on each side of each post. Joists should then be fitted connecting the bearers at smaller spans, from which you can then create your deck.

As with any building work, always ensure that you are following your local building codes, which will ensure that your footings are deep enough in the ground to provide a strong, stable base, and that you have positioned the footings properly (usually 6 feet apart). We recommend you check with TDCA for advice.

You must then consider waterproofing your work as it will be exposed to the elements all year around. You need to waterproof more than just the wood you can see. Water damage can start way below the surface, but by using joist tape and beam tape you will protect your deck for years to come.

You will also need to think about what type of wood you will use to build your substructure. Pressure treated lumber is often advocated for building substructures because it is less palatable to fungi. It is also extremely strong and resilient, not to mention well-priced. However hardwood options may be a more environmentally friendly alternative with similar or even better life-service.

Lastly, it is time to lay the deck boards over the joists. We recommend stainless steel screws, two in each board at every joist intersection. This will help with limiting the movement of your decking boards as they finally season in place whilst giving you years of enjoyment. Do check our other blog on maintaining your deck too.

Here’s an Ecochoice project: Hastings pier, where you can see steel bearers, sawn joists and planed smooth decking:

It is so important whether you are building your deck yourself or hiring a professional to do it, that you know the importance of each step and the ins and outs of the materials you are using. Researching the job in advance will ensure that you avoid the painstaking effort of having to do all of your hard work all over again and you can concentrate instead on maintaining your deck as a fun, social space to entertain for years to come.

At EcoChoice, we promote using FSC certified timbers for all purposes, from building, landscaping, civil and marine industries and residential or commercial decking is no different. It is important to know that your decking not only looks good, but has been responsibly harvested from the world’s forests, so contact us on 0345 638 1340 for a quote or for any advice.

Images: Ulga / Shutterstock.com, Nils Versemann / Shutterstock.com

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Safe decking installation

Ask Joe! Expert industry advice

Unsure which timer is best for your project?

Our timber experts have years of experience and will be able to match the perfect species to your project, as well as provide a quote for sustainable timber at highly competitive prices.

Frequently asked questions

Do you supply timber for domestic uses?

Yes, we supply timber for domestic applications as well as commercial and public constructions. From garden decking to shed cladding, we will be happy to supply smaller deliveries for home use.

Is your timber FSC-certified?

Yes, all timber we supply is FSC or PEFC certified and sourced from independently verified responsibly managed forests. If we can’t find your request in FSC/PEFC certified timber we’ll suggest an alternative that is certified or clearly note that the offer is minimum EUTR.

Where does EcoChoice deliver to?

EcoChoice delivers to construction sites, warehouses and homes across the UK, as long as there’s access and unloading for our trucks.

What are the best timber species for exterior use?

There are many different timber species suitable for exterior use and which is the best for your project depends on your requirements. In general, though, we recommend EkkiGreenheartOpepe and Oak for heavier civil/marine uses. For intermediary external use such as decking, where the timber needs to be both strong and durable but not on the same level as civil engineering (bridgespiling, etc) we usually supply CumaruIpe, Jatoba, and Balau. And for the lighter exterior use where the timber is non-structural such as cladding, we deliver CedarLarchThermowood and others.

Which timber is the most durable?

Durability Class 1 timbers are the most durable. This of course depends on the use (hazard) class they’ll be in service for. For direct ground and water contact such as sleepers, fenders, marine piling, etc, Ekki and Greenheart are known to be the most durable timbers available. For decking and cladding where there’s no direct ground contact (use class 3) there’s a much wider range of timbers such Larch, Cedar, Thermo modified Pine or Ash and others.

What’s the best timber for internal cladding?

Internal cladding, where your timber is not in ground and not exposed to the elements can be classed as either use-class 1 or 2 – in which case most timbers will meet this durability criteria. That is not to say they’ll be the best, since internal environments have lower humidity (moisture) levels than outside. So in these cases, it’s best to go for a kiln-dried timber cladding board as these are more stable and delivered already in lower MC (moisture content) than the usual fresh sawn timbers sent to external applications. A word of caution – as timber reacts to variations in moisture, it’s best to avoid cladding any areas inside your bathroom.

How can I make decking less slippery?

The first thing is to ensure your deck boards are kept clean from leaves and other debris which will, over time, cover the surface and make it more slippery. Grooved boards can be used to improve grip if installed and used perpendicular to traffic, so especially useful in narrow passages and footbridges. Lastly, you can add our Grip-Choice strips: these are a mix of epoxy with aggregates that add gripping ridges to your deck area. Gripchoice is an easy way to make decking less slippery and safer, especially over large areas or where there’s high traffic. We can pre-install Grip-Choice strips for your decking before delivery or ship the strips separately to add to your existing deck’s grooves as a retro-fit solution.

What wood machining services do you offer?

We can offer planing, sawing, drilling and profiling of rough-sawn wood to any profile you require: from handrails to large port fenders.

Can you supply pre-drilled timber?

Yes, we will be happy to provide pre-drilled timber which is tailored to your needs for quick installation, thus saving you valuable time on site.

What cladding profiles do you supply?

We provide a wide range of cladding profiles, including tongue and groove, featheredge and shiplap. You can check the standard profiles here – but we can also match or custom make profiles to suit your specific needs.

Does timber change colour?

Yes, timber is well-known for changing colour over time. Some species can darken quickly right after installation, and like most untreated wood will eventually weather to a beautiful silver-grey. Interior timber is less likely to change colour (depending on conditions), and timber can be stained, painted or treated with UV-resistant oils to reduce colour change.

Do I need to treat exterior timber?

Some timbers such as Oak and Ekki, can withstand the strains of exterior use without any treatment. However, to extend the lifespan and maintain the aesthetic of your wood, we do recommend treating your timber with stains and oils. Pre-treated timber, such as ThermoWood and OrganoWood, are low-maintenance options which are more durable, but can have their life service extended by applying a clean and stain maintenance schedule.

Do I need to treat interior timber?

Depends on what area the timber is being used. For floor joists and timber rafters, it is common to see timber treated, or least very well kiln-dried. Other uses such as flooring may benefit from varnishing while internal timber cladding for decorative purposes shouldn’t require any treatment other than if you want to change its colour with different types of stains or oils.

Where are you based?

We’re based in Cambridge, UK, and coordinate multiple sawmills all over the world to manufacture your order. We then organise delivery with a range of hauliers so that your orders gets to your site on time.

What are the usual decking sizes?

Timber decking is usually 21x140mm or similar. For heavier applications where there’s more load and traffic, we deliver 35 or 45mm thick boards (such as Hastings Pier). Narrower boards are also possible: 95-90mm is a standard width – but we can manufacture whatever size you require.

What are the usual cladding sizes?

Typical cladding section sizes are 18×95 and 18x145mm although we can always custom make a section to suit your project’s design requirements. That includes waney edge boards in Oak or Chestnut as well as extra wide 195mm boards.

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Marinella Li

Always helpful! One of our valued TDCA DeckMark and CladMark accredited supplier members which means their quality procedures are routinely audited and stand up to scrutiny giving you extra peace of mind.

5

Janet Sycamore

Having needed the supply of cladding, decking boards and other specified timbers through out the year Eco choice have been very helpful in sourcing the specified timbers and quantities required at a very competitive price.

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Tim Saunders

Great quality, service and price. A pleasure to deal with. I would highly recommend Eco Choice.

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Fantastic company- Mike and the team are the best in the business- worked with them for many years.

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  • 6 years ago

Great quality, service and price. A pleasure to deal with. I would highly recommend Eco Choice.

Emma Hurrell

  • 6 years ago

Fantastic company- Mike and the team are the best in the business- worked with them for many years.

Prem Raja

  • 9 years ago

Experts in Timber, Nationwide delivery

Joe Middleton

  • 3 years ago

Always helpful! One of our valued TDCA DeckMark and CladMark accredited supplier members which means their quality procedures are routinely audited and stand up to scrutiny giving you extra peace of mind.

Janet Sycamore

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