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Ultimate Questions Answered About Installing Composite Decking

We’ve trolled the internet and found the most common FAQs that people ask about how to install composite decking. Find below the answers to questions people regularly ask about.

What timber do I use for decking frame?

If you’re building your decking yourself, our advice would be to ensure the supporting structure is safe, secure and strong.

To ensure a strong and safe structure, we advise the use of c16 graded timber. This type of timber has been structurally treated and will be safe and strong for many years to come.

Ensure you put a piece of landscape fabric and gravel down to thoroughly protect against any possible rotting.

If you are raising the deck we would also advice 6 by 2 and for ground level 4 by 2 or 6 by 2 will be fine.

What is the joist spacing for composite decking?

Recommended joist spacing is 300mm apart. To ensure a strong long lasting substructure underneath your decking. It is extremely important you follow the installation guide of the supplier. You could go to 400mm apart with the joist space. Beyond this, the structure may experience bouncing leading to further strength and structural issue at a later date. It’s best to do it right first time.

How do you lay composite deck boards?

Laying composite decking boards is the same as laying wood decking, you can use all the same material and tools you would use on a wooden decking installation. You must ensure the correct spacing and gaps of 6mm are in place. Please do read the supplier’s installation guide to be safe and accurate.

Does composite decking expand?

Due to the changes in weather Composite Decking boards do go through thermal expansion and contraction. It is to follow the supplier’s installation guide especially on the spacing and gaps between the decking boards. If not this could cause future issues.

How to cut composite decking boards?

Composite decking boards can be cut just like wood, if you are using a tooth saw blade we recommend using a 40-44 tooth saw blade do this, the key reason for this is the more teeth the slower the cut and you run the risk of building the materials you are cutting.

When cutting with a 40 tooth saw blade on composite decking or any decking always bear in mind the slower the cut the better the finish, if you do rush the cut you will not get a smooth finish and may even have blade marks on the edge of your deck. So do go slow and get a smooth finish.

One thing you may notice once you have cut the boards on a capped composite decking board is the hairs left over, you can remove these in two ways. Sanding the cut area or best is to run a Stanley blade down the cut to get a smooth finish.

Can composite decking be stained?

Yes. First generation composite decking can be stained. (link). There is no need to stain Second Generation (link) due to its capping or shield (link).

If you are staining your first generation composite decking (link) please allow the fade (link) of the 3-month weathering process to be completed before applying any staining product. Due to the wood fibre surface, you can stain with most normal wood decking staining products.

Please thoroughly clean your composite decking area (link) before applying any staining products.

How much does it cost to install composite decking?

Installing composite decking compared to installing a normal wooden deck there is no difference apart from the spacing and gaps, in relation to materials cost for installation this is down to the design of your decking area.

One key factor to keep in your mind is the quality of the composite decking you are purchasing. This truly does make a huge difference.  Although over the years some fading will occur, you have to consider that all materials used have to be grade A and tested. If they are you will have no issues with colour for decades, for homemade tests follow the link.

Can you nail composite decking?

You can nail or screw composite decking boards (link) just like wood, we don’t recommend this as the head of the nails don’t sink into the composite decking material well. The safety and most efficient method to fix the boards to the joists or substructure is with the use of hidden fasteners (link).

How do you install composite decking with hidden fasteners?

Installing hidden fasteners is very easy. Most suppliers will supply a “T” clip hidden fastener. These are the method in our view compared to a metal hook fastening system. You could argue that a metal fastener is stronger, the downside is they hook over the screw heads making them difficult to access should you ever need to get under the boards or even want to use the reverse design. Some composite decking boards come different designs on opposite surfaces.

Another great thing with “T” fasteners is they offer a natural 6mm gap needed for expansion and contraction (link).

Should composite decking be spaced?

Composite decking should always be spaced with the recommended gap between the boards (6mm). Always follow the supplier’s installation guide

What type of screws do you use for composite decking?

Do you have to pre-drill composite decking?

Another benefit to composite decking (link) is you don’t have to pre-drill due to the advanced technology. This is normally a requirement for wood decking installations, therefore saving you time.


Can you screw into composite wood?

You can nail or screw composite decking boards (link) just like wood, we don’t recommend this as the head of the nails don’t sink into the composite decking material well. The safety and most efficient method to fix the boards to the joists or substructure is with the use of hidden fasteners (link).

How far apart should deck posts be placed?

The general rule of thumb with deck posts, they should be spaced no more than 2.4 meters apart. Most installers and fitters will position the deck posts every ever 1.2 meters to offer a completely rigid sub-frame.

Starting with your perimeter, mark the location of each deck post. These should be no more than 8 feet apart. Some builders position them every 4 feet for a completely rigid frame. The maximum distance between footings is determined by the size of your joist material.

Is composite decking slippery in the winter?

Once ice, snow and algae build up on a wooden deck during winter it becomes a serious slip hazard.

Composite decking will stand up to the harshest winter conditions becoming less of a hazard than it wooden cousin mainly due to its slip resistant design and surface properties.

The main reason a deck becomes slippy is the build up of algae, mould and mildew. These issues are almost completely resolved, especially in second generation composite decking due to its shielding.

To ensure your deck stays safe in the winter, Ultra Decking advise to regularly brush off any leaves and dirt. Also, give your composite deck a soft brush with warm soapy water every autumn.