Decking, when installed correctly, looks the part and functions, providing homeowners with years of longevity. This can be emphasised further by fitting newel posts, spindles, and balustrades properly, which makes the difference between a deck that looks great and one that actually feels safe to use.
Looking to put the finishing touches on a deck in the most professional way? This guide walks you through each element step by step, so you can get the job done confidently.
What You'll Need to Begin
Before you pick up a drill, make sure you have the following to hand: 100mm and 150mm landscape screws, 8mm galvanised screws (40mm and 63mm), a cordless drill and bits (8mm wood bit, 35mm forstner bit), a spirit level, tape measure, pencil, and exterior wood glue or silicone.
How to Fit Newel Posts on Decking
Newel posts are the structural backbone of your balustrade system, so getting them right from the start is essential. Plan where they’ll go before laying your deck boards.
For standard posts, fix them directly to the joists using 100mm landscape screws. Where possible, position corner posts so they can be secured through two faces into two joists running at 90° to each other, as this gives you far better stability than a single fixing point.
For heavier posts such as porch or lamp posts, you'll need 150mm landscape screws and a joist depth of at least 300mm (achievable by doubling up two 150mm joists). If your deck sits close to ground level and posts need to go into the ground, apply a waterproof wood preservative to the section that will be below ground.
Once your posts are upright and plumb, finish them with a ball cap or patrice cap.
Installing Decking Spindles
Spindles fill the space between your handrail and base rail, and the gap between each one is governed by safety standards. The maximum gap between spindles should be 100mm, which prevents small children from getting their heads through.
It's easiest to assemble your balustrading panels on a flat surface such as a garage floor before fixing them to the posts.
For colonial-style spindles, set centres at approximately 120mm to achieve the 100mm gap. For 57mm cedar rail systems, set centres at 137mm. Mark out your positions along both the handrail and base rail before fixing anything.
Make sure the groove of the base rail faces downward. Fix each spindle using No. 8 63mm galvanised screws. You can screw down through the top of the rail for a visible fixing, or pilot drill at 45° through the end of the spindle and screw up into the rail from underneath.
Repeat the process for the top rail. To hide the screw heads, place a second concealing rail on top and fix it from below using 40mm galvanised screws.
Lift the complete unit into position between your newel posts, keeping the bottom rail approximately 75mm above the deck board level. Fix the rails to the posts using the balustrading bolt method described in the next section.
How to Fit Decking Balustrades
The balustrade is the complete handrail assembly that runs between your newel posts. Building Regulations state that the maximum recommended length of balustrading between posts is 1800mm. If your run is longer than this, you must add an intermediate newel post.
Using an offcut of handrail, mark its profile onto the face of each newel post to establish where the handrail and base rail will sit. The bottom of the base rail should sit 75mm above deck board level, with the top of the handrail at 900mm above the deck surface.
At each marked position, drill the end section of the handrail using an 8mm wood bit to a depth of 60mm, measuring 10mm up from the groove. Then use a 35mm forstner bit to drill an access hole 18mm deep on the underside of the rail at 60mm from the end.
On the face of each newel post, drill a 9.5mm hole to a depth of 25mm at the marked positions, then screw in the threaded insert using a 6mm Allen key.
Screw the threaded bars into the inserts, position the rails onto the bars, and tighten using the combined pressure plate and nut supplied. Once secured, fill or cover the access holes with a cedar flush pellet and exterior wood glue.
Key Decking Accessory Measurements
Component | Key Measurement |
Max balustrade span between posts | 1800mm |
Handrail height above deck | 900mm |
Base rail height above deck | 75mm |
Max gap between spindles | 100mm |
Colonial spindle centres | 120mm |
Cedar 57mm spindle centres | 137mm |
Min. post fixing depth (heavy posts) | 300mm |
Finishing and Decking Maintenance Tips
Once everything is fitted, treat all cut ends with an appropriate wood preservative or end coat, particularly on pressure-treated timber. Any exposed end grain will absorb moisture if left untreated and will deteriorate far quicker than the rest of the deck.
Apply a decking oil or stain to the whole balustrade system annually to keep it looking its best and extend its lifespan.
Buy Your Decking Materials from Emerys
If you're based in the West Midlands and need decking components, including newel posts, spindles, balustrade rails, screws, and fixings, Emerys stocks everything you need to get the job done properly.
You’re welcome to visit our branches or get in touch to discuss your project.