How To Replace Parts of a Staircase | Wickes

Looking to make a big difference to your hallway? Replacing your stair rail can absolutely transform the space, and it’s a job you can do yourself. So, get your spindles, rail and newel posts, and let’s get started.

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Step-by-step guide

Before you build anything, you’ll need to take down your current stair bannister. Start by removing the spindles. The best way to do this is to saw the spindle in half and remove each half separately.

To remove the rail, unscrew the fixings in the newel post and pull out the rail. Different rails will be attached in different ways; Ours had a wooden plug that needed boring out with a Forstner bit, and then the fixing inside needed unscrewing from the front of the newel post.

Top tip: When removing the rail, it’s a good idea to have another person around to help hold and carry it from the other end.

Next, you’ll need to remove the newel post. Only remove newel posts if they do not form a structural part of the staircase. If you’re using a one-piece newel like we are, we recommend this is fixed central to the string and central to the first riser.

Note: If you’re cutting the existing post down and using the existing newel base with a new spigot newel, ensure that it is cut to the minimum cut off point height above the pitch line i.e 260mm for bottom newel and 195mm for top newel.

Remove the fillets from the base rail. You’ll also want to take out any screws fixing the base rail to the string. If the rail has been glued and secured with nails, gently pry it from the string with a small crowbar and remove the nails afterwards.

Once everything has been removed, clean up any sawdust with a vacuum.

You may need to shorten your newel post before you install it. To do this, decide on the height you’d like it to be and use a mitre saw to cut it down to size. The minimum height for a handrail is 900mm, so it’s best not to cut the newel any shorter than 950mm.

When we removed the previous newel post, a bolt and dowel remained. If fixings like these remain from your original post, leave them in and measure where they will sit on your new post. Drill holes to fit these existing fixings and dry fit to make sure the newel post slots into place. Apply wood glue to the holes and onto the side of the stair base, using a paintbrush to spread the glue across the surface. Push the newel post into position, knocking it in with a rubber mallet.

For our newel post, we used a socket wrench to secure a nut onto the existing bolt. Yours may be different, so check the instructions for installation tips.

Use the measurements from your old base rail to sketch out where you’ll need to cut the new one. Then double-check the angle of your stair rail using a sliding bevel. This is the angle you’ll want to cut the base rail at. Measure the distance between the top and bottom newel posts using a tape measure and make a mark this length on the new base rail. This will be your cutting line. Cut on the line with a saw and check the fit between the newel posts.

Dry fit the base rail to make sure your cuts and measurements are accurate.

Drill approximately 5 pilot holes along the length of the base rail at equal increments.

Apply a line of glue all the way up the centre of the string and onto each end of the base rail. Press the base rail down. To ensure it’s perfectly centred, measure each side of the rail with a combination square before making your first pilot hole in the string. Drive a screw into the pilot hole to secure the base rail and continue this process all the way up the stairs.

Measure the height you’d like the top of your handrail to sit at and make a mark. Remember that this needs to measure 900mm or higher, measured from the bottom of the base rail to the top of the handrail, so it will need to sit on or above this measurement.

Cut the handrail to size using your previous rail as a guide and cutting the ends at the same angle you measured with the sliding bezel earlier. Your handrail and base rail should be the same length and cut at the same angle.

Dry fit the handrail between your newel posts to check it fits.

Then find the centre of the end of the handrail and drill a hole into it with a 6.5mm diameter drill bit for softwood or 7.5mm diameter drill bit for hardwood.

Top tip: You don’t want to drill any further than 65mm, so mark this onto the drill bit with masking tape.

With your handrail on a flat surface, drill your hole, making sure you’re drilling perfectly straight. Then drill a counter-sinking hole using a 12mm drill bit. You’ll only want this one to be 10mm deep.

Top tip: Begin drilling at an angle so the tip of the spade bit catches the wood. Then gradually straighten out as you go.

Then secure the handrail to the newel posts using a Handrail to Newel Fixing Kit. This is essentially a screw with a hinge that lets you fix the handrail to the newel at the correct angle. First, use an adjustable spanner to drive the screw into the handrail until the centre of the bracket hinge is flush with the rail face. It’s a good idea to do this slowly so you don’t damage the wood.

Use an offcut of your handrail to mark the top and bottom edges of the rail - then mark the centre of where it will sit. Draw a horizontal line across this centre point and continue it around to the inside face of the newel post. Make a mark 25mm into this line. On the inside face, use a 25mm drill bit to drill a hole 60mm into the post.

Back to the front face, use a 12mm drill bit to drill into your centre marking until you intersect with the previous hole you made.

Sand off your pencil marks.

Place the fixing nut into the large hole on the inside face of the post, flat side first. Dry fit the handrail and then apply wood glue to the fixing.

Insert the handrail screw into the smaller hole. Tighten the mechanism up with a hex key in the larger hole.

Disclaimer: The rail to newel bracket only works if you are installing new newel posts. It is not suitable for use between existing fixed newel posts.

Confirm the angle of the rail.

Measure the height between the base rail and the handrail. You’ll want to measure from the bottom of their recesses, as this will now be the height of the spindle.

Top tip: Your tape measure may not reach all the way into the corner of the recesses, so use a ruler or combination square to get into these crevices, marking 10mm on each end and using your tape measure for the more easily accessible length in the middle. Add the extra 20mm to the tape measure measurement.

Cut each spindle at the angle of the rail, both at the top and bottom. These cuts should be angled in the same direction.

Get two spindle offcuts and place them on the base rail 100mm or less apart horizontally. Find the rake measurement between them and keep this number in mind for later.

Note: When installing spindles, there should be no gap greater than 99mm anywhere within the balustrade.

Note: if your spindles are turned, measure from the thinnest part of each.

To make sure your spaces will be equal all the way up the rail, do the following calculation:

Measure the overall length of the base rail on the rake. Estimate the number of spindles you’ll need, multiply this by the width of one spindle, and take this number away from the full length of the base rail.
Divide this by the number of spindles + 1 to get the length of each space on the rake. This number should be just below the rake measurement between your two offcuts that you measured previously. If it’s above, you’ll need to use more spindles and recalculate the spacing.

You can also use this general rule if you don’t want to estimate your spindle number:

Measure the horizontal distance between the bottom and top newel posts.
If using 32mm spindles, divide your measurement by 112 for turned spindles or 125 for plain spindles, then round up to the next whole number for total spindles required.
If using 41mm spindles, divide your measurement by 121 for turned spindles or 135 for plain spindles, then round up to the next whole number for total spindles required.

Top tip: If maths isn’t your thing, there are a few online tools that can help you work out these calculations.

Your base rail and handrail will come with a long plank of wood that fits snugly into their recesses. This is used to cut into fillets that slot between the spindles to space them out. Each fillet will need to be cut on both ends at the angle of your stairs that you previously worked out.

Add some PVA to the bottom of the first two fillets and place them at the bottom of the handrail and base rail against the newel post. Use a nail gun to secure them in place. Apply some PVA to both ends of your first spindle and slot this in next to the fillets. Make sure this is straight using a spirit level and secure with a nail gun.

Continue up the stairs in the same way until you get to your last fillets. These should fit perfectly into the final gap and may need a little tap with a mallet to fit snugly. Pin the fillets into place.

Finally, apply wood glue around the wood covering that comes in the handrail to newel fixing kit, line up the wood grain, and place it over the hole in the newel post. Tap it with a mallet.

If your newel post requires a topper, glue this on after installing the rest of the banister - it may also need a light tap with a rubber mallet to secure fully.