How to Fit a Bathroom Sink (Step-by-Step Guide)
Bathroom sinks are prone to chips, stains and scratches due to frequent everyday use. So, it’s likely that you’ll reach a point where you want to replace the sink to freshen up the appearance of your bathroom.
Whether it’s been a while since you last fitted a bathroom sink or you need some help doing the job yourself, we’ve got you covered in this step by step guide to installing a bathroom sink. We’ll look at:
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- What tools do I need?
- Remove the old sink
- Prepare the basin
- Install the basin
- Connect the basin
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What tools do I need?
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- Silicone or builders caulk
- Pliers
- Adjustable spanner
- Screwdrivers
- Plumbing sockets
- Pencil
- Drill
- Tape measure
- Spirit level
- Pipe and cable detector
You might also need a bucket for any waste or water and a sheet to keep the area clean.
Removing the old sink
If you are replacing an existing sink, you need to remove it safely first. If you are installing a new sink into a blank canvas then you can skip straight to step 6 in the next section.
This is what your sink and pipework should look like.
Step 1
Turn off the water supply and empty the faucet lines
Locate and turn off the stopcock by twisting it clockwise to turn the water supply off. Turn the taps on to relieve the pressure in the pipes and empty the faucet lines.
Step 2
Disconnect the P-trap pipe
Loosen the connecting nut by hand. You shouldn’t need to remove the P-trap pipe unless you wish to clear it of debris so you should place a bucket underneath to catch any dripping water.
Step 3
Unfasten the hot and cold water lines
Use a crescent wrench to disconnect the flexible lines that run between the underneath of the faucet and the shutoff valves. The faucet lines can be reused later if you wish.
Step 4
Measure the size of old sink
If your new sink will sit in the same place as your old one, you should measure the dimensions of your old sink first. That way, you know what size your new sink needs to be.
Step 5
Remove the sink
Cut the silicone if necessary and remove the existing sink unit but be careful in case there is still some water in there.
Prepare the basin
Once your old sink has been removed, it is time to install your new unit.
Step 6
Align with water pipes
Take your new pedestal and sink basin and move them into position, making sure they align with the pipework and sit flush against the wall.
Step 7
Check it is level
Use a spirit level to check the pedestal and basin are level and mark their position. Next, you will need to mark the position of the fixing holes which differ depending on whether you’re fitting to a masonry or a stud wall. The smaller holes are for fitting your sink to a stud wall or plasterboard and the larger holes are for fitting your sink to a masonry wall.
Step 8
Check areas around the basin are free of hidden pipes and cables
Move the basin and pedestal carefully out of the way and use a pipe and cable detector to check for any hidden pipes and cables.
Step 9
Locate the position of studs if fixing to a stud wall
Use a stud detector to check for the location of the studs if you are fitting the sink to a stud wall. You could fit the sink directly onto timber studs but if they’re not aligned with the fixings, you’ll need to install a support board.
Step 10
Fit the taps
Take care to lay the basin on the floor and fit the basin taps by following the manufacturer fitting instructions.
Step 11
Fill the basin waste
Apply some silicone to the washer and fit the basin waste. This creates a watertight seal.
Step 12
Secure washer & wipe the silicone
Tighten the nut using an adjustable wrench to secure the washer in place and wipe away any excess silicone.
Install the basin
Now it’s time to install the basin into your bathroom.
Step 13
Drill the holes
If you are drilling into a tiled wall, cover the tiles with masking tape before you start drilling and use an appropriate drill bit for the wall to drill your pilot holes.
Step 14
Install the fixing
Use wall plugs for tiled walls, a plasterboard fixing for plasterboard walls or a wall plug and fixing bolt for masonry walls.
Step 15
Drill the floor holes
When installing the pedestal, the type of floor you are installing it onto will affect the size of the hole you need. Drill 2 x 8mm holes approximately 40mm deep into concrete floors and insert a wall plug until it is flush with the floor or drill 2 x 4mm pilot holes, approximately 30mm deep into a wooden floor.
Step 16
Fit the P-trap pipe
Reattach the P-trap pipe to the waste system but make sure you do not overtighten the washers once they are in the correct position.
Step 17
Move the pedestal and basin into position
Once the pedestal is back in position, place the basin on top and use a spirit level to check it is level. It should be flush to the wall and the bolts should be through the holes in the back of the basin if you are fixing it to a masonry wall.
Step 18
Fix into position
It’s time to secure the sink into position but try not to overtighten the screw. Tighten the washers and fixing bolts into position on masonry walls or insert and secure a screw on either side on stud or plasterboard walls and secure the pedestal to the floor.
Connect the basin
Finally, connect the basin and your sink will be ready to use.
Step 19
Connect the flexi hoses
Using the same flexi hoses you disconnected earlier, reconnect these from the water supply to the tap.
Step 20
Connect the P-trap pipe
Connect the P-trap pipe to the outlet and secure it in place by tightening the nut by hand. These waste pipes will carry wastewater down the drain, away from the sink.
Step 21
Apply sealant
Use silicone sealant to fill the gaps between the basin and wall and the pedestal and floor and leave it to dry before switching on the water.
Step 22
Turn on the water supply
Open the hot and cold water valves back up by turning them anti-clockwise then turn on the faucets. Switch the taps on fully and allow the water to flow for around 2-3 minutes whilst you check beneath the sink for any leaks.
So there you have it. Your step-by-step guide to replacing a bathroom sink. This guide will help you fit full pedestal sinks from start to finish. However, if you are unsure about anything, to prevent causing any damage, you should always seek professional help.
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