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How to fit Belfast, Butler and Farmhouse Sinks.

If you are fitting a Belfast sink with a weir overflow like the one below then you will need to take particular attention to the order of fitting. The problem with fitting true Belfast sinks is that the weir overflow channel continues inside the moulding of the sink through to the underside. Effectively this means that the sink does not have a flat bottom and consequently cannot be simply slid in place.

Fitting a Belfast sink with a traditional, weir type, overflow.

Belfast sink weir overflow
underside of Belfast sink
Belfast waste outlet close up

If you look at the underside of a Belfast sink it will have a protruding waste outlet to incorporate the channel to take overflow water from the overflow to the trap.

On most base units, this will require a cut out in the base to accommodate the waste outlet. This obviously limits any sliding movements of the sink once in place. Make sure you leave a bit of play in the cut.

Practically speaking this protruding waste poses a dillema in fitting the sink. Firstly the sink must be in place before you fit the worktop, then once you fit the sink in place you block access to fitting the taps. You would usually fit the worktops before fitting the tap but in the case of a Belfast, it would become near impossible to have enough reach to fit them after the sink is fitted.  You can overcome these problems by fitting the Belfast sink using the following method.



Place the sink loosely in place in the base unit, (allow a bit of play when cutting out the base for the waste outlet.) see above  


Position the sink so the front (the apron) of the sink is in line with the worktops.


The radiused edge to the sides of the sink should now end approximately  to the front of the units.  This is not set in stone and you may wish to have the sink further forward or back to suit your taste.


Cut access holes, (or one larger inspection panel) to the inside rear of the base unit  to gain access to water pipes once fitted. Some units have a removable back panel, if not, consider fitting one ?


Attach the taps to the worktop, use long pipe tails or long flexible tails. Stand worktop onto base units on edge if it's easier,

fit the worktop, with taps connected into position.


Thread the flexible pipes, if used, through the void and into the holes in the rear of the cabinet, or locate pipes to holes if solid pipe is used.


Lower the worktop and ensure it is located in its final, fitted position.


Slide the sink slightly until you get the best fit.

It is usually recommended a nominal 10mm to overhang the sink but up to 15mm is fine to ensure a good even overhang.


At this point there is usually a small gap between the sink and worktop, fill the gap with a bead of silicone. See also below.

Pack the sink up to worktop with thin timber or plastic packers ensuring that they are not seen.


Clean off excess silicone with a damp rag or preferable a solvent cleaner.


Fit the tap plumbing, then the waste.

Steps to successfully fit an undermounted Belfast sink.

If your sink is not fitted with a weir type overflow then fitting the sink is much more straightforward.  You can fit the sink first, then attach the taps to the worktop, apply sealant to sink rim and finally lower the worktop into position.


This does however create some fitting problems. Firstly it is difficult to position and fit a solid surface worktop once the taps have been attached and secondly it is difficulty to accurately work out the final position of the sink prior to the worktop being fitted. This applies especially to ceramic butler sink which are rarely dimensionally accurate or exactly square.



It is much easier to fit the worktop first, fit the taps in place, slide in the sink,  apply sealant, pack up the sink until it mates well with the worktop and then clean off excess silicone sealant.

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Your Belfast base unit will need a hole to accommodate the waste outlet. Some base units have a slot for this purpose.

Stand the worktop and attach the tap. Using long flexible tails will ease the fitting.

Place the sink into position Usually around 15 to 20mm proud of the units at the front.  Bring up level to the units. If the sink is uneven, ensure no part of the sink is above the unit level.  Use packers under the sink if required.

Shaws large Belfast sink
Shaws large Belfast sink Detail

Run a bead of silicone around the perimeter of the sink, thread the tap pipe tails down the back of the unit and lower the worktop in place.

Adjust the sink until the front of the sink is flush with the worktop as shown on this Shaws of Darwin Belfast sink.  This is not set in stone and if it suits you can fit the sink further forward or back.

NOTE: If your base unit has a solid base, you may wish to pack the sink level with the units prior to fitting the worktops and also run a bead of silicone before the worktop is lowered. This is easier than it sounds, the Belfast sinks are rarely accurate and you will probably find you are unable to level off all the edges and will need to strike a compromise fit. By the end of the fit, unless you are continuously mindful, it is quite likely that the silicone has ended up anywhere but left on the sink rim. If you prefer to adopt the first method and you have a flat base on your unit you can always cut a slot or slots into the base and insert packing and sealant after the worktop is lowered into place. If need be, you can successfully force sealant into the intersection of the sink and worktop after it is in position and still achieve an effective seal.

belfast-sink-overhang 2
Belfast negative overhang detail

Depending on the cut of your worktop, the sink can be fitted with an overhang (usually 10 to 15mm,) a negative overhang or flush as shown on the previous Shaw Belfast sink photo.

Tip !  Try and resist the temptation to glue the Belfast in place before the worktop is fitted. As ceramic sinks are fired after moulding they are rarely perfectly straight or square.  You will need a bit of "wriggle" room to adjust the sink to a best fit after the worktop is fitted in place.

The  flexible water pipes will need to be threaded down the rear void of the unit and out through pre cut holes in the rear panel of the base unit.  


Tip!    Consider making an inspection panel to the back panel of the base unit, this will allow the service valves and the pipework to be situated in the rear void of the unit and will also eliminate the need to thread the flexible pipes into the unit.

 Special Offer. This Rak Ceramics, Gourmet 8, Belfast Style Sink with Weir Overflow for only £115.80 + £25 delivery.


Astracast stainless Belfast sink
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A Belfast sink with a weir overflow. The weir is usually to the right but can be to the left and even to the rear of the sink. Some Belfast sinks are reversible.

You may wish to read the section on removing a Belfast sink here as it also provides tips on making your sink easier to remove in the future when fitting it. This maybe required for example in changing or repairing taps.