Fitting a Vanity Unit


Most units come flat-packed and need no more than a screwdriver to put together. But as with all self-assembly furniture you should read the instructions and identify all the parts before going ahead.

Leave the doors off until all the plumbing work has been completed, but fit the top — it’s easier to cut in situ. You may have to notch or drill shelves to accept the pipes.


Cutting a basin hole

Many matched units are supplied with templates for cutting an inset basin hole. If not, or if you are adapting another piece of furniture, follow this sequence:

♦ Pencil diagonal lines across the top from corner to corner, then measure along these lines by equal amounts and link the marks to form a square which you can use as a positioning guide. Draw in any obstructions below the top too, so you can avoid them when cutting.

♦ Lay the basin upside down on the top and make sure it is positioned squarely — it may need to go nearer the back than the front if the edge of the top overhangs a front rail. If all is well, draw around the lip.

♦ Measure the depth of the lip, then cut a piece of wood to the same thickness and use it like a scribing block (see Trade Tip below) to mark a cutting line inside the outer one. Rub out the first line to avoid confusion.

After marking, drill a hole inside the cutting line wide enough to insert a jigsaw blade, then cut through the top in the normal way. Support the top near the end of the cut to stop it breaking away — but not with your fingers.

Semi-countertop basins should be supplied with a template for the cutout in the front of the unit.


Trade Tip

Marking a cutting line

“If there isn’t a template, draw around the basin, then cut a piece of wood to the same thickness as the lip overlap. Use this like a scribing block to mark an inner cutting line.”



Make up the basin with taps and waste outlet in the normal way.

Taps are normally supplied with rubber and steel sealing washers, but on thin steel and acrylic basins you may need to replace those on the underside with top hat washers so that the nuts can get a grip.

Mixers may have 10mm flexible tails and compression joints already fitted. You can extend these via flexible pipes (and reducing connectors if there are no joints), but take care not to over-tighten and strain the tails. Otherwise, fit flexible tap connectors, not forgetting the fibre washers used to make the seal at the tap tails.

Waste outlets for vanity basins come in several forms. Pop-up wastes are part of the tap and must be dismantled for fitting. The lever arm on the pop-tip connects via a ball and socket, and there may be a nylon cup washer to fit inside the capnut before it is tightened.

making up the basin for the vanity unit

Conventional wastes for use with integral overflows are best bedded on plumber’s putty — even where rubber washers are provided. Take care to align the slot in the outlet with the overflow channel.

Thin basins without overflows need combined waste/overflows similar to those found on baths. Bed one-part wastes in sealant, and apply a little more on the underside before and after threading on the overflow collar; then fit the washer and back-nut and tighten. With two-part wastes secured by a screw through the grid, make sure the upper washer doesn’t form a ridge around the grid; if it does, discard it and bed the grid in sealant.

Afterwards, fit the flexible overflow hose and threaded outlet.



For an inset basin, check the fit in the unit, then remove it and paint or varnish the edges of the cut-out to seal them. Follow by laying a bed of silicone sealant a-pop-up-area covered by the lip — or fit the strip seal provided — then refit the basin and press down.

A china or resin basin may be held purely by sealant, in which case leave the basin weighted down overnight to ensure a good seal. Thin basins may have fixing clips on the underside: tighten these evenly, to avoid distortion.

Semi-countertop basins can be bedded on silicone sealant laid around the unit cut-out, but this isn’t enough to hold them — most have additional wall or unit fixing brackets.

Installing the unit – Position the unit against the wall and check for level, then pack underneath if necessary using slips of plywood or old vinyl tile. The side panels may also need notching to fit over the skirting board or to accept the pipework.

When all is well, screw the unit to the wall and connect the plumbing.

installing the vanity unit

26. May 2011 by admin
Categories: Plumbing, Sinks | Tags: , | Comments Off on Fitting a Vanity Unit


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