Granite Laundry Sink Price: One Sink Is Priced by Volume, Not by Weight
A granite laundry sink price is not a weight question. A laundry sink is a shaped piece hollowed out of one block, so the quote follows outside volume, and the stone that was cut away has already been paid for. A 900×550×600 one-piece unit weighs 331 kg, with net stone at only 41% of its outside volume.
Granite Laundry Sink Price: How Many Pieces Are in One Sink?
A granite laundry sink price means nothing until you know how many pieces “one sink” contains. We build three types: a one-piece unit hollowed out of a single block, a tub set under a separate top, and a tub standing on a pedestal. A one-piece unit is quoted per unit. The assembled type is usually split into tub, top and pedestal, so the total you hear first may cover the tub alone. On Sesame Black G654 our quotation opens with the build type and then gives the piece count, because at the same outside size an assembled sink removes far less stone and lands in a different bracket for both material and labour. Settle the build type and the piece count before you compare a single figure.
How heavy is one sink, and how much stone is cut away?
The hollowed volume can be calculated before anyone quotes. With 60 mm walls and an 80 mm base, the cavity is 120 mm smaller than the outside in length and width and 80 mm shorter in height. Outside volume minus cavity volume gives net stone, and net stone times 2.7 t/m³ gives the weight. For the 900×550×600 unit: 0.297 − 0.1744 = 0.1226 m³, × 2.7 = 331 kg. The table shows one pattern: the bigger the sink, the lower the yield, because the 60/80 mm walls stay fixed while the outside keeps growing. Buy stone by the cubic metre and the removed share is still charged to the sink in front of you.
| Outside size (L×W×H) | Outside volume | Cavity volume | Net stone | Net weight | Yield |
|---|---|---|---|---|---|
| 700×500×550 | 0.1925 m³ | 0.1036 m³ | 0.0889 m³ | 240 kg | 46% |
| 900×550×600 | 0.2970 m³ | 0.1744 m³ | 0.1226 m³ | 331 kg | 41% |
| 1200×600×650 | 0.4680 m³ | 0.2955 m³ | 0.1725 m³ | 466 kg | 37% |
How thick must the walls be so the sink does not crack?
60 mm walls and an 80 mm base are what we run on Sesame Black. The tight spot is the corner where the base meets the walls: after hollowing there is only one transition left there, and every knock, lift and rush of water passes through it, which is why the base is 20 mm thicker than the walls. Water gives the second reason. On the 900 unit the cavity is 780×430; filled 450 mm deep, 0.78×0.43×0.45 = 0.151 m³, about 151 kg of water, or 46% of the sink’s own weight. The base carries water plus stone while the walls carry side pressure only, so the two should not share one thickness. Enough thickness plus a fall toward the drain is what keeps a sink on a balcony from showing hairline cracks first.
Where do the drain, the overflow and the washboard go?
The drain sits at the low point of the base, and the base is laid to a fall that runs toward it; we keep the hole centre 50 mm in from the inner edge. The overflow sits above the normal water line and takes a smaller diameter than the drain, so a rising level leaves through it first. A washboard only works on the one-piece build: it is a sloped panel with cross grooves inside the cavity, and both the angle and the groove pitch have to be on the drawing before the factory cuts it. An assembled tub cannot take a washboard, because the slope has to run continuous with the base. Fix these three and the cavity shape is locked, which is when hollowing hours can be quoted.
Why can a laundry sink not be quoted by the square metre?
Because there is no flat surface to unfold. Four lines make a quote readable. Stone is charged on outside volume times the block price per cubic metre, not on net weight, since the removed part has already been paid for: net stone is only 37% to 46% of the outside and the rest is cut away. Hollowing is labour, driven by how many cubic metres come out and whether the cavity carries a washboard slope. Edging and drilling covers rim profiling, the drain hole and the overflow hole, priced per spot or per metre. Packing means a crate on bearers for a shaped piece, never a slab bundle. Apply a slab price per square metre to a sink and the units no longer match; split the four lines first, then compare.
What numbers should I send with an enquiry?
Seven items, one figure each: outside length, width and height; cavity length, width and height; wall and base thickness; drain position and diameter; whether you want an overflow; whether you want a washboard, with its position and angle; quantity, packing, and whether the outer wall takes a bush hammered finish (if so, put it on the drawing). The first item sets the outside volume, which is the stone line. Cavity, wall thickness and washboard together set the hollowing hours, since a washboard is a sloped ribbed face inside the cavity and costs more labour than a flat base. Drain and overflow set edging and drilling, and the last item sets crating and loading. On loading: a 20 ft container takes about 28 t of net slab stone in our records, which divides into roughly 84 sinks at 331 kg, but that is the weight ceiling only. Shaped pieces travel one to a crate with bearers between crates, so the real count is set by how the crate outlines fit, and your forwarder needs the crate sizes to plan it.