Question 1

Which numbers actually fix the size of a platform coping?

Accepted Answer

Three numbers fix the size of a platform coping (also searched as platform cap), and each comes from a different place rather than from whatever is on the yard. Length sets the joint count, width sets how far the slab bears on the platform edge, thickness sets which block it is sawn from. The usual size is 1000×600×50mm. At 1000mm a piece weighs 81 kg, the compromise between fewer joints and a weight a gang can still handle. The 600mm width is the bearing width: enough to hold the walking edge down without covering the paving behind. The 50mm thickness is the half-finished slab it comes off, before facing, grooving and edging. If the drawing asks for 100mm or 150mm, it is no longer this slab: it comes off a thicker block, and the yield and the quoting basis both have to be worked out again. Those three numbers are a better question for the designer than asking the factory what it has in stock. Within one station the island platform and the side platform can take different sizes; copy another project's drawing and the piece either sits too high or fails to hold the edge.

Question 2

1000×600 or 999×598, and what do those 2mm buy?

Accepted Answer

A joint. The 999×598×50mm size gives up 1mm on each side, so two pieces laid together leave exactly 2mm, and that joint has to line up with the paving joints behind the platform, otherwise the whole edge wanders. The 1000×600 size is for runs where nothing behind has to line up, or where the back area is not jointed at all. Choose the wrong size and the site cuts: taking 1mm off is easy, but the cut edge is no longer a calibrated edge, the references for the round and the grooves move with it, and the joint steps. The price of the calibrated size is one extra stop on the saw for every piece, which is cheaper than rework on site. Mark on the order which segment takes 999 and which takes 1000. And the start of a calibrated run follows the paving's setting-out point behind the platform, not a measurement taken from the platform end.

Question 3

A piece weighs 81 kg, can two men lift it?

Accepted Answer

81 kg is about the limit for two men lifting a slab diagonally, which means one piece, not a day's work. On site it takes a slab clamp, or two men on one end and a third steering it in. At 600mm long the piece is 48.6 kg and two men can carry it, but 100 m of platform goes from 100 pieces to 167: 67 more pieces and 67 more joints, and levelling and lining up are paid per joint. Long pieces save labour, short pieces save lifting; the choice depends on whether the site has clamps and how many men are on the gang.

Question 4

The rounded edge and the top grooves, which one carries the cost?

Accepted Answer

Both run the length of the slab, so both are priced by the metre and barely move with width: the round is one edge from end to end, the grooves are one set of lines from end to end, and whether the slab is 600 wide or cut narrower, the machine travels the same distance. The cost sits in two places. One is the radius: a small R goes through in one pass, a large R needs the arc shaped in segments and checked against a template, which costs time and material. The other is alignment: the groove pitch and the distance from each piece's end to its first groove have to be on the order, because 1mm out at that distance throws the grooves one step sideways at every joint and the platform reads as crooked. Rounding turns a square arris into an arc, and the arc cannot be flamed to the edge: flaming loosens the crystals along the arris, the edge goes fuzzy, and it sheds grit the first time it is handled. That is why the rounding and grooving charges are quoted by the metre.

Question 5

Why do quotes come per linear metre, per square metre and per piece?

Accepted Answer

At 600mm wide one linear metre is 0.6 m², so the same batch quoted three ways gives three different numbers. Our 100 m² minimum comes to 166.7 linear metres, or 167 pieces; the 208 m² we record for a 20ft container comes to 346.7 linear metres, or 347 pieces, and that 208 m² at 50mm and 2.7 t/m³ is 28.08 tonnes, so the container meets its weight limit before its volume. Ask which basis a quote uses before comparing: formed square metres, linear metres, or pieces. The three bases are not three factories bidding differently, they are three readings of one batch, so settle the basis first and argue about the rate afterwards. The price is built from five parts — material, edge profile, grooving, sealing, and packing reinforcement — and each can be asked for separately.

Question 6

What has to be on the order before it goes out?

Accepted Answer

Seven items, none of them optional. The section as length × width × thickness, not just width and thickness; whether the run is the calibrated 999×598 size and which segment; the exposed edge as an R value, not the word rounded; the groove pitch together with the first-groove position; the face finish split into top face and the other faces; the total in square metres and in linear metres; and the packing with the six-face sealing, pieces per crate and corner protection. The first three decide whether the block is cut right, the last four whether the finished piece is right. In the drawings we receive, the item we see missing most often is the edge profile, because it appears in neither the square metres nor the tonnage, and it only surfaces when the stone reaches the site. We make this coping ourselves in G562 Maple Red: 100 m² minimum, five days to ship.

Piece length	Volume per piece	Weight per piece	Pieces per 100 m
1000mm	0.03 m³	81 kg	100
999mm	0.0299 m³	80.7 kg	100
600mm	0.018 m³	48.6 kg	167

Item	How to write it	If it is left out
Section	1000×600×50mm, length × width × thickness	Wrong blank, wrong weight and bearing
Calibrated size	999×598×50mm, with the segment named	Cut on site, calibrated edge lost
Exposed edge	R value, or the chamfer angle	Process and reject rate are guessed
Groove pitch and first groove	Pitch plus end-to-first-groove distance	Grooves step at joints, edge runs askew
Face finish	Top machine planed, other faces named	Wrong finish, anti-slip band reworked
Total m² and total metres	Both numbers, by segment	A m² quote drops the edge work
Packing and sealing	Pieces per crate, corner guards, six faces	Chipping in transit, sorting on site