Industry Standard Roll Widths are 3.71 mts wide and sold by the lineal metre.
If the area you intend to cover is wider than 3.71 mts, then you will need to join the grass.
Remember, two or more rolls laid side by side MUST be laid in the same pile direction – and this will determine how much grass you need. This will generally be more than the m2 of the area as there will be wastage. Draw a diagram of the area to be covered (preferable to scale) and the quantity of grass can be easily calculated
Assume you are covering an area of 7mts wide x 8mts long = 56m2
Divide the total width of the area by 3.71mts to give you the number of runs. Example: 7mts ÷ 3.71 = 1.9 runs (round up to 2 runs of 3.7mts).
Take the length of your area and multiply the number of runs. Eg: 8mts x 2 runs = 16 lin.mts. (x 3.71 m = 58.56m2)
Take the total m2 of the area to be prepared and multiply by depth of base material (in this instance 100mm = .1) Example: 56m2 x .1 = 5.6 cubic mts. of base material.
80% of the total amount of base should be 20mm grade 3 rock. Spread, level set for optimum flow to drainage point, screed, lightly compacted.
Then 10-20% of the base should 5mm FCR (fine crushed rock), spread, screed and heavily compacted, wet down. The end result should look like freshly poured concrete. No pertruding stones!!
Check manufacturer guidelines. EG; for Pro Lawn 25mm manufacturer recommends 10 kgs/psm of Silica Sand (kilm dried) per m2,Example: 56m2 x 10 = 560 kg of sand/25kg bags of sand = 27 bags.