The coverage rates of primers and adhesives are expressed in terms of the square metreage (m²) they will cover per litre (L) of product.

Because primers are applied to different types of subfloor surfaces, they are given an upper and lower coverage rate, with the lower one being for more porous surfaces.

For example, the container might state:

        Coverage: 8-10 m²/L

Adhesives are spread at a thickness that suits the nature of the job. The thickness is regulated by the depth of the notches in the trowel.

So an adhesive coverage rate might state:

       Coverage: 3 m²/L when using a 2.4 mm V-notch trowel

Example

Say you're going to coat this concrete subfloor with a primer, and the coverage rate is 8-10 m²/L.

Because the concrete surface is not perfectly smooth, you decide to use the lower rate of 8 m²/L.

Step 1: Find the area

This L-shaped floor is made up of two rectangles.

We know that the w/w width of the room (across the pile direction) is 5370. We also know that the width on the right hand side of the seam is 2630.

Therefore, the width of the room on the left of the seam is:

       5370 - 2630 = 2740

Now we can calculate the area of the two rectangles. Note that we'll have to convert the dimensions from millimetres to metres because we want to know the area in square metres, not square millimetres.

Left side:	2.74 x 1.75	=	4.80
Right side:	2.63 x 3.92	=	10.31
			15.11 m2

Step 2: Find the volume

The primer covers 8 m²/L, so:

       15.11 ÷ 8 = 1.9 litres.