The Brew Cabin

I intend to lay carpet stones in an area of the garden which gets very light foot traffic. The Bradstones brochure says for a "rustic effect" I can use sharp sand without cement as a base and to fill.

Am I likely to have any problems without cement? Also, how much sand will I need per square metre of stones?

Carpet Stones for patio areas are sometimes laid in much the same way as standard block paving, but the jointing is a problem, in that you can't (or shouldn't) use a rigid jointing material (such as mortar), and the wide joints make a flexible jointing medium (such as kiln-dried sand) open to abuse by weeds and the weather. The best solution for this is to use a limestone dust as a topping for the joints, as this almost 'sets' and gives a bit more protection from scour.

However, I'm not convinced that this is always a good methodology to use, even on a light-use pavement such as a patio. If the joints were closer, something less than 7mm, then I'd be more comfortable with it, but because they are 12-15mm in width, I prefer a rigid joint, so I'd opt for a rigid bed, and lay the mats on my usual patio flags bedding mix, which is 10 parts grit sand to 1 part cement, and then use a good mortar (a Class II) to point the joints.

Assuming you use a typical 40-50mm deep bed, then you should get around 10 square metres from each tonne of grit sand.