White(ish) jointing

[Ryan Bailey]

Hi there,

First off, brilliant website. I wish more "trademan" respected their trade and craft as much as you do.

I'm laying a grey indian sand stone (22m depth calibrated) with a minimal joint (3-5mm).

I would like to joint with a white, or very light grey, joint and have read your advice about using a white cement with silver sand.

My Question - you describe silver sand as similar to sharpe sand which I thought is best used for bedding? Other options available are Kiln sand which is white and very fine but really designed for dry application in block paving and not sure if it mixes well with cement. Or I see B&Q offering their own brand (Diall) white sand which again might be finer than silver sand but is B&Q and could be poor quality.

As per your advice i'll be jointing with a well mixed, but medium dry 3:1 mortar.

Cheers Ryan

[London Stone Paving]

Hello Ryan

Is the grey sandstone you are using sawn or riven?

If it is a riven material then you can expect +\- 5mm tolerance on the dimensions of the slabs. This tolerance means that a 3-5mm jointing gap is almost impossible to achieve. You will find that the edges of the slabs will bump into each other when trying to achieve such a small joint.

Even with precisely cut sawn material you will still find dimensional tolerances of +\- 2mm which again can make it extremely difficult to achieve a 3-5mm gap.

It will also be messy and time consuming to get the jointing mix sufficiently compressed into such a tight joint. This could impact on the durability of the pointing.

I know it's not what you want to hear but I have been in this game for along time and experience tells me sawn paving joints should be a minimum of 6-8mm and riven paving joints should be 10mm at the very least

Steve

[DempseyLiverpool]

As Steve said Ryan you'll never achieve 3-5mm joint with riven. I would usually lay to achieve 10mm joints but with size tolerance you end up with 8-15mm joints.

Silver sand is a lot finer than sharp. I've used it for pointing with opc through a gun and it gives a light grey finish.

Easypoint or Larsen GPM do light grey or white coloured mortars.