Rendering outside walls

[porky]

Can anyone tell me the best mortar mix for outside walls and which is the best sand to use. I had intended to use a sand,lime and white cement mix. Thanks

[Théière]

Sand effects the colour of the finished render so usually using a local sand is preferred to make the building fit it. Washed river sand is usually the lightest colour and often the choice if the budget allows.

A good mix of grades gives the strongest finish and exposes the aggregate so it forms part of the look.

It's important to know what the wall is made of but if it's natural soft limestone for instance then don't use any white cement in the mix.

You need to control the drying to prevent shrinkage and cracking.

http://www.stastier.co.uk/nhl/guides/recmix.htm