Mixes for Pointing

[therealAdamB]

Re-pointing house close to the sea. House is approx 1/2 mile from sea, several other buildings between house and sea so not directly blasted with salt spray.

House was pointed 2 to 3 years ago and now patchy places failing.

What is the best mix and or preservatives for mortar.

How long should it last.

 

[stuart45]

Using a good quality sand helps. A sand with too high a proportion of fines will dilute the cement binder and be more liable to fail near the coast.
A stronger mix of 3/1 or 4/1 could be required. It should last at least 20 years if done properly.

 

[ABCwarrior]

What is the house made of? Brick? Stone? If brick I'd opt for a 4:1 sand/cement mix. If it's stone I'd do it 3:1 sand/ NHL* 5 Lime mix.
Lime is more expensive but if it's stone cement will cause and/or accelerate any erosion. Lime allows the building to breathe, is self healing should it crack and looks better- takes a fair bit of aftercare to allow slow controlled carbonation to occur. It's not the HYDRATED lime you get in a builders merchants it's HYDRAULIC you need....
If you're close to the sea can you access any shell beaches? A good mix we used to use was 3:3:2- 3 parts sand, 3 parts shell(must be thoroughly washed to remove salt- fill a wheelbarrow and run a hose into it for half an hour) and 2 parts lime. Looks good washed to expose the aggregate once nearly set.

*NHL means Natural Hydraulic Lime, St Astier being a decent quality lime.