How do you point a stone wall?
Question:Hi, We are just renovating a stone cottage in Co Kerry Ireland. We are just about to have the walls sandblasted and just need to know what lime motar mix to use to point the walls. Any advice given will be great! Thanxs
Answers:
If the wall is stone you don't want to use a lime only mortar since you don' thave to match. Instead mix one part portland (Type I/II) with one part lime and six parts sand by volume. Or use one part type N Masonry Cement and 3 parts sand. This will give you a mortar that is easy to work with, does not shrink too much, and has a compressive strength of 750 PSI. If you do choose to use a lime mortar (which is no longer used because it is very weak and does not last nearly as long!) use one part lime to 2.5 parts sand. Make sure you do not use beach sand as it is rounded from erosion and does not interlock properly. After you apply the mortar and it starts to harden but has not dried out mist it with a hose so that it NEVER dries out for three to seven days for the best cure. It will cure without this step but will not be as strong and will be more likely to crack.
I usually use my index finger to POINT or maybe even a stick designed for that purpose It's called a Pointer. these modern gadgets they have out will work fine too you know the LASER Pointer
If the cottage does not have a cavity (solid stone walls) then you MUST use a lime mortar. The walls breathe the moisture out through the lime mortar and using cement seals the damp in. Look at http://www.ehsni.gov.uk/repointing.pdf... for more advice.
Ideally lime mortar should be left if sound. In fine joints, use a hack saw blade to rake out and waxed string before putting lime mortar back in. In tight joints, you might want to masking tape the surrounding stone.
Take your time and make sure you gauge the contents of the mix by using a suitable size bucket to avoid different colours in batches. I use Feb-Colour rather than coal dust or soot to darken the mortar.
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