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Questionbest mix for re-pointing
I'm about to re-point parts of the rear of our house. It is a brick house made in the 1920's. I'm reasonably experienced at pointing, but mostly stone - where it's always lime mortar. There are different points of view on the best mix in any given situation. The original mortar in this wall is a lime mortar. But the current pointing is strong cement, with black colouring - ash or something. I think this is fairly typical. Obviously it's going to crack out as the house moves, which has happened in several places.
I really can't be asked to chisel out the entire wall and re-point the whole lot. It's a big house. Eventually it will need to be done, but now is not the time. I've just got to stop the damp getting in for the time being.
I'd like to match the colour, so I'd need some sort of black powder to mix in. I'm guessing the merchant will stock something suitable? But mainly, I'm not sure which mix to use in light of the current pointing and original mortar.
If you are going to do remedial/repair works, go for a 5 sand, 1 cement and 1 lime, and use some Cementone to get a near match.
Doubtful wether you will get an exact match, if you invest in a electric mortar raking tool it wont take long to cut it all out, then you can repoint in a lime mortar mix, colour matched from Tradlime Co.
For less than a ton, you can get a makita 115mm cutter, which will take the mortar rake attachment, set it to the depth and away you go.
B J D BUILDING/ROOFING 19th Jun, 2011
Hi. Your always best to use a 4:1 ratio for re-pointing at a depth of 10mm, this as a rule when you do re-point the entire house your colour matching will be accurate. Never do it any stronger as the morter will harden and shrink slightly causing it to crack and Ultimately fall out.
You can get dyes for your morter from most diy shops. Different addatives though require different proportions of how much you add. you should work this out from the directions on the packaging.
Any further info please ask,
JohnVL 19th Jun, 2011
hi,has you said after time cement mortar will crack .this happens as the lime mortar behind it recieves no moisture,drys up and turns to dust .so yes i would suggest you repoint it all.if you still wish to do a patch repair.try using a lime mortar with a mortar cement colouring.from builders merchant.or just lime mortar ,if you plan on repointing the rest in the near future.As for the damp issue you may wish to treat bricks before repointing with a waterproofer.
y,not build 19th Jun, 2011
i would personally go for 4 to 1 mix with additive to get the color you want
but would avoid patching, you never get the right mix, with the time passing color fades,
for best effect repoint the whole side,
Building Division 9th Mar, 2013