Repointing

[happyaslarry]

Hi, My house needs repointing it was built around 1900s. I am thinking of raking it out with a grinder to about 10mm depth so i've got a good key for the mortar, Does this sound like i am going about it the right way. And as for the mortar to repoint what mix should i use as i am getting a little confused( i was going to do a 5 and 1 mix) with building sand and cement which many people have told me is a good mix, but someone has also informed me that i shouldn't use cement i should use lime instead, i am now a little confused someone please help.

 

[brumylad]

the main advantage of a lime mortar is that after 100 years your maintanace task is repointing as opposed to replacing half the brickwork.

The theory is that the efects of weather, time, frost etc cause the softer mortar to deteriorate and not the brickwork. The risk of using a rich portland cement mix, is that the motar is stronger than the bricks and the bricks will be damaged.

 

[Nige F]

try a look at this ...www.mikewye.co.uk

 

[happyaslarry]

So would you never point up with cement.

 

[brumylad]

why not try re-pointing a couple of square feet in an area of wall that is not "on show". Then you'll know whether this job is one u want to do yourself. If your doing the whole house it will be safer to hire scaffold or perhaps a tower.

I would try a mortar of one part lime putty to three parts sharp sand.

a cheap lime putty can be made by making a paste from water and hydrated lime, leave this in an air-tight container (could try cling film over a bucket) for at least 24 hrs.

put mortar onto a board or hawk and spread out to a thickness similar to the width of the mortar bed joints. push the mortar off the board into joint.

make sure to tool (finish) the pointing to make it smooth. Slide the pointing tool back and forth along the joint.

the trouble with repointing is the mess that can be left on the bricks. Lime mortar should be easier to remove than portland cement (with a stiff brush after a day or two)

 

[happyaslarry]

Hi, Guys thanks for your replys. I know i keep going on about it but could i use a mix of 5 - 1 - 1, 5 building sand, 1 cement, and 1 lime, this is a mix someone has sugested to me, he told be you could buy powded lime in a bag and just add it to the mix is this right.

 

[Thermo]

great job repointing. sun on your back, sit on a bucket, turn the radio on and away you go!

 

[brumylad]

I would avoid cement, as I say, if you make a mess on the bricks, getting cement off is a nightmare.

5-1-1 mix would be a good mix for bricklaying but bricklayers are neat workers, DIY re-pointers will not be at their first attempt.

I would try a patch using "bag lime" (powdered hydrated lime) available at any building merchants

 

[oilman]

Do as brumylad says, and don't use cement. There are two components in a wall, blocks and mortar. The mortar shold be softer and more porous than the blocks so water gets out through the mortar, and the mortar fails before the blocks. That way you only need repoint, the alternative is replacing the blocks. If you use cement water will try and get out and will move into the bricks, when it freezes, the bricks get damaged. Lime mortar is fine, why would you want to use cement other than most builders keep telling you to?

Lime is easy to use, it wont set while you take ages to use it up. I'd suggest you do all the raking by hand, and you need to go to about 3/4 inch deep. Question is does it really need repointing? Can you post a picture?

 

[happyaslarry]

Hi Guys, Thanks for all your reply's. I now no to avoid using cement. Would Hydraulic lime in powderd form and building sand be good to use and if so what ratio would the mix be, and would you mix it in the same way by hand as sand and cement. Any info i would be truly grateful for.

 

[oilman]

You could use hydraulic lime, and no.1 should do. You can also use the hydrated made up into putty first and add some brick dust if you want to make it set rather than just carbonate. 2:1 would be the strongest you need, and 3:1 will probably do, but this should be done by accurate volumes, not ill judged shovels full. Make sure you get the mix of sand to match your existing. Read some books before you start, it's not difficult but if you make a pig's ear everyone will see.