Pointing Wall

[doozer]

Hello,

Could someone please tell me the correct mixture of cement, lime and sand for re-poiting a wall.

It says 1 part cement, 3 parts building sand and ¼ part hydrated lime on this site http://www.ultimatehandyman.co.uk/RE-POINTING.htm but on other it says 1 part cement, 6 parts building sand and1 part hydrated lime.

Should it be builidng sand or sharp sand for re-poiting?

I am planning to re-point a wall that was build only 2 years ago but after the recent snow, all the poiting needs re-doing.

Any help would be much appreciated

Thanks

 

[^woody^]

I would ignore that advice from the handyman site

Pointing needs to be flexible or else it will crack and fall out in no time. It gets its weathering strength by ironing it smooth with the trowel or jointer.

And lime is optional, it only acts as a plasticiser or a lightener for the mortar.

The 6:1:1 advice is better, but if using lime, reduce it to 6:1:1/2

Otherwise just go for a 5:1 or 6:1 and add a bit of fairy liquid to help get a nice smooth finish

Use building sand, as rendering sand will just fall off your trowel and get the floor messy

 

[gregers]

dont flame me woody,but i was always told never to use fairy liquid and always use plastiser something to do with salts etc.runs away and hides

 

[noseall]

Air entrainers do just that. Make mortar workable, fluffy.

Agreed fairy has its fair share of salt, but hey, so do a lot of bricks.

 

[^woody^]

Yes the text book advice is not to use a detergent as it theoretically can affect the mix strength.

But I've not seen, or read about any problems or actual evidence that fairy or suchlike has caused any problems.

I used to say "use a plasticiser" and not "use fairy liquid", but it really does not matter, and everyone has some fairy in the kitchen so no need to buy any 'proper' plasticiser

The crucial thing is not to use too much, as then fairy or plasticiser, it will weaken the mix and reduce frost protection. Something like a teaspoon of concentrated per black (3 gallon) bucket

You can come back now

 

[gregers]

ok thanks

 

[stuart45]

Most bricklayers have used washing liquid, but on some sites the Clerk would never allow it. Technically it is said to produce uneven air bubbles in the mortar which can weaken it, and it also contains Sodium Cloride which is said to help rot the wall ties.

 

[^woody^]

Hehe, when is the last time there was a CoW on site? Do they still exist?

One I particularly remember, made us lay 450mm of inner or outer skin, and then we had to back it up, and he checked ties with a square both on the horizontal and vertical plane and measured to the drip to make sure they would be central in the wall.

And he had the top portakabin and would look out with binoculars like some Stalag camp komandant!

LOL those were the days

 

[stuart45]

They still advertise CoW training so there must be some still around.