Repointing

Serida

Hi there. I expect all you DIY people are busy doing just that on this beautiful weekend but just in case there is anyone reading this Forum I wonder if you could offer me some advice please. I have read all about repointing and have bought some cement and some building sand but it seems I also need hydrated lime which the DIY store didn't sell. Is it absolutely necessary to add the lime as surely the DIY store would have it in stock if it is? I really don't want to repoint with just the 6-1 mix of cement/sand if it is all going to come out. One site says "don't use a simple sand/cement mix as it will trap water in the wall and any frost will loosen it; also it will tend to set too quickly and form weak bonds to the bricks". If I do need lime, where can I get it from? Any advice would be very much appreciated. Thank you.

ormus

lime mortar was generally phased out with the new portland cement. and is only really used in older buildings. for old stone etc...
if your house was built after 1850/1900 ish, then you dont really need lime mortar on "modern" houses.
ie 99% of houses.

Will.ii.am

as above really,only needs lime in it if the original mortar has it in.Just wondering if you bought a plasticiser to go in the mortar??

bobhawke

The lime is added as a plasticiser, to make the mortar more workable.
If you have a nice stone wall then you would point it with lime mortar as it is weaker than the stone so the mortar breaks before the stone. If you point it with cement mortar then the stone breaks before the mortar.
Lime pointing is much more time consuming and more difficult though. It probably won't be sold in a DIY store as lime pointing isn't really a DIY task but you can pick some up at a builders merchant.

Buy some plasticiser for a few quid and use that instead of lime

Will.ii.am

yeah forgot to mention limes horrible to work with i wouldnt go near it unless you have to,stick to the plasticisers from the DIY store,10x more workable and bonds the mortar together a treat also prevents efflorescence on the brickwork.

Serida

Thank you everyone. No, I didn't buy any plasticiser - never heard of it actually - I'm an elderly widow and this is my first attempt at repointing. It's mainly for renewing between some of the patio slabs where I've pressure washed it away and a few odd house bricks (house built 1960).

societys_child

All kinds of useful info about about re-pointing patios:

http://www.pavingexpert.com/pointing.htm

Serida

Thank you Societys Child. I had no idea until I went to the website you suggested that there was so much to it! It's a science in itself and there was me thinking all I had to do was mix the stuff up and shove it down the gaps!

vaio

Serida wrote: »

Thank you Societys Child. I had no idea until I went to the website you suggested that there was so much to it! It's a science in itself and there was me thinking all I had to do was mix the stuff up and shove it down the gaps!

You don’t really want to get a PhD in pointing do you?

Your “mix it up and stick it in the gaps” plan will probably work just fine.

You will get a neater/better finish with experience so start on the least important and progress towards the more important/visible bits and remember if it does end up looking crap you can just wash it out and have another go tomorrow.

Plasticiser is useful but you’ll have to buy a gallon and end up using an eggcup full, a squirt of washing up liquid is a cheaper alternative and will be just fine for slabs