Repointing house walls

[tonysab]

Hi there, we need to repoint our exterior brick walls of the house (just half a dozen rows at the bottom), where the mortar has become loose and fallen out in places. Mostly this is around the damp proof membrane. I have never used cement in my life but am wondering from reading up on the subject, whether I can give this a go myself. I understand the basics to be -

1) Clear out loose mortar
2) Wet the area
3) Fill with new mortar

it would appear to be easier to use a hawk and tuckpointing trowel to fill the mortar. What I am unsure of though is what to use as the mix - I've no idea if this is limestone - can I just use something like "Cementone General Purpose Mortar" from Homebase - http://www.homebase.co.uk/webapp/wc...ay?langId=110&storeId=10151&partNumber=266258
we live in a 1920's bungalow but the areas concerned look fairly new-ish, the lower half of the bungalow is pebbledash painted apart from these half a dozen rows of bricks at the bottom. I can post a pic later if it helps.

Thanks in advance for any advice on the matter.

 

[tonysab]

Here is a pic of (part of) one of the walls in question, as you can see it has deteriorated quite badly in places. Thanks again if anyone can advise on the best mix to use for this.

Untitled

• tonysab
• 14 May 2012
• 1

 

[^woody^]

Are you really referring to tuck pointing? That style of pointing is not really appropriate for those bricks in that sort of location

A smooth weathered joint would be better, or half round

 

[tonysab]

OK there may be more than one definition for it - wikipedia lists something totally different - I am just after repairing the mortar, as described here - (which does refer to it as tuckpointing!) http://homerepair.about.com/od/exteriorhomerepair/ss/sbs_tuckpoint.htm

 

[^woody^]

Tuck pointing is a style which leaves the mortar proud of the wall and is usually used for stone

That tuck pointing tool can be used for filling joints, but that does not mean you need to specifically do tuck pointing

If you already have tuck pointing then yes go ahead. But as there is rendering above, all the rain water is running down onto the brickwork, and proud tuck pointing will be prone to early failure and can damage the bricks too

 

[stuart45]

Tuck pointing in the USA is what we call re-pointing here.
Tuck pointing here is a thin lime joint to make the brickwork look like rubbed work.
It must be an American site you looked at.

 

[tonysab]

Lol ah I see, makes sense. Thanks for clearing that up. So back to my original question - to repoint/repair the mortar shown in the picture, would a product such as that shown in the original post (from Homebase) suffice - a general mortar mix. I was just a bit worried about the sand/cement mix being a novice. Thanks again.

 

[stuart45]

Lol ah I see, makes sense. Thanks for clearing that up. So back to my original question - to repoint/repair the mortar shown in the picture, would a product such as that shown in the original post (from Homebase) suffice - a general mortar mix. I was just a bit worried about the sand/cement mix being a novice. Thanks again.

You could use it, but it's usually best to mix your own. The mix depends on the type of bricks used and climate, exposure etc. Old soft bricks built with lime mortar should be re pointed with lime mortar for example.
It looks to me like your wall has been weather struck and cut and the joints were not raked out enough before they were pointed, which often causes to joints to fall out when freeze/thaw takes place.
As a rough guide you normally repoint with a similar, but very slightly weaker mortar to the existing. The joints in a wall are a sacrifical item. If they are too strong the bricks can be damaged in time.
BTW your ground level is too high, it should e at least 6 inches below DPC, and not covering the air bricks.

 

[indigoblue]

Just as an aside here. I notice that you only have a very small gap between the physical dpc and the ground level on your bungalow. This should really be 150mm or 6" (2 bricks) at minimum. The fact that your ground level is so high in comparison could lead to bridging damp problems within your property.
Just a thought .... hope you didn't mind me mentioning this.

 

[tonysab]

Thanks guys for pointing out the height issue, I will have a closer look later, I suspect I have just topped up the surrounding area a bit too much with gravel.

With regard to the mix though, how do I know if its lime mortar? What mix of sand:cement:water should I use if I mix it myself. Sorry for the dumb questions!

 

[stuart45]

With regard to the mix though, how do I know if its lime mortar? What mix of sand:cement:water should I use if I mix it myself. Sorry for the dumb questions!

It's lime if it really fizzes up in vinegar. Cement mortar won't fizz as much.

 

[tonysab]

OK thanks. From what I have read would 1 part cement to 4 parts Building Sand be about right? Plus possibly Lime.

 

[stuart45]

1/1/6 lime/OPC/sand is quite a good general mix.
How old is the house? It looks like it could be 20's or 30's, which may well be a cement/lime/sand mix.