Repointing Victorian brickwork: are they using the right mortar?

Hi. I'm getting the brickwork on my Victorian terrace house repointed. Before the builders started, I asked what type of mortar they use. They told me lime mortar. But they're using Portland cement.

A couple of people have told me cement mortar is fine for brick. But I thought that's what you were not supposed to use for repointing old brickwork. Am I wrong?

I'd be really grateful for any advice.

 

Lime mortar is often used to repoint stone walls. Stone weathers more than fired brick and the lime mortar weathers down with the stone. If someone has used cement mortar to repoint stone in a few years it is common to see the pointing standing proud of the stone (a few mm or more above the surface of the stone).

In your case the use of cement mortar to repoint red brick shouldn't be a problem as fired brick doesn't weather as much as stone.

 

Lime is used for its breathing properties. Old houses need to breath. Depending on your bricks, they can become damaged by frost if cement is used. Lime is more flexible

 

where are you, and what colour are the bricks?

 

Hi. Thanks for your replies.

I'm in London. The bricks on the front of my house are red. The bricks on the back are yellow London stock.

 

Lime mortar shouldn't have any OPC added to it.

 

I believe you need lime mortar.

It helps the building breath, and as has been said it also saves the bricks.

Assuming you have solid walls and not cavity being that it's a Victorian house you definately need it to breath.

 

If your builder said he was going to use Lime mortar, then uses something else, He obviously lied. What else is he going to lie about?

 

Yes.

You point in lime mortar if the house was built with it. If it's cement mortar then you use that.

 

For your info ......

https://historicengland.org.uk/images-books/publications/repointing-brick-and-stone-walls/

https://www.limebase.co.uk/lime-mortars

What's happens if a strong cement mortar is used depending on the location of the wall regarding prevailing wind and rain is that instead of having to repoint in a few years time, is this.... the mortar will be fine but your bricks will erode. You want a weak mortar that evaporation of water in the wall will evaporate from.
I doubt your builder knows what he's doing ......Because many don't point old buildings sympathetically.

I've got images of stone work and brick where the substrate has eroded away but the cement rich mortar stands out in ridges !
Get another builder.
Lime breathes absorbs water and dry's out, cement is impervious. You need walls to breathe.

 

yellow London stock are not a strong brick.

Red ones vary. Photo may help.

 

These are a couple of pictures. I took the picture of the red bricks, which are on the front, a few weeks ago.

The builders have now completely repointed the front of the house. On the back, they've mainly been replacing damaged bricks and haven't done much of the repointing yet.

https://drive.google.com/file/d/1K5oe-iDFBoY5mO5u_TRJcatq4f6qc5xo/view?usp=sharing
https://drive.google.com/file/d/13hwbNu8UX3bBhgCw34KUG7guB64wfuGi/view?usp=sharing

 

Where the builders have left their materials, well as the bags of cement there are 2 types of sand - building sand and plastering sand. Is there any problem with using either of those?

 

The house was built between 1881 and 1891, probably around 1888.

 

I've spoken to the builders and they say they use a mixture of lime and cement (not just cement) in the mortar.