Damp Hearth and Wall

[stuart45]

IMHO, it could be tidied up to look fine. It really depends on individual taste. Some people dislike exposed brickwork, others love it. My eldest daughter really likes walls in pubs and restaurants, where the plaster has been hacked off exposing brickwork that was never intended to be seen. Show her a niche built in rubbed brickwork and she's not impressed. Bit like the banana taped to a wall.
My wife likes rustic brickwork as well, so I let my 15 year old grandson do the inner skin on a door block.

 

[Jonty1234]

The wall looks very impressive so well done to your grandson.
I'm in the 'for' rather than 'against' exposed brick camp. Although I could also be persuaded to like a banana on the wall if someone wanted to pay me that much for it.
Did you use lime mortar on the wall? The wall we are uncovering has what looks like lime mortar covered with gypsum plaster. Once we have removed any loose stuff I was thinking to make good any loose/damaged bricks and re-point with lime mortar. Any suggestions as to which type / where to get it from? We are based in London but I've seen quite a lot about mike wye and ty mawr ready made mixes online recently.

 

[stuart45]

The wall looks very impressive so well done to your grandson.

Thanks, I'll tell him. My wife spoils him, made me do the cuts for him as he's never used an angle grinder.
I've used NHL3.5 for the mortar, but it's a cavity wall, so dampness isn't so much of an issue.
For your pointing you could mix your own with hydrated lime and sharp sand.
With pointing it's important to get the style and colour right.
For example, with high class work such as rubbed brickwork, a bright, white contrasting mortar colour shows the detail better.
However, with rustic brickwork and large, irregular joints a darker, more toned down colour is better. Flush joints can also be slightly recessed to make them appear a bit smaller with bricks that have damaged edges.

 

[Jonty1234]

Thanks, I'll tell him. My wife spoils him, made me do the cuts for him as he's never used an angle grinder.
I've used NHL3.5 for the mortar, but it's a cavity wall, so dampness isn't so much of an issue.
For your pointing you could mix your own with hydrated lime and sharp sand.
With pointing it's important to get the style and colour right.
For example, with high class work such as rubbed brickwork, a bright, white contrasting mortar colour shows the detail better.
However, with rustic brickwork and large, irregular joints a darker, more toned down colour is better. Flush joints can also be slightly recessed to make them appear a bit smaller with bricks that have damaged edges.

Thanks for the very helpful info.
If there is potentially some dampness in the wall would there be a more suitable alternative or would NHL 3.5 also be OK? It's the back of a removed chimney breast so a degree of dampness is pretty likely even if I leave it to dry for a while.
Could the same thing also be used for the pointing? Or, if I were to go down the hydrated lime and sharp sand path what ratios would I be looking at? Similarly what is added to alter the colour?
Sorry for the amateurish questions. I understand the value of using lime materials but don't know the finer details of making it etc.
Thanks again.

 

[stuart45]

Rules of thumb for building and pointing. The mortar needs to be weaker than the masonry units.
When repointing use the same mix as the original, just a touch weaker.
For internal work that's protected from the weather, not a cavity wall, and time isn't an issue, a pure air lime mortar would probably be best.
You can get ready mixed in various colours. If you want to mix your own, the sand has a big influence on the colour, and there are dyes available.
It was generally accepted in the past that 3/1 was the standard mix for lime mortar, but analysis of old mortars have found them to be much stronger.
This is because when lump lime was mixed on site at 3/1, it expanded to make the mix more like at least 2/1.

 

[Jonty1234]

When repointing use the same mix as the original, just a touch weaker.

How would I go about that if the mortar mix is ready mixed? Add a small amount of water? If so, how much per 25kg of mortar mix etc? I appreciate that could be like asking how long is a piece of string..

For internal work that's protected from the weather, not a cavity wall, and time isn't an issue, a pure air lime mortar would probably be best.

What exactly is a pure air lime mortar? I tried googling this and most results relate to what seems to be normal lime mortar. I have copied below two sites that specifically seem to reference pure air below but am not sure if this is what you were meaning?

https://www.weselllime.co.uk/product/pure-lime-mortar-pre-mix-chalk-white/

No.1 Building Mix. – Vivus Solutions

www.vivus.solutions

I was originally looking at the Cumbrian or London mortar mix from Ty Mawr (link copied below) for both mortar and pointing. Would these be unsuitable or significantly different to the pure air lime mortar you reference above? One is darker than the other but my initial impression is that either would look nice. As a brickwork beginner i would probably lean towards pre-mixed rather than mixing my own as there are already enough things to get wrong.

Premixed Non-Hydraulic Lime Putty Mortars - Mortars - Products

Ty-Mawr

www.lime.org.uk

Thanks again.

 

[stuart45]

I was originally looking at the Cumbrian or London mortar mix from Ty Mawr (link copied below) for both mortar and pointing. Would these be unsuitable or significantly different to the pure air lime mortar you reference above? One is darker than the other but my initial impression is that either would look nice. As a brickwork beginner i would probably lean towards pre-mixed rather than mixing my own as there are already enough things to get wrong.

Premixed Non-Hydraulic Lime Putty Mortars - Mortars - Products

Ty-Mawr

www.lime.org.uk

Thanks again.

If you like these mortars, then these are non hydraulic air limes. It means that they cure by absorbing carbon dioxide and not through hydration. They are a softer mortar than the hydraulic mortars. Just pick the most suitable colour.

 

[Jonty1234]

If you like these mortars, then these are non hydraulic air limes. It means that they cure by absorbing carbon dioxide and not through hydration. They are a softer mortar than the hydraulic mortars. Just pick the most suitable colour.

Thanks for confirming. If there are some bricks where the existing mortar is a bit soft / powdery, is it necessary to remove all of this mortar i.e. as far back as possible, before relaying and ultimately re-pointing? I assume it probably is but I'm concerned that in some places this might mean I am effectively removing all the mortar from around the bricks. I don't necessarily have a problem doing this, as long as it is what I should be doing... It might actually help as it will mean I can tidy up / replace bricks easier.