Repointing a victorian terraced house: weather struck or flush?

[chriseastlondon]

Hi. I'm getting my house repointed. It's a terraced house in East London, built around 1888 and the front is all soft red bricks. The bricks aren't in great condition. The faces aren't perfect rectangles - they're quite bashed and chipped.

I need to decide between weather struck pointing and flush pointing.

It's being done with lime mortar (NHL 2). If I choose weather struck pointing, I'd get it done with a fine-texture mortar. If I choose flush pointing, I'd go for a coarser texture.

I'm a little undecided about which style to go for. I had a walk around my area and noticed all the houses where the bricks have been cleaned up and repointed seem to have gone for weather struck. It does look neat. However, I've read conflicting advice: some sources suggest it shouldn't be used on Victorian houses, others say it was used in the Victorian era.

I guess I'm leaning towards flush pointing if that's closer to how the house would have looked when it was built. I'd be grateful to hear what others think.

 

[stuart45]

The advantage of flush and finished with the Churn brush is that Carbon Dioxide can get through to the inside of the pointing better, and the joints are slightly more breathable.
However getting it done weather struck and cut does look neat if done properly. Remember there is a difference between weather struck, and weather struck and cut.

 

[^woody^]

Flush pointing has no weathering face and is not intended for external exposed masonry, especially lime mortar as it will erode away quickly.

 

[stuart45]

A lot of lime pointing is flush, finished with the churn brush.

 

[^woody^]

Does it (or the brick arises) last as long as when weather pointed?

 

[stuart45]

Ask me in 50 years when the results will be in.

 

[stuart45]

In theory the joint is more breathable when the aggregate is exposed, so moisture is taken from the bricks into the joints and it evaporates away, or freezes breaking down the joints rather than the bricks. As with any salts that can be washed through and crystalize should do the same.
Probably in practice either style of joint will be OK.
OP pay attention to the colour. Bright white lime joints can look a bit rough when the bricks are old and damaged. If the bricklayer uses the churn brush too early it can get some lime mortar over the brickwork as well.
If you go for weather struck a coco brush is better.
Soft Coco Brush | £6.25 | Conserv® (lime-mortars.co.uk)

 

[^woody^]

In theory the joint is more breathable when the aggregate is exposed, so moisture is taken from the bricks into the joints and it evaporates away,

I know you're the lime mortar-meister, but if that was true then surely by the same process the joints will absorb more water which will soak further into the wall (and the inside face) without an ironed joint to keep most of it out?

I've never bought in to this "breathable wall" concept that has been banded about since the internet allowed everyone and his collie to band it about, for others to repeat.
All walls get wet and they dry out, and lime is not some sort of magic lung transporting moisture.

 

[stuart45]

I know what you mean about lime absorbing moisture, but on solid walls it does seem to help the walls. It seems to allow air to pass through from the inside better to dry out the joints. They say if you looked at lime mortar through a microscope it has more of a honeycomb structure.
It depends on how much driving rain a wall is normally exposed to. There comes a point when a 9 or even 13 inch wall will allow the water through into the inside. This happened a few years ago when the whole country experienced a lot of wind driven rain.
They must have had problems in the 19th century to start using cavity walls.
Old properties are more about managing the damp rather than keeping it totally out.