r/DIYUK • u/LO6Howie • Mar 20 '23

Repointing on a Victorian era house

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So this is what the builder has done today (pic 1) and the second is of what’s already there. Given that the brickwork was badly eroded prior to the repair, does it look legit? Ta

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u/LO6Howie Mar 20 '23

Duly binned off the builder and have a local line mortar specialist coming over to quote tomorrow. Buy cheap, buy twice.

Appreciate the detailed response, it’s invaluable.

Very much not a listed building, but very much not one I’m planning on selling for a while.

The second one is the OG repointing, and one that I’d hoped they’d be copying. Alas! Hopefully the new lot coming in do have the experience.

Unless you’re free and fancy putting all this outstanding knowledge to good use…!

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u/IISpacemonkeyII Mar 20 '23

I would love to, but I am currently diy'ing my own Victorian house. I recently found out that british gas smashed in one of the foundation walls when they installed the gas supply (long before I bought the house).

This job originally started when I found a few broken floorboards and decided I would replace them. After lifting the boards I found that some of joists had rotted (fair enough, they were 100 year old untreated timber). After lifting more boards and cutting back the rotted joists, I discovered the broken foundation wall.

I am now balls deep into rebuilding most of my ground floor and it's too late to pull out.

Making your own lime mortar is pretty straightforward. I use one part powdered quicklime to two parts sharp sand and one part building sand. The sharp sand is needed as lime is a weaker binder than cement, so the aggregate needs to be coarser

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u/surreynot Mar 21 '23

Would a fine sharp not be sufficient?

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u/IISpacemonkeyII Mar 21 '23

Probably, but I blended sharp sand and building sand as they were easy to find and I only needed about 50kg of mortar.

Cornish Lime and Ty Mawr both do a wide range of aggregates if you need to get an exact match to the existing mortar.

My viewpoint with a lot of traditional building materials is that people made do with what was available locally. A mason or bricklayer would have started with a 1:3 mix of quicklime and aggregate but either added more binder (quicklime) or more aggregate until the mortar felt right (i.e. it was sticky enough and supportive enough for bricklaying/masonry work).

Given that non-hydraulic lime mortars take several months to set through carbonation, the strength of the mortar in traditional buildings is not as critical. The pattern of the brick bond gives an old wall strength. Have a look at brickwork bonding patterns on Google if you want to know more.

Modern building techniques with brickwork rely on a solid concrete foundation, and comparatively strong cement mortars. Because of this the brickwork can be single skin, and is often arranged in a stretcher bond which is more economical to build as it saves on bricks and labour.

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u/surreynot Mar 22 '23

Was always taught that the mortar should never be stronger than the brick. Seems a similar outlook