Repointing a 1960s bungalow, what mortar mix?

[wakewaterblue]

Hi all

I'm repointing a friends property in a couple of weeks, a 1960's semi detached bungalow, and this will be my 2nd time doing it, the first time was whilst I was an apprentice bricklayer a couple years back.... (I didn't finish the training so I am not a bricklayer currently!) so this is my first repointing job on my own. I have all the equipment, dust extraction, grinder with raking blade and raker bit etc. The mortar is failing as it's crumbling away. Looks like someone has not too long ago, repointed the back of the property and one side of it, in a bucket joint finish. It's not the neatest work and looks pretty rushed, I'm not convinced they have even raked out the crumbling existing mortar and just pointed sand and cement on top... however the areas that haven't been repointed need sorting. It is crumbling away with various holes and looks recessed as the top layer has just gone. So I took a sample and it fizzed away in white vinegar suggesting lime is present. I also added a sample into some water, shook it up and let it settle to see the different layers to establish ingredients that may have been used.

My initial thoughts were to do a mix of 6:1:1 - Sand, Hydrated Lime, Cement. I came across this after some basic research from someone online who said that would have been the likely mix back in the 1960's.

Given its a cavity walled property, I know it's not going to be Hydraulic Lime NHL 3.5. However, there seems to be some slightly more course aggregate in the mix upon visual inspection and the sample mixed in the water suggests that perhaps?

I have attached some photos to assist and would really appreciate someone's experienced suggestions on the correct mix. I would like to use hydrated lime if it was present before to be in keeping with what is there and to even assist somewhat in a colour match. What type of sand should I use?

Thanks everyone!

Image 1 - Existing mortar looking pretty recessed and failing!
Image 2 - Fizzing mortar in vinegar 

 

Edited February 25 by wakewaterblue

[wakewaterblue]

Image 3 - The more recent repointing which looks like it's potentially not been raked out and just cement and sand put-on top?

Image 4 - Same as above

[wakewaterblue]

Image 5 - Crumbling mortar just rubbing my finger on it

Image 6 - This is a more sheltered corner that shows where the old mortar hasn't failed as much and you can see it was originally bucket joint

Image 7 - This is a sample of the mortar mixed into water and left to settle. Am I correct I am seeing a layer of sand and a layer of aggregate and the cloudy part is the lime?

 

Edited February 25 by wakewaterblue

[MikeGrahamT21]

If its 60s build it'll be stronger than 6:1:1, try 5:1:1, without doubt there will be lime in there like you say.

 

It may just be trial and error trying a few different mixes and see what dries the best, assuming you are wanting it to match?

[wakewaterblue]

Thanks for your reply!

 

My friend isn't too bothered about it matching the existing old mortar as such colour wise, but the more recent repointing done by someone else is all over the place in terms of colour, finish and I think just put on top of crumbling mortar, and so at some point in the future they will want me to rake that out and do it again..... so I don't need to match up with that mortar anyway.

 

I think it would be important and right to match as best as possible with the colour and mix that was used in the 1960s so to put some lime in there.

 

So to make it stronger and do a 5:1:1, what sand would you think is best? There are certainly some small stones in the existing mortar, so maybe some type of aggregate as well?

 

It's interesting how different mortar mixes fail at different times, it looks like a lot of the other bungalows built in the same year in the same street have failed as well and it looks like the same person has repointed them really poorly! 

 

My parents house is a 1970 build and absolutely no sign of any crumbling or failing so far.... 

[MikeGrahamT21]

On 25/02/2025 at 09:29, wakewaterblue said:

Thanks for your reply!

 

My friend isn't too bothered about it matching the existing old mortar as such colour wise, but the more recent repointing done by someone else is all over the place in terms of colour, finish and I think just put on top of crumbling mortar, and so at some point in the future they will want me to rake that out and do it again..... so I don't need to match up with that mortar anyway.

 

I think it would be important and right to match as best as possible with the colour and mix that was used in the 1960s so to put some lime in there.

 

So to make it stronger and do a 5:1:1, what sand would you think is best? There are certainly some small stones in the existing mortar, so maybe some type of aggregate as well?

 

It's interesting how different mortar mixes fail at different times, it looks like a lot of the other bungalows built in the same year in the same street have failed as well and it looks like the same person has repointed them really poorly! 

 

My parents house is a 1970 build and absolutely no sign of any crumbling or failing so far.... 

 

I think back in the day they probably used a mixture of building sand and grit sand, but for pointing you really want building sand as the grit would likely get in the way.

 

You can get yellow or red sand, dependant on colour you want, the above looks like yellow.

 

I have a 60's bungalow, ideal homes build, they were quite well known for pushing the boundaries of building tech, bringing in some real weird and wonderful build styles, which they tested on live properties, all still standing. I had a builder once who worked on them when they first built these, and he said they had a huge machine mixing the mortar, but its was primarily sand and lime, with very little cement in the mix. Its stood up well, but it wearing out now, not a problem for me, as i've covered it all up with EWI.

[wakewaterblue]

Really appreciate your reply and time and sorry for my delay in getting back to you. Really interesting information and that you have a 60s home as well. What made you cover it up with EWI in the end? Yes the 60's seemed to be an innovative time, especially for weird and wonderful architecture so I have no doubt just the same was happening with building mechanisms and technology!

 

I've been advised by some bricklayers elsewhere who just do repointing work and are very knowledgeable on old lime work and also cavity properties. They both advised that 6:1:1 Yellow Sand (slightly grittier to match what is there), Cement (one said white cement would give a nice lighter finish) and Hydrated Lime. They said this is what would be ideal and what was likely used back then, perhaps not the white cement, but to lighten the mortar up a little could be a nice touch as the bungalow was built on chalk. There is some history online about the all the bungalows in this street. It was part of a self build scheme. The man in each family that got involved in this scheme, each had a trade and would help each other build their homes at the same time which took about 2 years and all done in their spare time. Must have been exhausting! One person online mentioned as a kid, they remember their dad building their bungalow. They recall helping their dad pick away at the chalk to dig the foundations out, must have been hard going. 

 

So I thought it would be nice to lighten the mortar a little to acknowledge the abundance of chalk in this area!

 

Whoever has repointed the back half and side of this bungalow has not raked it out and just done a thin layer of very yellow mortar on time, which is also started to come off in parts and the behind is crumbling! So at some point I will be doing all of that as well.

 

It is also a very exposed windy location on top of hill, so once things are dried out after a week or so, I might even roller on some Storm Dry to help it out for the next 60+ years or so!

 

[MikeGrahamT21]

I think I’ve seen an old clip of if not the same project, another one which had the same idea, could you imagine that these days? Just wouldn’t happen, everyone would be blaming others for this and that.

 

Most of my bungalow has been covered with varying extensions I’ve put on over the years and the small amount of visible brickwork wasn’t in very good condition, chipped bricks, cracked bricks (old soft London bricks) and it was due a repoint, so I thought I’d fix it all and give it a huge upgrade in insulation levels, did all the work myself over years and it’s turned out really well.

 

just got the top part of the gable end to clad at some point, tho this will be framed, rockwool and cladding board, need some scaffolding for that one though!

[Super_Paulie]

im doing the same thing on my 30's place, but on an internal exposed wall. I did various mixes and found out that by simply throwing a "1" of sharp sand gave me the aggregate look on the surface random enough to blend in. 

[wakewaterblue]

Yes I wanted to add a little more aggregate finish to the mortar as I can see on one of the pictures that hasn't got failed mortar, a bucket finish with a light colour mortar and you can see the aggregates in it. So not sure 100% on what mix to do. I was told yellow sand would be a little grittier but is 6:1:1 of yellow sand, cement and hydrated lime the best? I've been advised by 2 repointing brickies to do this mix and with these ingredients. Maybe I could add just a sprinkle of aggregates into the mix as I will only be doing small batches at a time?

 

Maybe I could do 5.5 yellow sand and 0.5 aggregate to make it up to the 6 parts?