Repointing areas of back wall of house

Discussion in 'Builders' Talk' started by David Sives-Rutherford, Oct 22, 2021.

  1. I have an old house, i think built in 1910, originally i thought it was sandstone, but looks to me a mixture of concreate and sand mix blocks,

    Ive noticed that some of the pointing is dropping out in certain places, Im looking to patch it up as some water is coming in, and running over the lintel.

    Can anyone recommend something i can pick up from say homebase or screwfix, that i can fill these holes in with ? obviously id like it to match the sandstone looking brick, not sure if i need lime in the mix or not.
     
  2. hadfield

    hadfield New Member

    Hi David - I'm looking to repoint my home too - similar era and similar materials. I've been reading that for breathability a lime mortar is the best way to go. Sadly it doesn't seem to be available off the shelf at Screwfix. That said, I've found some forum threads where a regular 3:1 mix is advised. "They've been using it for years" is cited in the following link on the topic https://www.mybuilder.com/questions/v/37072/lime-mortar-or-31-mortar-mix . I'll be keeping an eye on this thread for someone more experienced to chip in.
     
  3. Abrickie

    Abrickie Screwfix Select

    Photo would be helpful for people to be helpful ;)
     
  4. Abrickie

    Abrickie Screwfix Select

    If you note the 3:1 cement mortar is referenced for roof works, that and below ground is really the only places for that ratio;)
     
  5. Abrickie

    Abrickie Screwfix Select

    6:1 yellow sand to cement, with a little buff coloured mortar dye. The amount of dye is a mixture of experience and trial and error, if it looks close when you’ve mixed it, it’s too light ;)
     
  6. OnlyGus

    OnlyGus New Member

    Hi David, Hadfield is right when he mentions about lime mortar, if it was built in 1910 there's a very good chance that's what it is. If you repoint with regular cement it'll damage the bricks over time as the lime needs to breathe to let the moisture and cement won't let it do that. If there's too much water in the brick it will freeze in cold weather causing the bricks themselves to blow out. There's plenty of videos on youtube about how to mix and repoint with lime mortar, and although it is more faff than regular portland it'll give you the right finish with the right long term results.

    I've just done a quick search and there are companies that sell ready mixed (not SF or homebase though). If yours is only a small patch I'd go for that rather than buying a 20kg bag and mixing it yourself. Buying premixed will probably make it easier to colour match too.
     
  7. Abrickie

    Abrickie Screwfix Select

    No offence but that’s unlikely to be lime mortar pointing, whereas it probably was originally at some it’s been repointed with cement the bucket handle jointing is a bit of a clue ;)
     
  8. OnlyGus

    OnlyGus New Member

    Just a disclaimer, this is only what I've been taught and there are many ways of doing this. If someone has more knowledge please correct me.

    Hand tools are fine, but as your house isn't too old and presuming isn't listed and and you're confident with an angle grinder you can use mortar rakes to clean up the joints. I like the disks for the majority (85668) and the pointy ones (technical terms ) to clean up the corners (31307). There are different sizes for the different joint widths so see which ones are best for you.

    The general rule of thumb is to rake out the depth twice the width of the mortar joint, so if the joint is 10mm wide you rake out 20 mm deep. They were right with the brush to clean up but I like to use a bit more water than them. Lime isn't like cement in the way it cures and needs to be kept damp for longer. For small patches I use a little household spray bottle to really wet the area down. It also helps the mortar you're putting in stick to where you want it too.

    To put the mortar in I use a brick trowel in one hand (913ht) and a flat brick jointer like the one in this set (toolstation number 40920) and then clean up with a rounded bit of wood, but some (possibly most) prefer a rounded jointer like this for everything (82488). Lightly wet the area again before putting the muck in, start with verticals and then do the horizontal working from one end and pushing each bit of new mortar up against the last bit. Try not to smear too much on the faces of the bricks but lime is a lot more forgiving in the cleanup than cement. Slice off/ round off to slightly proud of your desired profile and scrape off any bits and then leave to dry off for a bit. When the mortar has dried/cured to be slightly lighter on the top and slightly more sandy brush it off with a soft brush, this'll help clean up any excess on the face and also smooth the profile to look less new.

    It's best practice to cover new lime with some hessian to keep everything a bit more moist and protect from the elements a bit, but so long as it's not too cold, hot, or wet you can generally get away without if you spray it every now and again. If it's going properly white it's too dry but that's more of a summer problem.

    Final word on PPE. Lime is evil to your skin and you don't feel the damage it's doing, gloves are recommended.
    Good luck!
     
  9. OnlyGus

    OnlyGus New Member

    Looking closer at the picture I reckon you're right, and it's possibly part of the reason the area is failing. The mortar is sacrificial and should always be softer than the bricks. I'm picky, but seeing someone has repointed lime with cement hurts me a little every time
     
  10. Abrickie

    Abrickie Screwfix Select

    IMHO an even big sin is gypsum based plastering on solid lime based walls :(:mad:
     
  11. thanks for info

    I managed to get those bits from b and q/screw fix :)

    i even boughtmyself a new angle grinder :)

    im pretty confident ill be okay, not great with heights, but ill need to overcome that.

    dave
     
  12. hadfield

    hadfield New Member

    Best of luck Dave. Let us know how you get on!
     

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