My 125 year old house has old brick foundation which is exposed in the basement. I would like to plaster but don't want to do the complete three stage plaster job; the grout is deteriorated in many places and may be too fragile to attach wire lath. I have heard of a product that is a pre-mixed renovating plaster, but I don't know if such a product will work. Any suggestions?

  • Just a thought: a lot of people really appreciate exposed brick. If it's structurally sound (assuming you repoint it) it may add value to the house.
    – DA01
    Feb 3 '15 at 3:04

This Old House's website advises getting a sample of the current plaster and mortar to s lab so you can get them accurately matched, if I remember correctly. They seemed to be saying that it was important that the brick and mortar be matched to each other, tho I'm not sure why..

  • 1
    Because you can't re-point old lime-based mortar with modern cement-based mortar.
    – iLikeDirt
    Feb 3 '15 at 1:07
  • That much i understand; what i want is details. Chemistry? Expansion forces? Other?
    – keshlam
    Feb 3 '15 at 1:34
  • Portland cement should not be used for the repair or repointing of older buildings built in lime mortar, which require the flexibility, softness and breathability of lime if they are to function correctly. -Wiki
    – Mazura
    Feb 3 '15 at 1:38
  • 1
    Right. Moisture in the wall is supposed to be able to escape through the lime mortar, which is softer than the bricks of that era. But modern cement is harder than old bricks, so the water trying to escape enters the brick instead, causing it to degrade and spall over time.
    – iLikeDirt
    Feb 3 '15 at 1:49
  • 1
    Here's the video of that episode... youtube.com/watch?v=KlTzOFj6cME
    – Randy
    Feb 3 '15 at 3:52

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