The winter was rough on my all brick house, most of all on the brick steps in front of my house. I did some research and bought a 4.5″ grinder and went to work cleaning out the mortar between the bricks in preparation for repointing.
My house is over 100 years old so this is not the first time some well meaning homeowner has tried to play mason. The last guy repointed with some very strong concrete over a much softer mortar beneath. (Which I read is a mistake, but moving on…)
Once I managed to get the concrete removed I discovered, by probing with a thin chisel, that the original mortar between the bricks is the consistency of sand in most places and blows out with compressed air without hardly any digging.
Is this because the mortar is bad? Does it need replacing?
How deep should I clean it out?
I was planning on using a Type N mortar mix although my research had indicated a Type O was more historically appropriate, because I want something that resists freezing a little better.
If you’ve gotten this far I am much obliged to your wisdom…
Thanks
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Replies
I'm not a mason so what I say is a compilation of things I've heard and read - could be wrong.
You do want a mortar that is not harder than the bricks themselves to avoid damaging them, but it is right for the surface pointing to be harder than the interior mortar. Where I have experienced this situation more has been with regards to stone work where in new construction a harder mix is used to grout or point up the surface.
Much very old mortar was lime based instead of portland based. That does leach out over time. More so in a scenario where water sits on and percolates through brick steps. The lime is disolved and leaches away, leaving only sand behind.
It is highly likely that you now need to demo and rebuild the whole set of steps but that is something that needs to be assessed on site.
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