Mortar in Wall

by Josh on July 7, 2008 · 5 comments

in Projects

I finally got my materials right and found some time to work on tuckpointing the brick for the wing walls in the old back stairs. I’m thinking of this as a practice opportunity because the whole area will be covered behind lattice and clematis vine eventually. Although it won’t be very visible, I hope that by filling in the large mortar gaps I can reduce water infiltration along the tuckunder garage foundation where there is some evidence of damage.

From what I can tell, the old bricks on the house are pretty soft inside. I have read that modern cement-based mortar can really tear up old bricks like these because when stress is applied, the bricks break or crumble before the concrete yields. To address this issue, I made a lime-based mortar which should remain softer than the bricks. Because of the extended calcification process of lime, this mortar is also supposed to self-repair small cracks in it over time– a nice feature.

Mixing Mortar Basic Recipe for Lime Mortar

  • 1 part hydrated lime (easier to find and work with than quicklime)
  • 3 parts all-purpose sand (sharper than play sand)
  • mortar colorant (optional– I used some left by the previous owners)
  • water

Add the dry ingredients to the water and mix until uniform. Wait five minutes, then mix again adding water or sand to reach the desired consistency.

For my project, I started with a wetter consistency so that the mortar would more easily flow into the deep crevices where the wall has sunken. I also sprayed all the bricks with water to help extend the curing time for the new mortar. For the wide gaps, I made a small trough out of some sheet aluminum and forced the mortar into the gaps with my square trowel.

Mortar Trough

For the places where the bricks hadn’t moved, I filled in the gaps in the mortar using a 3/8″ tuckpointing trowel taking mortar off a hawk. For this application, I experimented with a dryer mortar consistency and also with increasing the lime content. With too much water, the mortar just slid off the trowel. With too much lime, the mortar got overly sticky and more difficult to spread. With the rich lime mixture, I noticed the mortar making a cool sizzling sound while it sat on the hawk. I assume this was the lime cooking, though I didn’t notice any additional heat.

Patched mortar detail

After working at it for a couple hours I had used up a gallon pail of mortar and was ready to call it quits. (I covered more than the just the area seen in the picture above.) The results are far from professional, but I don’t think they look too bad for a first effort. To continue to keep the mortar from setting too quickly, I lightly sprayed water over the new mortar every couple hours for the next day or so. For some of the deep cracks, I intentionally left the mortar shallow, so that I can finish with a second layer once the first has dried.

{ 5 comments… read them below or add one }

Amalie July 8, 2008 at 8:22 am

Thanks for this post– we’re about to make a first attempt at tuckpointing our porch columns, so the more info I can arm myself with, the better!

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Derek July 8, 2008 at 12:18 pm

I’ve seen bricklayers brush the mortar after it’s almost set. I think this cleans it up a little. Thanks for the lime mortar recipe, I have some brick on my chimney that needs tuckpointing

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Josh July 8, 2008 at 2:55 pm

@Amalie: You’re welcome. Good luck with your tuckpointing project. I’m looking forward to reading about your results.

@Derek: Good point about the brushing. I forgot that step but remember reading about it. I’m sure that would clean things up nicely.

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Sandy July 8, 2008 at 3:31 pm

This is a good thing to know. I will have to tuck (no pun intended) this info away for future use! Great post!

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fred July 8, 2008 at 7:17 pm

Great pics. Your tuckpointing job doesn’t look bad at all, especially for someone who doesn’t do it for a living.

I esp. like the contrast with the red/grey colors.

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