Repointing a Stone Wall with Lime Mortar

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Our wall is cleaned up and ready for pointing. The joins are quite worn away and this project is very overdue.

First and foremost, you can not use concrete / portland cement in any masonry work on a house built before 1850, and maybe even until 1900. It’s worth asking a local mason to see what sort of bricks you have in your home. If they are new bricks and fired to be very hard, cement with confidence. However, older bricks, usually those with inclusions like small stones, have been hand-fired and therefore should only be pointed with lime-based mortar.

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Here is a close-up of the original mortar from 1832. The sand is course and filled with small rocks and pieces of shell. It is very likely that the materials for this wall were obtained from the nearby Delaware river.

 

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This quartz is enormous! When you’re really up-close to your masonry, you discover all the character.

It has taken years to build up the courage to face our basement wall. Years of sweeping up dust and bits of stone as the wall sheds. Years of research on how to make quicklime into lime putty and what ratio of lime putty to mix with sand to form the appropriate mortar for a row house built in 1832. Meanwhile, steadily voicing concerns that we were one rock away from the house falling apart around us. Finally, my husband said, “Make a plan already!” and so I did. I’m currently in the middle of earning my Master’s in project management which means I can’t write as often as I’d like to. It also means that any project I undertake is a good time to practice the project management skills I’m learning. So last month, I spent an entire Sunday researching lime mortar, again, and writing out a plan which included a list of materials needed, a work breakdown structure, and a timeline with actual real dates on it.

Download our repointing project plan.

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Section off the area with plastic sheeting. Misting the wall as you clean away loose mortar also keeps dust to a minimum.

The most challenging aspect of the project was the mortar itself. Quicklime is very caustic and corrosive. Turning quicklime into lime putty is time consuming, messy work; not something you would want to do in your kitchen. I was overjoyed to discover Ecologic natural hydraulic lime from Limeworks. Ecologic mortar is the perfect choice for older buildings that need lime mortar but it has the ease of modern mortar because you just add water. We used a ratio of three pints of water to 12 pints of Ecologic to obtain the perfect consistency. After trying to use several things to stir the mortar, we discovered that using our hands worked best. Mix for a good five minutes and definitely double up on the gloves since the lime is very drying. Also, use a face mask because the dust is irritating. Once it’s mixed, you don’t need the mask but keep the gloves on throughout the project. Mixing the mortar is very therapeutic and like building a sandcastle at the beach and we made small batches as we worked across the wall.

We’re lucky to live nearby one of Limeworks retailers, Killian Hardware in Chestnut Hill, Philadelphia, Pa. Killian’s is a fantastic place that carries many products for the older home. It’s hard to estimate how much mortar you’ll need for a stone wall since it’s irregular but we used four and a half bags. Ecologic is around $26 per bag and each bag covered about four-square feet worth of pointing.

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Ecologic mortar from Limeworks. Years of research and all the while, this fantastic product was just waiting to be discovered.

Repointing is messy work and you’re going to want to make sure the area is sectioned off with plastic, along with the floor.

Before we got started with the mortar, we cleaned out as much old mortar and debris as we could. For an interior wall, about an inch depth is recommended. Our wall had been shedding for so long that we only had to suck the loose sand out with the shop vac and give the rocks a good scrubbing with a stiff-bristled broom-head. We had no idea but there are a few very large pieces of quartz in our wall; one the size of a cantaloupe!

In terms of pointing, we had purchased trowels but discovered that using our hands was really the best method. Again, it’s going to be rough on your hands, as the lime is very drying, but our fingers could get the mortar in the crevices most effectively. The trowels were a bit expensive and using our hands saved us $30. We also didn’t need the wood or dowels for the palettes either, knocking another $6 off, making the overall budget for the project less than $200. The best method for applying the mortar was to take small lumps and work it into the joints slowly, like creating pottery. There is something very zen about working with your hands and really considering the shapes of the rocks and how to work the mortar around them.

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Here is our wall about half-way through the project. The difference was really amazing! Notice; if we had partially repointed the wall, we would have had to color-match since the old mortar is almost pink in comparison.

Overall, it took the two of us about 10 hours to repoint a 10′ by 12′ wall, including a lunch break and the two hours I worked by myself while my husband went back to Killian’s to get more mortar because we needed five bags instead of the two we originally purchased. The next day we devoted to clean up and a light spray of the wall in the morning, followed by one more spray before bedtime. It’s important to note that you do want to use the mortar during the more humid times of the year, so spring and summer. Lime mortar needs to dry slowly. Our basement is usually about 70 percent humidity which is excellent for the wall. When cured, the mortar should last a nice long time and not damage the stones and bricks like portland cement.

A final note; Ecologic comes in several color options and there are kits to further customize the color. We used the DGM 50 color because we wanted a nice contrast with the rocks and were doing the entire wall. You can send a sample of your mortar to Limeworks and they will help create a mortar that matches the color if you need to repoint in sections.

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The finished wall and everything back to normal!

We didn’t realize before the project but the repointed wall, with the brighter mortar, is much more welcoming than it was before. In a basement dining room/kitchen it’s very important to keep things light and cheerful to avoid the feeling you’re in a dungeon. We can also expect fewer drafts and less dust.

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2 thoughts on “Repointing a Stone Wall with Lime Mortar

  1. Pingback: We Repointed Our Wall! « storm under still water

  2. Thank you, thank you, thank you! Had I not run across this article, I would have for sure used the wrong thing. Very much appreciated!

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