As I had previously posted, we are keeping the chimney that runs though the kitchen. Aside from it being out of our budget to remove the entire thing, I think it adds a little architectural element to the room. That said, the mortar is over a 100 years old and crumbling, so need to replace it. Clearly, this is a much more involved process that I had originally thought, but I am the one that wants to keep it, therefore I am the one that is doing the work. It also gives me the experience working with brick and mortar, one of the few things I haven’t ever done in a home renovation. I am not sure what codes are in repointing brick, but I didn’t see anything and when the buiding inspector came, he didn’t mention anything and he knew we were keeping the brick. So I would suggest, defaulting to your town rules and regulations before attempting this yourself.
My first step was finding out where to begin. The chimney being so old, I knew this wasn’t going to be as simple as just mixing some cement and throwing it in the seams. So I googled repointing old brick and there was quite a bit of information. The most important being that your mortar needs to be softer than the brick used so as your chimney expands and contracts, the mortar allows this and doesn’t crack the brick. Unfortunately, that means finding a stone/mason company that carries the mortar mix you will need since you can’t just pick it up at Home Depot or Lowes. But, it’s not that expensive, I think we paid $50 for 2 bags of sand, 1 bag of lime and 1 bag of portland cement. The other important factor is knowing your mix ratio. For mine, it was a 3/2/1 (3 parts sand/2 parts lime/1 part cement). It’s important to have the right ratio because of what I mentioned about the expanding and contracting that happens with your chimney.
You will also need the right tools- a pein hammer, a chisel, a grout saw, a wire brush a couple different sized trowels and if you want, a repointing tool (tuck pointing tool). I chose not to use the repointing tool because I wanted the joints flush against the brick since it’s not a new chiminey, but that all comes down to personal preference. I also wore gloves for all of this because the dust can really dry out your hands.
This is what the old mortar looked like in the chimney. You can see how dirty and fairly unsupportive the mortar is. In some areas the mortar has completely turned to dust and not really even touching the brick in the joints.
The next step, which is probably the hardest and least fun is the clearing out the old mortar. I would lay plastic around the whole chimney to capture the dirt, old mortar and the water that’s in the next step. The suggestion is to remove about 1/2-3/4 of an inch of the old stuff. I noticed in this chimney there are areas where at least an inch is missing. Which is why, you only do one side at a time and not the entire chimney. As your chipping away and removing the old stuff, you can weaken the entire structure and the last thing I want is the chimney falling apart on me.
This next picture is the removed mortar. You can see the seams look much cleaner. You want to make sure as your clearing out the old stuff, you really remove any weak mortar.
Next, you will need to soak your brick and mortar. Now, because this is indoors, you can’t very well run a hose in and soak the thing. So, you start filling spray bottles and just start spraying. The brick will absorb the water quickly and you just keep going up and down. By the time you reach the bottom you just start over at the top again. I probably did this for a good half hour until it looked as if the brick wasn’t absorbing as quick. I believe the reason you do this is so the brick doesn’t absorb all the moisture from the mortar so it cures evenly, otherwise, your mortar will be too dry and will crack and basically be useless.
I did this step the night before I repointed. Then the fun part begins, mixing your mortar. You want the consistency of heavy pancake batter, essentially you want it to stick to the trowel. I then sprayed the brick again and let it sit for about 10 mins while I went to mix the mortar.Then you just start back buttering into the joints. Now, because my joints are all pretty uneven, it’s not as simple as it looks. In some areas I had to really make sure I tapped the mortar all the way into the joint. Other areas it was just a top coat because the seam was so tight.
I would add the mortar in about 3-4 foot sections at a time. You want to let the mortar harden a bit, 10-15 mins, then you use your wire brush to brush off the extra mortar that notoriously ends up on the brick. You want to make sure you give it time to harden, but not harden so much as to now have to chisel it off. This was a bit of trial and error for me, but found the time about 15 mins a good bet. When you are wire brushing, be sure to do it at a diagonal and not back and forth or up and down, otherwise will end up removing the mortar you just pointed in the joints! I don’t doubt a mason could have done this way cleaner, but there is some pride in knowing I did all this.
Working the corners/edge is not easy and found that the best bet is to get as close to the end as possibly without doing the corner and will just do the corner when I do the other side. I found that in doing that, the new mortar is a good base to start from and when you do the other side, the mortar has something to cling to. As I was working my way up the chimney, I would also spray the sections I had completed to keep the mortar moist as it cured. I found that prevented any cracking.
This is about halfway done. You can see that the mortar is flush with the brick which is the look I was going for. If you want cleaner seams, I suggest hiring a professional, especially if you are working with an old chimney. It will be nearly impossible to make those rounded seams that you see in new construction. Remember to keep spraying down your finished sections.
This is one side almost finished. I need to touch up some of the joints I rushed through and ended up scraping out, but it looks so much better than it did before. After it’s completely done, I will clean the brick with muriatic acid and then seal the whole thing. It’s not going to look perfect, especially because some of the bricks surfaces were old and peeling from age, but I think it adds to the character. Any really weak or damage bricks, I will replace with bricks we found under the porch that are of the same age. Because the age, you can’t replace with new bricks due to size and color difference. Mason yards usually have older bricks, so if you need to replace look for them there.