back up with the camera and show an overall view of what this things is.

We have pretty tough winters here in Chicago as well and a few years ago started caulking the joints on our coping (cap stones) except for fire pits and fireplaces. For us, this has been a successful transition from mortar to caulk. We normally gap our joints at 1/4" or 3/8" and fill with an exterior acrylic caulk which has some elasticity. Do not use silicone.

We do this on bluestone, limestone and also modular, cast coping. It works like a charm. There are some applications when we still use mortar but that's driven by aesthetics. From your photo I do not see a reason why exterior caulk will not work.

Most concrete supply houses and big box stores will carry an acrylic caulk that is suitable. If you have a Menard's in your area they carry a specific brand called 3006 White Lightning that comes in an assortment of colors.

The compromised joint you show in the photo is fairly typical, especially on the reveal (overhang). The joint failure is probably moisture driven, but could be part a bigger issue with the wall itself shifting from footing movement.

Lemont Landscaping · More Info

Keep your water and sponges clean and do one joint at a time. Good luck with your repair.

Thank you so very much. We don't have that store here, but I will look online for the product. Do I need to put a rubber or plastic filler in before the caulk because the joints are so wide? I am hoping the caulk comes in a gray color. Any tips on how to remove the mortar easily? Lastly, I suspect the joints that are not an overhang situation will make it tough for me to get all the mortar out. Can I caulk on top of mortar if I remove part of it?

Your install is stunning!

I will take a photo from farther away today. Thank you all.

A small chisel or screwdriver will work for removing the mortar. It will probably pop out more easily than you think. If there is residual mortar on the bottom that will not come out you probably could caulk on top of it. You do not need to put in filler in the joints prior to caulking.

You mentioned the joints are 1/2" but the photo appears to show a slimmer joint. A few words of caution: We have never caulked joints as wide as 1/2". If you cannot keep the caulk in the overhang because of the joint width you can simply tape the bottom of the joint with painters tape. Also, do not caulk if rain is in the same day forecast!

Thanks so much for the kind words on our project. Our guys take pride in their workmanship. Again, good luck with your repairs.

Bluestone St. Charles · More Info

@tiffew "Mortar drop" shown in the first photo is really common on the reveal, which is one of the reasons we have moved to caulk for most coping applications. It looks like you can chisel out the mortar in both instances and try the acrylic caulk.

Remember, use a couple of buckets so you have continuous clean water. Simply fill the joint completely, wipe with a damp sponge and take your time. Good luck!!

Thanks, all. I found this product online--is it similar to, better than, or inferior to, the product you mentioned earlier? http://www.sashco.com/products/mor-flexx/

Your second photo of the bluestone floor is gorgeous. I wish you were local!

I was thinking if the joints are pretty bad it might be better to remove the whole cap, chip the mortar off with a mason's trowel and reset all with fresh mortar. It's possible the original mortar could be inferior. Maybe the caulk is a better way to go, involving less overall effort. I have no experience with it so having nothing new to add here now.

@tiffew I cannot compare the two caulks since I am unfamiliar with the Sashco caulk, but it seems to be from the link what you would be looking for.

Yardvaark is also correct. It could have just been a sub-standard mortar mix. You could remove the coping and start fresh with new mortar, but I think you'll find the caulking procedure to be less effort and still effective.

There is no way my husband and I can remove all the capstones here--it's a very large space and neither of us have any experience with masonry. We also have, unfortunately, an immense amount of home improvement projects and very little time for these kinds of things. The mason who did this install would very likely have no interest in coming out and fixing it. When I told him we had a lot of cracking and mortar loss he said it's normal and to be expected. I'll try both of these caulks since I have multiple areas I can redo and see which ends up working better for our application. I'll post back with questions if I have them and photos of the finished job. Thanks again very much to you both.

Non-shrink grout works well with bluestone. Won't be as white as pointing mortar but it holds up really well.

I know this is an old post so not sure if I will get an answer but on the indoor bluestone install did you use a mortar to grout? If so what one because I like the color a lot. Also, what did you install the bluestone on. Was it cement or something else? We have a cement slab front porch and screened in porch we want to install on and just trying to figure out best practices. Screened in porch is going to have Sunscape screens/windows so he 3 season. It used to be decked before so our plan was to put down plywood and then cement board then mortar and install over that. Will that work? So many questions so sorry and thank you ahead of time!

I’m hooding you may still get a notice for this post but it’s 2021 and we are having the same motor issue....I’m mean exactly the same issue. Did you end up using the exterior latex caulk? If so how did it work out? And what color did you use? Any pictures of the finished result?

I did, yes. I’ll take some photos later today and post back. I used Moreflexx. We ended up having most joints redone by a mason because the latex caulk shrank and we had issues with mortar joints on the walls as a result of water getting into the capstone joints. I’ll give details later.

thanks that would great im really hoping to find a way i can do this repair myself instead of calling a mason every year. im in new jersey so we have very similar winters and moisture in the spring. i would love to know what you finally used that solved the issue

Did anyone find out what could solve this issue? I was thinking Moreflexx looked great but by Tiffew's comment, maybe not! :( I just mortared 1-1/2" thick bluestone over a 6x7 concrete stair stoop (that was hard but not impossible) and looking for the best grout to use to avoid cracking! It has southern exposure and bakes in the sun all day. I know Limestone would've been better due to the heat but I got a great deal. Thanks for any advice on the grout!

We ended up replacing the Morflex. I’ll find out what we used.