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hoping I can get some advice on this. We have a c. 1876 house in CT that has a half brick (above grade, mostly), half fieldstone (below grade) foundation. We are planning on repointing it, using lime mortar from limeworks. I'll post pics at the bottom.

Someone had mentioned they had concerns about mortaring a foundation that had never had mortar before. In the majority of the foundation it really seems like mortar was never there. There is mortar in a few places, but these look to me like later repairs, not necessarily original (see third picture-the top is mortarted to the side of where they knocked a portion of the foundation out for an addition and where it looks like they filled in a window). There's just dirt coming through most of the stones. There is occasional dampness in some sections but never actual liquid water that I've seen. It does get humid down there but the dehumidifier brings it down to about 40%.

Is anyone on here aware of any issues repointing (or perhaps mortaring for the first time) may cause? I had thought by using lime mortar I would be okay regarding any moisture that needs to get through and not do any harm, but now I'm nervous! We really just want to close up any holes for animals and keep the dirt from falling through. I have no desire to make the basement watertight and know that it never will be.

Will mortaring the stones keep the dirt that is currently coming through stuck behind it and increase pressure? I had been thinking of leaving the bottom layer or two unpointed as a route for water or dirt to escape if it needed. Will it be totally fine?

typical foundation construction. brick on top, stone on bottom. Notice there is a little dampness in the dirt coming through. looks like no mortar ever used? just dirt coming through mortar in the top, but this very much looks like a repair. foundation on the right was blown out to connect to an addition another section where I don't see any mortar, only right at the top where the stone meets the brick. there isn't really any dirt in this section as an addition was put on and the opposite side is now inside, no ground behind it.

Thanks so much for any help! This foundation has been here for 150 years and I'd hate to be the one to do something detrimental to it!

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  • "This foundation has been here for 150 years and I'd hate to be the one to do something detrimental to it!" Then why do anything at all? What kind of animals are you having issues with? How much dirt comes out and how often do you have to clean it up that it's an issue?
    – FreeMan
    Nov 14, 2022 at 16:28
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    Beacause it would def be less dungeon-y down there, keep animals and dirt out, and also that typically these types of foundations DO have mortar in them, it would be unusual if ours, built in the latter half of the 19th century, did not. Whoops, posted too soon!! we have mice come in, and we have actually found a bat (dead) too. Dirt I find hard to quantify. In one corner we had about 3 inches deep in a 4 sqft section. That's the worst. It had roots growing through it! We only bought the house a year ago though so idk how long it took to get that way
    – catheetiem
    Nov 14, 2022 at 16:55
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    A local stone mason will probably give the best advice, might be hard to find.
    – crip659
    Nov 14, 2022 at 17:56
  • Thanks! I did speak to the person at the place that sells the mortar-he is a mason and he said he didn't have any concerns about it. I was happy to hear that, but I was hoping to get some additional opinions too. The masons I've had look at the house (we were originally going to hire out all the repointing) have been less than satisfactory. None wanted to use lime mortar on our historic brick, and one said you can't even get it anymore so we would have to tear down and rebuild the chimney! I just bought the mortar yesterday, you can't buy it at home depot, but you can most certainly buy it.
    – catheetiem
    Nov 14, 2022 at 18:00
  • Fair enough. It just seems to fall into the "if it ain't broke, don't fix it" category to me... Man, tuck pointing is hard - I did just a little bit of it on our brick foundation. It'll take practice to make it look good! I'm no mason, so I can't offer much more advice than that.
    – FreeMan
    Nov 14, 2022 at 18:10

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I've had to do a similar thing with our house also in New England build circa 1867 with all dry stacked field stone. Had a few stone masons come out initially and had really bad experience with them both from a knowledge perspective and from their actual work... Pretty shoddy.

Lime mortar I don't see a problem with and have done similar myself. What you do want to stay away from which my prior owners didn't do... Is stay away from any latex paint and definitely don't paint the rock or mortar surfaces with dryloc no matter what you do this will destroy your basement walls.

Best of luck with your project I've used 100s of lbs of mortar and several weekend mornings of hard dedication and sweat equity repointing corner by corner my fieldstone (just cleaned out another corner today actually).

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  • Thanks so much!! We're nearly finished and I'm relieved to hear someone else has done the same with a dry stack. Same result with the masons here too, nobody wanted to use the right materials and one guy even said we'd have to remove and rebuild our chimney bc they don't make the mortar anymore! Like dude what are you talking about I have 6 bags of it in my basement right now! And yes def no paint going on these walls! Just this weekend I finished stripping the portion of the brick that had been painted. Thanks so much and best of luck with yours as well!!
    – catheetiem
    Jan 4 at 3:56
  • @keshlam, I've seen some very, very objectionable work on the This Old House YouTube channel. Specifically I recall watching them put a window into an interior, load-bearing wall and smashing a length of romex between the header and the wall's old top plate. Unless I see a credible explanation of the mechanics from This Old House, I have more faith in certain regulars in these forums.
    – popham
    Sep 30 at 3:44
  • @keshlam, yeah, and I also recall them mending a mutilated main beam in some basement with a steel angle and totally screwing that up, too. There are construction YouTubers with more professionalism than This Old House.
    – popham
    Sep 30 at 3:47
  • ... Sigh. I bow to the wisdom of not trusting TOH. However, the process they use for this tasks agrees with many other sites and videos, so they may be right on this one.
    – keshlam
    Sep 30 at 5:24
  • Anything from Tom Silva is gospel. I named my cat after him.... Otherwise, yeah.
    – Mazura
    Sep 30 at 10:34

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