Posts: 1,600
Threads: 0
Joined: Jan 2014
I have a circa 1880 home with an interior exposed rubble stone foundation. Mortar appears to be lime based, no cement, based on the softness. I am in the process of building a storage closet in a corner and would like to clean up the exposed stone, and possibly parge afterwards for appearance and to reduce dust. There will be approx 100sf to be pointed for this closet, and there's plenty more to work on if this not crazy difficult...
Has anyone undertaken this kind of project? A mason friend of mine recommends true historic lime mortar mix, vs a standard cementitious mortar (very pricey and haven't sourced it locally yet).
TIA
Posts: 1,936
Threads: 0
Joined: Feb 2008
I've done a few stone foundation basements with Duro-bond 90. It's a setting type joint compound for drywall but not the "easy sand" version. In fact, if you need to sand, about the only way I've found is a belt sander with 36 grit. So this isn't a flexible mortar. It does stick very well and sets up fast enough and dry enough to paint the next day. Doing a little quick math I'd say the first one, at my Dad's house, was 40 yr. ago. We picked at the loose stuff, wire brushed, and rinsed it off. Then we mixed in a bucket with a drill paddle and applied/spread/smoothed it with our hands in rubber gloves. I don't remember what paint we used but it went on with a commercial airless. It's occasionally brushed off and was washed a few times. Never re-painted, and it still looks good.
Sign at N.E. Vocational School Cabinetmaking Shop 1976, "Free knowledge given daily... Bring your own container"
Posts: 1,600
Threads: 0
Joined: Jan 2014
Thanks...did you use that for pointing the stone, or just the final wash coat?
Posts: 1,936
Threads: 0
Joined: Feb 2008
These basement foundations were field stone; still rounds, not really shaped except for the top course(s). At my Dad's there's red brick above grade on the front and sides of the house. The others are large split granite above grade. So I'm not sure what you mean by pointing in this case. I think of pointing more as the spaces between bricks, blocks, or stone shaped more uniformly. Picture walls made with basketballs, soccer balls, and footballs,with a few softballs and beach balls thrown in here and there. We filled and smoothed the spaces between them so they looked more like bulges than balls. So yes; it is technically pointing because it seals and adds support to the stones. For the most part we just filled all the spaces that I'd call crevices between the stones to gentle concaves that merged with the convex surfaces of the stones. The finished product left no cracks or spaces for spiders and very few horizontal surfaces for dust. It was not a wash coat at all. We did not completely cover any of the stones; that was not the intent.
Sign at N.E. Vocational School Cabinetmaking Shop 1976, "Free knowledge given daily... Bring your own container"
Posts: 1,600
Threads: 0
Joined: Jan 2014
Thanks...our foundation wall is a rubble stone made up of irregular shapes, and lots of small stones. Much of the mortar, being very soft, has fallen out, so in order to clean the wall up, I want to fill/point in the joints and then probably parge. These stones were never intended to be exposed. I daresay they are not aesthetically pleasing, but after pointing I may feel differently...
Posts: 869
Threads: 0
Joined: Jun 2008
02-25-2023, 10:34 AM
(This post was last modified: 02-25-2023, 10:36 AM by adamcherubini.)
Yeah I did it a year ago. We used regular ole quikrete mortar. We did excavate the exterior side, Parge and water proof. We installed a french drain to relieve any pressure. It’s been done dry no bulging or cracks.
Process invoked raking out anything loose, then refilling by hand. We used white stucco base which, if wet, stained the dark granite stones. Mixing the material pretty dry is helpful. Took us a while to get the hang of it. Our wall was 25’ long, 9’ high.
