Mortar to re-point limestone foundation
BryanSayer
| Posted in Construction Techniques on
Our house was built in 1901. We are in Columbus, Ohio. The foundation walls are local rock, probably something in the limestone family I would guess. I don’t know rocks well, but these are soft.
The SW corner of the house leaks badly, as in water pours through. Our weather comes from the west. I suspect acid rain has dissolved the mortar. I can tell some attempts have been made at “repairs” before.
I want to have that corner dug completely down and re-point all the joints properly. What type of mortar should be used?
Replies
INAM, but I use PCL Type-N for my 1892 brick house. The brick is incredibly soft, so anything more than that would probably destroy the brick. I usually mix it 16:4:1, sand:pcl:masons lime, I figure the extra lime can't hurt, and I am trying my best to get the proportions similar to the old mortar, which might be straight lime mortar. I used some straight lime mortar from Virginia Lime Works once, but it's hellishly expensive for anything other than a small repair. Get masonry sand as well, I found it makes all the difference.
Z
Re-pionting won't keep the water out no matter what mortar you use.
Some sort of curtain drain would be a better place to start.
Water POURS through this wall. I may need a curtain drain, but there is more to this problem. I'm just not sure what. I may have to install a video camera with a motion detector and record it.
The thing is pointing isn't going to address water infiltration in
the slightest.
You probably should bite the bullet and pay a professional to come and evaluate your sight. So many variables, it will be hard for anyone to solve your problem without being there.
You need to keep the water from reaching the foundation rather then trying to seal it out.
I'd be happy to pay a professional if I could find one that knew what they were doing. I've had several out, and a couple said that "they would get back to me".There isn't anyway to keep all water away from the foundation. This is the west side and our weather comes from the west. There is only about 5 feet of space between our house and the one next door, and only about 2 feet of it is mine.
"There isn't anyway to keep all water away from the foundation. This is the west side and our weather comes from the west. There is only about 5 feet of space between our house and the one next door, and only about 2 feet of it is mine."
Well, there IS a way, but you might not like it much. In that scenario, I'd trench 2' wide down to the footer, waterproof the wall with rigid foam panels, lay a foundation drain in the bottom (to daylight or a sump, if necessary), and backfill with pea gravel or other porous medium up to about a foot from the top, and fill that last foot with clay.
IME, the ONLY way to solve wet basement walls is to make the outside of the wall dry. Anything else is chasing your tail.
Mike HennessyPittsburgh, PA
Just wanted to register a vote for your plan.
The house was built in 1901. No footers, at least as we know them today. The wall is rough stone, so rigid foam wouldn't water proof it. And it still doesn't explain how water pours through. Seepage, I can understand.I'm considering a drain line. I would need to horizontal bore from the curb to a dry well. About a 20 foot run. Is that doable?
Actually, that's not all that unusual, and unless the outside is really irregular, rigid foam would work, if you foam it to the wall and seal the seams. Otherwise, they make waterproofing membranes that would work. Just don't bother trying to seal the foundation with mop-on -- it's probably too crumbly to hold up.
Water pours through because a subsurface drainage channel has developed. Perhaps from a broken downspout tile, or just runoff -- only digging will tell.
You really can't bore for a footer drain, because you need the porous backfill and waterproofing as part of the system -- the drain won't work unless the whole system works.
Drywells are only dry for about 10 minutes. Then they fill with water and plug up with sediment, and you're back where you started. If you can't get to daylight, you need a sump, pumped to daylight, or a drain. I've done one job where I brought the footer drain into the house's basement under the slab and tied into a floor drain (NOT a sanitary drain) there. But non-sanitary floor drains are few and far between.
Mike HennessyPittsburgh, PA
Do your downspouts feed into a drain tile, or do they just dump water on the ground?
I didn't explain that very well. The drywell would be in the front yard, tied to the curb drain out at the street. The "footer" drain would drain to the drywell, and when at the proper level, exit to the street. I'm not exactly sure of the elevation of the bottom of the foundation in relation to the street. Anyway, the point of the horizontal bore would be to go from the curb to somewhere in the front yard where water could be collected. I wouldn't try boring all the way along the wall.The idea of pouring a new wall actually has some promise to it.
You've mentioned that it "pours" in a couple of times.
First thing first- where is it coming from?
If it's drainage off the roofs that's one set of questions, and
if it's ground water run off that's another.
Plus are your neighbors having the same problems?
Do the detective work before you from a plan.
My neighbors say they don't have a problem. Based on the stains I would say this has happened in our house before.There is one downspout that needs an extension, but it is only half of the porch roof, so we are not talking about a huge roof area. Still it needs an extension which I plan to get this weekend.I think I'm going to install a video camera in the basement, maybe with a moisture detector so I can get a better sense of what is happening.
You know, something isn't right with this story.
Neighbors don't have a problem-
Not much roof volume-
"pouring" in is a bit extreme-
Correct me if I'm wrong but, it hasn't always
been like this.
Look around the neighborhood for something different. Try
and imagine the drainage for the whole area. I've seen things
like this happen when one guy diverts the water away from his house and ends up flooding another.
Or the city doesn't clean out a culvert and it floods an area. Or most
especially new houses that change the drainage pattern.
With two houses that close together eavestrough (on both) might be helpful too.
Do what a professional would do and for $250 or so have the old mortar analyzed by a testing agency. Then mix new accordingly.
Jeff
The problem with testing old mortar is that there have been repairs and patches and what not already, so I wouldn't necessarily believe that the results are what I should be using.
I distinctly remember that when Mr Yerby (a 60ish black man) repointed the limestone foundation of my parents' house he was quite explicit that "brick mortar" (containing lime) SHOULD NOT be used. (He dug out a lot of the stuff, and it easily separated from the stone, often turning to dust.)
Beyond that I can't remember what the mortar proportions might have been -- this was about 45 years ago.
Yeah, you want the mortar to be weaker than the brick so if there is movement you, hopefully, get a step crack and just have to repoint rather than replace a bunch of cracked bricks. You also want any vapour to pass through the mortar more readily than the brick (IIRC). Old houses may have really weak brick and need a correspondingly weak mortar. The foundation stone is, typically, substantially stronger.
In the past I've used regular premix mortar to do small repairs on stone foundations but I'm not sure that is correct (or optimal). Heritage type restorations would obviously require a different approach.
Edited 10/1/2008 8:23 pm ET by sisyphus
I imagine what Mr. Derby said (or meant) was don't use a mortar containing cement. Lime is/was the basic ingredient in mortars before the advent of portland cement.
No, he was quite explicit -- no lime.
Corporation: n. An ingenious device for obtaining individual profit without individual responsibility. --Ambrose Bierce
Your getting turned around somewhere. Ideally you
would want to use lime mortar. It's the portland cement you don't
want to use on limestone.
Agreed.Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
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Not what he said.
Corporation: n. An ingenious device for obtaining individual profit without individual responsibility. --Ambrose Bierce
Sorry, re-read to see that you are considering repointing the exterior for waterproofing (not the interior).
We used a 'battered' concrete pour to stabilize the stone and waterproof:
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