# 1860's foundation wall parging



## tenzo (Aug 12, 2007)

I'm the proud owner of a beautiful 1860's home in German Village in Ohio.









The house in in pretty good shape. At least good enough that I can tackle the problems one at a time.

I had some very minor spalling on the basement foundation wall. tapping the wall with my knuckles I found that it sounded hollow above the spots where the spalling was occurring. So I took a hammer and chisel and removed the parging (? 1/4 inch layer) over the walls off. I've taken out about about 10 sq feet total, from various spots on the wall

It looks like the foundation was originally sandstone and sand. In some places gaps have formed about the size of my little finger.

I'm guessing I need to scape out some of the sand and fill it in with a waterproof cement. Then restore the 1/4 inch waterproof skim coat (is this parging?) and then paint.

I have no idea what to use to tuckpoint (?) the stones and then what to use to parge or skimcoat the stones to give a waterproof layer.

Going to the box stores they just try to sell me hydraulic cement.
What products should I be using?

Thanks


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## yesitsconcrete (May 11, 2008)

spalling, as you describe, is usually from water penetration allowing soil acids to attack the mortar's lime thereby damaging the structural effectiveness of the parge coating,,, ' hollow ' sound's indicates delamination & adhesion loss,,, usually local mtls're used when possible so its either sandstone or limestone & the mortar's popp'd due to the water.

hydraulic's useless in this instance impo,,, we'd use std mortar mix w/hydrated lime for flexibility,,, stay away from those box store, too,,, on other days you can find those guys asking ' fries with that ? ',,, overheard 1 orange apron guy last nite recommending mortar mix for expansion jnt repair  :laughing:


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## Tscarborough (Mar 31, 2006)

That is a common issue when a cementious parging is used over a lime based mortar/parge coat. The parging itself is destroying the wall by trapping moisture which then deteriorates the lime mortar.

The proper fix is to remove the cementious parging, tuckpoint the foundation with lime mortar then parge with lime mortar.


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## tenzo (Aug 12, 2007)

What do I use to parge?

(I'm new at this)


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## yesitsconcrete (May 11, 2008)

if it were my house, i'd be removing all the parge,,, possible but doubtful that's an original finish anyway,,, the downside's all the addl work you haven't planned - upside's you'll be able to actually SEE what's happening to the basement.


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## tenzo (Aug 12, 2007)

I'll be selling the house in 2 years


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## Tscarborough (Mar 31, 2006)

http://www.diychatroom.com/showthread.php?t=11673


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## Tscarborough (Mar 31, 2006)

So basically, Tenzo, what you are saying then is that you don't really want to do it RIGHT, just good enough?

If you do not do it right, the foundation will continue to deteriorate, and if you sell it with a known defect (because now you know it has a defect), you will be liable unless you disclose.


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## tenzo (Aug 12, 2007)

Tscarborough said:


> So basically, Tenzo, what you are saying then is that you don't really want to do it RIGHT, just good enough?.


Not at all.
I want to fix what is wrong.

I don't see any need to take apart 1,200 sq feet of the good walls 'just in case' If I was trying to hide it I would not have removed the parding in the first place.

I've hunted down the cause. Repaired a possible roof leak. Cleaned the gutters, removed 5 tons of soil so that the dirt slopes away from the house and in the spring I'm going to reset the bricks on the sidewalk to make sure they are sealed (and possibly putting down a membrane.)

I've removed all the the loose parding, then removed 6 inches in all directions. I just don't think taking down what is good seems a good use of money or resources.


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## Tscarborough (Mar 31, 2006)

It is not good. It is the cause of the problem. Behind that non-breathing cementious parging, the lime mortar of the foundation is deteriorating rapidly.


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## yesitsconcrete (May 11, 2008)

have at it, -scar,,, i'm done,,, tenzo, don't underestimate -scar,,, not sure if he's an engineer, contractor, ??? but he's right,,, i'm just an old repair mechanic who's done wtrproofing, epoxy crk inj, undrwtr conc, roads, bdges, hgwys, airports, historical renovations - & other stuff


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## Tscarborough (Mar 31, 2006)

I am the same as you, Yesitsconcrete, but I study mortar and stucco especially. My first 10 years were concrete systems, my last 20 have been masonry. And I had to unlearn a lot from the first 10 to understand mortar and stucco.


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## Fishdaddy (Aug 26, 2010)

I have a similar spalding problem in my basementand was wondering how to identify if the parging is lime based or was portland cement added later.
The basement was painted so I'm thinking the spalding was caused by moisture trapped by the paint. My wife thinks the parging is lime mortar because it crumbles and looks like very rough agregrate sand was used.


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## nypwacom (Jul 22, 2010)

I have an !873 Victorian. The mortar has turned to dirt in most places. Some repair work occurred in the past. I started scrapiong out the dirt and filled it with Sakrete type n mortar mix and then parged over. I am thinking maybe this is over kill and I should just parge the walls. I have also contemplated adding additional metal supports between the concrete floor and the floor joists. Am I on the right track?


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## Tscarborough (Mar 31, 2006)

I am thinking you have killed your foundation.


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## jomama45 (Nov 13, 2008)

Tscarborough said:


> I am thinking you have killed your foundation.


Do you really think Type N is that bad? It's only 25% (IIRC) portland, it could realistically see 25+ years w/o any major problems...............or maybe I'm way off-base............


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## stadry (Jun 20, 2009)

sometimes 1 wonders if a sharp rap on their skull wouldn't be better than an honest attempt to transfer knowledge :laughing:


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## Tscarborough (Mar 31, 2006)

50% is sufficient to make it water resistant. Anything over 10% portland by volume is too much to apply over lime mortar. 25 years is pretty optimistic for a foundation wall assuming it is not in the desert in Nevada.

The foundation will be exposed to moisture on the outside and it will migrate into the joints and it will be trapped by the parging. I have seen some buildings repaired with portland tuckpoint mortar (and they are exposed both sides) that deteriorated within a couple of years. I have seen some that were done 20 years ago that are not falling down merely by coincidence.

Why do it wrong in the first place? Lime mortar is cheap, easy to work with, and maintains both the historical value and the inherent design of the structure.


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## Tscarborough (Mar 31, 2006)

Well meaning volunteers destroyed this old church.


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## stadry (Jun 20, 2009)

*someone should have pointed out the flexibility of the old mortars - what a shame ! then again, good intentions never accomplished anything :no:*


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## Tscarborough (Mar 31, 2006)

Here is an arch that was never tuckpointed, and while the mortar is eroded, the structure is sound.



This section of the same structure was tucked with portland mortar and it is not structurally sound.


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## jomama45 (Nov 13, 2008)

Tscarborough said:


> 50% is sufficient to make it water resistant. *Anything over 10% portland by volume is too much to apply over lime mortar.* 25 years is pretty optimistic for a foundation wall assuming it is not in the desert in Nevada.
> 
> The foundation will be exposed to moisture on the outside and it will migrate into the joints and it will be trapped by the parging. I have seen some buildings repaired with portland tuckpoint mortar (and they are exposed both sides) that deteriorated within a couple of years. I have seen some that were done 20 years ago that are not falling down merely by coincidence.
> 
> Why do it wrong in the first place? Lime mortar is cheap, easy to work with, and maintains both the historical value and the inherent design of the structure.


Sounds good, that's certainly the info I was looking for. :thumbsup:


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## nypwacom (Jul 22, 2010)

Why do you say this?


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## Tscarborough (Mar 31, 2006)

Lime mortar/plaster is breathable. Portland mortar/plaster is not.

When lime mortar remains saturated, it crumbles. Lime mortar is NOT hydraulic like portland cement. By putting a non-breathable coating over lime mortar, you are trapping moisture in the wall and the lime mortar will rapidly fail, especially if it is old.


Jomama, I normally only recommend up to 5% non-lime cementious material in a lime mortar, and up to 10% in lime plaster. In both cases for gauging only. I prefer to use brick dust, but it is not readily available.


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## nypwacom (Jul 22, 2010)

Thanks. The part that I parged I used the same mortar to peak from inside. Since it is the same material,would there still be a problem? Does adding additional supports make sense to you?


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## Tscarborough (Mar 31, 2006)

Lime mortar masonry construction is designed to breathe. Each "breath" takes 2 Seasons. In the warm wet season, moisture is drawn into the wall, and if properly designed (i.e. thick enough), the moisture will never or seldom fully penetrate the wall to the interior surface (ever hear of a clammy wall in a castle?). During the cool dry season, the moisture is drawn out of the wall.

By making one side of the wall water resistant, the wall be no longer breathe. Moisture will enter it but can not leave it. Once the moisture level reaches saturation, the lime will begin to decompose.

The options are to make both sides water resistant, or both breathable*. The latter is preferable, since you will almost always trap some moisture while doing the former.

Just as an FYI, modern construction is a barrier system, designed to prevent moisture from entering the wall at all, and providing a path for it to escape if it does.

*Edit-If one wall MUST be moisture resistant it has to be the one facing the water pressure, in this example, the outside of the foundation wall, and then the wall is considered a barrier wall system.


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## nypwacom (Jul 22, 2010)

Thanks


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## nypwacom (Jul 22, 2010)

Would I be better off just pointing the walls?

Would you recommend I remove the parge from the wall I did? Some of the walls are already parged. I have lived here 25 years, should I just leave them alone? Thanks


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## Tscarborough (Mar 31, 2006)

Hard to say with out actually seeing it. If it appears to be OK, I would leave it alone, probably. Any water intrusion issues?


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## nypwacom (Jul 22, 2010)

Not where it is parged. A couple spots near the floor I get some minor water during heavy rains. My concern has been the soil like nature of the mortar. It is like hard packed dust.


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## phillyhouse (Apr 3, 2011)

I have a field stone foundation in a ~100 yr old house an urban area and I'm planning to finish a portion of the basement. I was considering parging the wall prior to framing, but now I'm tempted to just leave it alone. I will be framing the walls leaving some space between the foundation and the wall for ventilation. There is some efflourescence but generally the basement is quite dry. Would you guys therefore recommend just leaving the foundation wall alone? Thanks.


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## bob22 (May 28, 2008)

Too many threads going on at once for me to keep track. IMO everyone should start their own thread.


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## Tinkertammy (Aug 13, 2012)

*Parging over stone foundation*

Hello, today I have repointed my foundation, half way through. My house is 1920 bungalow I live in Manitoba, Canada. Cold winters, hot summers. I think I'm doing a pretty good job. Some of the joints were more than 12" deep so have filled in as much as I could. After removing the mortar I blew out the remainder surface sand before I started. Now my questions are (btw I used a pre mix mortar, I just added water): How long do I have to wait before parging over the foundation? I'm confused as whether it's good or bad to parge over foundation as per some of the conversations I have read. If I parge, I'm thinking that I'm supposed to use same mortar 1/4 - 1/2" thick? The only exposed interior basement wall is the furnace room which I have to point some areas as well. It is completely parged over to look sort of smooth. Is that what I'm supposed to do to outside foundation or which would take away the "stone" look or what? I'm just a girl  lol Thanks!!


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