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Discussion Starter #1
I have a 120 year-old Victorian. The foundation is brick, double walled with a 2'' void between walls.

I went under my wrap-around porch for the first time in years and the mortar is badly deteriorated on the above-ground courses. It's not so bad that it's structurally a problem, but it may be a couple of years from now.

This part of the foundation gets no water. (8' deep porch with ground under the porch graded away from the foundation.)

It will be a nightmare to repoint it all. It's 35 feet long with only 30'' of clearance from the ground to the floor joists. I'd be laying on my side pointing bricks for a solid week.

Question - Can I stucco over it, using metal lath and a high lime mortar? Will this stop the deterioration or just cover the problem while things continue to deteriorate internally?

(Basement is dry and ventilated. 50 years ago it was stuccoed throughout with wire lath.)
 

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Your very best option would be to re-point using a mortar that matches the existing. You don't want a mortar that has a higher PSI rating than the existing.
As for applying a Stucco yes you can but DO NOT use any Lath the Stucco will adhere to masonry better than if Lath is used. Also Lath over masonry will cause the Stucco to crack. Also Stucco may very well cause a moisture migration problem in the outer wythe of brick.
If Stucco is selected the PSI of the mortar used should not exceed the PSI in the joints.
 

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Red Seal Electrician
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If going stucco, look at products with adhesion agents - or pre-coating with an adhesion modifier (i.e. specialized paint-on glue).

Metal lath will likely create bigger problems trying to attach it, and you may get rust bleeding as moisture permeates the wall.
 

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Adding an adhesive agent?
Some bonding agents if not applied correctly can become a bond breaker.
Some bonding agents if covered before it has dried will fail.
Acrylics cannot be used as a surface applied bonding agent.
A dash bond coat would be the best to use over a masonry substrate.
If an acrylic is used in the mix it will increase the PSI rating of the mortar being used which will effect the underlying mortar & brick bad idea to do this.
Using a Specialized Paint or Glue I don't know of any paint or glue made for use with a mortar based Stucco.
 

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Discussion Starter #5
Thanks for the info CB and U2.
Can you explain about ``Also Stucco may very well cause a moisture migration problem in the outer wythe of brick''?
Moisture going from in to out, out to in, or both?
Will this migration compromise the stucco or will it impact the brick and mortar in the outer wythe?
Also, why is the foundation so bad here? Below grade it is fine. Above grade and exposed to the weather is fine. The deteriorated part is above grade and exposed to NO weather. I'd think it would be in great shape. Is it because it's too dry?
 

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Thanks for the info CB and U2.
Can you explain about ``Also Stucco may very well cause a moisture migration problem in the outer wythe of brick''?
Moisture going from in to out, out to in, or both?
Will this migration compromise the stucco or will it impact the brick and mortar in the outer wythe?
Also, why is the foundation so bad here? Below grade it is fine. Above grade and exposed to the weather is fine. The deteriorated part is above grade and exposed to NO weather. I'd think it would be in great shape. Is it because it's too dry?
First you should go to the post in this section by FLUKE SG2 thread posted this site @ 03:22 this date NOTE what is said about mortar joint failure (bricks loose) An improper mortar applied a masonry substrate will cause the mortar joint failure than brick failure next. Your brick have a softer mortar than the mortar used in the Stucco mix. The soft joint mortar will allow moisture to migrate @ a faster than the very hard dense Stucco mortar. Keep in mind the moisture is trying to get to the surface of the Stucco but it can't all make it to the surface it is trapped in the mortar joints. The moisture will migrate up through the brick from the soil & will carry SALT and the Salts will attack the Lime & mortar breaking it down and leaving the sand. As for the below grade brick my bet is there is NO Stucco covering those brick & they are performing as designed. You stated that the interior was Stucco years ago now with the exterior stuccoed the moisture has no where to exit.
Question you state ( above grade & exposed are fine ) Do these brick have Stucco applied? Keep in mind the wrong mortar applied over Brick will cause the problem you have. Any mortar over Brick should have a lower psi then the joint mortar I will also bet that your home brick joints are a Lime Based mortar. Go in the basement & tap on the Stucco with a plastic hammer or a wooden mall & see how many hollow spots you have my guess is 40% is delaminated. Also note that it will take many years for the problem to show up
you may see defects after 15 / 20 years.
 

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Discussion Starter #7
Interior with stucco over lath - You're exactly right. A third or more is delaminated. And there are white spots and stains over most of it, likely the salts you are talking about.

Outside - No stucco anywhere. Below grade fine everywhere. Above grade which is painted and in the weather is fine. My problem is the above grade, unpainted portion which is under a porch. Neither the brick nor the surrounding soil gets much water at all.

I've attached two images.

Clearance is really the issue for repointing it (which seems like the optimal thing to do). There's only 30 inches between the ground and the porch floor joists. If I were 25 I'd do it. I'm not. I've called several masons and have two coming in for quotes. But 3 that I spoke to wouldn't even look at it when I told them it was under a porch.

That's why I've been asking about stucco. (I know I have to repoint the parts with loose bricks.) I could physically do the stucco. I just don't want to bury a problem - not fixing it or even making it worse.
 

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Red Seal Electrician
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Adding an adhesive agent?
Some bonding agents if not applied correctly can become a bond breaker.
Some bonding agents if covered before it has dried will fail.
Acrylics cannot be used as a surface applied bonding agent.
A dash bond coat would be the best to use over a masonry substrate.
If an acrylic is used in the mix it will increase the PSI rating of the mortar being used which will effect the underlying mortar & brick bad idea to do this.
Using a Specialized Paint or Glue I don't know of any paint or glue made for use with a mortar based Stucco.
I don't know the particulars, but my father was a master stucco tradesman (and bricklayer), and I was his teenage helper back in the day. Many cementitious surfaces got brush coated with a watered-down white-glue-like solution to increase adhesion. Some stucco mixes had fibre reinforcement. Dunno whats right for brick/mortar... never got on with that chemistry or the trade.

If you can find any 75-80yo retired stucco guys around... they probably have a solution. Most of them are not online. :wink2:
 

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I don't know the particulars, but my father was a master stucco tradesman (and bricklayer), and I was his teenage helper back in the day. Many cementitious surfaces got brush coated with a watered-down white-glue-like solution to increase adhesion. Some stucco mixes had fibre reinforcement. Dunno whats right for brick/mortar... never got on with that chemistry or the trade.

If you can find any 75-80yo retired stucco guys around... they probably have a solution. Most of them are not online. :wink2:
You just quoted an OLD Plaster / Stucco trade person 83 years old.
 

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Interior with stucco over lath - You're exactly right. A third or more is delaminated. And there are white spots and stains over most of it, likely the salts you are talking about.

Outside - No stucco anywhere. Below grade fine everywhere. Above grade which is painted and in the weather is fine. My problem is the above grade, unpainted portion which is under a porch. Neither the brick nor the surrounding soil gets much water at all.

I've attached two images.

Clearance is really the issue for repointing it (which seems like the optimal thing to do). There's only 30 inches between the ground and the porch floor joists. If I were 25 I'd do it. I'm not. I've called several masons and have two coming in for quotes. But 3 that I spoke to wouldn't even look at it when I told them it was under a porch.

That's why I've been asking about stucco. (I know I have to repoint the parts with loose bricks.) I could physically do the stucco. I just don't want to bury a problem - not fixing it or even making it worse.
I see what I think is old Grey mortar in some of the joints in the photo if it is the grey , hard & dense mortar it is a big part of your problem. The wrong mortar has caused the soft mortar to move along with the moisture migration.
Weather you believe it or not that wall has a moisture problem. Quote " Proper repointing can last years, improper repointing will do little to extend the life of the masonry and may lead to irreversible
damage to masonry units. "
See if you can locate this report Repointing Historic Masonry Structures. By Edward A. Gerns and Thomas R. Wegener.
The Stucco on the interior also could be a factor in this damage.
Here are some more articles & info you can use as a reference.
Preservation Briefs #2 Repointing Mortar joints in Historic Masonry Buildings By Robert C. Mack FAIA 7 John P. Speweik. John Speweik was with the National Lime Association, than worked with Virginia Lime Works, than moved to Edison Coatings. I don't know if he is still working he is about my age call Edison Coatings see if they know where he is.
Another good article by John Speweik Return to Lime Putty Mortar, Masonry Magazine September/October 1997.
Why using Modern Mortar Can Damage a Historic House by John Speweik Old House Journal July / August 1997.
Lime's role in Masonry Construction magazine August 1996.
Also contact U. s. Heritage Group, Inc. , 3516 North Kostner Ave. , Ciicago, IL. 60641.
PH # 773-286-2100 www.usheritage.com they can also help with mortar selection.
In Canada contact Heritage & Traditional Masonry, 7 Graig Street, Perth, Ontario Canada PH # 613-267-2859 ext 5602
Last do some reading @ this site Historic Scotland www.historic-scotland.gov.uk
 

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Many cementitious surfaces got brush coated with a watered-down white-glue-like solution to increase adhesion. :wink2:
Could be this.https://www.toolstation.com/everbuild-506-contractors-pva/p18844?msclkid=e3497b65ee7b1019430b24067e74331d&utm_source=bing&utm_medium=cpc&utm_campaign=PLC+Construction+&+Insulation+|+Brands&utm_term=4578641333740077&utm_content=Construction+&+Insulation
Some plasterers use it a lot on older walls, although it's water soluble and not the best for damp areas. Also known as school glue.
SBR is better.
 

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Discussion Starter #13
Thanks all for the help.
Masons showed up to work on a building addition down the street after my last post. I asked them if they'd look at my foundation.
They were awesome. It wasn't cheap, but having three twenty year-olds out there for three days rather than me under there for two weeks made it worth it.
They used Type N mortar.
Thanks again.
 
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