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Can Portland based stucco be applied over old soft


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Trying to determine a new siding for a house built in 1880 with structural brick exterior walls 3 layers thick....

Can a Portland based stucco be applied over the soft brick?

There's very few houses this age left around here and even less are brick and I'm having hard time finding this information but have found many companies in New England area that stucco over 1800's houses with brick walls with Portland stucco...

I've done a lot of it over concrete block with a scratch and brown coat then final stucco such as Arcusstone.. Brick is currently painted and assuming I need to try and remove first but do I need to repoint before stuccoing?

Thanks for any help I may receive. :)

Inside of brick walls appear to be a harder stucco applied directly over brick

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Directly onto the brick. No.

On wire lath attached to the brick. Maybe. If the mortar joints are sound enough to hold lath fasteners.

A better approach may be to install lath on pressure treated furring strips.

I suggest you contact the Brick Industry Association (they may have changed the name) or the Portland Cement Association and see if they have any publications or technical advice on this. Some contractors are willing to do about anything and will tell you they have never had a problem doing it this way. You don't want to be the first (that you know of) to have a problem.

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Definitely no on direct application...disaster.

Definitely yes with some as yet unspecified combination of a breathable membrane (Vaproshield type stuff) and metal lath over a Stuccoflex or similar substrate. Works like an absolute charm, presupposing one is doing all the fenestrations, angles, vertices, and what have you with reasonably considered and executed sheet metal work.

If you got a CNC sheet metal shop near you, it's remarkably simple; they'll roll out custom profiles from a rough sketch while you wait.

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Would someone explain why all brick from the 1800's is 'soft'? Or is it the lime based mortar that's being referred to?

The bricks from that period are not fired "through", like modern bricks with the holes. They are fired to a hard skin.

Once the skin has failed (called spalling - a result of applying Portland-based mortar for repairs or repointing), the soft inner part of the brick is exposed and erodes quite rapidly.

http://www.oldhouseweb.com/how-to-advic ... onry.shtml

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Would someone explain why all brick from the 1800's is 'soft'? Or is it the lime based mortar that's being referred to?

The bricks from that period are not fired "through", like modern bricks with the holes. They are fired to a hard skin.

Once the skin has failed (called spalling - a result of applying Portland-based mortar for repairs or repointing), the soft inner part of the brick is exposed and erodes quite rapidly.

http://www.oldhouseweb.com/how-to-advic ... onry.shtml

Thanks Bill.

Marc

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Brick manufacture was a remarkably tricky operation. The old kilns had notoriously uneven heat, and brick quality varied wildly throughout a batch. Some of them are punk; those go in the inner wythes. The reasonably hard tempered one's go up on the parapets, cornices, rowlocks, and other details with major exposure. Field brick was somewhere in the middle ground.

And it all goes to shit if the mortar isn't right. Doesn't matter how good the brick is, if the mortar's incompatible, it goes to shit, in 10, or 30, and sometimes 70+, but it goes to shit.

If the brick is halfway decent (no spalling), limewash is the miracle. It nourishes the wall. Get it mixed right, it's (sort of) possible to "restore" the brick and mortar.

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Stucco has been applied over the soft low clay content

Common brick low fired solid type in the southern states since the 1890s.

The lime based stucco was applied over the brick with the motor jonts raked to allow for a keyway for the stucco.

In the thirties a change to a portland based stucco started.

To apply stucco over any painted product you must apply lathing wire .case hardened nails are installed with a special tool with a magnet that holds the nail.

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...btw re old brick lore, a guy named Rex Roberts who built low-cost DIY homes in the 50's and 60's said in his book, "Your Engineered House", that the reason barns in New England are red is that ships from England in colonial days used old brick as ballast on their trips to the colonies, where they unloaded the bricks to load up on cotton, tobacco etc. As the brick piled up somebody figured out how to take skim milk, which accumulated as a by-product of cheese/butter making, and mix it with powdered brick to make a good barn paint, which idea caught on. Before long everybody had a red barn.

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The milk and lime part certainly, but the most common belief is they used ferrous oxide mixed into the milk and lime, not ground up bricks. Farmers used rust for a lot of things, one of them being it was a natural fungicide. Barns in Europe were red for the same reason.

Brick was really expensive; I tend to doubt they were grinding them up. Maybe, but I doubt it.

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...btw re old brick lore, a guy named Rex Roberts who built low-cost DIY homes in the 50's and 60's said in his book, "Your Engineered House", that the reason barns in New England are red is that ships from England in colonial days used old brick as ballast on their trips to the colonies, where they unloaded the bricks to load up on cotton, tobacco etc. As the brick piled up somebody figured out how to take skim milk, which accumulated as a by-product of cheese/butter making, and mix it with powdered brick to make a good barn paint, which idea caught on. Before long everybody had a red barn.

Bricks used as ballast and then distributed for any use in America has been proven to be only folklore many, many times. Using brick dust for pigment is also folklore. Iron oxide was THE pigment.
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Bricks used as ballast and then distributed for any use in America has been proven to be only folklore many, many times. Using brick dust for pigment is also folklore. Iron oxide was THE pigment.

I heard the masonry retaining walls along the river in Savannah were built out of ship ballast. . .

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Thank you mythbusters. Have to admit it is a colorful if fanciful story. Two followups come to my mind. What was used for ballast on ships then?

Soil, quarry waste rock and overburden. Some colonial governments eventually had to create legislation prohibiting the jettisoning of ballast into the major shipping harbors.

There were also many passengers, slaves and goods being shipped to the Americas from Europe, Africa and the Caribbean, adding significant weight to the inbound ships.

How was the iron oxide harvested/gathered in quantities enough to make enough paint for all those barns?
Plentiful amounts of hematite were obtained from iron ore producing mines and quarries. I live just a few miles from an iron furnace and ore mines from 1727. Much of the ore was hematite.
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Maybe myth....

I've read that some of the shippers, after having been barred from dumping ballast into the harbors, figured out they could bring flagstone, bricks, or other items they could sell.

The ballast on a ship isn't enough to pave a road or build a seawall; it was small time trading where the captain could make a few extra dollars.

Truth or myth?

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