Crumbling common brick

[Phil Gould]

These photos are from a 1920s condo building in Chicago. Three story courtyard building with gangways on both sides. The side walls are common brick, which requires mortar with high lime content. I'm thinking the parging is portland cement, so that water can't get out and is wicking up the wall and rotting the masonry. The wall in the first photo faces south, and is next to a gravel parking pad that is relatively flat. The other side of this wall is a covered gangway, with bricks that are less porous than common brick. There is efflorescence and crumbling mortar on the inside wall. The second photo is the inside of the gangway on the north side of the building, also with parging. The sidewalks in the gangways have underground drains and reasonably good slope away from the walls.

I recommended evaluation and repair by a mason familiar with this type of building. Is my opinion correct, anything else to mention?

[Eric Barker]

Your recommendation is short and sweet! I was in the city today for a mold investigation for a homeowner who moved in last year. His H.I. told him that some tuck pointing was all that was necessary - ouch! There is a difference between tuck pointing and repair - the latter is more $$$$. This place is wicking water like a sponge big time. The water is actually warping the wood floors inside. Basement is going to require gutting. I'm pretty sure that once the remediation company starts opening things up they'll find all kinds if expensive stuff. I don't know who the H.I. was but I hope he's got some reserves set aside.

[peter legeros]

BSI-011: Capillarity—Small Sacrifices — Building Science Information (http://www.buildingscience.com/documents/insights/bsi-011-capillarity-small-sacrifices/?searchterm=rising) damp

I think the attached article on rising damp especially the rules of thumb in Figure 6 regarding the 3/4 width of wall for sacrificial parge coat and the impermeable membrane extent along the interior is interesting.

[Jerry Peck]

BSI-011: Capillarity—Small Sacrifices — Building Science Information (http://www.buildingscience.com/documents/insights/bsi-011-capillarity-small-sacrifices/?searchterm=rising) damp


Spoken with plain, clear, and easily understand wording, such as:
"Some of the tiniest pores can be found in wood, concrete, mortar and brick. Guess what we like to build out of? Yup, wood, concrete, mortar and brick. The theoretical limit of capillary rise in concrete is about 10 kilometers—and folks that is not a typo—it really is about 10 kilometers or about 6 miles. Concrete sucks big time. In wood it is about 400 feet—the height limit trees can grow to is set by the size of the capillary pores in wood. Ever wonder how leaves get water? When you go into a forest and listen very carefully you don’t hear any pumps pumping water upwards a couple of hundred feet do you? Capillary suction is powerful stuff. When you add salt to the water the power becomes explosive—literally as we shall see."

[Michael Thomas]

For future reference, just ran across this article on "rising damp", which also included one of the best (most succinct) explanations of efflorescence I've yet found:


This moisture will dissolve soluble salts from the building materials such as calcium sulphate, and may also carry soluble salts from its source. If the moisture evaporates through a permeable surface, these salts will be left behind and form deposits on or within the evaporative surface. Where there is a large evaporative surface, salt crystals are deposited as a harmless flour-like dusting on the surface. If evaporation is restricted to localized areas such as defects in an impermeable paint finish, then salt deposition is concentrated, forming thick crystalline deposits with the appearance of small flowers; hence the term 'efflorescence'. When evaporation occurs within the material, salts can be deposited within the pores. The expanding salt crystals in these locations may result in fractures forming in the material and spalling of the surface. This type of decay may be seen in porous brickwork or masonry.

Rising Damp (http://www.buildingconservation.com/articles/risingdamp/risingdamp.htm)