Masonry Consulting Experts Focused on Chicago and Chicago's North Shore
Saturated split face block parapet wall, needs to be flashed, vented and sealed. Ukranian Village, Chicago IL
Common Masonry types and why they leak...
Wet Building Solutions evaluates and provides repair recommendations for all types of masonry, but is focused on relatively new masonry buildings in Chicago and the North Shore.
Most buildings with severe moisture intrusion issues are constructed with Split Face Block and/or Concrete Block. These materials are highly porous and must be sealed regularly to resist wind driven rain. Many of these buildings have a brick facade with block structural wall on the front and single-wythe block on the other three walls.
Many buildings have Renaissance Stone or Pre-Cast Concrete as details around windows and doors or a cornice. Historically, these details were Limestone. Limestone leaks, but water filters through it slowly. Water runs freely through Pre-Cast, right into your home.
3 More Reasons Masonry / Parapet Walls Leak
Split Face Block parapet with flat concrete capstone - no overhang or groove under the stone, no flashing or drip edge –Wicker Park, Chicago
1. Weather Exposure
Parapets are the short walls that extend above a flat roof along the perimeter of a building. They are decorative, but also conceal rooftop AC units, and provide privacy and safety for rooftop decks.
Parapets take a lot of abuse. They are exposed to wind driven rain and snow on all 3 sides - the interior, the exterior and the top. How a parapet is finished determines how much water seeps into the wall from the top.
- Capstone - Limestone or Renaissance Stone? Both leak - but vinyl self-adhered flashing should be installed between the capstone and top of the wall – see #3
- Metal Coping - The length of the coping legs matters. Best practices says both legs should be 4" long or longer – We say 5"
- Clay Copings - need to be in good condition, right size for the wall and the mortar needs to be intact, no tar or black goo stop-gap fixes.
"Spalling" on brick building near structural supports for balconies – Uptown, Chicago
2. Mortar with Portland Cement
Most contemporary parapets are built with mortar containing Portland cement, which allows moisture to enter and traps moisture behind it.
If you have a historic brick building, it should be tuck-pointed with lime mortar. Tuck-pointing (which is actually called re-pointing) with mortar containing Portland Cement can damage historic and contemporary brick.
"Spalling" is caused by water entering through the mortar, then absorbing into the brick, freezing in the winter and popping the face off the brick, thus compromising the look and strength of the brick.
Missing Mortar, no Flashing or Drip Edge under Pre-Cast Concrete Capstone on leaking common brick parapet wall – Lakeview, Chicago
3. Stone and other porous materials
Parapets on contemporary buildings constructed with Split Face Block, Concrete Block, or Brick Facade with a Block Structural wall behind it are often finished on top with Renaissance Stone, AKA Pre-Cast Concrete. It is extremely porous, far more porous than traditional Limestone.
Metal drip edge and mason's flashing should be installed underneath all Capstones. We evaluate wet walls everyday with neither of these standard building materials. Walls without mason's flashing and metal drip edge are essentially open to the sky.
Solution - Parapet Wall Ventilation
Ventilation Planning is key...
We have found that parapets and masonry walls dry quickly when an escape route for water vapor is provided. At this installation in Milwaukee in March, the contractors said they could see the steam rising out of the wall.
Another customer in Bradenton, FL had a similar experience. He was sitting on the parapet in August watching the sunset. He said the backs of his legs were burned by the steam coming out of the wall.
Venting Parapets with Metal Copings
Venting Parapets with Capstones
Venting Parapets with Clay Copings
