Parapet Wall
Parapet Wall
Damp areas under the coping stones of parapet are a major cause of defective, displaced and damaged PARAPET WALLS. Due to extreme weather and sudden changes in weather New York City property owners face damages to their parapet walls. Inspections should be performed every year to avoid major damages in future.
Signs and Causes of damaged parapet walls
- Ineffective or Absent damp proof course (DPC)
- No drips installed
- Weepholes absent
- Internal dampness due to mortar erosion in brick joints
- Roof deck movement
- Freezing temperatures causing water to freeze in damp areas
Process of building/restoring parapet walls
- Remove and install new coping stones with DPC under it
- The DPC ought to extend approximately 3/8" past the surface of the brick and must receive complete support across the cavity from either slates or cement tiles.
- Place movement joints roughly 1/4" away from corners and then at intervals of at least 13 feet
- Remove the parapet and reconstruct it, integrating a suitable DPC and, if needed, a damp proof tray (DP).
- All lap joints must be completely bonded. If a new DP tray is installed, ensure it overlaps the top of the skirting of the waterproof membrane.
- If there are nearby trees, make sure to regularly remove debris, especially during the autumn season.
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If the pointing above the asphalt skirt becomes detached or dislodged:
>Remove the asphalt, leaving 2 to 2-1/2" below the existing chase
>Cut a new chase of the correct size and shape
>Relay the asphalt with a weathered top and space for pointing.
>Point with a cement:sand mixture (1:3) between the top of the asphalt and the underside of the chase. - If the DPC is in good condition but lacks weepholes, create weepholes at every fourth course, ensuring that the DPC remains undamaged during the process.
If the aforementioned repair does not resolve the issue, it might be necessary to reconstruct the parapet.
Reconstruction of Parapet Walls
Demolish the parapet and reconstruct it, integrating a new DP tray with all laps fully bonded. Ensure that the damp proof tray extends over the top of the skirting of the waterproof membrane. Introduce movement joints approximately 1/4″ from corners and at intervals of at least 13 feet. If the skirting is cracked:
- Remove the asphalt vertically and horizontally for about 50 mm from the angle fillet.
- Provide an adequate key to the vertical substrate.
- Roughen the surface for concrete; for brickwork, brush off joints rather than deeply raking them out.
- Optionally, apply cement:sand mixed with PVAC or bitumen rubber emulsion to the vertical surface.
- Re-lay the asphalt on isolating felt horizontally to match existing levels, ensuring a minimum thickness of 1/2" vertically with a minimum 2" angle fillet.
- Use a free-standing curb detail with an apron flashing where the deck is likely to move in relation to the wall.
When you identify any of the aforementioned PARAPET WALL issues CALL MAKKAH CONSTRUCTION AT (718) 908-4716. It’s essential to take the time to plan proper repairs. Incorrectly replacing bricks, painting brick surfaces, using inappropriate mortar, or other materials may exacerbate the problem. We conduct thorough research, consult and undertake repairs that are tailored to address the root cause and will provide long-lasting solutions. Investing time and effort into proper repairs now can help prevent further damage and ensure the longevity and integrity of your structure.