Installing new weep holes in existing masonry buildings with painted and/or rendered finishes should be done in compliance with the guidelines outlined in The National Construction Code Part 5.7 'Weatherproofing of Masonry' to ensure effective water drainage without causing damage to the existing finishes.
Here's a step-by-step guide for installing new weep holes:
1. Inspect and Plan:
Refer to Clause 5.7.6, which requires weepholes to be installed around the full perimeter of the masonry building at every 1.2m, and above any openings wider than 1.2 meters. Inspect the masonry walls and plan the weep hole locations accordingly. Careful attention and pre-inspection shall be carried out to check for the presence and location of existing flashings within the wall, and whether there cavity is 'dirty'. A dirty cavity is one that has discarded mortar along it's which can often be left in the wall during construction. This blocks up any weepholes and allows water to 'bridge' any existing cavity flashings. Where the cavity is found to be clean, the owner may proceed with the following steps. Where there is a dirty cavity, this will need to be cleaned prior to installing weepholes. If there is no flashing, the owner may consider installing one. However this can be quite an expensive element of work and while preferable, may not be critical to the weephole installation in every case.
2. Choose the Right Tools:
Use appropriate masonry drill bits and drills with adjustable depth settings to control the depth of the weep holes. An Arbortek 'Allsaw' with plunge blades or similar type mechanical tool is often used in this type of work as they are able to remove mortar from brick walls.
3. Mark the Locations:
Mark the locations of the weep holes on the masonry walls. Ensure they are spaced at 1.2m centres, are level, and at the correct height. Careful assessment of any existing flashings shall be considered to ensure the new weepholes work with the flashings, and that the new work does not damage any existing flashings.
4. Prepare the Area:
As part of good practice, protect the surrounding area and finishes from dust and debris during the installation process, using drop cloths or plastic sheeting, and vacuum attachments on mechanical tools.
5. Remove Perpend Joint:
Carefully remove any mortar in the perpend joint at the marked locations to provide a totally open and clear perpend joint.
6. Clean the Weep Holes:
After the perpend joint is opened and cleared, remove any debris and clean the weep holes to ensure they remain clear and unobstructed. During this process check the cavity is also clear of any debris (a 'dirty cavity' may cause weepholes to not work correctly).
7. Install Weep Hole Insert:
If weephole sleeves are to be used, insert them into the perpend joint openings. We often use sleeves similar to these. However there are a variety of options available to suit the particular project.
8. Repair and Repaint/Render:
This can often be a substantial cost in the work when the existing wall finishes are of paint and / or render, as the full wall usually needs to be re-finished to provide the best cosmetic result in order to conceal the repair work. Repair any damage caused during the installation process. Use matching paint or render, in accordance with good practice, to blend the repaired areas with the existing finishes.
10. Monitor and Maintain:
Regular inspection and maintenance of the weep holes is important to prevent blockages and ensure their continued effectiveness in draining water away from the masonry walls.
By following the above guide, and adhering to good practice, homeowners can install new weep holes in existing masonry buildings with painted and/or rendered finishes while ensuring proper water drainage and preserving the integrity of the finishes. Seeking professional assistance from experienced contractors such as Conspar can further ensure compliance with the guidelines.