Waterproofing

Waterproofing

In our previous blog on Damp Proofing, we discussed the DPC line (damp proof course) and how to fix damp problems below this line. In our DIY blog today, we will discuss problems occurring above your DPC line and how to rectify these problems. Water ingress into any wall will need to escape, it will look for cracks and easy ways out to start with, and may develop into blisters or flaking paint. One must remember that plaster and mortar are very porous and absorb moisture the same way a sponge would, so even a small crack on the top of a parapet that allows water into the wall, may result in peeling or damaged paint. Waterproofing issues are most common on homes with flat deck roofs and parapet walls. Homes with tiled roofs that have a pitch and overhang, will only experience waterproofing problems if the roof tiles are cracked or moved out of place, water can also get in through holes in ridging or in areas on the flashing of the valleys. It would be best to call in a roofing company for advice.

Often homes with flat-deck roofs have the deck waterproofed but the parapet walls get forgotten about, or the parapet walls are waterproofed, but they are cracked and the waterproofing has split, rendering the system useless in that area. When the tops of these parapet walls are cracked, and water lies on them, the water gets absorbed into the wall by the porous plaster. The wall gets warmed during the day and evaporates out the easiest possible way, remember the airbricks in the old homes? Those were to allow moisture to evaporate out the walls in case there was any water ingress. If there is no way out, it pushes the paint off the wall, and this is the problem we end up with. The best option is to stop water getting into the wall in the first place, so we need to seal all possible entry points.

First you will need to get up on your roof and inspect the surface, take your time here and look for cracks, holes or any areas where water can get in and mark them off. Remember to include the tops of parapet walls. If your roof has a torch on system and is coated with a silver bitumen top coat, then you will need to use bitumen products. If the roof has an acrylic system (acrylics are usually other colours and not silver), you may use an acrylic waterproofing product for the repairs. First, the area around the crack or opening, where the repairs will be done, must be cleaned of dirt and chalking paint, you can use a scouring pad and water for this. Then, any loose areas of waterproofing or paint around the crack must be removed or scraped off. You’re now ready to make the repair.

Acrylic System: Apply a liberal coat of Paintcors Aquaseal over the cleaned area with a brush (approximately 50mm either side of the crack). While the Aquaseal is wet, use the brush to embed a cut to size piece of waterproofing membrane into the wet Aquaseal. Make sure there are no air pockets under the membrane and it is completely stuck to the surface. Allow to dry for 2 hours on a warm summer day, if it’s a cold winter day you should double the recommended drying times. Apply a second liberal coat of Aquaseal over the membrane ensuring the membrane is completely saturated, allow it to dry for 6 hours. Once the patch is nice and dry you can apply a finishing coat of Paintcors Ruvacryl or Elegance in the colour of your choice to protect the patch from UV damage. Allow it to dry for at least 24 hours before it gets wet, keep an eye out on the weather forecaster on our website for rain.

Below is a picture of a flat deck roof with a new acrylic system being applied.

Floorcoat
The next picture is of a cracked parapet wall on a flat deck roof that is in desperate need of waterproofing.

Bitumen System: Apply a liberal coat of black bitumen sealer over the cleaned area with a brush (approximately 50mm either side of the crack). While the bitumen sealer is wet, use the brush to embed a cut to size piece of waterproofing membrane into the wet bitumen. Make sure there are no air pockets under the membrane and it is completely stuck to the surface. Allow to dry for 2 hours on a warm summer day, if it’s a cold winter day you should double the recommended drying times. Apply a second liberal coat of black bitumen sealer over the membrane ensuring the membrane is completely saturated, allow it to dry for 6 hours. Once the patch is nice and dry you can apply a finishing coat of bitumen silver to protect the patch from UV damage. Allow it to dry for at least 24 hours before it gets wet, keep an eye out on the weather forecaster on our website for rain.

Below is a typical bitumen silver roof with a torch on waterproofing system. This system is looking worn and needs a fresh coat of bitumen silver, the black underneath is the torch on sheets starting to show through the worn out silver paint. Remember the silver is there to protect the torch on system from UV, which will cause cracking, so it is very important to do a maintenance coat every 3 years. Often a maintenance coat will not only protect from UV but will fix minor leaks too.

The next picture shows a repair patch that has been done on a silver bitumen roof, notice how the patch has started delaminating and black bitumen underneath can be seen, this is a classic example of an area in need of repair. To ensure your patch does not delaminate as seen below, make sure you clean the surface thoroughly before making the repair.
If you are unsure or require any further assistance call us on 011 794 2885 to speak to a technical rep or email us at tech@paintcor.co.za

Leave a Reply

Your email address will not be published. Required fields are marked *

Contact Us