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Hello,
I have a query hoping someone can assist with - I have completed the brickwork for an outdoor kitchen project using standard maxi's which I have built over our existing honed aggregate (as a footing) under our alfresco. I am going to render most of the project then cover in a texture product like Dulux's Acratex. My question is do I need to apply waterproofing to the bottom half coarse given they are built over our aggregate (100mm thick and 2.5 years old - have never had any rising damp in the alfresco that I am aware of as it is also under the main roof), and if so, can I use my left over Davco K10plus or is there a more suitable brush on product.
The second question is if I need to brush on a waterproofing membrane, can I render over it (was looking to use Dulux p400 as base render however given that's over $40 a bag, am open to other pre-mixed render product which are water repellant and can be screeded over a waterproofing membrane (Davco PM render?, Westbuild Render+?)
Attached are some pics and you can see the extent of roof cover - the main back wall with the LPG gas drawer is the only area which can get wet in winter from rain when a SW rain, hence the question around waterproofing membrane on the lower coarse and an acrylic style render to repel water.
Thanks!
Hi @GregM,
When creating a brick wall, a damp course is usually essential. In standard brick construction, you’d have a damp course layer one brick course up from the base to prevent moisture from rising from the ground. Without it, water pooling at the bottom can wick up through the bricks and mortar lines, potentially causing damp issues higher up the wall. In your case, since you’ve built directly over an existing honed aggregate slab without a damp course, the base of the bricks could absorb water if it pools there, so some form of waterproofing is sensible.
For the lower course of bricks that might get wet during rain, applying a waterproofing membrane externally is a good precaution. Davco K10 Plus could be used, but it’s primarily designed as a under tile adhesive waterproofing system, so adhesion of a render directly over it isn’t guaranteed. If you go this route, a test patch first is essential.
A safer option is to render the wall directly with a suitable exterior render, like Davco PM Render. It will give you a solid base for your textured coating like Dulux Acratex without risking delamination. Another approach, if you want to maximise waterproofing and finish quality, is to coat the entire wall with a waterproof membrane, then fix exterior blueboard over it and apply your texture coating to the blueboard. This effectively encloses the bricks behind a waterproof barrier, protecting them entirely and giving you a smooth surface for your acrylic textured finish.
Please let me know if you have any questions.
Mitchell
