Can I pick your brains? On houses, render always stops before the ground with a stop bead, and this seems to make sense so that the dpc isn't bridged. But in gardens, walls are commonly rendered from the ground up (including gardens I've designed in the past...). But doesn't this mean that damp can rise up through the render, get behind it and cause the whole finish to blow, or at least discolour?
And while I'm on the subject, what about the tops of rendered walls - do others think it's safe to just render the top as well, with beading on the corners, or would good practice always include frost-proof copings with overhangs, drip grooves, and dpcs?
I'm starting to think that the lowest 150mm of a rendered wall (and step risers) should be unrendered, which then suggests use of engineering brick or similar, and a very different look. I don't want clients to be looking at a damaged wall or steps after a couple of winters. But am I being over-cautious? Any thoughts?
When doing cellars to stop damp seeping through once plastered, to seal the walls we used a product called
This process is called tanking & is well suited to render
You're absolutly right that the render shouldn't go down to the ground. Ideally there should be a couple of courses of engineering bricks before the stop bead however this can have a big impact on the way things look we sometimes stretch this a bit depending on circumstances.
Rendered wall tops can and do work if they are constructed properly. Rendering over a fine mesh can help as can a very slight dome to make sure that water can get away. The big problem is that water tends to run off in the same places which can cause algae to form or 'stain' marks that look unsightly. Therefore rendered walls always need to be cleaned regularly to keep them looking at their best.
have a look at this garden we constructed 4 years ago. The walls are still intact and looking good and they've now been through two incredibly harsh winters
Thanks All, very useful to have your input! Given the hard winters we've been getting I am inclined not to take chances with the design but as you say Dave this will impact on the look, especially where there are complex arrangements of steps, raised planters, walls etc. All part of the challenge!