K-Rend Monocouche vs Silicone Render

If you’re thinking about rendering your house, or redoing old render, you’ll quickly run into three names: “K-Rend monocouche”, “silicone” and good old “sand and cement”. They get talked about as if they’re three rival products. They’re not quite that, and knowing the difference will help you ask better questions when you get quotes.

First, clear up the names

Sand and cement is the traditional render. It’s mixed on site, applied in two or three coats, and usually finished smooth or textured and then painted.

K-Rend monocouche and silicone are products from one brand, not a type of render (more on our K-Rend monocouche and silicone in Birmingham and Solihull page). The brand is best known for its monocouche (single coat) renders: through-coloured, applied thickly in one go and scraped back to an even finish. Other makers do the same thing, such as PRB and Weber. The same brand also makes K-Rend silicone. So “K-Rend monocouche vs silicone” is really “monocouche vs silicone”.

Silicone render is a thin, coloured top coat. It goes over a properly prepared basecoat with mesh bedded into it. The silicone makes the surface water-repellent while still letting the wall breathe.

Sand and cement: cheap to make, more upkeep

Good points

• Materials are easy to get and well understood.
• Any decent renderer can patch it or match it.
• It’s a fair choice for small repairs, garden walls and outbuildings.

Downsides

• It’s hard and rigid, so it tends to crack when a building moves slightly.
• It normally needs painting, and then repainting every few years.
• On older solid-brick houses it can trap moisture in the wall.

That last point matters in the Midlands. Many Victorian and Edwardian terraces in Birmingham, Coventry and the Black Country have solid walls with no cavity. On those, a hard cement render can hold damp in rather than keep it out. A breathable lime render is often the safer choice. If you have an older house and someone wants to put cement render straight on, ask why.

Monocouche (K-Rend monocouche and similar): no painting, one look

Good points

• The colour runs right through, so there’s no painting.
• It’s one thick coat, so it’s quick to apply on a large, straightforward wall.
• The scraped finish looks crisp and modern.

Downsides

• The colour is fixed. If you want a change later, you’re painting over it or starting again.
• On shaded or north-facing walls, under trees, or where gutters overflow, it can pick up green algae or dirty streaks over time.
• It needs a sound, suitable background. It isn’t a cover-up for poor walls.

Silicone thin-coat: the most forgiving finish

Good points

• It sheds water well, so it tends to stay cleaner than painted or plain cementitious finishes.
• It’s slightly flexible, so it copes better with small movements.
• There’s a wide range of colours and grain sizes.
• It works on new block, over old render that has been properly prepared, and as the finish coat on insulated render (insulation boards fixed to the outside walls).

Downsides

• The finish is only as good as the basecoat under it. Mesh, beads and a flat, consistent basecoat are what make it last.
• It has weather limits. It shouldn’t go on in frost, heavy rain or very hot sun. A good renderer will check the forecast and won’t rush it.

For transparency: on most of our domestic jobs we use a polymer basecoat with mesh and a sprayed silicone top coat. We also quote monocouche where it suits the house.

So which suits a Midlands house?

These are rules of thumb, not hard rules. A good renderer should look at your actual walls before recommending anything.

• 1930s semis with tired pebbledash or patchy render (very common from Solihull to Sutton Coldfield): silicone over a new basecoat is usually the cleanest way to get a uniform, low-maintenance finish.
• 1960s–80s estate homes and extensions in block or brick: monocouche or silicone both work. Silicone gives you more colour choice; monocouche gives you a scraped look with no painting.
• Victorian or Edwardian solid-wall houses: think about lime first, and get advice from someone who understands breathable walls.
• Garden walls, outbuildings and small patches: sand and cement, painted, is often perfectly sensible.

Questions worth asking any renderer

1. What’s the background, and does any old render need to come off?
2. What system will you use, basecoat and top coat, and is it one manufacturer’s system?
3. Will you use mesh, and what beads (corners, stop ends, a bellcast at the bottom)?
4. How will you keep the render above the damp-proof course and away from the ground?
5. What happens if the weather turns on the day?

If the answers are vague, keep looking. You can see how we approach jobs on our rendering Birmingham and rendering in Shirley pages.

Want someone to take a look?

RCR Connections Ltd is a Birmingham based plastering and rendering company covering the whole of the Midlands. If you would like us to look at your walls, WhatsApp me on 07453 614095, message the page, or use our contact page. You can also see our plastering and rendering services and finished work on our projects page.