How thick is render?

Question

Can anyone explain the thickness I should go for and why? This is for an external wall

Aaron · Answer

Hi June,

Depending on the render (sand & cement) or monchouce-/silicone render it can range as a general guide it will be 12-15mm (sand and cement up to 25mm in some case)

It's thickness is to keep out the elements protects from moisture, cracking, delaminating.

How this helps

Aaron The Plasterer

Gioni · Answer

Cavity Walls (Standard Modern Build)
This is the most common method for houses. It consists of two layers (leaves) with a gap in the middle.  
• Recommended Thickness: 300mm to 350mm total.
• The Breakdown: * 100mm outer leaf (brick or stone).
• 100mm–150mm cavity (filled with insulation).
• 100mm inner leaf (concrete or aerated blocks).
• The "Why": The cavity prevents moisture from "bridging" from the outside to the inside, while the thick insulation layer is mandatory in most regions to meet modern energy efficiency standards.
2. Solid Timber Frame
If you are going for a sustainable, breathable build, timber is the way to go.
• Recommended Thickness: 250mm to 300mm.
• The "Why": Timber itself is a decent insulator, but you need depth to pack in high-performance mineral wool or sheep's wool. Because there is no "hollow" cavity like a brick wall, you can save a little bit of floor space while achieving the same warmth.
3. Solid Masonry (Old School or Tropical)
Used primarily in warmer climates where "thermal mass" is more important than insulation, or in historic renovations.
• Recommended Thickness: Minimum 215mm (9 inches).
• The "Why": A single skin of brick (100mm) is rarely strong enough or waterproof enough for an external wall. You need at least a "double-brick" thickness to ensure the wall doesn't buckle under the roof's weight and to provide a buffer against driving rain.

How thick is render?

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