How much does a bag of Weber render cover?

Weber UK

In this blog we are going to approach one of the commonly asked questions… “How much does a bag of Weber render cover?”

Firstly we need to clarify which render product we are talking about, in this article we will focus on our biggest sellers weberpral M and weberpral D monocouche render.

One 25kg bag of weberpral M or weberpral D monocouche render covers approx 1 sqm*

*But of course, there are always caveats to this, here are some of the considerations when planning your render project.

1. Which render finish?

Scraped texture
25kg bag = 1m2 approx.

The most popular finish for monocouche is scraped textured. In a standard installation, when you apply weberpral M or weberpral D render you need to apply to a thickness of 18mm to allow it to be scraped back to minimum of 15mm.

This calculation does not take into consideration any wastage or irregularities in the substrate

Spray roughcast texture
25kg bag = 0.7m2 approx.

More traditional in style the spray roughcast finish creates a slightly thicker render coverage on the wall, but creates less waste as you are not scraping the surface away. Start with a 15mm first pass and spray a further 5-7mm of render to create the texture.

The coverage may vary dependent on the machine used and roughness required.

2. Exposure to weather

In line with BS EN 13914-1:2016 the thickness of a render is largely dependent on the exposure of the building. Categories for exposure are calculated using a driving rain index (litres/m2 per spell).  Check out details on the NHBC website


Scraped texture – initial pass of 18mm, scraped back to 15mm
25kg bag = 1m2 approx.

Spray roughcast texture – initial pass of 15mm, further spray textured pass of 5mm
25kg bag = 0.7m2 approx.


Scraped texture - initial pass of 13mm, further pass of 10mm scraped back to 20mm
25kg bag = 0.7m2 approx.

Spray roughcast texture – initial pass of 20mm, further spray textured pass of 5-7mm
25kg bag = 0.5m2 approx.

Note: for buildings with fully filled cavities in sheltered to moderate locations, 20mm of finished render would be required as noted in NHBC clause 6.11 Table 6guidance should be sought from house builder

3. Render detailing

Quoins, raised bands, keystone plinths etc…

If you are ‘adding’ details to a building and are forming them using render (rather than preformed moulds) you need to consider the additional render you are likely to use, and that they do not exceed the recommended maximum thickness of render (40mm). These would need to be formed as an integral part of the render application and not added on to the surface of the render to minimise water ingress.

4. Render wastage

When planning your project it is always advisable to consider wastage and we would advise including a calculation of 10% for waste.

Note: for machine application, for a typical 25mm render hose 15m long, there is approx. one bag in the pipe

Need more help?

On our website each product has a handy Consumption Calculator, this will give you an approximate usage figure for your project, if you require more detailed assistance with your specification please contact our Technical Team:

call: 01525 718 877 (option 2)

Click Compare to help you choose the right product for your project, if you need further assistance please email