Can You Paint Pebbledash?

What is pebbledash?

Pebbledash is sometimes referred to as roughcast. The reasoning behind this is the application and resultant texture on the exterior wall. Some form of lime or cement-based render is applied to the wall and whilst wet, the pebbledash is applied. The mixture contains sand, small gravel, and often pebbles, giving the name to the finish. The process includes literally throwing the mixture at the exposed wet cement. That can come via a trowel or scoop, or alternatively, the pebbledash slurry can be sprayed on.

When pebbledash is not painted, the external façade of your property will tend to look fairly dated. Perhaps that is not surprising as pebbledash became increasingly popular in the 1920s. The demand for cheap housing rose during the inter-war period, and pebbledash was a simple decorative finish that could be used to mask any potential shoddy workmanship. Architecturally, pebbledash is derided for looking rather ugly: ‘one often recoils with acute distaste from [pebbledash’s] coarse and lumpy texture and its drab yellow-brown colour’. (The Pattern of English Building, Alec Clifton-Taylor, 1962)

Medieval buildings and buildings from the Edwardian era also utilise pebbledash. The major benefit is the rigidity of the construction. Houses are much sturdier when pebbledash is paired with solid brick construction. However, the same rigidity is an issue, as a lack of flexibility leaves a building susceptible to structural movement. Structural movement results in potential cracking. Pebbledash already has issues preventing water ingress, and potential cracks further exasperate the issue.

Painting over pebbledash

By nature, pebbledash is not a smooth surface. Therefore, painting the surface is a difficult endeavour that is time-consuming. You will also require a couple of specialist tools to ensure good coverage. Given that a pebbledash exterior is likely to be older, it may display signs of wear and tear. So repairing the surface prior to any painting will also be a time-consuming and potentially expensive venture. Ultimately, it is possible to paint pebbledash, and here is how you do it:

1. Clean and repair surface - A stiff brush is the best option for removing dirt and debris from the surface. A gentle jet wash is also an option. At this stage, an inspection is also required, and mortar is used to fill in and repair cracks in the pebbledash.
2. Prepare area - Masking tape is a useful product for marking off windows, doors, and other areas you don't want to be painted. This can include verges, soffits, and fascia.
3. First coat - Given the rough texture of pebbledash, it is incredibly difficult to get total coverage with paint. Using a masonry brush will allow you to cover between every small chunk of aggregate.
4. Second coat - A secondary coat will ensure full coverage and a more homogenous finish.

As a practice, painting pebbledash is an option, however, we would strongly discourage people when they consider this an option. The reasons for this are numerous and include the lack of weatherproofing and minimised thermal performance.

Correctly covering pebbledash

Using One Coat Dash Cover (OCDC) is the ideal option for covering pebbledash. It is possible to remove the pebbledash covering physically; however, it can prove to be extremely difficult as it can chip off in chunks. The endeavour can also prove to be expensive. Removing pebbledash completely tends to be the safest procedure as you strip back every possible loose piece. OCDC can produce a homogenous surface in one pass, which is ideal for the application of render. Since it is a lightweight and breathable formula, it does not put pressure on the pebbledash. Therefore, any trapped moisture within the pebbledash can escape easily, and moisture build-up can be minimised.

To install OCDC, follow these steps:

1. Priming the pebbledash - Remove any loose elements of the pebbledash prior to priming. EWI-310 Universal Primer ensures the surface will last and is suitably abrasive for the application of OCDC.
2. Preparing OCDC - OCDC comes as a dry mix; therefore, it needs to be prepared with clean, potable water and mixed with an electric paddle mixer to create a homogenous substance. The product is known for its quick-drying properties; therefore, depending on the weather, you will have anywhere from 1 to 3 hours of working time. It is advisable to mix the OCDC throughout the process to ensure the correct consistency.
3. Applying OCDC - As EWI-065 is an extremely lightweight system, it can be applied to a thickness of 20mm in one go. The mixture can be hand-applied or spray-machine-applied, and should not exceed 50mm. A robust system is crucial to the final envelope; therefore, you should embed Fibreglass Mesh into the layer of OCDC. EWI Pro's Orange Fibreglass Mesh is water resistant and protects from alkali damage due to the acrylic acid copolymer liquid.

Decorative finish & painting pebbledash

Once the basecoat layer has been set and cured, you can apply a decorative finish. Both Silicone Render and Silicone Paint will provide a hydrophobic envelope for the system. A layer of Silicone Render will require the basecoat layer of OCDC to be primed with Topcoat Primer. This provides a mechanical key to aid adhesion. The silicone render can be tinted to any Pantone, RAL, or NCS colour; therefore, you have total artistic freedom in your choice. Painting your home does not actually require planning permission unless the property is a listed building. You can choose to use silicone paint to cover the OCDC layer and gain benefits similar to those of silicone render. Therefore, once covered with OCDC, you can paint pebbledash. Crucially, it will be a much simpler endeavour when you have a smooth surface to work on.

What about insulation and pebbledash?

A retrofit involving the covering of pebbledash does present an opportunity to install external wall insulation. The creation of any form of thermal envelope will increase the thermal comfort of a household, as well as reduce the cost of bills. When choosing to install external wall insulation on top of pebbledash, you can just follow the same steps as a regular substrate. EWI-225 Premium Basecoat acts as the adhesive that provides a stable and robust layer on top of the pebbledash. As it is vapour permeable, the whole system can still breathe. The application of the adhesive stabilises any loose pebbledash.

Pebbledash is not a huge issue in construction terms, but it is incredibly unsightly for most and prone to cracking due to how inflexible it is. You can paint pebbledash, however, you do not address most of the issues by doing so. OCDC is the premier and specially designed solution, and pairing it with Silicone Render or Silicone Paint achieves just the finish you desire. Moreover, you retain the low maintenance level of your façade that pebbledash provides without the ugly retention of pollutants. Silicone products can be washed down easily to refresh the façade.