Maintenance of weberpral monocouche renders


weberpral M (and weberpral D) may be cleaned periodically by the use of a pressure washer incorporating a mild detergent or road traffic film remover in water. The spray pattern should be adjusted to form a fan rather than a jet and care must be taken at the exposed edges. The interval between treatments is purely dependant upon the amount of ground floor pedestrian ‘traffic’ and local atmospheric conditions. Organic growth should be brushed off the surface and subsequently treated with weber CL150 — this will act as an fungal, mould and algae remover.


Once applied, weberpral products are finished materials and repairs are always likely to be visible. For this reason we would, in general, recommend that full panels be removed and replaced. Where the elevation includes an Ashlar effect the cuts could be used as edges of the panel. Render repair will appear to be ‘new’ at first in comparison to the existing, but these should tone down and ‘weather in’ over period of time. The quality of the repair is very much based upon the skills and patience of the tradesmen undertaking the works. The below gives solutions to specific issues when considering repairs:

Damaged render

weberpral products are through-coloured materials and as such small knocks and abrasions will not be as noticeable as with traditional painted renders. If a repair is deemed to be necessary, the material should be removed back to the substrate, a key provided by means of weberend aid and new material applied proud of surrounding surfaces. This should then be scraped back flush when the set allows. Please note that the existing render should be protected with masking tape to avoid staining. For all small repairs including crack repairs weber arêtes chrono can be used to accelerate the setting process of the weberpral render and allow the scraping process to be completed shortly after application.


Please note for the prevention of cracking please see the Weber Monocouche Best Practice Guide. Straight line cracking is not typical of render failure, but rather of the reflection in the render of a crack in the substrate. The cause should be investigated prior to repairing the crack in order to ascertain the likely event of any further movement or whether remedial works are required. The works could include repairs to the substrate by pinning or resin bonding or introducing a movement joint. This assessment should be undertaken by a structural engineer. Inconspicuous cracks that remain dry and sound are usually best left alone. Cutting and repairing, however carefully done, invariably results in some differences in appearance over the area of the repair.

Repair methods

There are two different methods of crack repair. Repair Systems 1 and 2 are designed for repairs to cracks where the issue of further movement has been assessed and is deemed remote or has been accommodated for by the introduction of an adjacent movement relief joint. System 1 is  for aesthetic repairs to hairline/fine cracks and System 2 is for cracks that are visibly open and any other forms of damage, requiring a patch type replacement.

Repair system 1

  • Using a mini disc cutter, run a cut through the crack in order to open the crack to the thickness of the cutter blade.
  • Dry mix by volume 6 parts weberpral M (or weberpral D) with 1 part weber arêtes chrono. Then add a dilution of 2 parts clean water mixed with 1 part EVA or waterproof external grade PVA to produce a workable consistency. (Please note it is imperative that the additive to water ratio is measured correctly because, if the dilution is too strong, this will affect the finished colour of the repair).
  • Fill a cartridge with the mixed product and load into a cartridge gun. Cut the nozzle to suit the crack width and inject a bead of product into the crack ensuring that you do not overlay the material over the existing render but that you form a protruding nib of material 2-3mm in front of the line of the existing render.
  • Allow the repair material to stiffen for a period of between 20-40 minutes (dependent on temperature) then remove the nib carefully by using the edge of a small filling knife. If the scraping process is completed after the 40 minute period, it is likely that a much lighter shade of repair will be achieved than the existing render, which will not blend in.

Repair system 2

  • Using a disk cutter cut a straight line 50mm either side of the crack, then remove the render back to the substrate between the cuts.
  • Stick masking tape tight to the outer edges of the cut edges then prime the inside cheeks of the render cuts and exposed substrate with a dilution of 3 parts clean water and 1 part EVA or waterproof external grade PVA.
  • Whilst the primer is tacky, skim a layer of mixed weberpral including weber arêtes chrono if desired into the void. Immediately push into the applied material a piece of Weber alkali resistant meshcloth cut to width followed by a further coat of weberpral applied over the mesh so as to fill the void and overlay the product onto the masking tape and past the existing thickness of render by 3mm.
  • Allow the product to pick up sufficiently until it is firm enough to allow for the scraping process and remove the 3mm of excess product back to the line of the existing thickness of render. The edge of a filling knife could be adopted for this process. Brush the product down to remove the scraping dust and remove the masking tape. Scraping too early or too late in the set of the material will affect the cured shade of the product and will prevent a colour match being achieved to the existing render.


Once render has been repaired, weberend protect is a water-repellent coating used for protecting external renders from water, oil and graffiti which maintains the surface aesthetics and allows the substrate to breathe. 

weberend protect repels water and causes liquid to bead on the surface resisting water ingress and protecting the substrate. The product is vapour permeable, however, which allows the substrate to breathe, giving long lasting protection and algae control whilst retaining the original appearance of your monocouche render.


weberpral scraped finish renders are suitable for painting if desired. webersil P is a high performance mineral paint that gives exceptional long term durability and performance. It is anticipated that the use of this product will not detract from the low maintenance benefits of the weberpral monocouche render. Providing that the monocouche render is clean, dry and sound, a direct application of the webersil P is appropriate.

The first coat of webersil P should be diluted with between 10% and 15% clean water and the paint then applied with a medium pile wool paint roller. 24 hours later a second coat is applied, this coat should be undiluted. The application should be in a criss-cross pattern ensuring that the paint is applied evenly minimising any effect on the scraped texture of the monocouche.

Please note when the product is applied to a sprayed roughcast texture brushes may need to be adopted for the method of application.

webersil P is manufactured in a wide range of colours. It is not possible to match a synthetic product to a mineral render. This is particularly prevalent in the case of coloured renders as there are many influencing factors surrounding the application that will affect the final cured shade of colour; in particular the point at which the laitance is removed by scraping in the setting process of the render. Spillages do stain and are difficult to remove so protect vulnerable areas thoroughly and wear suitable protective clothing. Tools can be cleaned with clean water.

Contact us

If you have any questions or would like assistance, please contact our technical team:

Our technical team is available Monday to Friday, 8:30am until 5.00pm.

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