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Common Rendering Problems

When rendering a building’s exterior, certain issues are likely to arise. These issues include fading, cracks, mould, and leaks. In this article, we will explore these common rendering problems and provide solutions to fix them.

It is important to understand the potential challenges that come with rendering a building’s exterior. By being aware of these issues and knowing how to address them, you can ensure that your building remains in good condition and maintains its aesthetic appeal.

Common Rendering Problems

The Common Causes of Render Defects

Render defects are a common issue on external walls, and they can be caused by a variety of factors. These include weathering, structural movement, and moisture penetration.

While some render cracks may only be cosmetic, others can lead to serious structural issues if not addressed promptly.

Homeowners may need to repair or replace the render, which can be a costly process. It is important to identify and fix render defects early to avoid potential structural problems.

Main Causes of Exterior Render Defects

Exterior render defects can be caused by various factors. One of the main causes is moisture behind the render, which can penetrate through the wall, leading to penetrating damp. This can result in timber decay, stained plaster, and mould.

Rising damp is another factor that can have a significant impact on the structure of a building, causing bulging and warped walls, floorboards, and skirting boards, and even rotting.

Inadequate preparation before a rendering job can also contribute to issues with the surface. It is often necessary to clean the wall of dust and dirt before applying the render to ensure proper adhesion.

The application of two coats of render is standard, with the strength of the first coat varying based on the type of brick and stone used. It is important to allow the wall to dry properly before applying the second coat.

Patch render repairs can be done for both large and small areas or the entire house. Surveyors can identify signs of rising damp and recommend the best solution. Proper preparation and application techniques can help prevent exterior render defects.

Avoiding Renders That Are Not Breathable

To prevent damp problems from arising in the building envelope, it is important to choose renders that are breathable. This is because water is a significant cause of damage to buildings, which can be introduced by wind-driven rain or moisture that is trapped underneath render.

If the wall is not waterproof, the resulting damp can lead to discolouration and damage.

To avoid the dreaded damp, it is recommended to clean and maintain the render. Keeping it clean will help to reduce the risk of dampness and avoid any organic growth. There are a variety of different types of render, and some are more flexible than others. It is important to choose the correct one for your needs.

Some renders, such as silicone, are designed with breathability in mind. This will prevent the build-up of fungus and algae and provide a highly durable finish. On the other hand, there are other types of render that are less breathable and will allow the moisture to soak in over time. This means that the wall will need to be treated with a waterproof exterior coating.

Repairing Common Rendering Problems

Rendering a house is not an easy task, and it can be a frustrating experience for those who lack the necessary training and experience.

Even the most experienced DIY enthusiast can make mistakes that can lead to common rendering problems. Fortunately, repairing these issues is not as difficult as it may seem, especially when you hire a professional rendering company like Ralph Plastering.

When it comes to repairing rendering problems, homeowners should consider hiring qualified contractors who are licensed and insured. Recommendations from work colleagues or family can be helpful in finding the best contractors in the area.

One of the most common rendering problems is cracking. Structural movement, temperature changes, and incorrect initial curing can cause cracks. These fissures can deepen with time, allowing moisture to permeate the render and damage the structure.

To fix this issue, the damaged render layer needs to be removed, and the surface needs to be cleaned and primed before applying a new layer of render.

Another rendering problem that is seen in most properties is moisture penetration. This can cause penetrating damp, which can result in timber decay, stained plaster, and mould. Fixing this issue would involve identifying the source of the moisture and fixing it accordingly. The render may also need to be removed and replaced, along with any damaged materials.

It is important to note that rendering is a job that requires the right tools and materials, as well as the proper training and experience. Homeowners should not attempt to fix common rendering problems on their own, as this can lead to further damage and costly repairs. Instead, they should hire a professional rendering company to ensure that the job is done right the first time and save money in the long run.

Can render be applied over existing rendering?

In general, it is not recommended to apply render over existing rendering. The new render will not stick to the wall properly and will eventually crack and fall off. It is usually best to remove the old render before applying a new two-coat render. However, there is an exception to this rule.

Wethertex AX1 Pliolite One Coat Render is a product that can be applied over existing rendering. This product has a lifespan of over 40 years and is ideal for making good a house with rough render. It is also suitable for homes with poor render, but render that has not blown (come away from the wall).

This product boasts long-life, through-coloured protection, proven to work for up to 45 years. AX1 Pliolite Thin Coat Render is a flexible, waterproof, and breathable render specially developed to provide the highest quality protection. It is a one-coat render that creates a beautiful and durable finish.

It is important to note that when rendering over existing rendering, there are many unknown factors regarding the suitability of the new render.

These unknown factors include the strength, bond, thickness, and quality of the existing render, as well as any existing applied surface treatments which could affect the adhesion of the new render. Therefore, it is always best to consult with a professional before proceeding with any rendering work.

RAL or British Standard (BS) Colour

When it comes to rendering, the use of RAL or British Standard (BS) colour is an important consideration. These colour specifications were originally created for camouflage and signalling, and have been used in industry and construction for many years.

Today, they are still in use and are a way to ensure that the paint used for rendering is of the correct quality.

A RAL or British Standard colour has a number assigned to it, which can be applied to the central colour location. This number is one of the criteria of product quality.

However, it is worth noting that different paint suppliers may use different names for the same colours, and not all of these names are approved by RAL. This can make it difficult to distinguish genuine colour products from those that do not conform to RAL.

To ensure that the colour of a product meets the required specifications, RAL has a system for providing colour samples. Manufacturers and suppliers can enter into a contract to obtain these samples, which includes a guarantee that the colour will be produced according to specifications.

If you are planning on re-rendering your exterior walls, it is important to check if building regulations apply, as depending on the extent of the work, they may be required. Additionally, if your property is listed and part of a group of properties, it may be necessary for the render to be a specific RAL or British Standard colour.

To choose the right colour for your render, you can use the filters on a render colour chart, or try a colour simulator to see what your home might look like in various colours. The Weber range offers a variety of colour options to choose from.

What to Look for When Assessing Render on Your House

When examining the render on your house, there are several signs to look out for that may indicate that it needs replacing. The most obvious sign is the presence of cracks in the walls. These can be either tiny hairline cracks or larger ones, with the latter being more concerning.

To test the render, tap the wall with a chisel or a typical tuning fork. If the render is in good condition, it should produce a ringing sound. However, if the render is bad and has blown, meaning that the coating of render has come away from the bricks behind it, the chisel or tuning fork will make a dull, hollow sound.

Another sign that the render needs replacing is if the wall is bulging outwards. This can be a very bad sign and requires immediate attention from a wall coating company. Damp on the interior walls is also an indication of bad render on the outside.

It is essential to keep a close eye on the condition of the render on your house and look out for these signs to ensure that it is in good condition and does not require replacing.

Getting the Wall Patch Repaired vs a Complete Re-render

When deciding whether to patch a damaged wall or re-render the entire wall, a survey of the wall’s condition is necessary. While patch repairs can be difficult to match to existing render and may show through masonry paint when painted over, a textured exterior wall coating can effectively hide repairs. This is especially true for walls that receive direct sunlight.

The render on the outside walls of a home serves a crucial function and should be kept in good condition. A wall coating can help achieve this goal by providing superior protection from weather elements such as cold, snow, frost, damp, pollution, and more.

Ultimately, whether to patch or re-render the wall depends on the extent of the damage. If the damage is minor and localized, patching may suffice. However, if the damage is extensive or widespread, a complete re-render may be necessary. Homeowners should seek professional advice to determine the best course of action.

To obtain a quote for rendering repair and protection, homeowners can contact Ralph Plastering at 020 4524 3056 or submit an enquiry through our contact page.

Frequently Asked Questions

What causes render bulging and detachment from walls?

Render bulging and detachment from walls can be caused by several factors, including poor application, inadequate curing time, and incorrect mix proportions. If the render is applied too thickly, it can cause the render to bulge and detach from the wall. Similarly, if the render is not allowed enough curing time, it can result in bulging and detachment. Incorrect mix proportions, such as using too much water, can also lead to bulging and detachment.

What are some common defects sssociated with rendering?

Common rendering problems include cracking, crazing, and efflorescence. Cracking occurs when the render dries too quickly or when there is movement in the wall. Crazing is a network of fine cracks that can occur due to shrinkage or over-trowelling. Efflorescence is a white, powdery substance that appears on the surface of the render and is caused by the migration of salts to the surface.

What underlying issues result in the render failing?

Underlying issues that can result in render failure include poor substrate preparation, incorrect mix proportions, and exposure to harsh weather conditions. If the substrate is not properly prepared, the render may not adhere correctly, leading to failure. Incorrect mix proportions can also lead to failure, as can exposure to harsh weather conditions such as heavy rain, high winds, and freezing temperatures.

What are some typical complications encountered with rendered walls?

Typical complications encountered with rendered walls include cracking, bulging, and detachment, as well as staining and discolouration. Cracking, bulging, and detachment can occur due to poor application, inadequate curing time, and incorrect mix proportions, as outlined above. Staining and discolouration can occur due to exposure to pollutants, such as acid rain and traffic pollution.

How can we prevent problems related to rendering of a house?

To prevent problems during the rendering of a house, it is important to ensure that the substrate is properly prepared, that the mix proportions are correct, and that the render is applied evenly and at the correct thickness. It is also important to allow adequate curing time and to protect the render from exposure to harsh weather conditions.

What are the steps involved to address render coming away from a structure?

If render is coming away from a structure, it is important to address the issue as soon as possible to prevent further damage. The first step is to identify the cause of the problem, which could be poor substrate preparation, incorrect mix proportions, or exposure to harsh weather conditions. Once the cause has been identified, the render can be removed and the substrate prepared correctly before reapplying the render. It may also be necessary to apply a primer or sealer to the substrate before reapplying the render.

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Ralph Plastering is a highly recommended plastering company in South London and Surrey providing all aspects of plastering, dry lining, rendering and external wall insulation services.

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