How to repair cracks in house render


Render is a wall coating that is applied to external walls in order to boost the appearance of buildings and to make them more aesthetically pleasing. It is usually applied on top of brickwork on a property, and can be done to most properties so long as they are owned and not a listed building. As well as changing the look of a house, Action Properties, Inc. says, render can help to protect the building from damp and moisture-related problems, and can provide improved energy efficiency by adding a small insulated layer to the house.

Sometimes, however, as with paint and most other DIY materials, render can crack, especially on old building restorations. Cracking happens for a range of reasons, and how easy the crack repair will be depends on the property and the extent of the cracking and repairing needed.

What causes render to crack?

There are a few things that can cause render cracks, resulting in properties needing render crack repair. The likeliness of each render issue depends on the location and type/size of property, as well as the quality of render applied on the house. We spoke with We Do Render Rendering Specialists from the UK about the different causes so we get the facts right!

Drying out

When render is applied, it is left to dry. Sometimes, in dry or windy weather, the render will dry too fast and subsequently begin to crack. Likewise, some render will be more exposed to heat or harsh winds during its lifespan, and as a consequence may crack much quicker than the same render on a different property.

This cracking can be hard to prevent, as it is often due to the local weather as well as the position of the house. The only thing that can really be done is render crack repair and, if the cracking continues, ask a professional whether the render on the building is the most suitable material possible. If it isn’t, homeowners could consider changing the material used for their rendering.

Rising damp

Rising damp is probably one of the most common causes of render repair. It occurs when water and moisture travel up through the exterior wall coatings through capillary action, ultimately damaging the external rendered walls and the render itself. This can cause small hairline cracks which may eventually grow into larger cracks along the exterior walls. Typically, rising damp is very easy to spot in a wall coating as it will be plainly visible on the render surface.


Homes in areas of extreme weather may notice that they have to render crack repair more than other properties. This is due to the effect of the weather; meteorological events such as hail, ice, and snow can cause the render to crack – especially old render. This will result in much more frequent render repair work for homeowners and may require a change in exterior wall coatings.

Poor application

As with many property development jobs, a poor application can lead to issues further down the line. Poorly applied render is much more likely to require render crack repair than well-applied wall coating. If the render used was the incorrect render for the property, or if the fibreglass mesh is missing from the base coat, then the render is much more likely to crack. Whilst homeowners can repair cracks caused by these, they would be better off removing the old render and rendering the property again rather than continuously repairing rendering and filling cracks.

Is cracked render a big deal?

Cracked render is often overlooked, especially by those who aren’t familiar with the cladding or if the cracked render is on external rendered walls. Most of the time, this is not the end of the world. However, with some causes of cracks in existing render, render repair is essential in order to protect the house.

For cases of cracked render caused by dampness, for example, render repair is essential but homeowners must first solve the cause of the damp. Failing to do so will lead to further render repair being required later on as well as potential structural damage.

Cracked render may also be less protective and may not help as much with energy efficiency. More so, the render will not have the same appearance if cracked and thus will not help to uplift the look of a property.

How to repair cracks in render

If your existing render has cracks, repairing them is not too hard. It is not a case of simply filling the cracks with caulk, unfortunately, but with this step by step guide, it should be relatively simple.

1. Make sure you have safety gear

You will need work gloves and goggles for this job. Make sure you have both before you begin to repair your render.

2. Remove existing render

The first step requires you to remove the existing render around the crack with a bolster chisel and short-handled sledgehammer. Carefully chip the old render away, making a small patch without any render in.

3. Repair the steel mesh

You may spot that the steel or fibreglass mesh is broken. If that is the case, you will need to either repair or replace the mesh by attaching it to the wall using galvanised nails.

4. Apply the render

Apply your pre-mixed render solution onto the wall using a trowel. The patch should be thicker than the original render.

5. Smooth it out

Smooth out the render, making sure that it is in line with the rest of the render on the wall. You can do this with the trowel, but make sure you are quick so that it does not start to dry.

6. Use a finishing tool

Render is usually textured, and you will want your small patches of new render to match the old render, so use a finishing tool on the render whilst it is still wet in order to provide that texture and ensure that it matches.

7. Let the render dry

You should then leave your render crack repair to dry, checking it occasionally to see the progress.

8. Paint the render

Once the new render is dry, you can paint it to match the colour of the existing render. Before you paint you must seal the wall. Apply your paint in thin coats so that you do not accidentally make your new render a deeper colour than the rest of your wall.


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