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How Do You Repair Cracks In External Rendered Walls

26 July 2022

Cracks on rendered walls are unsightly, but the biggest concern relates to the property's condition. Cracks are never a welcome addition to a property, and if they aren’t repaired in an orderly fashion, they could be a sign of significant issues to come.

Whether you have old render that is past its best, or your exterior wall coatings are in poor condition, it is best to carry out quick and effective render crack repair.

This guide informs you on how to repair cracks in external rendered walls and provides tips and guidance on preserving your walls for many years to come.

Is It Easy To Render Crack Repair?

There are a few ways to repair cracks in exterior walls, depending on the severity of the damage to the render surface. You can simply use a render repair kit for hairline cracks, which is readily available from most hardware stores. These usually come with a render repair compound and render reinforcement, like fibre tape.

Crack on Rendered Wall

Filling Cracks Is Essential

You may need to remove the render entirely and start from scratch for more significant cracks. This is a more invasive repair job, so it's best to consult with a professional before proceeding. They will be able to assess the damage and advise you on the best course of action.

In either case, once the render is repaired, it's essential to protect it from further damage. This means regular maintenance and inspection, as well as taking measures to prevent cracks from forming in the first place. Some render reinforcement products can help with this by providing an extra layer of protection against impacts.

If your property suffers from damp, or there is a lot of rain, damp can ruin your life. Old render and cracked render is a genuine concern for the quality of the building, and the health of those inside it. This is why filling cracks and ensuring the surrounding render is in good condition is essential.

Can Render Be Repaired?

Yes, render can be repaired. The best way to do this will depend on the size and severity of the damage. You can usually use a render repair kit for small cracks and holes.

If you are dealing with hairline cracks, or minimal problems with the wall coating or surface, the repair work shouldn't be too hard. This guide tells you what you need to do to ensure your wall is in great condition, and to prevent further cracking in the future.

However, if the surface of your wall coating is cracking badly, and in poor condition, you should call on an expert for professional crack repair services.

If you don't, you run the risk of more cracks appearing, and this could cause significant problems. The cost to repair extensive cracking is high, so be proactive in managing the wall coating of your house or building.

What Tools Do You Need When Repairing Cracks In A Rendered Wall?

To successfully repair cracked render, the following tools are of great assistance, so take a note of them before conducting brickwork and cracked repairs:

  • A mortar board and mortar joints
  • Bucket
  • Cement
  • Chisels
  • Craft knife
  • Dust sheets
  • Float
  • Hammers
  • Sand
  • Spade
  • Trowels – gauging and laying up
  • Water and a mortar plasticine mixture

With so many tools required to do a good job, it is easy to see why many people call on an expert. Professionals have access to these tools all year round, allowing them to spread their cost over many projects, and speed up acquiring these items.

Tool to repair crack walls

Remove Render From Around The Cracks

If you are looking for a step by step guide into repairing cracks in rendered walls, this guide will be of use.

Laying a sheet on the ground to pick up falling render, brick, cement and sand will make the cleaning process easier.

If patches of render have fallen off the wall, you should remove the remaining pieces from around the cracks. A craft knife is a good way to remove the affected issues, but in some cases, you might need something more substantial.

A hammer and bolster chisel will make quick work of larger areas, and some professionals use an angle grinder to cut through stubborn sections. Of course, it might be possible to consolidate and save the render in some cases, so seek advice before removing this work.

Does the wall sound hollow? Be sure to check if the substrate has come away from the wall coating or brickwork. If the render has come loose from the surface, even in small patches, you will need to repair the crack.

You can tap the wall of your house with a hammer, and if you hear a hollow sound, this section needs to be replaced.

Take the time to dust out the affected section, leaving it as clean and dust-free as possible. This will create a better finish later.

Using a cloth or sponge, which has been dipped in water, you should wet the cavity of the wall. It is helpful to improve the adhesion of the filler, and you can do this by painting the internal sections with a PVA adhesive.

Prepare the render and apply it in a thin coat, and then in other thin coats is you desire. Using a filling knife, apply rendering or filler into the crack of your wall. Depending on the extent of the gap to fill, a small amount of rendering might be more cost-effective. Most professionals believe filler is an easier and more convenient solution, but it can be more expensive.

Check for air pockets in the wall, which you can do by prodding the knife into the cavity. If you find air pockets, add more filler and smooth the affected area out.

Once cracks and gaps have been filled, you should smooth the mixture over the wall surface.

Once the filler has dried, you can redecorate the wall if you desire. If you want to add a splash of colour to the render or brickwork, you can do so. Once dried, you can easily paint over render with a paint brush, but make sure the edges are filled and that the area to be painted is dry. A coloured finish over renders or brick is appealing, but it needs to stand up to damp and challenging weather.

Improving the appearance of buildings is important, but taking care to ensure render or filler is dry before you paint is essential, and worth repeating.

Review the wall, ground and any rough edges to ensure everything is clear, and enjoy your work. You can hire a professional to do this work for you, and this will make dealing with mortar and cement easier, but for many people, the time and money saved, not to mention the satisfaction of doing DIY work, is a good reason to not search for a professional!

Render Crack Fillers

As the name suggests, fillers are a great way to care for render cracks, and you have many solutions. Not only do you have a broad range of brands and makes to choose from, you even have:

  • Repair mortar products
  • Silicone render
  • Masonry filler

Fillers are often a short-term fix as opposed to a dependable long-term solution. Also, some fillers are very noticeable, requiring additional work to cover up their presence. However, if all you need is an affordable or short-term solution, this is a viable option to strengthen your property and prevent cracks from worsening.

What Causes Cracks In Rendered Walls?

There are a few different things that can cause cracks in brick rendered walls. The most common is render failure, which happens when the render hasn't been applied correctly or has started to degrade over time. This can be caused by poor quality render, incorrect mix ratios, or render that hasn't been allowed to cure correctly.

Your House Might Crack

Another common cause of cracks is movement in the underlying structure of the wall. This can be due to settlement, thermal expansion and contraction, or even normal wear and tear. If the render cannot flex with the wall, it will eventually crack.

A quick overview of common reasons for render cracks include:

  • People didn’t follow a proper process for rendering
  • Bulging with the render
  • Rendering has been damaged
  • Rendering wasn’t mixed effectively
  • Shrinkage has affected the render and problems develop in small areas
  • Trapped water has frozen in the render
  • Your property is moving, and the render cannot cope with this
  • Issues with damp patches or damp spots at your house

Some of these issues are more common than others, but all are likely to affect rendering, causing cracks.

Protecting The Render

While repairing cracked render is important, homeowners should also look to protect the render from future problems.

An additional coating is a good idea, and this bonds with the render, adding an extra layer of protection. This step reduces water absorption, minimising the likelihood of water freezing and causing cracks. Water will roll off the surface more easily. Also, this layer doesn’t impact the breathability of your rendered walls, so there are no issues with this.

Another great reason to add this protective layer is it keeps your walls cleaner. Dirt and grime wash away more quickly, reducing maintenance time in caring for your property. This layer also minimises the likelihood of mould and algae gathering on your walls.

Do Cracks In Walls Mean Subsidence?

Not necessarily. Cracks can be caused by several different things, as mentioned above. However, if you do notice cracks in your walls, it's essential to get them checked out by a professional just to be on the safe side. They will be able to assess the damage and advise you on the best course of action.

Wall Crack

How Long Should Rendering On External Walls Last?

Rendering should last for many years, often between 20 and 40 years, but it will eventually need to be replaced.

Can You Skim Over The External Render?

You can skim over external render, but it's not always the best option. Skimming render is only suitable for minor imperfections and won't fix more significant problems, like cracks.

It's also essential to make sure that the render is compatible with the existing render before you start skimming. If it isn't, you could end up causing more damage.

If you're not sure whether skimming is the right option, it's best to consult with a professional before proceeding. They will be able to assess the damage and advise you on the best course of action.

Repairs Are Worth The Time And Effort

Carrying out render crack repair is usually more affordable than applying new render to a whole wall, and is often just as effective. Hairline cracks might not seem damaging but if they are allowed to fester, new cracks form and the cost of repairing the existing render increases sharply.

This is a job worth doing, for many reasons, including the kudos you'll feel when carrying our cracked repairs.

This guide to render crack repair will hopefully preserve your brickwork, improve the appearance of your building and provide you with confidence in the quality of your home or buildings.

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