How to repair cracked, loose or hollow render

extensive repairing of render and pebbledash

Do the external walls of your home have cracks?

I don’t need to tell you that is not a good sign. Cracks are serious issues that must be attended to and not ignored, and definitely not covered over, or filled in with some cheap silicone mastic either.

The walls of your home are terribly important and must be kept in good condition as if not, further, and more expensive, problems will eventually surface, leaving you to foot the bill and to wonder why you did not get the problems attended to in the first place.

If you have at least SOME diy experience then sometimes the repairs can be done by yourself, but again, you need to be at least familiar with some tools as it is not as easy as you think!

Tools needed:

  • Laying up trowel
  • Float
  • Gauging trowel
  • Hawk (mortar board)
  • Bucket
  • Dust sheets
  • Spade
  • Sand
  • OPC Ordinary Portland cement
  • Water and febmix (like unibond)
  • Small hammer and large “lump” hammer and cold chisel.

If patches of render have fallen off cut back the edges to sound plaster. The best tool for this is a craft knife. You can cut back using a bolster chisel but you risk loosening adjacent plaster.

This is a bit of good advice but is best suited to someone who has at least some experience of repairing rendering and using the sort of tools that people use to render and work with mortars.

When you are preparing the surface to repair, Ensure that the edges of the patch are cut square to provide a key for the new mortar, and eliminate feather edging.

Where render is cracked or hollow it may be possible to consolidate and save it and further advice should be sought before hacking it off, especially if it is believed to be very old. However if it is beyond repair or not worth saving hack it off, cutting back round the edges to sound plaster.

Rendering

Get your tools and equipment ready and clear the area to work around.

Firstly, you need to identity the bad areas and then mark them with chalk. To check for hollow render, lightly tap a hammer on the walls and when you hear a hollow sound, that is where the bit of render has come away from the substrate and needs to be replaced.

Use the chisel and lump hammer to cut away the bad render. Be careful not to be too enthusiastic and start lifting off the good render around the bad bits. You can also use an angle grinder, which is good for cutting out cracks for repair too.

Rake out any loose pointing in the wall behind and repoint roughly. Brush out loose dust and apply the render in thin coats following the guidance above and taking care to ensure that it is well pushed in beneath the undercut edges of existing plaster.

rear now with repaired rendering

Patch render repairs, large and small areas, or whole house.

Apply the final coat with a neat butt joint between the old and new and with a slight bulge in the middle of the patch so that the final consolidation will create a flat patch, flush with the surrounding render.

Do not feather the edge of the patch over the surrounding plaster. Push back and consolidate the patch with a wood float. For small patches it is best to use miniature wooden floats which can be made by fixing a small handle to a short piece of batten and rounding off the edges with sandpaper.

Invisible patch repairs

NPA makes sure that when they do a job on your house, all repairs needed to the exterior walls, such as fixing cracks and loose or hollow render, must be made good.

Our teams are so skilled that if we have to repair a patch of render, once our exterior wall coating system is on top of the render, you will NOT see where the repair was, guaranteed!

The importance of render.

Render is something that has to stand up to the great British weather and has to protect your house, but it can’t do it on it’s own. Render needs a covering or wall coating applied to it, to protect it from the weather.

Unpainted render may actively soak up rainwater and if the following night time temperatures are cold, that water will freeze inside the wall, cracking the render as the water expands into ice and pushes the rendering away from the brick beneath.

cracks in walls

If this is happening to your render, it must be repaired very soon or damp and mould may appear inside your house.

Paint affords only decorative qualities to the wall and therefore a weatherproof wall coating must be applied in order to correct any weakness in the wall in relation to weather resistance.

Call us for more info on 0800 970 4928

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