What do we need to do about cracked render?

When we bought our house six years ago the surveyor noted it had been poorly rendered. Over the past couple of years I’ve notice more cracks appear in the surface across the house. Can these be repaired or do we need to replace the render? How much is a job like that likely to cost (2 storey, semi detached double fronted house approx 12 meters wide) – ballpark figures would be helpful – I don’t even know if it’s hundreds or thousands! Also as slightly stupid question but is render coloured? the house is a cream colour and it doesn’t look like it’s been painted as there is no flaking – or could it be some alternative coating has been used (it’s smooth not rough) Thanks for any advice you can offer.
Ytherupaxim -20th Feb, 2011 Plastering

There are a few things to look for,

Are the cracks all joined together?
when u tap the render where it is cracked does it sound hollow?
Is it soft ? Crumbling?

If the answer to the above is yes then it will probably need to be removed as it is not adhered to the substrate (background)

This is due to a number of things

The background was not prepared properly ie not dampened down, no PVA applied, mortar joints not raked out etc,

It was applied in too warm a condition so it dried to quickly or applied in too cold condition and the frost effected the curing and subsequently caused the cement to fail and hence has no strength.

The topping coat is a stronger mix than the scratch coat which means the base coat willl be able to flex, expand more than the top coat and again cause the top coat to crack and come away from the wall,

The mix altogether is to weak,

If it is old render and seems solid it could be just cracks from movement off the property over the years but if the surveyer has stated it is a poor job I doubt this to be the case.

To hack off the old render, prepare the background, re render and apply paint or a finishing coat including scaffolding and removal of waste you are going to be looking at £2500 plus as a guestimate.

There are new polymer through colour renders that are out on the market that are normally applied in one coat which are pre coloured and once they have been floated and has set is the finished product they are normally applied with plastic coloured angle and stop beads to match the colour of the render

hope this helps


Tom Lyon

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