How to repair blown render patches...

BertieUK

I live in a 1950's Bungalow and the render in a few places on the front wall has blown. I was wondering if I could drill holes in the render and fill with a material that was thin enough to spread over a small area and fill the voids.


I would be grateful to hear of anyone that has experienced and overcome this problem and what filler they may have used.


Regards...

SailorSam

My porch is rendered and last year when i was repairing a couple of sections i just chisseled around the loose stuff until i hit solid material.

Tucker

It doesn't sound like a very convincing solution.

When mine cracked and the moisture made it swell, I think the the best advice was to remove and redo. It's been spot on for 6 or 7 years since then.

macman

No, hack it off back to sound plaster and re-render.

Plasterer

Hi Bertie
What type of render are we talking here?
The blown will have to come off and be rendered again - however once you start removing the blown render don't be surprised if a lot more comes of than you would first think. You may end up redoing all of it.

BertieUK

Plasterer wrote: »

Hi Bertie
What type of render are we talking here?
The blown will have to come off and be rendered again - however once you start removing the blown render don't be surprised if a lot more comes of than you would first think. You may end up redoing all of it.

The term render that I refer to is what you see quite common on older bungalows where the finished plaster was coated in a roughcast then painted with waterproof paint. I may have used the wrong term, (render)not sure sorry.


Let me run through what I found, I wanted to put up a new house number plate, so when I went to drill the holes the surface sounded hollow when tapped and when the drill went past the first few mm there was a hollow space before the brick/block of the wall. At this moment when you view the surface it looks quite normal and certain small areas sound hollow when tapped.


Kind regards...

Plasterer

Ok
With rough cast it is fairly difficult to match existing unless you know what your doing (right size stone, throwing action etc) you will need to get the blown cast off though as if water is getting in it will only get worse and possibly start causing you damp problems. How much of an area are you talking?

BertieUK

Thanks.. We are only talking about less than 10% of the total area.

Plasterer

Are you going to have a go at repairing it yourself? If so I can talk you through the process if it helps?

BertieUK

Plasterer wrote: »

Are you going to have a go at repairing it yourself? If so I can talk you through the process if it helps?

That would be very kind of you, thanks...

Regards...

Plasterer

Remove all loose render.
Damp down the area in question.
Mix a 4-1 render sand cement mix (put a splash of feb plastersiser in the water) apply to the wall using a trowel. When this starts to firm up a bit put a scratch into it -this is the scratch coat and will give a key for the next step.
Leave the scratch coat for at least two days before next stage.
Now mix a 5-1 rendering sand cement mix (put a glug of waterproofed in the water) damp down the scratch coat and apply this mix know as a butter coat over the top - now comes the fun and messy part.
Mix three part stones to one part cement to one part sand in a mixer add water(with a glug of waterproofer in) until you have a wet slurry mix.
When the butter coat starts to tighten this is when to apply the stone mix-don't let the butter coat go too firm equally it doesn't want it be too wet.
Tip your stone mix into a builders bucket and get your trowel. Stir the mix with the trowel and literally pick the stones up with the back of your trowel and almost like a flicking action throw the stones onto the butter coat. If they bounce of too much the buttercost has gone too dry if they hit and slop and sag the buttercoat is too wet if most stick and don't cause the buttercoat to splater it's just right.