Breached external render?...

[ColLo]

Hi all,

I'm after some advice after attempting to have some internal plastering done. I called in a plasterer to re-plaster our hall, stairs and landing. Landing was fine, but when he came to do the hall, the old plaster crumbled when he applied the pva. He believes the external render is letting in water somewhere which has knackered the internal plaster - he's called the job off and can't continue until someone certifies the wall is dry enough to plaster. Fair enough

I'm having trouble deciding how to continue. The plasterer thinks we need to go back to the brick and start over as a minimum but this wouldn't cure the source. Before he went, he reckoned I should call the insurance company out and get them to check the render with a view to them paying for any re-rendering.

Do I...

Call insurance company and get them to send someone out to check the external render?
Get a surveyor in myself to check where the water is coming in from the external wall (our down pipe brackets seem to be quite loose also, so could be here, or a roofer commented that the porch roof was cr*p?)
Get a rendering company in to check the quality of the external render?

We've had a couple of damp specialists in who said there isn't a problem with rising damp etc, it's just "a problem with rendered houses".

Any advice? I'm having trouble weighing up the options - each one seems expensive!!

Ta.

 

[marshman]

How old is your house.

 

[ColLo]

it's a 1930's semi, three-quarters rendered.

 

[marshman]

1. Did you ever see any sign of damp on this wall ?,
how high up the wall is the old plaster crumbling ?,
2. did the damp specialists tell you that there was any salts coming out where the plaster has crumbled ?.
If 1 or 2 of the above is a yes then you need to get someone to look at the render outside.

I think the plaster has just broke its surface as I suspect its lime putty plaster and once the surface has come away
it would be very lose and crumble under the towelled finish which is quite normal for old lime plaster.
So if you never saw any signs of damp or salts, then you could just chop this patch out, wet the bricks down with water
then patch this in with hardwall, then pva the whole wall including new patch and skim it all.
I'm sure some of the other old boys on here could confirm that once the face has come off the old lime render
then the old lime scratch coat is very crumbly and you can just rub it out with your fingers.

I don't think your plasterer has much experience with old plaster.

 

[ColLo]

Thanks for the reply marshman, I appreciate it.

To answer your questions
1. Yes, I've taken a look and below the landing window there is a crack in the brickwork which follows through to the external render - highly likely water has got in here. It's crumbling below this window. I've also tapped around on the wall and it sounds solid in some places, hollower in others.
2. The specialists came in before we had the plaster removed so didn't comment on the salts. I've just checked though and there are salts on several of the bricks (though they are not all in the same place)

Below the window, the plaster has definitely broke its surface, I can see that where the plaster remains - it is no longer attached to the wall.

I think it makes sense to get someone in to look at the render and let us know whether it needs repair or a complete re-render.

One more question if we do go down this route, the plasterer mentioned that the pointing may need renewing but I read elsewhere on this forum that if you are rendering it may not be necessary as the render will fill any gaps??

Thanks again.

 

[marshman]

I think it makes sense to get someone in to look at the render and let us know whether it needs repair or a complete re-render.

One more question if we do go down this route, the plasterer mentioned that the pointing may need renewing but I read elsewhere on this forum that if you are rendering it may not be necessary as the render will fill any gaps??
.

Yes, as we can only go on what's described nothing beats on site viewing.

Pointing where you are going to render is pointless as it will be filled and the rougher the surface the better.
use a waterproofer in the new render and you'll have to have that crack filled on the outside.