HP12 washed away

[Mr Blobby]

HP12 base coat was applied on garage wall in the rain and now looks like this 

 

They told me it would be fine when I pointed at the skies during application.  Of course they would say that.  But it's not fine.

 

In fairness this base coat is just to seal the blockwork before battens are applied and cladding over the top, but even so, it looks like salts all washed out all over.

 

 

Bill has arrived. What do I do here?

Edited January 22 by Mr Blobby

[Russell griffiths]

Get them to re do it, or don’t pay. 

[Mr Blobby]

10 hours ago, Russell griffiths said:

Get them to re do it, or don’t pay. 

 

All of it, or some of it. 

 

Builder thinks most of it is ok. 

 

Lot's of salts on the surface and light patches, is this just aesthetic, or will the mortar be weakened? 

 

Also, I asked for the base coat to have a break at the dpc to not bridge it.  My builder rolled his eyes, and insists this is nonsense. Render scratch coat is always applied as a single coat over the dpc to the ground. 

 

Bridging the dpc seems wrong to me, is it?

[Russell griffiths]

Your builder still thinks it’s 1980. 
break at dpc for me. 

[Nickfromwales]

4 hours ago, Mr Blobby said:

Bridging the dpc seems wrong to me, is it?

Yup. Why introduce any unavoidable risk, especially if you're cladding over it which would make rectifying any feck-ups a costly process.

 

4 hours ago, Mr Blobby said:

Builder thinks most of it is ok. 

 

Lot's of salts on the surface and light patches, is this just aesthetic, or will the mortar be weakened? 

It's more of disappointment / frustration vs life or death, so patching it in should be fine if it's not the fundamental rain screen.

[saveasteading]

I don't know the product, but would be wary that the rest will continue to fall off.

That might  get stick behind battens and be worse than having nothing.

No money until this is sorted.

 

Make sure you put this in writing. Keep it reasonable but robust.

Is it holding your project up?

The experts above can advise if it needs to be removed and prepared before redoing.

[Mr Blobby]

On 23/01/2026 at 08:07, saveasteading said:

I don't know the product, but would be wary that the rest will continue to fall off.

That might  get stick behind battens and be worse than having nothing.

No money until this is sorted.

 

Make sure you put this in writing. Keep it reasonable but robust.

Is it holding your project up?

The experts above can advise if it needs to be removed and prepared before redoing.

 

 

Not paid for this yet.  Its been raining every day since it was applied two weeks ago hence not seen the renderer since.  I'm pretty sure he will try an ddo a small patch on this where it is coming off the wall and leave all the washed out parts in place.

 

What's really annoying about this is that when it was lashing down with rain I asked them if they planned to cover it and they just ignored me and carried on.  Said it would be fine.  What a waste of time.  Our builder agrees it needs to be fixed but is downplaying it and I get the sense it will be patched up at minimal effort.

 

I think I'll send him an email now.

 

 

[Nickfromwales]

4 hours ago, Mr Blobby said:

 

I think I'll send him an email now.

Best to yank the band aid off and state that you’re not willing to accept substandard work, much as they wouldn’t accept you paying them short on a Friday