Breathable paint on lime render

[LauraP]

In 2022, my Victorian house had lime repointing plus lime render skirting with 2 coats Earthborn Eco Pro white mineral paint system incl. primer.

I’ve had the builder back a few times to repaint the white skirting area around the bay window as it bubbles and flakes off. (Pics 1&2 are my house.) This year she has recommended removing the black weed mat under the stones as she thinks water isn’t draining away quickly in heavy rain although there is a slope away from the house. She suggested getting large flagstones (pic3 is her house) to stop rain dripping from the windowsill to the wall. Do you think this would help?

Pic2 shows the paint flakes off in a section away from the windowsill too. She has also suggested smaller pebbles might reduce rain splashback.

 

[a twig]

If there is that much splashing first port of call would be to check rainwater goods (gutters, down pipes etc) are working correctly.

The blistering does suggest that either the paint isn’t as breathable as advertised or something was done wrong in the application

 

[a twig]

Do you know what primer was used?

 

[LauraP]

Sorry, no. I don’t know which primer was used. I can add that on the side of the house where there is paving, the paint on the skirting has been fine.

I’ve had the guttering checked and cleaned so can report there are no issues.

I’m not really aware of any splashing but this was a suggestion from the builder.

It’s blistering in a few places. The builder redid the painting a few times last year and used a different breathable paint this year (don’t know the name but it was a more expensive paint) but it blistered within a day.

 

[LadyArowana]

I can add that on the side of the house where there is paving, the paint on the skirting has been fine.

I’ve had the guttering checked and cleaned so can report there are no issues.

Next time there’s heavy rain it might be worthwhile umbrellaing up and going out to have a look at the two sides and seeing if there’s any difference in what’s going on. I agree it’s an odd thing if both sides were treated the same, and it would make more sense if it was the paving slab side which was having issues, but that’s old houses for you, never the easiest of mistresses

 

[LauraP]

Thank you. I’ll keep the umbrella ready to check this week. Good idea.

 

[aockenden]

I’ve never seen limewash bubble… just sayin.

 

[LauraP]

It wasn’t limewash. It was initially 2 coats Earthborn Eco Pro white mineral paint system incl. primer.

It’s been redone this year with a different “eco breathable” paint. The builder told me it was more expensive and better but I don’t know the brand.

 

[LauraP]

If I wanted limewash this area, do I need to remove all the Earthborn paint? And if so, how would I do that?

 

[aockenden]

It wasn’t limewash. It was initially 2 coats Earthborn Eco Pro white mineral paint system incl. primer.

It’s been redone this year with a different “eco breathable” paint. The builder told me it was more expensive and better but I don’t know the brand.

Yes I know.. that was my point. I honestly don't trust a lot of the eco breathable paints out there on the market. Yes if you were going to redo in limewash you have to remove the existing non-breathable, bubbling layer of paint from the wall otherwise the non-breathable underlying layer will still just trap moisture against the masonry and cause all the higher layers to blow off the wall (taking the limewash with it). You could always try stripping a small section back to the masonry (or lime render or whatever) and then limewash only that section directly onto the underlying lime render substrate. Then wait and see if it bubbles! If it's proper straight-up limewash (aka, non-hydraulic lime + water) applied directly to the masonry / lime render, it won't.

A heatgun and a clean scraper knife thing is the first port-of-call for me when stripping paint. Avoids the mess and danger of chemical strippers / solvents.

 

[LauraP]

Thank you for your advice. How would I remove the Earthborn paint? Would sanding work? I don’t want to damage the lime render below.

 

[aockenden]

A heatgun and a clean scraper knife thing is the first port-of-call for me when stripping paint. Avoids the mess and danger of chemical strippers / solvents. It's worth a shot to see how it goes.

 

[LauraP]

A heatgun and a clean scraper knife thing is the first port-of-call for me when stripping paint. Avoids the mess and danger of chemical strippers / solvents. It's worth a shot to see how it goes.

Thank you for the advice.

 

[malcolm]

It does seem that the paint isn't breathable enough to handle all the water that is trying to get through it. The wall trying to dry is good so the problem is the paint.

Removing paint from lime is tricky as the lime is quite soft. The usual method is DOFF hot water jet washer with paint stripper but this will damage the surface of the lime.

Worth contacting the manufacturers for removal advice. If you can get back to lime or re-render then limewash is the best coating for this sort of thing.

 

[LauraP]

It does seem that the paint isn't breathable enough to handle all the water that is trying to get through it. The wall trying to dry is good so the problem is the paint.

Removing paint from lime is tricky as the lime is quite soft. The usual method is DOFF hot water jet washer with paint stripper but this will damage the surface of the lime.

Worth contacting the manufacturers for removal advice. If you can get back to lime or re-render then limewash is the best coating for this sort of thing.

Thank you, that's really helpful. I'll discuss this more with the builder so I don't damage the lime render.

 

[malcolm]

The other thing that might help a bit is to have a gap between the lime render and ground in case it's sucking water up from the bottom. Could reduce the amount of water getting in.