Our 4-bed farmhouse was built in 1860/1900 using lime mortar and has been painted several times over the years since the 80's. The previous owners repainted about eight years ago using, I believe, Sandtex masonry paint judging by a can left in the garage when we moved in.

I need to repoint and repaint the whole house as we had cavity walltie failure last year (1900 cavity with iron fishtail ties) and the brick stitching repair has left the 1900 part looking like a peppar pot. It also became apparent that a previous owner repointed sections using cement mortar and also what looks like polyfiller!

Whilst looking into lime repointing I've leant that these masonry paints are latex based and tend not to let the house breathe causing damp problems which we are seeing. I'd like to remove all of this paint, repoint and then repaint with a breathable product. Can anybody suggest a decent method of removing masonry paint other than manual scraping which will take months? I've looked at chemical strippers, heat guns, sandblast, dustless etc. but I want to hear of proven successful methods that others have used.

Thanks

A look at the Sandtex web site shows on its first line - quote -
"With microseal technology, our masonry paint ensures that surfaces are dirt resistant, breathable and waterproof"

So if it is Sandtex it should be breathable.

Before you try to remove what you have - find out what you have ! (e.g. contact the previous owner and ask them).

I would be surprised if a sealed outer skin on a cavity wall would cause damp on the inner skin. What are the damp problems you are seeing. it could be that during the wall tie repair debris fell down the cavity causing a bridge and thus causing the damp - just a thought, but without details that is just speculation. Also were the damp issues evident before the wall tie work.

Posted By: fostertomIs this a new formulation of Sandtex, moving with the times? AFAIK it's always been classed as imprevious.

I don't know - it is just what their web site advert says. However even if it is impervious I would be surprised if a sealed outer skin on a cavity wall would cause damp on the inner skin.

Is it stone or brick.
If stone, which is basically impervious, could you just scrape out the pointing (which you are doing anyway) and then repaint?

Posted By: delpradoThe key is to buy the cheaper one Peelaway 1 rather than 7 as its highly caustic only rather than relying on some nasty chemical

???????

Sodium hydroxide and calcium hydroxide (Peelaway 1) ARE nasty chemicals. By comparison water and benzyl alcohol and kaolin are fairly benign.

Exactly, its not like the stuff that causes harm to aquatic life etc.

Agreed the parts of peelaway 7 arent bad either but they are much less effective.

Whereas most paint strippers contains horrendous carcgingenic stuff

I'd rather have the house without paint but I fear it hides nasty brick work and the new ties will show with their mortar spots.

MonsterMonster I don't doubt that you have bad paint of some sort on the outer skin of the wall but I don't see how any damp would transfer to the inner skin unless the cavity is bridged. Perhaps remove a brick on the outer skin in an area where damp is shown on the inner skin to see how the damp is transferred to the inside.

<blockquote><cite>Posted By: Peter_in_Hungary</cite>MonsterMonster I don't doubt that you have bad paint of some sort on the outer skin of the wall but I don't see how any damp would transfer to the inner skin unless the cavity is bridged. Perhaps remove a brick on the outer skin in an area where damp is shown on the inner skin to see how the damp is transferred to the inside.</blockquote>

The majority of the damp is showing on the outside skin brickwork that is internal within the extension. The other damp is external where the paint is peeling. We have one room where damp is in a corner of a chimney breast (chimney previously taken down under roof line). The chimney breast is opened and is internal so in effect the rear of the fireplace is the external skin making its side a bridge across the cavity. This damp I believe it's from water ingress from the outside skin.

Apparently the house has had cavity wall insulation as listed on the council building regs website but when opening up the wall when replacing Windows/doors and bricks taken out for tie inspection nothing has been seen. I'm rather hoping that cavity insulation was charged for but not actually done!

There probably is something bridging the cavity. One interesting point is that the top 6 feet or so of the gable ends are solid brick. The house was built from the ground as cavity and the pointy bit of the gable is fished as solid brick work. Bear mind this was 1900 and cavity walls were just coming into being.

All this aside my primary aim is to get the exterior paint off before repointing and painting. I think it's going to be a case of testing various methods on small patches and see what works best. Manually scrape where possible as a starter.

The trouble with powered mechanical methods like sand or water blasting, needle gun etc is that you're working on a hard bit and come to soft bit and before you know it you've dug a hole in the masonry.

Posted By: fostertomMonsterMonster, does your house have 10mm 'bricklaying' joints, or fine 3mm joints like in early part of the video you posted?

If the latter (and even if the former) then you have potentially very fine brickwork. As you're already talking of cutting out all joints and lime-repointing, it might be worth spending the money on a detailed restoration varying area-by-area, including in some places hand-tooling the paint like restoration stonemasons do, and finding a colour/texture matched way to re-point the wall-tie holes. Areas of surface-damage or spalling, once cleaned of coatings, can look acceptable, like honourable scars!

From memory over 10mm. In some places where a previous owner has noticed the horizontal cracking due to the wall tie failure the mortar is at leat 15mm! I honestly would not say it's fine brickwork but very standard looking in the main. I've manually removed some paint and the bricks vary from yellow to red. Admittedly there are places where some doors and windows have been bricked up using more modern bricks. In these case I suspect they have been laid with cement mortar (and slapped on at that).

Where the paint has scraped off from old brick there appears to be a powdery white layer.

Thanks for the update. Has taking the paint off solved the issue?

I stripped masonry paint off my brickwork. Used the DOFF system and got someone in as it's a horrible job. - paint stripper and a hot water pressure washer. On bricks it doesn't cause much damage but on stone you need an operator who is prepared to be careful.

You'll find after many years soaking wet the lime mortar will have gone. It doesn't like being soaking wet.

{quote}The bottom line is that the house feels warmer and drier after stripping and repointing.[/quote]

It will do. When you get condensation (aka rising damp) it means your wall is sodden wet. Once that is sorted letting the wall dry to the outside you don't get the condensation any more. Probably a few degrees increase in temperature on the inside of the wall equivalent to a fair bit of insulation but more problem free.