Hello.
I am in the process of fixing up the laundry room in our basement, the house was built in 1950.
The dilemma is that under the easily removable plastic paint, the plastered brick wall is painted with two layers of a paint that chalks when you scrape it. Is it possible to tile over such a paint or must it be removed, and if so, how???
Staffan
I am in the process of fixing up the laundry room in our basement, the house was built in 1950.
The dilemma is that under the easily removable plastic paint, the plastered brick wall is painted with two layers of a paint that chalks when you scrape it. Is it possible to tile over such a paint or must it be removed, and if so, how???
Staffan
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If the paint chalks, it is likely silicate paint, i.e., essentially water glass. It is moisture permeable and not very suitable for building on, which your predecessor tried to cheat away by painting over it with a non-moisture permeable plastic paint that you probably could easily peel away in large chunks?
Unfortunately, you can't 'prime away' the chalky property and hope for good adhesion for the fix. You need to scrape and brush away the chalking first, which could also be salt efflorescence from the mortar in the wall. (If the drainage outside is malfunctioning, the salt will creep towards the inside. It can be seen as white 'curtains' on untreated stone surfaces.)
You would then be wise to dig up outside and fix the drainage and add insulation to the wall before tackling the inside. Otherwise, you'll have moisture seepage issues in just a year. (Stone walls can withstand moisture quite well since stone is not a hygroscopic material like wood is. But the tiles will come loose and fall off.)
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Byggaren
Unfortunately, you can't 'prime away' the chalky property and hope for good adhesion for the fix. You need to scrape and brush away the chalking first, which could also be salt efflorescence from the mortar in the wall. (If the drainage outside is malfunctioning, the salt will creep towards the inside. It can be seen as white 'curtains' on untreated stone surfaces.)
You would then be wise to dig up outside and fix the drainage and add insulation to the wall before tackling the inside. Otherwise, you'll have moisture seepage issues in just a year. (Stone walls can withstand moisture quite well since stone is not a hygroscopic material like wood is. But the tiles will come loose and fall off.)
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Byggaren
I am now in the process of removing the paint using a paint scraper. The big dilemma is that the plaster is so porous that it can be scraped off with fingertips, albeit in small amounts. I have test-primed the scraped plaster and after that, it no longer crumbles. Can such a surface suffice for tiling?
The foundation has now been re-drained.
The advice-seeking: Staffan.
The foundation has now been re-drained.
The advice-seeking: Staffan.
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Since there are three 'experts' on the forum (john_h, ACME, and lyckekonsult) who, according to themselves, are greater 'professionals' in the field of tiles and plaster than jawen and myself, I will refrain from giving you further advice here on the forum. If you still want it, you can PM me directly.
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The Builder
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The Builder
jon_h said:
Wouldn't it be better, now that you've found your way here, to give the thread starter your advice instead of criticizing mine? Then we could switch roles for a while
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Byggaren
jon_h said:
Then we agree. That was exactly the advice I gave to TS. Priming loose plaster doesn't succeed. It comes back to haunt you.
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Byggaren
A small update.
The paint was scraped off moderately well and the very porous plaster was primed several times with a varying degree of diluted primer. The tiles are still where they should be (on the walls) and with no signs of falling off.
In other words - so far, all is well.
Staffan
The paint was scraped off moderately well and the very porous plaster was primed several times with a varying degree of diluted primer. The tiles are still where they should be (on the walls) and with no signs of falling off.
In other words - so far, all is well.
Staffan
... had a question earlier, is it possible to paint a basement wall with silicate paint and then successfully tile a section of it... since I would like to paint a wall now but not prevent tiling the same in the future...
My experience is that when the plaster turns to "sand" when you scrape it, it's often lime plaster. Lime plaster that gets too much moisture seems to disintegrate into its components. I've vacuumed away plaster from wall surfaces when the paint has been gone.
Everything is relative and depends on how it looks in your house, but doing expensive surface treatments without knowing if the underlying surface is secure can be problematic. Tiles make the wall more airtight than, for example, silicate paint, which might cause the lime plaster to fail.
There's another factor to consider. Those who know about this say it's unsuitable to use, for instance, cement-based plaster on lime plaster. Cement-based is both denser and especially "stronger/harder," which means it can detach from lime plaster, or I've seen that "density" causes peeling of paint/plaster around a cement-based plastering as moisture takes the path of least resistance toward warmth.
If I were to speculate, it might work to tile over cement-based plaster painted with silicate paint. When it comes to lime plaster or other plaster that has transformed into "more or less loose powder," it's probably best to ensure the substrate is secure so that the tiles don’t fall off. Tile adhesive is probably cement-based, which might conflict with lime plaster and risk detaching.
Another aspect is that if it concerns basement walls, there will likely always be some additional ground moisture independent of drainage. Tiles without a moisture barrier will let out quite a bit in the joints, so it probably works well if not too much moisture is introduced. Having a semi-tight layer of paint behind the tiles can cause problems.
The basic advice tends to be to remove the paint if it's cement-based plaster. If it's lime-based, you should probably decide on a case-by-case basis, but as mentioned, I've vacuumed away many kilos hanging on walls. Tiles and the adhesive weigh quite a few kilos and wouldn't have stayed securely on the walls I refer to.
Then there are spaces in basements where I only want a good surface finish and am willing to address it if something detaches. In spaces where I've wanted it to be "top-notch," I've ensured the substrate is as stable as required to avoid redoing it. A laundry room renovated to full living standards with wall-mounted furnishings must hold up, and in those cases, I've done it by the book. Paint removed and any loose substrate, then the right materials to ensure it lasts "forever"
Everything is relative and depends on how it looks in your house, but doing expensive surface treatments without knowing if the underlying surface is secure can be problematic. Tiles make the wall more airtight than, for example, silicate paint, which might cause the lime plaster to fail.
There's another factor to consider. Those who know about this say it's unsuitable to use, for instance, cement-based plaster on lime plaster. Cement-based is both denser and especially "stronger/harder," which means it can detach from lime plaster, or I've seen that "density" causes peeling of paint/plaster around a cement-based plastering as moisture takes the path of least resistance toward warmth.
If I were to speculate, it might work to tile over cement-based plaster painted with silicate paint. When it comes to lime plaster or other plaster that has transformed into "more or less loose powder," it's probably best to ensure the substrate is secure so that the tiles don’t fall off. Tile adhesive is probably cement-based, which might conflict with lime plaster and risk detaching.
Another aspect is that if it concerns basement walls, there will likely always be some additional ground moisture independent of drainage. Tiles without a moisture barrier will let out quite a bit in the joints, so it probably works well if not too much moisture is introduced. Having a semi-tight layer of paint behind the tiles can cause problems.
The basic advice tends to be to remove the paint if it's cement-based plaster. If it's lime-based, you should probably decide on a case-by-case basis, but as mentioned, I've vacuumed away many kilos hanging on walls. Tiles and the adhesive weigh quite a few kilos and wouldn't have stayed securely on the walls I refer to.
Then there are spaces in basements where I only want a good surface finish and am willing to address it if something detaches. In spaces where I've wanted it to be "top-notch," I've ensured the substrate is as stable as required to avoid redoing it. A laundry room renovated to full living standards with wall-mounted furnishings must hold up, and in those cases, I've done it by the book. Paint removed and any loose substrate, then the right materials to ensure it lasts "forever"
A tip.
Removing paint from plaster is time-consuming and using the wrong machine can make the walls look like a moon landscape without a smooth surface. I've tried it, and in some places I succeeded (failed) and where I succeeded best there were pits 20-25 mm deep.
There are machines from Flex, Festool, and Protool that allow you to set the sanding/milling depth, making it much easier to get a flat surface afterward. It won't be 100% flat but significantly better. They have a type of milling stars underneath. Available at many rental companies and worth the money if you have larger areas. Additionally, if you connect a good extractor, it becomes almost dust-free, which is incredibly good for your health. Sanding stone and concrete release particles that are very unsuitable to inhale. It is so dangerous that craftsmen should have both approved vacuum cleaners and respiratory masks when sanding. The particles are hazardous and can cause silicosis. I and several others who renovate on our own say that "no problem," as I don't do this every day. When I learned the facts about this, I got both respiratory protection and a good vacuum cleaner. Apparently, it doesn't take a massive amount to potentially have problems with reduced lung capacity in the long run. I've met some who have been affected, and it's scary to see lungs progressively deteriorate and not take in enough oxygen. One of the people passed away because, in the end, even pure oxygen didn't work.
Gosh, this turned into a post about risk and safety, but having seen the people and read a bit about it, an approved vacuum cleaner that captures the small, most dangerous particles, and good respiratory protection became high priorities on the equipment purchase list. A poor vacuum cleaner sucks up a lot of material but blows the dangerous particles throughout the entire space, ensuring you breathe them in. The dangerous ones are practically invisible.
Besides the health aspect, some jobs became significantly more enjoyable. Connecting machines to vacuum cleaners makes it almost dust-free
Removing paint from plaster is time-consuming and using the wrong machine can make the walls look like a moon landscape without a smooth surface. I've tried it, and in some places I succeeded (failed
) and where I succeeded best there were pits 20-25 mm deep.There are machines from Flex, Festool, and Protool that allow you to set the sanding/milling depth, making it much easier to get a flat surface afterward. It won't be 100% flat but significantly better. They have a type of milling stars underneath. Available at many rental companies and worth the money if you have larger areas. Additionally, if you connect a good extractor, it becomes almost dust-free, which is incredibly good for your health. Sanding stone and concrete release particles that are very unsuitable to inhale. It is so dangerous that craftsmen should have both approved vacuum cleaners and respiratory masks when sanding. The particles are hazardous and can cause silicosis. I and several others who renovate on our own say that "no problem," as I don't do this every day. When I learned the facts about this, I got both respiratory protection and a good vacuum cleaner. Apparently, it doesn't take a massive amount to potentially have problems with reduced lung capacity in the long run. I've met some who have been affected, and it's scary to see lungs progressively deteriorate and not take in enough oxygen. One of the people passed away because, in the end, even pure oxygen didn't work.
Gosh, this turned into a post about risk and safety, but having seen the people and read a bit about it, an approved vacuum cleaner that captures the small, most dangerous particles, and good respiratory protection became high priorities on the equipment purchase list. A poor vacuum cleaner sucks up a lot of material but blows the dangerous particles throughout the entire space, ensuring you breathe them in. The dangerous ones are practically invisible.
Besides the health aspect, some jobs became significantly more enjoyable. Connecting machines to vacuum cleaners makes it almost dust-free
Thanks for the info, in my case I have lots of lime plaster on the walls in the rest of the house, but the basement walls seem to be cement-based (except in one room in the basement where the wall has been plastered, it has been some kind of pantry...)
I'm probably thinking of painting the walls white and installing a shower cabin and/or bathtub, but it would be nice to tile instead... At least over the bench and bathtub. Only one wall is an exterior wall.
I'm probably thinking of painting the walls white and installing a shower cabin and/or bathtub, but it would be nice to tile instead... At least over the bench and bathtub. Only one wall is an exterior wall.