I'm working on my basement in a house from 1937. The previous owners were foolish enough to frame and insulate directly against the exterior walls without any form of drainage.
I have now drained (about 2 years ago) and removed all tar and applied 150mm of isodrän, laid macadam and filter fabric, etc., against the exterior wall. Then I tore everything off the interior walls and let them dry out for about 1 year.
Now I've started scraping off all the loose plaster with a "bark scraper" on the walls. It works really well, but it's a real pain of a job. My question is how much more than the loose parts should be removed? There will be some left that one could remove with a giraffe sander or something similar. Does it need to be completely clinically clean before applying new plaster? I should mention that it is going to be roughly plastered and then painted with a nice grayish color that allows moisture to pass through. I will also be replacing drains, wells and installing pipes for three water radiators.
But as mentioned, is there anyone experienced in the masonry and plastering industry who can give me an answer?
Hi,
I don't believe it needs to be "clinically clean" for new plaster to adhere to the wall, plaster mortar C adheres really well once it has cured. However, make sure to prime before plastering to increase adhesion.
Your walls look very good, I had large chunks coming off, between 2-4 cm in places. So your walls look good to me. Not the most fun task, but it looks nice and makes a big difference.
Hi,
I don't think it needs to be "clinically clean" for new plaster to adhere to the wall. Plaster mix C adheres really well once it has cured. However, make sure to prime before plastering to increase adhesion.
Your walls look very good, I had large patches that were coming off, between 2-4 cm in some spots. So your walls look good to me. Not the most fun task but it looks nice and makes a big difference.
Ok, I'll have to go rent a giraffe sander and go over all the walls too. Pretty decent at least. Took the picture after 4 hours of intense scraping with the pickaxe.
Hello, From my perspective, I want to congratulate you on having a good methodology for creating favorable conditions for the best possible basement climate.
"Many" people drain and remove loose plaster and renovate to living standards without being aware that the walls have often accumulated quite a lot of moisture. That is, more than what is "normally added" moisture.
If you are going to renovate any part of the basement to a more living-area environment, there are more or less good solutions. I have tried to learn what is required to make it work, and so far it has worked well. If you have such thoughts and want to brainstorm ideas, I will share my experiences.
Now I see that you are going to use a giraffe, and a good piece of advice is to use a good extractor as there will be a lot of particles in the air. Some of the particles, the very smallest, such as quartz dust—extremely tiny stone particles—are dangerous to inhale. I also suggest that you supplement with some form of respiratory protection.
Regarding the new surface, you have already been advised to use primer. The reflection on the choice of plaster is that if the previous plaster was lime-based, it is less suitable to use cement-based plaster outside as they are stronger and probably denser from a moisture perspective. I use the word probably because there are many "mixes" of plaster. Just wanted to tip you about this factor. Otherwise, it sounds like your walls will have good conditions to maintain the chosen finish for a long time.
The choice of flooring affects the moisture load on the walls. As an extreme, a "waterproof" floor causes more of the moisture in the ground to rise through the walls. I suspect you have also thought about this
In addition, in my experience, it is good to use a dehumidifier to take care of the added moisture. Ventilation is to facilitate air exchange. Warming and ventilating to remove moisture is more expensive than letting a dehumidifier handle the added moisture beyond what follows with a normal ventilation flow.
I have chosen to maintain quite low relative humidity. Some say it becomes expensive, but once you've gotten a basement really dry, the difference in energy cost between keeping RH50% and RH60% is not that large. However, the difference makes a good effect in that the lower level keeps materials and walls dry with a margin and reduces the risk of peeling paint, plaster, or other moisture-related issues.
Another tip is to ensure there is no stagnant air in the basement. If you look at the floor plan, it might be enough to make a hole and install a small fan to circulate the air in the basement. I have done so and installed a fan that uses 1.6-1.7 watts 230V, moving about 100m3/h. That amounts to over 16KWh/year. It is very quiet and unnoticeable, but the entire basement essentially has the same climate and no stagnant air. By moving the air, the likelihood of any room or area in the basement having elevated relative humidity that could cause problems or issues is reduced. We have furniture and some fixed furnishings, so it's good not to have stagnant air.
The combination of keeping the air circulating in the basement with a good dehumidifier works fantastically well.
One challenge is getting the ventilation right since we have a lower temperature in the basement than in the residence. In the residence, there is also natural ventilation which works excellently, but the lower temperature in the basement meant I needed both air intake and exhaust air in the basement.
Ventilation is handled by natural ventilation with air intake in the basement and exhaust in a ventilation duct that is in the chimney, which is built from the basement upwards. It's not obvious that it works depending on how the chimney is otherwise used. A simple way to test that the exhaust air goes out the correct vent is to use a cigarette lighter or candle, which is enough in my house to see that the exhaust goes to that vent.
Since the fan circulates the air in the basement, I've chosen to have an air intake vent open in just one room.
In part of the basement, there is a guest room where I increase the temperature when guests are coming. To avoid heating the entire basement, a door is closed. To maintain air rotation, that door has several 30mm holes at the bottom. A little warm air follows through, but as we know, warm air rises, so the energy that follows at the bottom becomes bonus energy to the rest of the basement, but in practice, we quickly get the guest area up to 22 degrees while the other parts of the basement rise by 0.5 degrees, which naturally increases if guests stay longer.
Hello, From my perspective, I want to congratulate you on a good methodology for creating favorable conditions for the best possible basement climate.
"Many" people drain and remove loose plaster and renovate to living standards, unaware that the walls have often accumulated quite a bit of moisture. That is, more than the "normally introduced" moisture.
If you are going to convert any part of the basement to a more livable environment, there are more or less good solutions. I've tried to learn what is required to make it work, and so far it has worked well. If you have such thoughts and want to discuss ideas, I will share my experiences.
Now I see that you're going to use a giraffe sander and a good piece of advice is to use good extraction as there will be a lot of particles in the air. Some of the particles, the very smallest of quartz dust, for example, are extremely small stone particles that are dangerous to inhale. I also suggest that you complement with some form of respiratory protection.
In terms of new surface, you have already been advised to use primer. When considering the choice of plaster, if the previous plaster was lime-based, it is less suitable to use cement-based plaster on the outside as they are stronger and likely denser from a moisture perspective. I use the word likely because there are many "mixes" of plaster. Just wanted to tip about this factor. Otherwise, it sounds like your walls have good chances to maintain the chosen finish for a long time.
The choice of flooring affects the moisture load on the walls. As an extreme case, a "waterproof" floor makes more of the moisture in the ground rise through the walls. I suspect you've also thought about this
In addition, it's my experience that it's good to use a dehumidifier to manage the moisture that is introduced. The ventilation is to ensure air exchange. Heating and ventilating away moisture is more expensive than letting a dehumidifier handle the additional moisture beyond what accompanies normal ventilation flow.
I've chosen to maintain a relatively low relative humidity. Some say it becomes expensive, but once you have a really dry basement, the difference in energy cost between maintaining RH50% and RH60% is not that great. However, the difference significantly impacts by keeping the materials and walls dry with margin and reducing the risk of peeling paint, plaster, or other moisture-related issues.
Another tip is to ensure there is no stagnant air in the basement. If you look at the floor plan, it might suffice to make a hole and insert a small fan to circulate air in the basement. I've done so and installed a fan using 1.6-1.7 watts 230V moving about 100m3/h. It's just over 16KWh/year. It's very quiet and not noticeable, but the entire basement essentially gets the same climate and no stagnant air. By moving the air, the likelihood is reduced that any room or place in the basement develops elevated relative humidity that could cause problems or inconvenience. With furniture and some fixed furnishings, it's advantageous not to have stagnant air.
The combination of keeping air rotation in the basement with a good dehumidifier works wonderfully well.
A challenge is getting the ventilation right as we have lower temperatures in the basement than in the residence. In the residence, it's also natural ventilation, which works excellently, but the lower temperature in the basement necessitated both air in and air out of the basement.
The ventilation is managed with natural ventilation with air in the basement and exhaust air in a ventilation channel in the chimney, which is built from the basement upward. It’s not always evident that it works, depending on how the chimney is otherwise used. An easy way to test that the exhaust air goes out the right vent is to use a cigarette lighter or candle, which suffices in my house to see that the exhaust air goes out that vent.
Because the fan circulates air in the basement, I have chosen to keep the air-in vent open only in one room.
In a part of the basement, we have a guest room where I raise the temperature when guests come. To avoid heating the entire basement, I close a door. To maintain air circulation, that door has several 30mm holes at the bottom. Some warm air follows, but since warm air rises, the energy that comes through the bottom becomes bonus energy to the rest of the basement; in practice, we can quickly raise the guest area to 22 degrees while the rest of the basement rises 0.5 degrees, which naturally increases if guests stay longer.
Good luck with the continued work.
Hi. Thank you very much for incredibly useful info.
There will be no framing and insulation. I have seen too many horror examples of this, and the house wasn't built that way originally.
I have made a hole in each room where air supply devices will be installed. I have also opened up the chimney in the boiler room that previous owners had bricked up. There is also an exhaust hole in the laundry room that they sealed with foam, which I have removed, and I will install exhaust devices in these two holes in the form of a pax fan or similar to run constantly and increase operation at higher humidity levels.
The walls will be brushed and then painted with silicate paint; on the floor, I am planning for tiles for maximum breathability. I'm considering Platon mats in two rooms with an air gap along the walls and then regular oak flooring. I don’t know how well this would work, but according to an acquaintance at OCAB in the moisture department, this should be an adequate solution for the floor to breathe.
The heat source will be 3-4 water radiators and possibly an air-to-air pump intended to circulate the air in the rooms.
I hope this will be enough to create a good basement climate, making it feel nice to go down there, even in winter.
There are some alternative solutions for improving the climate in basement houses. Among others, there is a material called träullit which has good insulation properties and has been used as interior insulation in basement houses since the 1940s. I am aware that interior insulation is taboo in the eyes of many specialists, but 70 years of field trials are quite sufficient for me.
Rendered träullit has been on exterior walls in my basement for 70 years. That solution has been in many old basements since the houses were built.
The mantra that everything on the inside of a basement becomes problematic is a truth with modification. I have also seen some problem basements and heard several experts say that certain things are impossible. I'm not too fond of that word
It's a bit too late to expand on it today, but if I take one of the rooms that is newly renovated, it's probably not possible to determine whether it's in a basement or not. Besides the fact that the ceiling height is lower
These aren't rendered walls; the solution permits traditional wall coverings. It provides higher comfort and with some complements, the same solution will be used in the other half of the basement where there should be a living climate.
I am confident with the technical solution. It will have to be on another occasion if you are interested.
There are some alternative solutions for improving the climate in basement houses. Among others, there is a material called träullit that has good insulation properties and has been used as internal insulation in basement houses since the 1940s. I am aware that internal insulation is taboo in the eyes of many specialists, but 70 years of field tests go a long way for me.
Plastered träullit has been on the exterior walls in my basement for 70 years. That solution has been in many old basements since the houses were built.
The mantra that everything on the inside of a basement becomes a problem is a truth with modification. I have also seen some problem basements and heard several experts say that certain things are impossible. I am not so fond of that word
It's a bit too late to develop it today but if I take one of the rooms that is newly renovated, it might be hard to tell if it's in a basement or not. Except that the ceiling height is lower
They are not plastered walls, but the solution allows for traditional wall coverings. It provides higher comfort and with some additions, the same solution will be used in the other half of the basement where it should be a living climate.
I am confident with the technical solution. It will be at another time if you are interested,
Hi.
I have read a bit about this and also checked a supplier's website, but it does not state on their site that you install it indoors?
It might be an idea to get better insulation value in that case. But I will probably stick to plastered walls with silicate paint.
The question is how I should solve the floor in the best way? The house is located on a sand ridge, and when I drained, there was really nice "cable sand" around the entire house that was really dry and fine. I have also replaced the sewer stack and made a hole inside the house for this. There was also such sand under the entire slab where I dug (dry and fine). However, the previous owner painted the floor with some kind of paint that has mostly flaked off. My thought is to sand down the floor and lay a thin crust with fiber-reinforced self-leveling compound to even out the entire floor as it has a slope of about 27cm inside the laundry room.
Does anyone know if it's okay to use fiber-reinforced compound regarding "breathability" on the floor? Or should you use concrete? With concrete, I would have to level much higher since I would need reinforcement as well. Which I don't want as I don't want to take any height from the rooms.
You should naturally do what you feel comfortable with. However, träullit has been installed on the inside of my house's basement walls for 70 years. It was said to be very common in houses built at that time. The manufacturer can probably confirm that.
Since the paint has peeled, you probably have some additional moisture coming from below. There are figures for the impermeability of many materials, or in this case, how so-called diffusion-open different materials are. As a layman, I've looked at a lot of materials but haven't delved into self-leveling compound. In the rooms where self-leveling compound was used in the basement, there is an open waterproofing and tiles in one area, and in another, tiles were laid on the self-leveling compound. The self-leveling compound had fiber reinforcement, and it has worked well. We paid a bit of extra attention to ensure that the walls had open paint on the opposite walls to where we installed the waterproofing. This has worked well, and I have the appropriate type of measuring instruments, so I've followed up, and it has worked well.
I've collected some tables where different materials have been compared. I can take a quick look and see if there is anything about self-leveling compound. I'll post if I find anything.
Hello, From my perspective, I want to congratulate you on a good methodology for creating optimal conditions for the best possible basement climate.
"Many" people drain and remove loose plaster and furnish to living standards without realizing that the walls have often accumulated quite a lot of moisture. That is, more than what is "normally added" moisture.
If you are going to furnish any part of the basement with more living space quality, there are more or less good solutions. I have tried to learn what it takes to make it work and so far it has worked well. If you have such thoughts and want to discuss ideas, I am happy to share my experiences.
Now I see that you are going to use a giraff, and a good advice is to use a good extractor as there will be a lot of particles in the air. Some of the smallest particles, such as quartz dust = incredibly small stone particles, are dangerous to inhale. I also suggest you complement with some form of respiratory protection.
Regarding the new surface, you've already been advised to use primer. The reflection on the choice of plaster is that if the previous plaster was lime-based, it is less suitable to use cement-based plaster outside as they are stronger and likely denser from a moisture perspective. I use the word likely because there are many "mixtures" of plaster. Just wanted to tip you about this factor. Otherwise, it sounds like your walls have good conditions to maintain the chosen finish for a long time.
The choice of flooring affects the walls' moisture load. As an extreme, a "waterproof" floor makes more of the moisture from the ground rise via the walls. I suspect you've also thought about this
In addition, it is my experience that it is good to use a dehumidifier to handle the moisture that is added. Ventilation is for air exchange. Heating and ventilating away moisture is more expensive than letting a dehumidifier handle the added moisture beyond that which comes with a normal ventilation flow.
I have chosen to maintain a rather low relative humidity. Some say it becomes expensive, but once you've gotten a basement really dry, the difference in energy cost between keeping RH50% and RH60% is not that big. However, the difference has a good effect as the lower level keeps materials and walls dry with a margin and reduces the risk of peeling paint, plaster, or other moisture-related issues.
Another tip is to ensure there is no stagnant air in the basement. If you look at the floor plan, it might be enough to make a hole and insert a small fan that circulates the air in the basement. I have done so and installed a fan that draws 1.6-1.7 watts 230V that moves about 100m3/h. That's over 16KWh/year. It is very quiet and hardly noticeable, but the entire basement essentially gets the same climate and no stagnant air. By moving the air, the probability that any room or place in the basement gets elevated relative humidity that can cause problems or inconvenience is reduced. We have furniture and some fixed furnishings, and then stagnant air is not good.
The combination of keeping air circulation in the basement with a good dehumidifier works fantastically well.
A challenge is getting the ventilation right since we have a lower temperature in the basement than in the residence. In the residence, there is also passive ventilation that works excellently, but the lower temperature in the basement meant I needed both incoming and outgoing air in the basement.
The ventilation is managed with passive ventilation with incoming air in the basement and outgoing air in a ventilation channel in the chimney that is built from the basement upwards. It is not obvious that it works anyway depending on how the chimney is otherwise used. A simple way to test to see that the exhaust goes out the correct vent is to use a cigarette lighter or a candle which is enough in my house to see that the exhaust goes out the vent.
Since the fan circulates the air in the basement, I have chosen to have the incoming air vent open only in one room.
In part of the basement, there is a guest room where I increase the temperature when guests are coming. To avoid heating the entire basement, a door is then closed. To maintain air circulation, that door has several 30mm holes at the bottom. A little warm air follows, but as is well-known, warm air rises, so the energy that follows at the bottom becomes bonus energy for the rest of the basement, but in practice we quickly get the guest area up to 22 degrees while the rest of the basement rises 0.5 degrees, which naturally increases if guests stay longer.
Good luck with the continued work.
I would love to hear about your experiences with living space quality in the basement
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