ᐅ Basement Renovation in an Older Home: Do It Yourself or Hire a Professional?
Created on: 6 Oct 2021 15:02
P
piepen55
Hello everyone,
I just registered to gather some experiences and opinions regarding the following situation. Briefly about the conditions: We are renovating an old building (built around 1930), which is being converted from a two-family house into a single-family house and upgraded to an energy-efficient house standard 70 or 55. Currently, we are working with architects and an energy consultant to finalize the scope of the construction measures. This means that until we obtain the building permit (also called planning permission), we want to focus on the basement. Based on any feedback we receive here, we hope to better assess whether this is a good idea.
About the basement: It consists of three rooms with a total area of about 56 m² (600 sq ft), which previously housed a workshop (with heating system), a storage room, and a "sanitary area" (bathtub, shower, toilet). Two rooms have window wells, while the third room’s window well was bricked up because a conservatory was built above it. The last-mentioned room (which I call the wine cellar, as we had to dispose of a lot of wine there) was the storage room. This room’s walls were constructed as follows: brick wall → plaster → polystyrene insulation → wood paneling (tongue and groove boards). So far, we have removed everything except the plaster, as the boards were extensively moldy. Since the plaster also shows efflorescence, it will be removed soon. The wine cellar floor currently has particle boards screwed down (previously covered with PVC flooring), and there is a vapor barrier visible underneath the particle boards. The particle boards are also damp. What is beneath the vapor barrier, I don’t yet know.
The other two rooms have tiled walls. Here, the grout, especially along the exterior walls, is at least partially blackened (the closer to the floor, the darker it gets). We will also remove everything down to the foundation walls in the coming weeks. Once we have completely gutted the basement, the question is how to proceed. The planned future uses for the basement are:
The expert advised installing a horizontal damp-proof course just above the basement floor and another barrier near ground level, as water rises through capillary action. With some handyman skills and good tools (both of which we have), it could be done ourselves. The costs would be manageable in this case, whereas hiring a specialized company would likely run into the mid five-figure range. However, his conclusion was that despite all efforts, the rooms could never be made completely dry.
The specialist from the renovation company, on the other hand (understandably from his perspective), recommended against attempting this ourselves, stating that the market solutions for installing a horizontal barrier typically last only 5 to 10 years. He also advised injecting and sealing a similar "barrier material" vertically into the entire affected walls. Furthermore, he said moisture had almost reached the ground floor, the mold was highly dangerous, and cracks could also develop. Whether this was partly alarmist, I cannot judge. We are currently awaiting the company’s offer for the recommended measures. Both the independent expert and the specialist agreed that the rooms are more "wet" than just "damp." The specialist’s conclusion was that the rooms can be dried enough to allow for building a “children’s room” inside.
A third option suggested by our architect is to proceed with the gutting to the foundation walls as planned, make the window wells more air-permeable, and then observe how the moisture conditions develop.
Given the intended use, we certainly do not require completely dry rooms. However, we are naturally concerned about moisture spreading to the upper floors. Installing a horizontal damp-proof course sounds plausible to me, especially since we cannot access the walls from the outside anyway.
My questions to those who have read this far (thanks for that!) are:
Best regards!
I just registered to gather some experiences and opinions regarding the following situation. Briefly about the conditions: We are renovating an old building (built around 1930), which is being converted from a two-family house into a single-family house and upgraded to an energy-efficient house standard 70 or 55. Currently, we are working with architects and an energy consultant to finalize the scope of the construction measures. This means that until we obtain the building permit (also called planning permission), we want to focus on the basement. Based on any feedback we receive here, we hope to better assess whether this is a good idea.
About the basement: It consists of three rooms with a total area of about 56 m² (600 sq ft), which previously housed a workshop (with heating system), a storage room, and a "sanitary area" (bathtub, shower, toilet). Two rooms have window wells, while the third room’s window well was bricked up because a conservatory was built above it. The last-mentioned room (which I call the wine cellar, as we had to dispose of a lot of wine there) was the storage room. This room’s walls were constructed as follows: brick wall → plaster → polystyrene insulation → wood paneling (tongue and groove boards). So far, we have removed everything except the plaster, as the boards were extensively moldy. Since the plaster also shows efflorescence, it will be removed soon. The wine cellar floor currently has particle boards screwed down (previously covered with PVC flooring), and there is a vapor barrier visible underneath the particle boards. The particle boards are also damp. What is beneath the vapor barrier, I don’t yet know.
The other two rooms have tiled walls. Here, the grout, especially along the exterior walls, is at least partially blackened (the closer to the floor, the darker it gets). We will also remove everything down to the foundation walls in the coming weeks. Once we have completely gutted the basement, the question is how to proceed. The planned future uses for the basement are:
- Housing the heating system
- Laundry
- Tool storage/workshop
- Storing food and beverages, including space for a freezer
The expert advised installing a horizontal damp-proof course just above the basement floor and another barrier near ground level, as water rises through capillary action. With some handyman skills and good tools (both of which we have), it could be done ourselves. The costs would be manageable in this case, whereas hiring a specialized company would likely run into the mid five-figure range. However, his conclusion was that despite all efforts, the rooms could never be made completely dry.
The specialist from the renovation company, on the other hand (understandably from his perspective), recommended against attempting this ourselves, stating that the market solutions for installing a horizontal barrier typically last only 5 to 10 years. He also advised injecting and sealing a similar "barrier material" vertically into the entire affected walls. Furthermore, he said moisture had almost reached the ground floor, the mold was highly dangerous, and cracks could also develop. Whether this was partly alarmist, I cannot judge. We are currently awaiting the company’s offer for the recommended measures. Both the independent expert and the specialist agreed that the rooms are more "wet" than just "damp." The specialist’s conclusion was that the rooms can be dried enough to allow for building a “children’s room” inside.
A third option suggested by our architect is to proceed with the gutting to the foundation walls as planned, make the window wells more air-permeable, and then observe how the moisture conditions develop.
Given the intended use, we certainly do not require completely dry rooms. However, we are naturally concerned about moisture spreading to the upper floors. Installing a horizontal damp-proof course sounds plausible to me, especially since we cannot access the walls from the outside anyway.
My questions to those who have read this far (thanks for that!) are:
- Should we install the horizontal barrier ourselves, or
- hire a company to do it as they propose, or
- gut the basement first and wait to see, or
- are there other ideas?
Best regards!
Winniefred9 Oct 2021 11:06It was similar for us. A detached house from 1921. The previous owner had sealed off one room completely with Styrofoam and boards, which of course caused mold underneath. We also removed plaster with efflorescence. In two rooms, we have screed on the floor, and in two others, tiles (no mold or anything like that). We noticed moisture mainly in the first 50-70 cm (20-28 inches) above the floor, but it stops after that. Our house had a bitumen-based horizontal barrier, but after 100 years it’s naturally crumbling away. It’s also clear that the moisture comes from the surrounding soil. Our house is on a slope; the front of the basement is almost completely underground, but at the back, it’s just a few centimeters (inches).
So, what we did: Removed everything, boards and so on, took off the plaster, and removed added interior walls. That immediately got rid of the mold. That was four years ago. We ventilate especially well in winter. In summer, we don’t air out during the day due to high humidity! I started re-grouting and this winter I plan to apply new renovation plaster. In one room, I fully re-grouted and then whitewashed the walls. For cost reasons, we initially decided against basement waterproofing. We would definitely have to excavate around the house, re-seal from the outside, and install a new horizontal barrier. That costs a lot of money, and we have been using the basement without problems for four years, with the same kind of requirements you have. We have a garden fridge down there, washing machine, dryer, workshop, and also store supplies and such. If we ever save enough money to redo the exterior paving, we would likely do the waterproofing then, and also renew the exterior renovation plaster at the same time. So for now, we will apply renovation plaster inside and let it do its job, then see how things develop over the next few years and decide on further steps as needed.
When a house is 90 years old, I don’t see any reason to panic. That’s exactly the advantage of older buildings—they have stood for a long time. There is no reason why things should suddenly get worse. On the contrary, conditions will likely improve if you give the old lady a bit of relief through careful removal of added walls and good ventilation. Personally, I don’t see a need for drastic action if you don’t need the basement to be completely dry. These basements were deliberately built as partially damp basements. Of course, masonry is not better off with moisture, so it surely doesn’t hurt to give the old lady somewhat drier feet. It doesn’t have to be completely dry. I rather wouldn’t leave it that way forever.
At least, that’s my amateur assessment. 😉
So, what we did: Removed everything, boards and so on, took off the plaster, and removed added interior walls. That immediately got rid of the mold. That was four years ago. We ventilate especially well in winter. In summer, we don’t air out during the day due to high humidity! I started re-grouting and this winter I plan to apply new renovation plaster. In one room, I fully re-grouted and then whitewashed the walls. For cost reasons, we initially decided against basement waterproofing. We would definitely have to excavate around the house, re-seal from the outside, and install a new horizontal barrier. That costs a lot of money, and we have been using the basement without problems for four years, with the same kind of requirements you have. We have a garden fridge down there, washing machine, dryer, workshop, and also store supplies and such. If we ever save enough money to redo the exterior paving, we would likely do the waterproofing then, and also renew the exterior renovation plaster at the same time. So for now, we will apply renovation plaster inside and let it do its job, then see how things develop over the next few years and decide on further steps as needed.
When a house is 90 years old, I don’t see any reason to panic. That’s exactly the advantage of older buildings—they have stood for a long time. There is no reason why things should suddenly get worse. On the contrary, conditions will likely improve if you give the old lady a bit of relief through careful removal of added walls and good ventilation. Personally, I don’t see a need for drastic action if you don’t need the basement to be completely dry. These basements were deliberately built as partially damp basements. Of course, masonry is not better off with moisture, so it surely doesn’t hurt to give the old lady somewhat drier feet. It doesn’t have to be completely dry. I rather wouldn’t leave it that way forever.
At least, that’s my amateur assessment. 😉
@Winniefred Thank you for your detailed post and description. The situation really does seem comparable, even though we’re not building on a slope. We also have screed in two rooms and tiles in one, which I plan to remove as well. Your post reinforces my opinion to first let the basement “air out” and then possibly retrofit a horizontal damp-proof course later. The 70,000 euros this would cost is simply something we cannot and do not want to afford at the moment.
Winniefred11 Oct 2021 09:0070,000€???? 😱 😱 For what? How do they come up with that amount? You could practically build a simple basement new for that...
70,000 euros for horizontal barrier and injection in floor and walls...
Today, I lifted the chipboard in the wine cellar. Underneath was a black membrane and then directly sand (or compacted clay?). What would be the best type of flooring to install here? Should I pour a screed?
Today, I lifted the chipboard in the wine cellar. Underneath was a black membrane and then directly sand (or compacted clay?). What would be the best type of flooring to install here? Should I pour a screed?
piepen55 schrieb:
70,000 Euro for a horizontal barrier and injection in the floor and walls...
Today, I lifted the chipboard panels in the wine cellar. Beneath them, there was a black membrane and then directly sand (or compacted clay?). What would be the best type of flooring to install here? Should I pour a screed? Nothing. Just leave it as is. If no mold appears between the subfloor and the chipboard, then leave it. If there is mold on the board, then remove the boards and membrane and live with the sand floor.
Whatever flooring you put in now will cause dirt, work, cost money, and will most likely make the room worse in some way. Considering the space is only used for laundry and storage, it’s not necessary.
Winniefred12 Oct 2021 10:29What’s underneath will be the original floor. I would check if you can live with that. I’m not sure what else could be put in there. Screed would just seal everything up again, wouldn’t it?
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