I'm planning to start renovating our basement in our 60s house.
"Original" 60s basement: The floor consists of a painted concrete slab and the walls are painted with what I assume is plastic paint. Both walls and floor seem to be in reasonably good condition. The basement walls are uninsulated and no drainage has been done, but it both looks and smells OK to me.
I want to make the walls breathable and would like to have vinyl or parquet flooring.
Searching around and feel that I need to understand what I have today first, to make the right decision on how the renovation should proceed. I'll number my questions so you can answer the ones you feel like:
1- How do you know if the concrete slab (floor) in the basement is insulated? Drill a hole and look to see if you find foam plastic?
2- How do you know if the green paint on the concrete slab today needs to be removed first? Assuming it's epoxy paint from the 60s, I don't know if it breathes.
3- How do you know if a Platon mat WITHOUT mechanical ventilation is sufficient as a floor base, or if it also needs mechanical ventilation?
4- Is there any point in insulating the walls from the inside, when you're already working with the walls? I understand that you should never insulate from the inside, is that correct?
"Original" 60s basement: The floor consists of a painted concrete slab and the walls are painted with what I assume is plastic paint. Both walls and floor seem to be in reasonably good condition. The basement walls are uninsulated and no drainage has been done, but it both looks and smells OK to me.
I want to make the walls breathable and would like to have vinyl or parquet flooring.
Searching around and feel that I need to understand what I have today first, to make the right decision on how the renovation should proceed. I'll number my questions so you can answer the ones you feel like:
1- How do you know if the concrete slab (floor) in the basement is insulated? Drill a hole and look to see if you find foam plastic?
2- How do you know if the green paint on the concrete slab today needs to be removed first? Assuming it's epoxy paint from the 60s, I don't know if it breathes.
3- How do you know if a Platon mat WITHOUT mechanical ventilation is sufficient as a floor base, or if it also needs mechanical ventilation?
4- Is there any point in insulating the walls from the inside, when you're already working with the walls? I understand that you should never insulate from the inside, is that correct?
1. You can almost assume that the slab is uninsulated. 99% of the slabs were uninsulated in the 60s.
2. That you don't have any problems today is a good indication for both the floors and walls. The combination of tight paint and incoming moisture often shows well through bubbling/peeling paint and plaster, primarily on the lower parts of the walls. Time is an important factor. If it's old paint that still holds up well after 10-20 years or maybe even more, I wouldn't be worried at all. However, if it is relatively newly painted, there is reason to be attentive and take a closer look. Newly painted surfaces might indicate that plaster and paint have started to peel and that a quick fix was made before a sale. The fix can, of course, be well done, but usually also includes re-drainage if there have been moisture problems.
3. It is again about whether there is incoming moisture. There are simple ways to check. For example, placing squares of plastic wrap and taping around them. If there is incoming moisture, there will usually be a lot of condensation on the inside of the plastic. Note that this can vary with the seasons depending on the moisture conditions in the ground outside.
4. No, according to me at least. Opinions sometimes differ here. But if you want to go for the really safe solution that is also easy to monitor over time, it is plaster and permeable paint that is required on the inside. Some build braced constructions with air gaps, steel studs, and drywall. These are admittedly better than the older constructions where wood and insulation were placed directly against concrete/masonry, but they still introduce uncertainty regarding the concrete walls' life behind the insulation.
2. That you don't have any problems today is a good indication for both the floors and walls. The combination of tight paint and incoming moisture often shows well through bubbling/peeling paint and plaster, primarily on the lower parts of the walls. Time is an important factor. If it's old paint that still holds up well after 10-20 years or maybe even more, I wouldn't be worried at all. However, if it is relatively newly painted, there is reason to be attentive and take a closer look. Newly painted surfaces might indicate that plaster and paint have started to peel and that a quick fix was made before a sale. The fix can, of course, be well done, but usually also includes re-drainage if there have been moisture problems.
3. It is again about whether there is incoming moisture. There are simple ways to check. For example, placing squares of plastic wrap and taping around them. If there is incoming moisture, there will usually be a lot of condensation on the inside of the plastic. Note that this can vary with the seasons depending on the moisture conditions in the ground outside.
4. No, according to me at least. Opinions sometimes differ here. But if you want to go for the really safe solution that is also easy to monitor over time, it is plaster and permeable paint that is required on the inside. Some build braced constructions with air gaps, steel studs, and drywall. These are admittedly better than the older constructions where wood and insulation were placed directly against concrete/masonry, but they still introduce uncertainty regarding the concrete walls' life behind the insulation.
The basic construction is certainly widespread slabs (popularly called soles) under the brick walls and thin (5-7 cm) unreinforced and uninsulated concrete slabs between the soles. Such a basement should be kept cool, otherwise there is a risk of moisture condensation on walls and floors.
Hi, thanks for all the answers!
The fact that it must be kept cool was new to me. I was planning on having it comfortably heated. How do I ensure that I have such a construction, and what are my options if I want it heated?
The fact that it must be kept cool was new to me. I was planning on having it comfortably heated. How do I ensure that I have such a construction, and what are my options if I want it heated?
Cellar cool means about 16 degrees. With higher temperatures, the amount of moisture that can be held in the air increases, and thus the risk of condensation on cold floors and outer walls. The best solution to this problem is external insulation of the basement walls. You will need to chip up the concrete slab (not so difficult when it's thin and unreinforced), possibly excavate a few cm, install insulation, and pour a new slab. There are other methods, but they usually add too much height.