ᐅ 30-year-old basement is damp. Should it be waterproofed? If so, how?
Created on: 13 Jan 2024 21:38
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Narma89
Hello everyone,
We are in the process of buying a house built in 1991, which we have also been living in for almost two years, so we basically know its flaws and issues. Yesterday, a building surveyor came and did not find any additional defects.
Besides the poor insulation of the attic floor, the biggest problem is the damp basement. We have saltpeter efflorescence on several walls. During the first summer, a lot of wood I had stored in the basement molded, which was most likely because I kept the basement windows open all summer. By now, I realize that wasn’t a very smart choice.
The surveyor mentioned two options: either excavate everything and waterproof from the outside or use a resin injection method from the inside. I would really prefer not to excavate because both terraces would have to be removed, as well as the landscaping. For the resin injection, I have a quote from acquaintances from 2021, which was €480/m² (about $480/sq ft). For the size of the basement, that would be about €50,000 ($50,000) without considering inflation, so probably closer to €60,000 ($60,000).
Now my question is, how urgent is the problem? How damaging is it to the building structure?
In my research, I have often seen the recommendation to first apply a horizontal barrier and then a vertical barrier from the inside. This would keep the basement itself dry, but the masonry would still remain damp. Is that even useful?
Would proper ventilation in the basement perhaps already help? The basement is only meant to be used as storage and a workshop, where I build things every few weeks. So it doesn’t actually need to be as dry as living spaces, but I have also read that moisture can eventually rise into the ground floor.
Additionally, the interior walls are the most affected, which I cannot explain. Pictures 1 and 4 show exterior walls; pictures 2 and 3 show interior walls.
Thank you very much in advance for your help!
We are in the process of buying a house built in 1991, which we have also been living in for almost two years, so we basically know its flaws and issues. Yesterday, a building surveyor came and did not find any additional defects.
Besides the poor insulation of the attic floor, the biggest problem is the damp basement. We have saltpeter efflorescence on several walls. During the first summer, a lot of wood I had stored in the basement molded, which was most likely because I kept the basement windows open all summer. By now, I realize that wasn’t a very smart choice.
The surveyor mentioned two options: either excavate everything and waterproof from the outside or use a resin injection method from the inside. I would really prefer not to excavate because both terraces would have to be removed, as well as the landscaping. For the resin injection, I have a quote from acquaintances from 2021, which was €480/m² (about $480/sq ft). For the size of the basement, that would be about €50,000 ($50,000) without considering inflation, so probably closer to €60,000 ($60,000).
Now my question is, how urgent is the problem? How damaging is it to the building structure?
In my research, I have often seen the recommendation to first apply a horizontal barrier and then a vertical barrier from the inside. This would keep the basement itself dry, but the masonry would still remain damp. Is that even useful?
Would proper ventilation in the basement perhaps already help? The basement is only meant to be used as storage and a workshop, where I build things every few weeks. So it doesn’t actually need to be as dry as living spaces, but I have also read that moisture can eventually rise into the ground floor.
Additionally, the interior walls are the most affected, which I cannot explain. Pictures 1 and 4 show exterior walls; pictures 2 and 3 show interior walls.
Thank you very much in advance for your help!
Try to get a few more quotes. Ideally from a local construction company with a small number of employees. My quote for excavation, new bitumen coating, insulation, dimpled membrane, and backfilling is roughly 18,000 for about 60m2 (645ft2). The quotes have varied significantly. The most surprising was a company recommended to me online. They wanted 72,000 😳 but that included additional injection.
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Buschreiter17 Jan 2024 06:42Recently, I had a company here that sealed two weak points. They first identified where the problem was and then specifically addressed those areas. One spot I had noticed was condensation, according to the expert, because I had apparently ventilated too much in the summer (beginner’s mistake). The entire repair – for a 2-meter (6.5 feet) high crack in a corner and a wall measuring 1.5 x 2.25 meters (5 x 7.4 feet) – cost 2,000 euros net. So far, everything has remained watertight, even during continuous heavy rain.