Hello everyone,
In 2015, I carried out a full renovation of a house built in the 1970s (including triple glazing). At that time, I had someone advise me against cavity wall insulation because my cavity already contained a 1cm (0.4 inch) thick layer of polystyrene, and they said you can ânever really make it tightâ if the polystyrene shifts or becomes misaligned.
After a year, I developed mold in the bedroom (which I managed to control with a dehumidifier and targeted heating), and now I have found mold in the external corners of another room that is currently only used as a storage space. Because of this, I wanted to have it checked again.
So, I invited this expert back. He said that if there is already a problem, something should be done, and that they could inject fine beads into the wall to press the polystyrene boards back against the internal masonry, carefully filling the cavity. The beads from his current supplier are much finer than before. He said it couldnât really get worse. He also mentioned that the beads tend to spread everywhere and that he generally doesnât like using them because they can cause a lot of hassle, but with my cavity only 2.5â3cm (1â1.2 inches) thick, nothing else would fit. The price he quoted was very reasonable!
To be sure, I wanted a second opinion. The second contractor recommended foaming the masonry. He advised against using beads as they wouldnât reach all areas. According to him, foam often resolves these situations without problems. The loose boards would be pressed back into place as well. However, his price was about 50% higher than the first offer.
For me as a layperson, the advantage of foaming is obvious: everything stays in place and nothing shifts anymore, right? Also, beads donât fly around through every hole in the wall.
I asked the first contractor about the foam. He advised against it, saying that the foam formulations without formaldehyde (a carcinogen?) used in recent years do not have enough strength and tend to break down over time. Foam containing formaldehyde would affect the indoor climate due to the lime sand brick and would generally not be permitted.
Two companies rejecting each otherâs preferred method. Since I have no expertise, Iâd like to ask for advice here. Iâm currently leaning toward the bead solution again because I know someone who was annoyed by the beads but could at least confirm their effectiveness. Also, it is significantly cheaper for me.
In 2015, I carried out a full renovation of a house built in the 1970s (including triple glazing). At that time, I had someone advise me against cavity wall insulation because my cavity already contained a 1cm (0.4 inch) thick layer of polystyrene, and they said you can ânever really make it tightâ if the polystyrene shifts or becomes misaligned.
After a year, I developed mold in the bedroom (which I managed to control with a dehumidifier and targeted heating), and now I have found mold in the external corners of another room that is currently only used as a storage space. Because of this, I wanted to have it checked again.
So, I invited this expert back. He said that if there is already a problem, something should be done, and that they could inject fine beads into the wall to press the polystyrene boards back against the internal masonry, carefully filling the cavity. The beads from his current supplier are much finer than before. He said it couldnât really get worse. He also mentioned that the beads tend to spread everywhere and that he generally doesnât like using them because they can cause a lot of hassle, but with my cavity only 2.5â3cm (1â1.2 inches) thick, nothing else would fit. The price he quoted was very reasonable!
To be sure, I wanted a second opinion. The second contractor recommended foaming the masonry. He advised against using beads as they wouldnât reach all areas. According to him, foam often resolves these situations without problems. The loose boards would be pressed back into place as well. However, his price was about 50% higher than the first offer.
For me as a layperson, the advantage of foaming is obvious: everything stays in place and nothing shifts anymore, right? Also, beads donât fly around through every hole in the wall.
I asked the first contractor about the foam. He advised against it, saying that the foam formulations without formaldehyde (a carcinogen?) used in recent years do not have enough strength and tend to break down over time. Foam containing formaldehyde would affect the indoor climate due to the lime sand brick and would generally not be permitted.
Two companies rejecting each otherâs preferred method. Since I have no expertise, Iâd like to ask for advice here. Iâm currently leaning toward the bead solution again because I know someone who was annoyed by the beads but could at least confirm their effectiveness. Also, it is significantly cheaper for me.
Similar topics