Hello forum,
In our newly built house from 2018, which we had built as a turnkey project, there is unfortunately a recurring mold problem on the wooden ceiling of the masonry utility room.
This approximately 9 m2 (97 square feet) extension to our residential building has a cavity wall (sand-lime brick and facing brick), but it is not insulated and is unheated. It has a flat roof made of a wooden structure and bitumen membrane. The roof is also not insulated. We store garden tools and bicycles in this room. For ventilation, the construction company installed two core-drilled holes with a diameter of DN100 (about 4 inches) in opposite walls (one near the top and one near the bottom). There are rust covers with insect screens in front of the openings. The room also has a window, but it remains closed at all times.
Unfortunately, moisture forms under the roof battens during the cold season. After the first winter, mold was clearly visible between the purlins. I initially attributed this to residual construction moisture. The problem recurred in the second winter. When everything had dried out in the summer, I removed the mold both mechanically and chemically and then applied a wood stain. However, in the third winter, I had to realize that my measures did not help. Mold formed again.
I contacted the construction company and asked whether this is a fundamental design issue and if improvements are needed. Our former site manager said that this is state of the art and that we should protect the room from cooling by using an electric heater. However, I really do not want to heat a utility room used for garden stuff.
In the fourth winter, I installed a bathroom fan with humidity control in the ventilation duct. It ran almost continuously because the humidity was so high. Mold was perhaps somewhat less severe that winter, but it was still present.
So something clearly needs to be done. A friend of mine who is a roofer said he would install an external roof insulation. To me, that sounds like a construction defect. What do you think? What are your technical suggestions? Is this a construction defect in your opinion? How would you approach the construction company?
Thank you very much for any input.
In our newly built house from 2018, which we had built as a turnkey project, there is unfortunately a recurring mold problem on the wooden ceiling of the masonry utility room.
This approximately 9 m2 (97 square feet) extension to our residential building has a cavity wall (sand-lime brick and facing brick), but it is not insulated and is unheated. It has a flat roof made of a wooden structure and bitumen membrane. The roof is also not insulated. We store garden tools and bicycles in this room. For ventilation, the construction company installed two core-drilled holes with a diameter of DN100 (about 4 inches) in opposite walls (one near the top and one near the bottom). There are rust covers with insect screens in front of the openings. The room also has a window, but it remains closed at all times.
Unfortunately, moisture forms under the roof battens during the cold season. After the first winter, mold was clearly visible between the purlins. I initially attributed this to residual construction moisture. The problem recurred in the second winter. When everything had dried out in the summer, I removed the mold both mechanically and chemically and then applied a wood stain. However, in the third winter, I had to realize that my measures did not help. Mold formed again.
I contacted the construction company and asked whether this is a fundamental design issue and if improvements are needed. Our former site manager said that this is state of the art and that we should protect the room from cooling by using an electric heater. However, I really do not want to heat a utility room used for garden stuff.
In the fourth winter, I installed a bathroom fan with humidity control in the ventilation duct. It ran almost continuously because the humidity was so high. Mold was perhaps somewhat less severe that winter, but it was still present.
So something clearly needs to be done. A friend of mine who is a roofer said he would install an external roof insulation. To me, that sounds like a construction defect. What do you think? What are your technical suggestions? Is this a construction defect in your opinion? How would you approach the construction company?
Thank you very much for any input.
S
Stefan00119 Jun 2022 17:40I have exactly the same construction setup and the same problem but am currently in the first year.
For about a month now, I have also installed a bathroom exhaust fan that monitors the dew point, so it only runs when the absolute humidity inside the room is lower than the humidity outside.
At the moment, the fan runs about 40-50% of the time, especially during the day. I am curious to see how this will perform in winter. However, this ventilation solution doesn’t seem like a permanent fix to me right now. I would also prefer a long-term solution involving insulation or similar measures.
For about a month now, I have also installed a bathroom exhaust fan that monitors the dew point, so it only runs when the absolute humidity inside the room is lower than the humidity outside.
At the moment, the fan runs about 40-50% of the time, especially during the day. I am curious to see how this will perform in winter. However, this ventilation solution doesn’t seem like a permanent fix to me right now. I would also prefer a long-term solution involving insulation or similar measures.
MeTheBuilder19 Jun 2022 23:25I have decided to take the official route through the construction company and file a defect report. What do I have to lose? So far, I have shown goodwill and tried to manage the problem myself, but without success. Let’s see what happens. The main thing is that the report is submitted within the five-year period.
In another case, the construction company had already repaired the defect free of charge, but that defect was undisputed (the roller shutter motor had wound up and torn its own cable due to incorrect installation).
In another case, the construction company had already repaired the defect free of charge, but that defect was undisputed (the roller shutter motor had wound up and torn its own cable due to incorrect installation).
MeTheBuilder22 Aug 2022 12:00We sent the construction company a formal complaint regarding this issue.
Of course, they have not addressed the matter.
They continue to claim that we need to control the humidity by heating and ventilating to keep it below 60%.
I believe such advice might be reasonable for living areas, but what about unheated utility rooms???
I’m seriously considering hiring an expert. However, if that doesn’t help either, I might be stuck with costs that could be higher than a new roof.
What would you do?
Of course, they have not addressed the matter.
They continue to claim that we need to control the humidity by heating and ventilating to keep it below 60%.
I believe such advice might be reasonable for living areas, but what about unheated utility rooms???
I’m seriously considering hiring an expert. However, if that doesn’t help either, I might be stuck with costs that could be higher than a new roof.
What would you do?
S
Stefan00122 Aug 2022 13:06Hmm, the question is to what extent you can get information for a small fee from the Homeowners’ Association or a similar organization.
I would also find it difficult right now to assess whether the construction method is truly state of the art, even if it is a very poor standard.
I would also find it difficult right now to assess whether the construction method is truly state of the art, even if it is a very poor standard.
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