Hello,
I bought a house and afterwards unfortunately noticed that the 125m2 (1,345 sq ft) large western half of the roof is drained through a lifting station in the ground floor. It has been like this since the 1980s, but I don’t want to leave it that way. It only takes a power outage or the lifting station to fail during heavy rain to cause problems. The house was never designed to drain without a lifting station, but I would still like to find a way to do it.
The gutter on the west side is high enough (60cm (24 inches) above ground level), and I could lead the water with a slope in a pipe along the 12m (39 ft) long north side to the sewer. However, at the northern end of the west side, the roof is extended by about 2m (6.5 ft) because the room below is a bit longer than the others. The gutter of the extended roof section would also be high enough for the sewer connection, but the pipe would then run in front of the windows on the north side. That’s why I researched and came across box gutters or roof-integrated gutters. My idea was to convert the west side gutter into a roof-integrated gutter and then run it over the extended roof section. The few square meters of roof underneath would simply drain into the garden through the existing downpipe.
I hired a roofer, but he is not entirely comfortable with this plan. When I asked, he said that if the gutter overflows, water could get into the house. Unfortunately, the alternatives (infiltration or a second external pump basin) involve civil engineering work, and the garden is not accessible by excavator. Also, I am already annoyed by the one lifting station, and the soil is very compact and extremely unsuitable for infiltration.
What do the construction professionals say? Is something like this generally feasible or complete nonsense? I have attached two sketches of the west and north sides; the extended part of the roof is slightly longer than shown in the construction drawing.
I bought a house and afterwards unfortunately noticed that the 125m2 (1,345 sq ft) large western half of the roof is drained through a lifting station in the ground floor. It has been like this since the 1980s, but I don’t want to leave it that way. It only takes a power outage or the lifting station to fail during heavy rain to cause problems. The house was never designed to drain without a lifting station, but I would still like to find a way to do it.
The gutter on the west side is high enough (60cm (24 inches) above ground level), and I could lead the water with a slope in a pipe along the 12m (39 ft) long north side to the sewer. However, at the northern end of the west side, the roof is extended by about 2m (6.5 ft) because the room below is a bit longer than the others. The gutter of the extended roof section would also be high enough for the sewer connection, but the pipe would then run in front of the windows on the north side. That’s why I researched and came across box gutters or roof-integrated gutters. My idea was to convert the west side gutter into a roof-integrated gutter and then run it over the extended roof section. The few square meters of roof underneath would simply drain into the garden through the existing downpipe.
I hired a roofer, but he is not entirely comfortable with this plan. When I asked, he said that if the gutter overflows, water could get into the house. Unfortunately, the alternatives (infiltration or a second external pump basin) involve civil engineering work, and the garden is not accessible by excavator. Also, I am already annoyed by the one lifting station, and the soil is very compact and extremely unsuitable for infiltration.
What do the construction professionals say? Is something like this generally feasible or complete nonsense? I have attached two sketches of the west and north sides; the extended part of the roof is slightly longer than shown in the construction drawing.
Hi,
Honestly, if you really want to drain the roof using an above-roof gutter without having to install a second pumping station or create absorption through the garden, it could theoretically work, but... well, “practical” is another matter. The problem with the above-roof gutter isn’t just the installation and the pipe in front of the windows – that can be managed somehow – but the question is how reliable the whole system is without additional safety measures, especially during heavy rain. Will you be able to maintain the system reliably with regular upkeep? And how can you be sure that the gutter can handle the water continuously without problems? There could be unwanted blockages here and there, even if you regularly remove debris. The roofer probably simply has concerns about the long-term stress and maintenance – which is understandable.
Sure, the pumping station on the ground floor is a real headache. I understand your approach, but it might be worth considering whether an additional solution on the building’s side would be more sensible in the long run. Or are you really prepared to put more effort into the roof and risk compromising half a system?
Maybe an experienced drainage professional can offer another perspective? I would recommend reopening the discussion and focusing more closely on the technical details.
Honestly, if you really want to drain the roof using an above-roof gutter without having to install a second pumping station or create absorption through the garden, it could theoretically work, but... well, “practical” is another matter. The problem with the above-roof gutter isn’t just the installation and the pipe in front of the windows – that can be managed somehow – but the question is how reliable the whole system is without additional safety measures, especially during heavy rain. Will you be able to maintain the system reliably with regular upkeep? And how can you be sure that the gutter can handle the water continuously without problems? There could be unwanted blockages here and there, even if you regularly remove debris. The roofer probably simply has concerns about the long-term stress and maintenance – which is understandable.
Sure, the pumping station on the ground floor is a real headache. I understand your approach, but it might be worth considering whether an additional solution on the building’s side would be more sensible in the long run. Or are you really prepared to put more effort into the roof and risk compromising half a system?
Maybe an experienced drainage professional can offer another perspective? I would recommend reopening the discussion and focusing more closely on the technical details.
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