ᐅ Flat roof with green roofing without parapet wall (without raised curb)
Created on: 19 Dec 2018 12:02
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Christian K.C
Christian K.19 Dec 2018 12:02Hello everyone,
We are planning a flat-roof house and need to install an extensive green roof. We would prefer to do without a parapet, but we were advised against it. One reason given was that a parapet is necessary for green roofing, which I have also partially seen mentioned online. Another reason was that, due to the edge location, wind can blow the vegetation away if there is no parapet.
However, I have also heard that parapets were commonly used in the past, but nowadays there are other options available. I’m not sure how effective these are or how well they hold up against wind. Can you share any insights on this?
Here is an example of a green roof without a parapet.
I would also like to know if the height of the roof build-up changes when the parapet is omitted, and consequently if this affects the overall height of the house.
Best regards,
CK
We are planning a flat-roof house and need to install an extensive green roof. We would prefer to do without a parapet, but we were advised against it. One reason given was that a parapet is necessary for green roofing, which I have also partially seen mentioned online. Another reason was that, due to the edge location, wind can blow the vegetation away if there is no parapet.
However, I have also heard that parapets were commonly used in the past, but nowadays there are other options available. I’m not sure how effective these are or how well they hold up against wind. Can you share any insights on this?
Here is an example of a green roof without a parapet.
I would also like to know if the height of the roof build-up changes when the parapet is omitted, and consequently if this affects the overall height of the house.
Best regards,
CK
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Mottenhausen19 Dec 2018 12:38Regarding the height of the house, you need to check which element is referenced. What does the building plan or local regulations say? Sometimes a maximum parapet height of, for example, xy cm (xy inches) is required; other times, the highest point of the house counts, such as the chimney or photovoltaic system; sometimes the eaves height applies (in which case the parapet may exceed that).
In your sketch, the flashing (No. 27) functions as a low parapet; there must be some kind of closure. The sloped gravel bed (No. 28) does not allow steep slope angles because crushed material is not used at this point. The thickness of the planting soil and water retention layer (No. 8) is determined by the planned plant species.
Are you referring to the roof overhang, which would be omitted if there were a parapet?
In your sketch, the flashing (No. 27) functions as a low parapet; there must be some kind of closure. The sloped gravel bed (No. 28) does not allow steep slope angles because crushed material is not used at this point. The thickness of the planting soil and water retention layer (No. 8) is determined by the planned plant species.
Are you referring to the roof overhang, which would be omitted if there were a parapet?
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Christian K.19 Dec 2018 12:53Thank you for the quick response.
If I am reading the development plan correctly, measurements are taken at the ridge height. "The maximum allowable ridge height for roofs with a pitch greater than 15° is 12m (39 ft). The maximum allowable building top edge for roofs with a pitch of 15° or less is 9m (30 ft)."
Which measurement would this correspond to in my drawing? The "25, 24, 27, or 10," simply put? I think it’s the 10, because that is the highest point, but I am hoping for a lower value.
1. We want to know if it is possible, as some advise against it due to wind and other factors.
2. We want to plan the ceiling heights properly and therefore need to know which point should be used for calculations. With a parapet, this would presumably be the parapet itself, and we hope that if it is omitted, the building height would be somewhat reduced. However, if point (No. 10) is taken as the building height, then it doesn’t make a difference.
If I am reading the development plan correctly, measurements are taken at the ridge height. "The maximum allowable ridge height for roofs with a pitch greater than 15° is 12m (39 ft). The maximum allowable building top edge for roofs with a pitch of 15° or less is 9m (30 ft)."
Which measurement would this correspond to in my drawing? The "25, 24, 27, or 10," simply put? I think it’s the 10, because that is the highest point, but I am hoping for a lower value.
Mottenhausen schrieb:What do you mean by that?
The graded gravel bed (No. 28) does not allow for steep slopes because crushed material is not used at this location.
Mottenhausen schrieb:We have two reasons:
Are you referring to the roof overhang, which would be omitted with a parapet?
1. We want to know if it is possible, as some advise against it due to wind and other factors.
2. We want to plan the ceiling heights properly and therefore need to know which point should be used for calculations. With a parapet, this would presumably be the parapet itself, and we hope that if it is omitted, the building height would be somewhat reduced. However, if point (No. 10) is taken as the building height, then it doesn’t make a difference.
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