ᐅ Flat Roof vs. Hip Roof vs. Hip Roof with Exposed Rafters – A Cost Comparison
Created on: 4 Jan 2018 09:06
M
Marcello
Hello,
I am generally interested in understanding the cost relationship between the following three roof types (floor plan approx. 12x8 meters (39x26 feet)):
I realize that the price depends on many factors, but a rough general estimate would be sufficient for me (cost relationship, not exact cost). Logically (and without any construction experience ), I would assume that a flat roof is less expensive than a closed hip roof, which in turn is less expensive than a hip roof with exposed rafters, since the exposed rafters require additional aesthetic work (on the other hand, the ceiling slab is omitted). I could be wrong about the flat roof though. It’s certainly more than just a concrete slab plus insulation.
A rough comparative example calculation would already help me to finalize my building plan. Something like, “if a flat roof costs 30,000 then a closed hip roof is about 20% more and a hip roof with exposed rafters is roughly twice as much.”
I am generally interested in understanding the cost relationship between the following three roof types (floor plan approx. 12x8 meters (39x26 feet)):
- Flat roof.
- Hip roof (between 10°-20° slope).
- Hip roof (between 10°-20° slope) with exposed rafters.
I realize that the price depends on many factors, but a rough general estimate would be sufficient for me (cost relationship, not exact cost). Logically (and without any construction experience ), I would assume that a flat roof is less expensive than a closed hip roof, which in turn is less expensive than a hip roof with exposed rafters, since the exposed rafters require additional aesthetic work (on the other hand, the ceiling slab is omitted). I could be wrong about the flat roof though. It’s certainly more than just a concrete slab plus insulation.
A rough comparative example calculation would already help me to finalize my building plan. Something like, “if a flat roof costs 30,000 then a closed hip roof is about 20% more and a hip roof with exposed rafters is roughly twice as much.”
That depends on which types of structures you are comparing. A flat roof can be made of wood (more affordable but more prone to damage) or have a solid waterproof concrete slab. Compared to the wooden beam ceiling of a house with a pitched roof, this might be an additional cost. On the other hand, you don’t have shingles or similar materials… I think it’s difficult to give a general answer.
Our planners (flat roof, concrete) say the costs are about the same. When I look at the cost calculation and search for the mentioned extra 20,000 euros, a comparable pitched roof would probably be a bargain… which doesn’t seem right.
Our planners (flat roof, concrete) say the costs are about the same. When I look at the cost calculation and search for the mentioned extra 20,000 euros, a comparable pitched roof would probably be a bargain… which doesn’t seem right.
The most cost-effective roof pitch for a gable roof is around 22° (22 degrees). This is the simplest roof shape. A flat roof, frankly, is only cheaper if you don’t care about waterproofing.
Below this pitch, special roof tiles or shingles are usually required, and the entire roof covering becomes more complex because wind and weather don’t become any less harsh. Roof coverings are in a way like “dry stone walls”—the flatter the roof, the more difficult it is to ensure waterproofing, and the roof tiles or shingles bear different pressure on the battens.
With a steeper roof pitch, the roof surface area increases, which only makes sense if you use the space underneath. However, local building codes or planning permissions might require a pitch of, for example, 30°, even if you don’t plan to use the attic space.
Giving the roof more sloped sections (hipped or pyramid roofs instead of gable) means creating ridges where the sloped surfaces meet. This requires angled cuts of the roof tiles or shingles at the roofing level and special tiles or shingles such as ridge tiles, as well as more complex sheet metal / flashing work. This roof type is also more complex at the structural frame level.
Open eaves usually shift the insulation into the roof slope. With hipped or pyramid roofs, it is also difficult to aesthetically align the ridges with the interior walls’ layout. The sloped “ceiling” ends up having awkward corners. If you hope to save money with open eaves: that is clearly a top-tier mistake that will backfire.
Besides roof shape and pitch, there is also the dimension of the roof construction: trusses are cheaper than rafters, and there are various types (such as attic trusses and the practically “in the way” timber-frame trusses in the attic).
There are also solid roof constructions, and this list is by no means complete. This is just to explain the main cost-influencing factors in basic terms.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
Below this pitch, special roof tiles or shingles are usually required, and the entire roof covering becomes more complex because wind and weather don’t become any less harsh. Roof coverings are in a way like “dry stone walls”—the flatter the roof, the more difficult it is to ensure waterproofing, and the roof tiles or shingles bear different pressure on the battens.
With a steeper roof pitch, the roof surface area increases, which only makes sense if you use the space underneath. However, local building codes or planning permissions might require a pitch of, for example, 30°, even if you don’t plan to use the attic space.
Giving the roof more sloped sections (hipped or pyramid roofs instead of gable) means creating ridges where the sloped surfaces meet. This requires angled cuts of the roof tiles or shingles at the roofing level and special tiles or shingles such as ridge tiles, as well as more complex sheet metal / flashing work. This roof type is also more complex at the structural frame level.
Open eaves usually shift the insulation into the roof slope. With hipped or pyramid roofs, it is also difficult to aesthetically align the ridges with the interior walls’ layout. The sloped “ceiling” ends up having awkward corners. If you hope to save money with open eaves: that is clearly a top-tier mistake that will backfire.
Besides roof shape and pitch, there is also the dimension of the roof construction: trusses are cheaper than rafters, and there are various types (such as attic trusses and the practically “in the way” timber-frame trusses in the attic).
There are also solid roof constructions, and this list is by no means complete. This is just to explain the main cost-influencing factors in basic terms.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
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