ᐅ Flat Roof vs. Hip Roof vs. Hip Roof with Exposed Rafters – A Cost Comparison

Hello,

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.”

Don’t be mistaken: properly waterproofing a flat roof costs a lot of money.

So, is a flat roof more expensive than a hip roof?

Properly sealed, I would gladly choose any type of roof.

A flat roof is generally estimated to be around 20,000 more expensive. I heard this statement from a knowledgeable professional.

Interesting. I always thought a flat roof would be easier (in terms of cost) to build.

But this actually works in my favor, since according to the following thread, it looks like I can most likely plan with a pitched roof

https://www.hausbau-forum.de/threads/gebaeudehoehe-von-8-5-m-mit-Keller-und-2-Vollgeschossen.26383/page-2?_params=Array

And how about the following hip roof variations:

• 10° hip roof, without exposed rafters.
• 10° hip roof, with exposed rafters.
• 20° hip roof, without exposed rafters.
• 20° hip roof, with exposed rafters.
• 30° hip roof, without exposed rafters.
• 30° hip roof, with exposed rafters.

Are there any general rules? For example, “with exposed rafters is cheaper than without” or “steeper roofs are more expensive than roofs with a lower pitch”? Just to gather some more experience for further planning.

Take a look at what is included in the standard package of different home builders. In my opinion, it is likely that these represent the more cost-effective options. I believe there is a predominance of hip roofs without visible rafters, using pre-fabricated truss structures (this type makes it difficult to move freely inside the attic space). These trusses typically come as ready-made solutions (economical). I am not sure what roof pitches are common with these.

I think you will need a professional designer or architect for the building permit / planning permission anyway. They will be able to answer your questions more accurately.