ᐅ Construction costs for terraces and similar elements in cost estimates according to DIN 276
Created on: 16 Oct 2018 15:51
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Pyrate
First of all, hello to everyone in this great forum!
We are also future homeowners and currently have some questions about construction costs during the conceptual planning phase.
The plan is for a Bauhaus-style house with about 200 sqm (2,150 sq ft) over two floors. We now have initial designs including a cost estimate based on DIN 276.
We have generally liked the idea of having roof overhangs on the south side with covered terraces on the ground floor and balconies on the upper floor underneath. One of the concepts includes exactly this, while the other does not.
However, with the concept that includes covered outdoor areas, the costs according to the DIN 276 estimate skyrocket. The architect explained that the covered terraces and balconies are fully included in the cost estimate, specifically in the parameters of usable floor area (UFA), gross volume (GV), and gross floor area (GFA).
This means that the concept with 200 sqm (2,150 sq ft) of “indoor” space without any overhangs, terraces, or balconies is cheaper than the concept with 180 sqm (1,940 sq ft) of indoor space plus 40 sqm (430 sq ft) of covered balcony/terrace area. The UFA of the first building is 200 sqm (2,150 sq ft), while the second is 220 sqm (2,370 sq ft). Multiplied by the same construction cost index (CCI) values, the second building is more expensive even though it offers less indoor space.
My question is this: Is it really true that the cost estimate does not distinguish between fully enclosed living space and a terrace covered by a projecting roof? The latter should be significantly cheaper to build than true living space, right? Even if it is structurally connected to the main building as a cantilevered roof extension...
I would greatly appreciate your advice here.
We are also future homeowners and currently have some questions about construction costs during the conceptual planning phase.
The plan is for a Bauhaus-style house with about 200 sqm (2,150 sq ft) over two floors. We now have initial designs including a cost estimate based on DIN 276.
We have generally liked the idea of having roof overhangs on the south side with covered terraces on the ground floor and balconies on the upper floor underneath. One of the concepts includes exactly this, while the other does not.
However, with the concept that includes covered outdoor areas, the costs according to the DIN 276 estimate skyrocket. The architect explained that the covered terraces and balconies are fully included in the cost estimate, specifically in the parameters of usable floor area (UFA), gross volume (GV), and gross floor area (GFA).
This means that the concept with 200 sqm (2,150 sq ft) of “indoor” space without any overhangs, terraces, or balconies is cheaper than the concept with 180 sqm (1,940 sq ft) of indoor space plus 40 sqm (430 sq ft) of covered balcony/terrace area. The UFA of the first building is 200 sqm (2,150 sq ft), while the second is 220 sqm (2,370 sq ft). Multiplied by the same construction cost index (CCI) values, the second building is more expensive even though it offers less indoor space.
My question is this: Is it really true that the cost estimate does not distinguish between fully enclosed living space and a terrace covered by a projecting roof? The latter should be significantly cheaper to build than true living space, right? Even if it is structurally connected to the main building as a cantilevered roof extension...
I would greatly appreciate your advice here.
M
Mottenhausen16 Oct 2018 17:50It depends on how closely an architect is involved in the construction process, or if they just spend all day creating beautiful and expensive renderings.
Thank you for your initial comments. I would like to explain a bit more about what we are aiming for.
We are currently considering two concepts:
- Option 1: No roof overhangs or terraces, with 200 sqm (2150 sq ft) of living space, which fits exactly within our budget according to the cost estimate.
- Option 2: 180 sqm (1940 sq ft) of living space, with access from the upper floor to a 40 sqm (430 sq ft) terrace on the south side. This terrace also functions as a structural sunshade for the ground floor. Additionally, the upper floor terrace is covered by a corresponding roof overhang, providing further structural sun protection.
The problem is that option 2 is significantly more expensive, based on the cost estimate, than option 1, because the 40 sqm (430 sq ft) terrace and the volume between the terrace and the roof overhang are fully factored into the cost calculations.
While the costs obviously won't be one-tenth of those for fully enclosed space of the same volume or terrace size, logically, it should not cost the same as fully enclosed space either, right?
We are currently considering two concepts:
- Option 1: No roof overhangs or terraces, with 200 sqm (2150 sq ft) of living space, which fits exactly within our budget according to the cost estimate.
- Option 2: 180 sqm (1940 sq ft) of living space, with access from the upper floor to a 40 sqm (430 sq ft) terrace on the south side. This terrace also functions as a structural sunshade for the ground floor. Additionally, the upper floor terrace is covered by a corresponding roof overhang, providing further structural sun protection.
The problem is that option 2 is significantly more expensive, based on the cost estimate, than option 1, because the 40 sqm (430 sq ft) terrace and the volume between the terrace and the roof overhang are fully factored into the cost calculations.
While the costs obviously won't be one-tenth of those for fully enclosed space of the same volume or terrace size, logically, it should not cost the same as fully enclosed space either, right?
Mottenhausen schrieb:
It depends on how closely an architect is involved with the construction, or if they just spend the whole day designing nice and expensive pictures.But that should be possible to find out...
Pyrate schrieb:
No. 2: 180 sqm (1,938 sq ft) living area, and on the south side I can step out from the upper floor onto a terrace that is 40 sqm (430 sq ft) in total, which at the same time provides structural shading for the ground floor. Additionally, the upper floor terrace is covered by an appropriate roof overhang, which also acts as a structural sunshade.Try to let go of the estimate and the idea that you can somehow convert your design 1 into design 2. Take a different approach...so I understand you correctly (can’t you even share a hand sketch?):
- You have a building with 180 sqm (1,938 sq ft) of floor area. Plus a 40 (!!) sqm (430 sq ft) terrace as a cantilever. So it’s not like the ground floor has 110 sqm (1,184 sq ft) and the upper floor 70 sqm (753 sq ft) with the terrace resulting from that—instead, the terrace is a full cantilever? And this cantilever is fully covered by a roof overhang??? Sorry to say it like this, but no wonder the costs are skyrocketing...
...maybe I’m just too dumb to understand the “structural sunshade” for the ground floor.
Pyrate schrieb:
Number 1 without any roof overhang or terraces, with 200 m² (2,150 sq ft) of living space, which exactly fits our budget according to the cost estimate.This has already been mentioned here. The cost estimate comes with a tolerance of about +/- 30%, or should at most, otherwise you might end up in court later. Nowadays, as a client, I would assume the +30% as a given. So: if your budget barely covers the cost estimate, it’s time to hit the emergency brake.
Just out of curiosity: Did I understand correctly that you basically want to build a 40 m² (430 sq ft) rooftop terrace? That would mean 40 m² (430 sq ft) of covered terrace on the ground floor and 40 m² (430 sq ft) of covered rooftop terrace. So he calculates 80 m² (860 sq ft) of covered terrace, applying their area at a 1:1 ratio based on one quarter of their size for the cost — that doesn’t seem unrealistic to me and also corresponds to the common method of counting terraces at 25% to 50% of their area for living space calculations.
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