ᐅ Living area approximately 8 m² smaller in the permit drawings compared to the design (general contractor)
Created on: 16 Apr 2025 11:23
I
ITSM2025
Hi everyone,
Unfortunately, I thought I was smarter than everyone else here in the forum (I have been a quiet reader for a while) and believed I could rely on the general contractor’s planning. Now, right from the start, things are becoming "interesting." I’m not sure whether my frustration is justified or if this is just standard practice in the construction industry. Here’s the situation:
Based on the preliminary design from the general contractor, we awarded the contract (signed the agreement) with the expectation that the room sizes would match the preliminary design. The house is planned as a KfW 40 energy-efficient building with sand-lime brick, insulation, and brick veneer. This was included in the offer along with additional requests, and the design was adjusted accordingly, if necessary. So, it’s not like the general contractor was unaware of our KfW 40 project. Now we have received the building permit drawings showing roughly 8 m² (86 sq ft) less living space due to suddenly thicker walls, both external and internal. The exterior walls were increased from 42.5 cm (17 inches) to 49 cm (19 inches) thickness. And this was done inward, not outward. In other words, each side has lost 6.5 cm (2.5 inches) of interior living space. Calculated in euros, that’s about €22,000 less living area based on the price per square meter. Or, in other words: the general contractor now has to buy fewer sand-lime bricks and build with less material, with less plastering, tiling, screed, underfloor heating, pipes, etc. However, there was no price reduction.
Is this common practice? Should one accept something like this?
Additionally, the attic floor has lost 13 cm (5 inches) in width and 6.5 cm (2.5 inches) of interior height due to the knee wall being shifted further inward. We had planned to convert this space later, which now seems hardly worthwhile. The general contractor knew about this in advance and even planned wiring and such in the attic/roof space.
How do you assess this situation, and how would you proceed?
Thank you very much in advance!
Unfortunately, I thought I was smarter than everyone else here in the forum (I have been a quiet reader for a while) and believed I could rely on the general contractor’s planning. Now, right from the start, things are becoming "interesting." I’m not sure whether my frustration is justified or if this is just standard practice in the construction industry. Here’s the situation:
Based on the preliminary design from the general contractor, we awarded the contract (signed the agreement) with the expectation that the room sizes would match the preliminary design. The house is planned as a KfW 40 energy-efficient building with sand-lime brick, insulation, and brick veneer. This was included in the offer along with additional requests, and the design was adjusted accordingly, if necessary. So, it’s not like the general contractor was unaware of our KfW 40 project. Now we have received the building permit drawings showing roughly 8 m² (86 sq ft) less living space due to suddenly thicker walls, both external and internal. The exterior walls were increased from 42.5 cm (17 inches) to 49 cm (19 inches) thickness. And this was done inward, not outward. In other words, each side has lost 6.5 cm (2.5 inches) of interior living space. Calculated in euros, that’s about €22,000 less living area based on the price per square meter. Or, in other words: the general contractor now has to buy fewer sand-lime bricks and build with less material, with less plastering, tiling, screed, underfloor heating, pipes, etc. However, there was no price reduction.
Is this common practice? Should one accept something like this?
Additionally, the attic floor has lost 13 cm (5 inches) in width and 6.5 cm (2.5 inches) of interior height due to the knee wall being shifted further inward. We had planned to convert this space later, which now seems hardly worthwhile. The general contractor knew about this in advance and even planned wiring and such in the attic/roof space.
How do you assess this situation, and how would you proceed?
Thank you very much in advance!
ypg schrieb:
However, the section in the scope of work regarding wall thicknesses and energy standards is actually missing now.Here you go:
Exterior walls – double shell – facing masonry:
(Optional feature upon agreement)
The wall structure consists of:
• Inner layer of aerated concrete, highly insulating, λ = 0.13 W/m² · K, thickness = 17.5 cm (7 inches), with approximately 1.5 cm (0.6 inches) of lime-cement plaster, projecting corners with corner protection profiles
• 2 layers of high-quality cavity insulation WLG 035: thickness according to thermal protection verification
• Outer layer: facing bricks VMz, price category: up to €800.00 per thousand including VAT, delivered to construction site, format: NF, thickness = 10 – 11.5 cm (4 – 4.5 inches), laid with lime-cement mortar, brushed out, cleaned, and pointed with cement mortar, expansion joints with silicone at the corners of the house / not maintenance-free, window and door lintels: “Grenadier” facing brick lintels, cantilevered
Optionally: decorative masonry in the facing layer is possible (special service according to written offer/order)
• Horizontal and vertical moisture barriers according to base detail
• The base area must be protected against construction moisture before paving begins using a thick coating or a studded membrane with fleece, provided by the builder. Our external waterproofing ends at approx. –0.20 m (–0.7 ft) from the finished floor level; the remainder is the builder’s responsibility during paving
• Note: When choosing facing bricks with a rough, fired surface, the joint mortar may fill in the rough texture during pointing. This is not a defect.
____________________________________
ITSM2025 schrieb:
Here you go:
Exterior walls – double-layer – facing masonry:
(Optional upgrade subject to agreement)
The wall construction is as follows:
• Inner leaf made of aerated concrete, highly insulating, λ = 0.13 W/m²·K, thickness = 17.5 cm (7 inches), with approximately 1.5 cm (0.6 inches) lime-cement plaster, protruding corners protected with corner beads
• 2 layers of high-quality cavity insulation WLG 035: thickness according to thermal insulation certificate
• Outer leaf: facing bricks VMz, price category: up to €800.00 including VAT, delivered to construction site, format: NF, thickness = 10–11.5 cm (4–4.5 inches), laid with lime-cement mortar, raked joints, cleaned and repointed with cement mortar; expansion joints with silicone at building corners / not maintenance-free; window and door lintels: “Grenadier” facing brick lintels, spanning without support
Optional: decorative brickwork in the facing layer available (special service according to written offer/order)
• Horizontal and vertical damp-proof membranes see base detail
• The base area must be protected on site against construction moisture before paving begins with a thick coating or dimpled membrane with fleece. Our external waterproofing ends approximately 0.20 m (8 inches) below finished floor level; the remainder must be completed on site as part of the paving work
• Note: When choosing facing bricks with a rough, burnt surface, the jointing mortar can fill the rough texture. This is not a defect.
____________________________________ And here is an excerpt from the contract regarding KSL.
1 piece of inner leaf of the exterior masonry, thickness = 17.5 cm (7 inches), made from KSL stone, RDK 1.8,
to be provided as an addition instead of aerated concrete.
ITSM2025 schrieb:
And here is an excerpt from the contract regarding the lightweight concrete blocks (KSL).
1 piece of inner leaf of the external wall, thickness = 17.5 cm (7 inches), made from KSL blocks, thermal conductivity coefficient 1.8,
to be produced as an additional cost instead of aerated concrete. And here is this from the offer:
The basics are:
- VOB – Part B + C, latest version (available for review with us)
- Construction specification: Classic December 2024 (primary over drawings)
- Construction drawings: ground floor, upper floor, roof plan, and elevations
- Building Energy Act (Gebäudeenergiegesetz)
K a t j a schrieb:
In my opinion, any extension must always be built outward, if only because otherwise all other dimensions no longer fit, such as stair riser height, door widths, distances between walls, or even closet dimensions. If the structural engineering calculations have already been completed, that can be the better approach (to maintain the dimensions of the ceiling panels).
ITSM2025 schrieb:
And if it can only be done at significant additional cost, then please have him compensate by increasing the gable and knee wall height by 6.5 cm (3 inches). With the floor plan and area, that would work for us. My main point here is that we decided to sign the contract based on the floor plan and agreed price. We are also paying the additional 14,000 € for KfW 40 to properly equip the house. [ / ]
And here is an excerpt from the contract regarding the aerated concrete blocks (KSL).
One piece of inner leaf of the external masonry wall d = 17.5 cm (7 inches), made of KSL block, RDK 1.8, instead of aerated concrete, to be manufactured as an add-on. Why are you hesitant to simply (re)change the wall element?
ITSM2025 schrieb:
I will report back in a week on what comes of it. I doubt there will be a good agreement, but we’ll see. What causes your doubt, especially considering the cross gable change works in your favor?
ITSM2025 schrieb:
Outer leaf: facing bricks VMz, price category: up to €800 (approximately USD 860) including VAT, delivered to site, format: NF, thickness = 10 – 11.5 cm (4 – 4.5 inches), laid with lime-cement mortar, struck out, cleaned, and jointed with cement mortar, with expansion joint silicone on house corners / not maintenance-free, If the facing bricks have format NF, the thickness is not “10 – 11.5 cm” (4 – 4.5 inches), but “11.5 cm” (4.5 inches).
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11ant schrieb:
If the structural calculations are already done, this might be the better option (to maintain the dimensions of the ceiling panels).
Why are you hesitant to simply switch back the wall element?
Where does the doubt come from, considering the change to the cross gable in your favor?
If the facing brick is NF format, then d is not "10 - 11.5 cm (4 - 4.5 inches)", but "11.5 cm (4.5 inches)". I want to use aerated concrete blocks because of the sound insulation, which we unfortunately need at our location.
I can hardly imagine it without a major discussion. If it’s already starting this way, I suppose we shouldn’t shy away from discussions and just see how it goes.
A different question: does anyone have an idea why the right side of the garage wall is thicker than the left? On the left it’s 11.5 cm (4.5 inches) aerated concrete blocks, and on the right it should also be 11.5 cm (4.5 inches) including the 11.5 cm (4.5 inches) facing brick, right? Something doesn’t add up here again.
ITSM2025 schrieb:
Just a different question: does anyone have an idea why the right side of the garage wall is thicker than the left? The left side is made of 11.5cm (4.5 inches) calcium silicate blocks, and the right side should also be 11.5cm (4.5 inches), including 11.5cm (4.5 inches) facing bricks? Something doesn’t add up here.Right side: 11.5cm (4.5 inches) calcium silicate block + cavity + 11.5cm (4.5 inches) facing brick = 26cm (10 inches)
Left side: this is basically the exterior wall of the house. Instead of brick facing, just 11.5cm (4.5 inches) calcium silicate block is used.
What would you have expected here?
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