We are standing in the finished shell, happy about every plastered wall, every new insulation board, and every cable protruding from the walls. But while the house is visibly growing, costs are also growing in parallel, and more than expected. Time for an interim balance.
The completion of the shell marks the end of the largest construction phase. It was already clear since the shell construction work was commissioned that it would be more expensive than estimated. But this isn't the only point where the estimate differs from reality.
House Construction Cost Estimation: Where Planning and Reality Diverge
Estimates remain empirical values. They help to get an idea of the total budget. However, they are no more than a rough orientation. Homeowners should never make the mistake of relying exclusively on these figures.
A realistic comparison is only possible once several quotes have been obtained. The reasons are simple: rising material costs, the workload of the companies, and also regional price differences influence the construction costs of every building project.
Shell Construction and Earthworks: Our Biggest Price Jump
Right at the start of construction, we hit the first setback: the quotes for the shell, sewage, and earthworks were significantly above the plan. And now? There aren't many ways to reduce costs here. While you can counteract high costs in plumbing, flooring, or electronics by adjusting material and scope, this is hardly possible with the shell. The only option: replanning the floor plan, area, and statics.
With a price difference of nearly +25% between the estimate and the quote, our only choice was to go back to the planning stage. Fortunately, our architect found a solution to simplify the statics and insulation, which could be integrated inconspicuously into our existing floor plan. Nevertheless, the costs remained above the original estimate.
The price jump in our shell construction shows the influence individual circumstances have on costs. Our architects usually work in regions with high construction activity where many companies compete for contracts. In our building area, there are only a few providers for shell construction work. Additionally, most new houses nowadays are prefabricated houses, so construction companies are reducing their capacity for single-family homes. When they submit a quote, they calculate the price so that the effort is worthwhile for them.
In 2024, the cost estimate for earthworks, shell construction, and the interior staircase was €265,000. Two companies were considered for the contract, with their quotes differing by only a few hundred euros. We ultimately chose a contractor whose initial bid was €293,365 – however, the final costs now stand at €283,000.
Interior and Exterior Plastering: High Prices Despite Many Quotes
We also had trouble finding an affordable company for interior plaster, exterior plaster, external thermal insulation composite systems, and the facade in the region. Despite many quotes, prices remained above the estimate. In the end, these works also turned out more expensive than planned.
The estimate for these two items was €73,500. After deducting discounts and early payment rebates, the cost increases here are still quite moderate—totaling €74,700.
Wooden Facade Cladding: Additional Costs for Aesthetics
The facade cladding is purely a design element. This was important to us from the start, and that's why we were willing to spend money: specifically, 7,000 euros were planned. The quotes we received were more than twice as much.
We didn't want to do without it and looked for ways to reduce costs together with our architect. Originally, the house was supposed to be clad with wooden slats from the street side in the west to half of the south side. We decided to only clad the street side and stop at the corner. This way, the wood look still has an effect, while it would have been barely visible on the south side. Additionally, we switched from the originally intended Accoya wood to glazed spruce.
Of course, we could have skipped it entirely and saved the most. However, that would have meant giving up a central design element of our house. For us, the wooden facade gives the house its character; without it, something essential would be missing.
Steel Exterior Staircase: Costs and Planning of Metalwork
When even the standard model is significantly above the estimate, there is little room to save. That was exactly the case with our exterior staircase. All quotes were above the calculation. Surprisingly, the custom-designed railing made hardly any difference in price. For once, we could choose the more beautiful look without a guilty conscience.
Here, too, at €17,000, we were well above the budgeted costs of €12,000.
The Biggest Cost Driver: The Homeowners Themselves
The most expensive decisions are not made on the construction site, but in the showroom. We would have liked to say that only rising material prices are to blame. The truth is: we caused many of the additional costs ourselves.
Whether flooring, light switches, or kitchen cabinets: you compare materials, feel the surfaces, and see the difference in quality. In a direct comparison, it’s hard to choose the cheapest option. When is saving sensible? And when would you regret in hindsight not having chosen the higher-quality product after all?
Here are the items where we couldn't say "no," even though it would have worked more cheaply:
Electrical Work in House Construction: How Additional Requests Change Costs
Even small things add up. With the first quote, we were still within budget for the electrical work. But as the electrical planning became more specific, more points were added that seemed sensible and drove the price up bit by bit.
- Light switches: After the electrician showed us the various switch ranges and their colors, we switched from the "Standard" Busch-Jaeger Balance model to Busch-Jaeger future linear. The surcharge here was about €600.
- Sockets: In some places, we had deep sockets installed, as well as separate supply lines to the sub-distribution board. This keeps the option open for us to retrofit smart home actuators ourselves later.
- Roof heating: It wasn't originally planned. However, it is necessary to prevent water from freezing in the gutter.
- Media channel: A media channel was to be integrated into the TV wall in the living room so that cables could be laid invisibly later.
- Motion detectors: For more comfort and safety, controllable motion detectors are being installed in the outdoor area.
Each point viewed individually has little impact on the budget. But many small items quickly turn into large sums. While we were initially fully on budget with the electrical work, our extra requests ended up costing an additional €3,000.
Glass Stair Railing: A Costly Extra
In the cost estimate, the material for the interior staircase railing and the void was not specified. Only during the detailed planning did we decide on a glass railing. This allows light from the upper floor to fall unobstructed into the lower floor.
In principle, this would also have been possible with a metal railing. Visually, however, we liked glass better, so in the end, we consciously chose the more expensive option.
Instead of the originally planned €4,500 for a metal railing from the locksmith, we are now at €9,640 for a glass railing.
Windows and Front Door: Why We Deviated from the Standard
Plastic windows – we wanted to save with them, the one item that stays predictably under budget. With the first quotes, it became clear: that's not going to happen.
Even for the plastic windows, the quotes for the window construction work were significantly higher than the estimated price. However, the quote for the higher-quality wood-aluminum windows was cheaper than expected. And so the difference between the two variants was surprisingly small: the wood-aluminum windows were 10,000 euros more expensive than the plastic variants, totaling only about 6,000 euros over budget after the discount.
Rarely was it so easy to decide on an upgrade. Besides the small surcharge, there was another point: in the detailed plans, we saw that the profiles of the plastic windows for our corner glazing would have been a good three times wider than for wood-aluminum. That would have lost exactly the design element we liked so much about the draft. In this case, we might as well have scrapped the corner glazing and executed the corner more simply and cheaply in reinforced concrete or masonry.
Cheaper Than Expected: Where We Were Able to Save Costs
Not all quotes were above the estimate. There were also positive surprises with some trades: they became cheaper without us having to cut services or compromise on quality.
With the photovoltaic system, we benefited primarily from market developments: since 2024, prices for PV modules have fallen. Additionally, we decided against a battery storage system for now. We want to retrofit this at a later date.
The garage door is also cheaper than assumed in the cost estimate. And that's without any changes to size, features, or appearance.
It was similar with the sanitary objects and the ventilation system. Here, too, the final quotes were below the estimate.
These items show: cost estimates can deviate in both directions. But even if individual items turn out to be cheaper, in total, it usually ends up being more expensive than originally estimated.
Summary
Currently, we are about 7 % over the original budget. This shows once again: when building a house, you should always plan for price increases and never max out the budget completely. Especially at the beginning, a few hundred euros more here and there seem harmless. In total, however, they make a big difference.
If the budget is exhausted, refinancing can be a solution. However, one should keep in mind that increased interest rates can make financing more expensive. This not only means a higher monthly burden but can also delay construction or lead to individual trades only being completed after moving in, once money is available again.
Therefore, plan for buffer space deliberately and calculate conservatively. It was exactly this buffer that ultimately gave us the necessary peace of mind.
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