Cost estimation for interior finishing, any experiences?

Were all individual prices for the trades listed for you?

That is exactly my current problem. I was given prices, but only total prices without price details for individual trades. I can get those too, but I have to sign something and pay first. However, I would like to know in advance what I am paying for.

Elsewhere I just read that, unlike a general contractor, an architect is not allowed to offer a fixed price. I don’t quite understand that yet. I go to the architect with my idea, who makes a concrete plan. Do I already get a cost estimate then? Let’s say roughly, then he awards the trades and realizes, oh, everything costs twice as much?! Of course, that wouldn’t be a good architect if he miscalculates like that, but the risk exists. I understand that you can’t fix all prices 100% in advance, but most should be known BEFORE signing any contract. I don’t want to pay double later than I initially thought... Why is an architect not allowed to offer fixed prices? He must also present some reasonable calculation before building begins.

Yes, very good.
Well informed is half built.
And you then live on a property where your children can climb a 10m high pile of earth? Surely part of it will be stored on the site (if suitable for that) for refilling and the rest? Exactly the amount of your cellar?

If I worked in a job where everyone finds out the price through an internet inquiry, I wouldn't have a house now!

And still, what does that help you? I believe many people who approach it like you forget that much is a mixed calculation and secondly, the price must also cover a warranty!

For me, it is much more interesting what price stands as the final price for everything, whether the socket costs 50 or 100€... it's about an overall package!

If you quote me, why do you leave out "alle"? Don’t all costs occur for you?

I left all that out because, as with house construction, not all costs can be calculated in advance. But some certainly can.

Just a different question, since we have already progressed so far in the discussion. Let’s say you have a shell house built by a general contractor and do the rest together with an (interior) architect. How does that work, for example, with the underfloor heating? Pipes have to be laid for that. If the whole house already stands as a shell house, plans must already exist showing where pipes should go, where windows should be, doors, etc., so a pure shell house actually doesn’t make much sense, right? I assume heating pipes have to be laid before everything is finished up to the roof in terms of construction, don’t they?

If I really gauge you now, you want the most precise planning certainty possible, right? Have you already thought about a prefabricated house? We wanted two things: the best possible planning certainty and the shortest possible construction time. We got that from our prefabricated house provider (timber frame construction). Before we signed the contract, we negotiated as much as possible into it and gave ourselves a 10,000 buffer for "Upgrades." These mainly concern the interior fittings, such as bathrooms, number of sockets, and blinds. The standard that the house provider offers is "adequately good," not the cheapest, but no eye-catchers. All brand-name products. So we can possibly save money here, if necessary. The biggest unknown was always the earthworks part. That caught us off guard. But no surprises from the house company so far, and you know relatively early on what the house will cost you in the end. Planning-wise, almost everything is possible, it’s all a question of money. But here, too, you find out the exact price before giving up a right of withdrawal. Our house was 190,000 in the basic version with 140 sqm. Then we added controlled residential ventilation, a wood stove, and a bay window and are now at 215,000. That already includes all floor plan changes. That will be the total cost of our house. The only unknown is the selection of fittings. Here we could spend a lot of money. But it’s in our hands. Just as a suggestion: good wooden prefabricated houses hardly differ from solid houses. Our provider installs massive wooden panels behind the drywall, so you can hang every cabinet on them with a simple 3.5 cm Spax screw. I think I can sell my drill. Maybe you can take this as a suggestion. I can name our provider in a PM if you like.

Hello Chris,

A single-family house is to be built in Brandenburg (near Berlin) with a built-up area of 11.7m*10.37m including a basement with a white tank. Construction style is solid with a high-quality clinker facade (which has a distinctive color and is not in "standard brick red"). In terms of energy measures, besides the solid double-shell construction with good insulation (e.g. mineral fiber) and correspondingly insulated roof, basement/floor slab and windows, only a geothermal heat pump will be used, which is excellently suited for the region (constant annual temperature > 10 °C already from 25m depth).

So about 200 sqm living space plus a basement as a white tank. The base price of the single-family house should be around EUR 350k plus costs for the geothermal heat pump, the plot, personal extras, as well as ancillary construction costs amounting to EUR 35k (only if the plot is actually uncritical; otherwise about EUR 10k more).

We also do not want a room ventilation system or the like because we have all found them disturbing and noisy so far (including the one in our current rental apartment), at least I do, my fiancée is not quite as sensitive.

You should discuss the topic of ventilation again in a joint conversation with an energy consultant – there are excellent ones, for example at the energy agencies of the federal states. Besides a high comfort gain, it primarily ensures the permanent exclusion of mold bacteria; if you both work full-time and therefore have no opportunity to ventilate thoroughly at least 3 times a day, there is no alternative. These devices also do not produce “noise” if the system itself is not a cheap product and secondly is installed and adjusted by a specialist company. Costs range – depending on the provider – between EUR 7k and 9k including installation.

A different question, since we have come so far in the discussion. Let’s say you have a shell house built by a general contractor and do the rest together with an (interior) architect. How is it then, for example, with the underfloor heating? Pipes have to be laid for that. If the whole house already stands as a shell house, plans must already exist beforehand where pipes should go, where windows, doors, etc., should go; in that case a pure shell house doesn’t really make sense, right? I think you have to lay heating pipes before the construction is complete all the way to the roof, right?

A “shell house” is nothing other than an enclosed building envelope: bricks plus cladding, roof truss including roofing, windows and front door.

A building application must also be submitted for a shell house and part of this application is the drainage planning; without this you will not get a building permit. If you hand over this part to a general contractor/building contractor (GU/BU), their work ends at this point.

Of course, you then still have to coordinate the interior finishing, for which execution planning is required. That means for you, you either have to make an appropriate agreement with the aforementioned GU/BU to provide this service or find another architect who will create this planning for you. The latter option would, in my opinion, be the wiser choice, as this additional architect can also assist you with the tendering and subsequent cost control. However, with this model you have to be aware that you will effectively pay for architectural services twice.

Best regards

So a base price of 350,000 EUR is too high. For example, I have an offer for a turnkey house with 180 m² including a basement without a white bathtub for 260,000 EUR. Of course, quite a bit will be added to that, but 90,000 EUR are still missing. However, that is not dramatic, I will simply draw the floor plan I sketched with Revit smaller, I already know where the space will be "stolen" from. Thanks anyway for the cost estimate.

As for the ventilation ... yes, that is currently a main topic of discussion with us. I have not yet encountered a silent one even in show houses (where I think they make an extra effort to sell their services). The no-mold argument is heard most frequently. However, I must also say that my father has had a solid house (36.5 exterior wall, I don't know the exact composition) for over 20 years and does not ventilate nearly three times a day. However, mold inside or algae outside (the house is plastered) have yet to appear. The heating consumption (unfortunately I have no idea about the theoretical requirement, but it is probably quite high) is just below the 2009 energy saving ordinance level. Additionally, we were told that with a ventilation system you can no longer open the windows, or rather should no longer ventilate through the windows, and we definitely do not want that. For example, in our current apartment, we completely turn off the heating in summer and always keep some windows tilted. Of course, energy is lost with tilted windows, but a turned-off heating system does not consume much. As you rightly say, we will get professional advice from an energy consultant again. ​Thanks for the clarification about what a shell house is. I thought doors and windows were missing too, meaning it is only a brick shell. One option that I think I would like (of course, it depends on what it costs) would be planning by the architect, execution by a general contractor (so you don't have to deal with dozens of individual craftsmen, but only one construction company), and supervision by the architect. However, as far as I have seen, the tendering of trades is a relatively small item in the HOAI, so that option could be too expensive.