Cost estimation for renovation

Hi everyone,

Similar to Altbau1930, we were offered a house relatively cheaply:

1000 sqm plot, 190 sqm living space for ~210,000€

Basically, everything needs to be done; we were with an independent financing advisor yesterday who considered our estimate to be good. But when I see some costs here, I’m a bit afraid of being off. The first craftsmen were there yesterday (electrician and a small construction company for drywall etc.). Our estimates were about 20% above the verbal prices. Offers should come soon.
Roofers, heating engineers, chimney sweeps, and carpenters are scheduled for Friday.
Our own contribution would be chasing slots for electrician and heating engineer (if new pipes are needed for domestic water).
The challenge is an approx. 40 sqm pool extension, which is currently used as a studio with rather shaky timber frame and cheap planks. We would like to put a living/dining room in that space.
We have allocated €10,000 from the flooring costs for that. The rest of the ground floor has real wood floors which were renovated 4-5 years ago and can be used as is. The children's rooms also all have 4-5 year old parquet; only the hallway and kitchen would be fitted with new floors (approx. 40 sqm).
The construction company is supposed to build at least 3 walls, decommission the old chimney, core drill for a new chimney in the living/dining area, and reduce 2 large windows facing the garden (it used to be a 50 sqm living/dining room, and we want 3 rooms there). Doors include a new front door for ~€6500 and several simple interior doors for €300. 2 bathrooms would also need to be completely redone.

Electricity €15,000
Heating €20,000
Construction company €15,000
Floors €15,000
Bathrooms €25,000
Wallpapering/Painting €5,000 (material only)
Roof insulation €7,500
Doors €10,000
Windows €5,000

Are our estimates with €117,500 (we would take €120,000 from the bank) realistic or are we off? An energy consultant for KfW has also been requested; we would take about €35-40,000 from KfW151.

Thank you very much for any input!

Hello Kayser,

an estimate from a distance is always a bit difficult, I realize that myself here. However, 210,000€ purchase price for a house with such renovation effort is quite high. On the other hand, 1000sqm of land is very large, and it also depends on the area.

We have about 520sqm of land, and it is currently priced at 120€/sqm, so pure land value around 63,000€. We pay a total of 100,000€ (partial gift).

Your cost calculation should roughly be correct, but I miss your calculation for the new chimney. Should it be a stainless steel chimney outside? Then you should add at least 5,000€ more, plus (if desired) a stove of about 5,000€ including installation. Also, your 10,000€ for new doors is quite high, or is there an (expensive) front door included?

Also, if it all works out in the end, one should possibly factor a new kitchen and maybe various furniture into the financing, unless you don’t need new ones or have saved the money elsewhere.

One often reads here: add about 20% on top of the cost estimate for old building renovations, because something unforeseen can always come up during the renovation, or you can use the money afterward for outdoor facilities if necessary.

For us, the most important item is the roof, because these costs we currently cannot estimate. In the week after next, a master roofer who is also an energy consultant will come, and then we will get a price indication. If we come to, for example, 50,000€ costs for the roof alone, we will pay correspondingly less for the house, that is agreed.

The roofer should also tell us which new windows harmonize with the future roof insulation: double or triple glazing. Because we definitely want to avoid external insulation, and with triple glazing it can be that the energy regulation also requires external insulation because the windows are too tight and condensation water finds its way through the walls (that’s how I understood it).

We also met with an independent financial advisor, and we are aiming for a total sum of 250,000€. When we have the quote from the roofer and the energy concept, the advisor will run through various financing scenarios, also with KfW Bank and taxes that we will get back later. It is all complex anyway...

Previous cost estimate:

- Electrician: 12,000€ (3 floors each 60sqm, all work including new distribution boxes)

- Windows: 11x partly custom sizes, with new manual shutters: 11,000€

- 2 new bathrooms (we are forgoing bathtubs): 10,000€ with at least 50% own work (demolition and possibly tiling with professional help)

- new interior doors/frames: 2,000€

- possibly new water pipe (still needs to be checked): 4,000€

- 2 new instantaneous water heaters, new standard: 1,100€

- 1 wall breakthrough 2.50m wide: 3,000€ including steel beam

- gift tax: around 20,000€

- materials for own work (drywall, filler, paints, wallpaper, small parts, lamps, machines/tools, floor sandpaper rental, waste container): 8,000€

- cash for helpers: approx. 2,000€

That adds up to 73,000€ so far.

The rest will, as mentioned, be invested in the roof. We want to do everything now; in 5 or 10 years you don’t want to start somewhere again and also have to refinance.

We will only start work earliest at the end of the year anyway. We estimate the conversion time at 4 to 6 months.

We also discussed yesterday that it might be better to involve an architect who can estimate the renovation costs more realistically than we can. That also gives a bit of security. We will see.

Your calculation sounds good. What does not sound good is the issue with the windows again. Even new double-glazed windows are airtight. Moisture settles where the dew point is undershot. If the insulation value of the windows is worse than that of the wall, then it is usually the window first. Otherwise, it can be the walls. However, this depends on the humidity. And that is controlled by the heating and ventilation behavior. Basically, you have it under control yourself. But an energy consultant really makes sense and should know about it.

I'm really curious to hear what the energy expert will say about that!

By the way, I found some benchmark values for drywall work:

- Cladding ceilings with Rigips/Vermacell: approx. €60/sqm complete (substructure/material/installer)

- Cladding sloping roofs with Rigips/Vermacell: €40/sqm complete/as above.

In addition, painting or wallpapering will be added. Here, you can calculate €7 to €10/sqm complete with everything, depending on the requirements for material/quality.

Regards

Floor coverings are still missing from the list, or did I overlook something?

Before such a complete renovation, an inventory/survey should always be carried out, in which the current condition of preservation and the renovation effort are recorded. Any building damages/moisture damage, for example, belong to this and should be remedied before further renovation work. The survey and the subsequent renovation planning with cost estimation are carried out by an architect.

In a renovation without this preliminary work and without renovation planning in the overall context of the building, uncoordinated craft services, unnoticed building damages that only become apparent during the conversion, and structural patchwork must be expected. Building physics errors in insulation measures cannot be ruled out either. Craft companies are not planners.

The building insulation is missing from the list. New windows in an uninsulated 1930s building can lead to condensation on the cold inside of the outer walls if the Uw value of the windows is lower than that of the walls. For heating planning, a heating load calculation and system dimensioning are necessary. This should of course take into account the renovated=insulated condition, otherwise an oversized heat generator will be installed, which will no longer operate economically in the case of any later building insulation and may possibly fail technically earlier.

According to your description, some of the planned shell construction work also possibly involves structurally relevant interventions in the building fabric and is therefore subject to building permit requirements.

The requirements of the Energy Saving Ordinance regarding building insulation and system technology must also be taken into account, e.g. retrofit obligations.

Therefore, it is recommended to commission an architect/building energy consultant with a comprehensive assessment and planning.