Good morning Sirooris,
About ~1.5 years ago, we faced the same questions when we decided to purchase a single-story fully basemented house with 120 sqm from 1971 in our desired location in the Rhine-Main area. Our plan was from the outset to completely overhaul the house and redo everything, including major changes to the floor plan + doubling the living space by building a knee wall.
We planned a lot of DIY work, but still commissioned the crucial trades, such as: new solid construction floor, roof structure / roof, gas-water-bath, windows, from specialist companies.
To give some orientation about the prices, I am writing below on your list what costs we encountered as far as we have already gone or have offers for.
- Insulation of walls, basement and roof
Basement exterior insulation (bitumen and studded membrane), drainage, inspection shaft with excavator work 7,000€.
Basement ceiling insulation material for 120 sqm costs about 2,500-3,000€, we will do this as DIY at the end or after moving in. Exterior wall insulation
- New roof covering
Dismantling the old roof + roof structure took 1 Saturday with 5 people, 2,000€ disposal (however with gables).
New roof structure + roof including 4 roof windows with electric shutters 46,000€
- Heating replacement
Removal of the old oil tank by a specialist company cost 1,200€.
Dismantling the old heating system took 3 hours of DIY with 2 men.
New gas condensing boiler with solar and underfloor heating in a dry construction system (necessary due to existing floor build-up height) and completely new pipelines + second heating circuit for towel warmers in the bathrooms as well as new water pipes cost 48,000€
- Pipeline replacement
Is included in the heating position.
- Electrical system renewal
Is completely installed DIY, costs an incredible amount of time: preparation by reading in and execution. Upstairs is going faster now because I have some practice. New fuse box connection as well as later connecting the cables is done by a friendly master electrician (who thankfully checks my DIY work), so the price is not representative. However, I am already at about 10,000€ including switch program for the materials.
- Radiator replacement or better yet: installing underfloor heating
Heating is included above. The underfloor heating in the dry construction system costs about 19,000€ + 2,000€ for insulation and 5,000€ for the dry screed on then almost 240 sqm floor area. The 19,000€ is included above so here only +7,000€ to get the floor ready for covering.
- New stairs
We had a concrete staircase poured on site which is quite cheap at 2,500€. However, it needs some post-treatment, so about 3,000€ in the end. Railing and handrail are drywall in our case; the handrail is covered with Nero Assoluto as are the window sills and kitchen countertop. The marble costs 700€.
- New windows
All windows new and with electric shutters including a large lift-slide door and aluminum front door and basement window cost us about 30,000-35,000€. According to the offer it was 28,000€ without the basement windows, I only have a partial invoice, not the final bill yet.
Electric garage door with remote control about 2,000€
- Installing electric shutters
- New doors
About 200-300€ per door with frame
- New front door
Is included in the window price. Ours is completely anthracite with 2 x 80 cm wide light shafts left and right and costs about 3,000€ according to the offer.
- New bathrooms
We were at the selection appointment 2 weeks ago and are still waiting for the offer. A reference from the same selection house and an equally expensive local installer is from the family at 20,000€, since we have somewhat larger showers and a bathtub, I better calculate 30,000€.
- New plaster on the house
I am still waiting for an offer; according to the architect's estimate 25,000€ including exterior insulation. I estimate it will cost more with insulation.
- New exterior paint
Included in the plastering
- Moving/removal of possibly load-bearing walls to create larger rooms
This cost us the most DIY time on the ground floor. The entire demolition, reconstruction, inserting steel beams, partly re-bricking etc. took about 6 months with about 20 working hours per week. Most costs were for disposal (this also includes removal of asphalt screed etc.).
Disposal: about 10,000€, I haven't calculated it exactly
Reconstruction material: 5,000€
- Attic conversion
Building up knee wall 1.20m + gable and load-bearing interior walls and chimney 37,000€
Non-load-bearing interior walls made of drywall, under-rafter insulation of the roof, knee wall out of insulated OSB, all covered with OSB and drywall as plaster for the ground floor cost (material only) 6,000€.
DIY working time 150 hours.
Additional costs included construction site setup with crane and scaffolding ~7,000€ for 5 weeks
Architect phases 1-4: 6,000€
Structural engineer: 2,500€
Building permit: 800€
Construction management is in the hands of my grandfather, a civil engineer, so free of charge. The architect would have charged 10,000€ for that.
Building up knee wall 1.20m + gable and load-bearing interior walls and chimney 37,000€
What? That's exactly what lies ahead of us as well. May I ask what makes the presumably manageable masonry work so expensive?