Excavate from basement or not?

[Kalinikus]

Like so many others, we have decided to renovate the basement in our 1920s house and are seeking some advice.

Background: We plan to demolish the old boiler room and create a laundry room (approx. 15m2). The adjacent room, which is the current laundry room (approx. 20m), we intend to convert into a guest room/rec room with a solid pine floor that was leftover from another renovation. (Wood flooring is a must according to my partner).

We are trying to save money and are considering skipping the demolition of the current laundry room and laying wood flooring on the existing slab instead. Thick wood floors are not the best for underfloor heating and provide a softer warmth even without underfloor heating.

Having read through various threads and recommendations, we are considering the following: Technical solution without pouring a new slab: concrete | Platon | chipboard | screwed wooden floor. I assume we should also install or prepare for an active fan to ventilate the floor. Then we need to remove the old drain and roughly pour/self-level to even out the floor, which currently slopes towards the drain in the entire room.

However, Platon installation is not cheap or simple, and we're thinking it might actually be cheaper to demolish this area as well. It would then, for example, be profitable to use a concrete mixer truck instead of mixing by hand. We received a quote of about 35,000 SEK to demolish and pour with underfloor heating (+ materials for concrete/insulation/reinforcement) in the current laundry room.

Technical solution with a new base slab and underfloor heating: concrete | adhesive with moisture barrier | wooden floor (or vapor barrier + chipboard and then screw).

Alternatively, we could demolish and lay a new slab without underfloor heating and save 16,000 SEK. But that feels a bit pointless when we've already demolished. The benefit of demolishing is also better ceiling height in the guest room, which is already 5cm lower than the boiler room due to the higher floor level.

Is there a flaw in the technical solutions?
Long-term/short-term recommendations?
Anything I've missed?
Reflections?
Am I thinking correctly with the materials for the rec room roughly as below if I'm to compare the costs that it might be about the same?

Pouring:
- Polystyrene . 50 SEK/sqm
- Macadam . 1000 SEK
- Reinforcement . 100 SEK/sqm
- Concrete mixer truck . 9000 SEK/2 (approx. half a truck per room)
- Moisture barrier, etc. 1000 SEK
= approx. 9,000 SEK

Platon solution:
- Platon mat 2500 SEK
- Joint tape 2000 SEK
- Edging 1000 SEK
- A few bags of rough concrete 200 SEK
- self-leveling compound 2000 SEK
= approx. 8,000 SEK

Thank you in advance for your wise advice ☺️

 

[oscarwww]

Have you started chiseling yet? Or hired a company?

 

[Kalinikus]

Have you started demolishing yet? Or hired a company?

It's full speed ahead! After some chaotic dusty demolishing & sanding that covered half the house in dust, we are almost ready for the concrete truck!

All walls were sanded down to remove as much paint as possible. Then most of them were plastered. Some will have inner walls with wet room boards to enclose pipes, etc. The guys managed to demolish/break away some stones that were sticking out really well so the floor level is completely fine. We had to compromise on the insulation so it's only 5 cm in some small areas, but otherwise, it's consistently 10 cm. Nice for the guest room, which is now about 5-10 cm higher in the ceiling.

A bit uncertain about the concrete now since they wanted me to order it from a concrete company and just say "basement concrete." Does anyone have any good tips or will it resolve itself in conversation with the concrete company? Tips on concrete companies in the Stockholm area would also be appreciated ☺️

Thanks in advance