How much time/money to break away concrete

[DarrenB]

We have a current concrete patio, adjacent to the living room, where we plan to build a winterized conservatory, but we want to chisel out the concrete foundation to be able to insulate and lay underfloor heating and the conservatory over it (Alu-pulpit with glass/glass roof from Willab).
This is to ensure that the living room floor and the conservatory floor are on the same level.

A few questions:

1. The current concrete foundation is 80 cm high from the ground. How much do I need to chisel away to make room for insulation, underfloor heating, screed, surface layer, etc.? Do I need to build 20-30 cm high if I already have such a thick concrete slab?

2. Approximately how long will it take to chisel away 400x300x20 cm of concrete, including any reinforcement?

3. Approximate cost of the work if contracted out (within Sthlm)?

 

[Per i Hamrånge]

I have a current concrete patio, adjacent to the living room, we are going to build an insulated sunroom on but want to break out the concrete foundation to be able to insulate and install underfloor heating and the sunroom on it (Alu pulpit with glass/glass roof from Willab). This is so the living room floor and the sunroom floor will be on the same level.

A few questions:

1. The current concrete foundation is 80cm high from the ground. How much do I need to break away to make space for insulation, underfloor heating, floating, surface layer, etc.? Do I need to build 20-30cm high if I already have such a thick concrete slab?

2. Approximately how long does it take to break away 400x300x20 cm of the concrete, including any reinforcement?

3. Approximate cost of the work if outsourced (Within Sthlm)?

I can't imagine it's a slab that's 80cm of homogeneous concrete. It must be a slab that is cast on something (gravel?). This slab might be 10-20cm thick. So when you break it away, you will have solved the problem. Make a test hole first so you know what's underneath and how thick it is.

 

[DarrenB]

I can't imagine it's a slab that is 80cm of homogeneous concrete. It must be a slab that is cast on something (gravel?). This slab could be 10-20cm thick. So when you break it away, you will have solved the problem. Make a test hole first so you know what's underneath and how thick it is.

Yes. It's a concrete block. It is a former garage ramp made of concrete which has then been cast over to create a concrete terrace.

 

[Per i Hamrånge]

Yes. It is a concrete block. It is a former concrete garage ramp that has been cast over to create a concrete patio.

Yes, then it becomes tedious. I have no idea what it would cost. Either you rent a demolition hammer and wear yourself out, or you open your wallet and hire a company with proper equipment.

I have used a rental demolition hammer to break up a 4x2m 0.3m thick slab. It's doable but taxing. It took a few days. Whether it is feasible to just shave off 20cm from your 80cm slab, I don't know. But a demolition hammer is not exactly a precision instrument. It might just as well end up removing twice as much.

Also, keep in mind that there will be a lot of concrete rubble to handle. Disposal can cost money.

 

[hempularen]

If it really is homogeneous, but it sounds very strange. Even a ramp is not cast homogeneous. So I would guess that the right method is a demolition machine. A chiseling machine mounted on a small excavator.

One might possibly consider if it would be better with diamond sawing. Like sawing 20 cm deep cuts in a grid and chipping away the cubes.

Guessing 20 - 60,000. And on top of that a transport cost and tipping fee.

 

[leby]

Got 2 retaining walls removed, they were about 5 meters long and on average 1.2 meters high, about 30 cm thick. A 6-ton excavator with a demolition hammer reduced them to "gravel" in about 2-3 hours. May have cost around 5000 ca.

 

[Prodigys]

If it really is homogeneous, but that sounds very strange. Even a ramp is not cast homogeneous. So I would guess that the right method is a demolition machine. A chipping machine mounted on a small excavator.

One might possibly consider whether it gets better with diamond sawing. Like sawing 20 cm deep cuts in a grid and breaking away the cubes.

Guessing 20 - 60,000. And on top of that a transport cost and tipping fee.

If you're going to saw, just rent a floor saw and fix the grid over a weekend.