ᐅ Pouring concrete on a concrete slab (rammed concrete), raising the basement
Created on: 4 Nov 2024 08:56
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OzCi1305Hello everyone,
I am currently renovating my house.
The house is built on a strip foundation, and the basement floor is made of rammed concrete.
In the basement, one room is about 7 cm (3 inches) lower than the other rooms.
The goal is to bring all the rooms to the same level.
My screed installer advised me to first level that room with concrete before installing the insulation panels.
Now, my question regarding the procedure:
Can I simply lay steel reinforcement mesh on the floor and then pour the concrete?
Or should a vapor barrier or something similar be installed underneath first?
If I lay down the steel mesh, how much overlap should I have between the mesh sections?
I am currently renovating my house.
The house is built on a strip foundation, and the basement floor is made of rammed concrete.
In the basement, one room is about 7 cm (3 inches) lower than the other rooms.
The goal is to bring all the rooms to the same level.
My screed installer advised me to first level that room with concrete before installing the insulation panels.
Now, my question regarding the procedure:
Can I simply lay steel reinforcement mesh on the floor and then pour the concrete?
Or should a vapor barrier or something similar be installed underneath first?
If I lay down the steel mesh, how much overlap should I have between the mesh sections?
B
Buchsbaum0664 Nov 2024 11:36How large is the room?
Are the foundations dry, or is moisture rising through them?
Is there a damp smell in the basement?
Is there waterproofing between the concrete and the foundation?
Are empty conduits planned to be installed, and is everything needed already in the ground?
You can’t just lay a steel mesh and pour concrete over it.
I would install a layer of bitumen damp-proof membrane on the bottom, then a construction foil layer that extends up along the walls.
Use spacers for the steel reinforcement and place wire mesh panels on top. Edge insulation strips are essential around the perimeter. The concrete slab must not be connected to the foundation or the wall—it needs to be able to move independently.
Then pour the concrete. It’s not rocket science. Possibly include electrical or plumbing lines within the slab as well.
Are the foundations dry, or is moisture rising through them?
Is there a damp smell in the basement?
Is there waterproofing between the concrete and the foundation?
Are empty conduits planned to be installed, and is everything needed already in the ground?
You can’t just lay a steel mesh and pour concrete over it.
I would install a layer of bitumen damp-proof membrane on the bottom, then a construction foil layer that extends up along the walls.
Use spacers for the steel reinforcement and place wire mesh panels on top. Edge insulation strips are essential around the perimeter. The concrete slab must not be connected to the foundation or the wall—it needs to be able to move independently.
Then pour the concrete. It’s not rocket science. Possibly include electrical or plumbing lines within the slab as well.
That is already very helpful. Thank you.
The room is approximately 6m x 3m (20ft x 10ft) in size.
Okay, edge insulation strips so that the concrete slab can move. The floor does not absorb moisture, and there is no damp smell in the room. Would a vapor barrier sheet be sufficient then? Or would you still recommend installing a bitumen membrane?
The room is approximately 6m x 3m (20ft x 10ft) in size.
Okay, edge insulation strips so that the concrete slab can move. The floor does not absorb moisture, and there is no damp smell in the room. Would a vapor barrier sheet be sufficient then? Or would you still recommend installing a bitumen membrane?
Hello "OzCi1305",
With a total area of 18m² (194 ft²) and only 7cm (2.75 inches) of leveling height, we end up with just 1.26m³ (44.5 ft³).
Using concrete for leveling is not very practical, especially since no ready-mix truck will come for such a small amount.
The use of reinforcement mesh is even less sensible. What would be the point? Bending moments are excluded, and with only 6m x 3m (20 ft x 10 ft), no harmful tensile stresses occur in mortar, whether concrete or cement screed.
I would do it like this:
Apply a waterproofing layer across the whole surface (loose laid, seal overlaps with appropriate tape, 15cm (6 inches) overlap at the sheet edges) and extend it up the walls to the finished floor level plus 5cm (2 inches). (The excess visible later will be trimmed by the floor installer to the exact finished floor height.) Secure the waterproofing membrane against slipping or sagging on the walls (with small nails or tape).
Attach 5mm (0.2 inches) thick setting strips (roll goods) to the wall surfaces and also secure them against slipping.
Then apply a cement screed, optionally with a plasticizer, over the entire surface. The plasticizer should help achieve proper compaction throughout the 7cm (2.75 inches) thickness of the mortar layer.
Please note that with the described construction there is no thermal insulation within the cross-section.
An effective insulation layer for ground-contact structures usually requires about 10cm (4 inches) thickness, but you don’t have that build-up height.
So the floor will remain cold.
Unless the "tacker plates" you mentioned are system panels for a floor system that include a laminated insulation layer.
If not, you will have to consider something else.
While a standard build-up wouldn’t be possible due to limited height, you can still get some insulation by using 25mm (1 inch) thick insulation boards above the waterproofing layer.
On top of this, a PE foil as a separation layer, then a calcium sulfate flowing screed (liquid screed) with a thickness of 35mm (1.4 inches). Not a conventional cement screed, but a CAF one!!!
This would be a special build-up with some thermal insulation.
----------------------
Good luck: KlaRa
With a total area of 18m² (194 ft²) and only 7cm (2.75 inches) of leveling height, we end up with just 1.26m³ (44.5 ft³).
Using concrete for leveling is not very practical, especially since no ready-mix truck will come for such a small amount.
The use of reinforcement mesh is even less sensible. What would be the point? Bending moments are excluded, and with only 6m x 3m (20 ft x 10 ft), no harmful tensile stresses occur in mortar, whether concrete or cement screed.
I would do it like this:
Apply a waterproofing layer across the whole surface (loose laid, seal overlaps with appropriate tape, 15cm (6 inches) overlap at the sheet edges) and extend it up the walls to the finished floor level plus 5cm (2 inches). (The excess visible later will be trimmed by the floor installer to the exact finished floor height.) Secure the waterproofing membrane against slipping or sagging on the walls (with small nails or tape).
Attach 5mm (0.2 inches) thick setting strips (roll goods) to the wall surfaces and also secure them against slipping.
Then apply a cement screed, optionally with a plasticizer, over the entire surface. The plasticizer should help achieve proper compaction throughout the 7cm (2.75 inches) thickness of the mortar layer.
Please note that with the described construction there is no thermal insulation within the cross-section.
An effective insulation layer for ground-contact structures usually requires about 10cm (4 inches) thickness, but you don’t have that build-up height.
So the floor will remain cold.
Unless the "tacker plates" you mentioned are system panels for a floor system that include a laminated insulation layer.
If not, you will have to consider something else.
While a standard build-up wouldn’t be possible due to limited height, you can still get some insulation by using 25mm (1 inch) thick insulation boards above the waterproofing layer.
On top of this, a PE foil as a separation layer, then a calcium sulfate flowing screed (liquid screed) with a thickness of 35mm (1.4 inches). Not a conventional cement screed, but a CAF one!!!
This would be a special build-up with some thermal insulation.
----------------------
Good luck: KlaRa
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