Hello!
I'm working on a multi-year sub-project in a 1920s house in Lund (2.5 stories + basement). In one of the storage rooms, I've started by removing old ceiling plaster and clearing out all the junk and debris. Left were beams, upon which a lower plank floor rests (I assume it's a bit higher to the actual floor on the entrance level).
I wanted more space and volume in the basement and began by filling the spaces (about 60cm wide) with stone wool and screwing up plasterboards below. The plasterboards are about 3 cm _above_ the underside of the beams. The beams are thus exposed, and I'm thinking of painting them white.
I'm mostly satisfied, but wanted a bit more soundproofing, and the ceiling material should be heavy for that. Then I got the idea to remove the plasterboards and instead cast the spaces between the beams with concrete, but still have them somewhat visible as they are today. I thought of nailing up rough-sawn planks to hold the concrete, so that the wood leaves a slight impression in the concrete. That should do the trick?!
My questions to this altogether excellent forum are as follows:
1. Is this even a good idea?
2. How thick should I cast and how do I attach the reinforcement (and what should it look like)?
3. Is there a risk of cracking (it will be reasonably consistent temperature around 18-19 degrees and dry)?
4. Do you have any other thoughts that I haven't considered?
Grateful for some expert comments!
/Johan
I'm working on a multi-year sub-project in a 1920s house in Lund (2.5 stories + basement). In one of the storage rooms, I've started by removing old ceiling plaster and clearing out all the junk and debris. Left were beams, upon which a lower plank floor rests (I assume it's a bit higher to the actual floor on the entrance level).
I wanted more space and volume in the basement and began by filling the spaces (about 60cm wide) with stone wool and screwing up plasterboards below. The plasterboards are about 3 cm _above_ the underside of the beams. The beams are thus exposed, and I'm thinking of painting them white.
I'm mostly satisfied, but wanted a bit more soundproofing, and the ceiling material should be heavy for that. Then I got the idea to remove the plasterboards and instead cast the spaces between the beams with concrete, but still have them somewhat visible as they are today. I thought of nailing up rough-sawn planks to hold the concrete, so that the wood leaves a slight impression in the concrete. That should do the trick?!
My questions to this altogether excellent forum are as follows:
1. Is this even a good idea?
2. How thick should I cast and how do I attach the reinforcement (and what should it look like)?
3. Is there a risk of cracking (it will be reasonably consistent temperature around 18-19 degrees and dry)?
4. Do you have any other thoughts that I haven't considered?
Grateful for some expert comments!
/Johan
Last edited:
I'm a bit hesitant...
While concrete is indeed heavy, it also has a high E-modulus and achieves a reasonably high moment of inertia - the last two are unfavorable factors for sound insulation.
If your main purpose is indeed sound insulation, you will likely get a better result by adding more layers of gypsum. Possibly even on the upper floor, on the floor.
One disadvantage of your construction is the exposed beams in the basement. If you apply the additional gypsum layers (preferably two layers!) under the beams, you will get better insulation.
While concrete is indeed heavy, it also has a high E-modulus and achieves a reasonably high moment of inertia - the last two are unfavorable factors for sound insulation.
If your main purpose is indeed sound insulation, you will likely get a better result by adding more layers of gypsum. Possibly even on the upper floor, on the floor.
One disadvantage of your construction is the exposed beams in the basement. If you apply the additional gypsum layers (preferably two layers!) under the beams, you will get better insulation.
Hello anaitis and thanks for the input!
But what is and what does the E-modulus and moment of inertia mean?!
I have actually considered more layers of drywall. Then I would indeed have to raise the first board a couple of centimeters, but it's probably less work than casting...
That's right - besides sound insulation, it was the surface finish and surface durability I'm after.
/Johan
But what is and what does the E-modulus and moment of inertia mean?!
I have actually considered more layers of drywall. Then I would indeed have to raise the first board a couple of centimeters, but it's probably less work than casting...
That's right - besides sound insulation, it was the surface finish and surface durability I'm after.
/Johan
The Young's modulus describes how a material reacts when subjected to stress. How much it lengthens or compresses under a given stress. Simply put, a low Young's modulus results in a yielding material.
The moment of inertia is used to understand how the geometric cross-section of a load-bearing element affects its deflection and stress.
The product of these two parameters gives the stiffness of the load-bearing element.
Low stiffness is advantageous when it comes to sound insulation.
The moment of inertia is used to understand how the geometric cross-section of a load-bearing element affects its deflection and stress.
The product of these two parameters gives the stiffness of the load-bearing element.
Low stiffness is advantageous when it comes to sound insulation.