Hello, it's getting closer to our kitchen renovation, which also means that three walls will be demolished. We live in a functional house. According to the drawing and technical description, I've figured out that the floor structure between the floors is 2" 7" and is spaced 50cm apart across the house. There is a load-bearing wall extending from gable to gable. However, we’re not going to touch this wall; the walls we’re planning to demolish are on one side of this wall. The flooring structure, as described above, will span 4-4.5 meters between the load-bearing wall and the exterior wall. How much load capacity does it actually have? We have a small bathroom, maybe 1.5x1.5 meters, with a cast floor and a bathtub above. This bathroom is located in the corner between the gable of the house and the load-bearing wall, so it might relieve quite a bit. But the question is whether the floor structure supports enough load?
According to Boverkets Konstruktionsregler, a 45x145 can have a maximum free length of approximately 2.3 meters or approximately 2.7 meters, depending on whether it is a K12 or K24. This refers to a beam with supports at each end.
If your beams span from wall to wall with support in the middle, the maximum free length is approximately 4.4 meters or approximately 4.6 meters. Both examples refer to a floor structure with cc600 and a glued 22 mm particle board as framework cladding.
If your beams span from wall to wall with support in the middle, the maximum free length is approximately 4.4 meters or approximately 4.6 meters. Both examples refer to a floor structure with cc600 and a glued 22 mm particle board as framework cladding.
Okay, so as you mentioned, from outer wall to outer wall with a center support wall in the middle, and the distance I believe is 4.20 (without pulling out the tape measure again). cc could be 600, or my rough estimate might be off. Here's what's written in the description of the drawing (from -42)ACME said:
"Outer walls of one layer 2" and one layer 1½" grooved plank
Interior walls of one layer 2" grooved plank and 1" filling, 1" rough plank, and masonite on both sides
Second floor joists 3x8" with blind-bottom and paper as well as 2x5 for soundproofing joists
Attic joists 2½x7"
Vaults are cast throughout the basement with cross reinforcement
Outer cladding paper 1" grooved boards and patent batten"
So I probably lied, "second floor joists" must indeed be between the floors, so it's even 3 inches 8?
Yes, that's how I would interpret it.
What is the load-bearing capacity for such a construction then?ACME said:
What I'm pondering is that if it's the right dimension according to the building regulations, it should support everything, but the question is HOW MUCH does it support? I was just thinking about the bathroom located on the upper floor with the cast floor, etc.
How many kg your construction can support is not something I can answer, and I guess an engineer would need a bit more information to calculate it. For example, details on how the structural cladding looks and is attached, and how any cutouts and reinforcements are executed.
The figures above come from a handbook published in pocket format by Svenskt Trä. You can register at http://www.traguiden.se/TGtemplates/TGLogin.aspx?id=144 to access similar tables, but I don't think you will find any data on three-inch timber. The width doesn't significantly impact the strength of a joist - it's the height that is crucial. I have heard that in a strength calculation, the width measurement is counted only once, but the height measurement is counted three times.
The figures above come from a handbook published in pocket format by Svenskt Trä. You can register at http://www.traguiden.se/TGtemplates/TGLogin.aspx?id=144 to access similar tables, but I don't think you will find any data on three-inch timber. The width doesn't significantly impact the strength of a joist - it's the height that is crucial. I have heard that in a strength calculation, the width measurement is counted only once, but the height measurement is counted three times.
So a 3x8" with support in the middle where the length from the support to the outer wall is 4.2 meters should have no problem at all holding up a bathroom of 1.5x1.5 meters with a cast floor and a bathtub? The bathroom is placed in the corner between the support and the outer wall, so it's not in the middle of the surface either, for that matter.anaitis said:
How are you with statics?jon_h said:
Forgot the formulas?
Section modulus: W=b*h*h/6 (I've forgotten how to write square and cube notations)
Moment of inertia I= b*h*h*h/12
i.e. width in the first power in both formulas.
I have probably never read the formulas. But the strength tables I have read do not show this. For example, the difference between c/c 600 and c/c 300 is not particularly large when it comes to bending stiffness, which exactly corresponds to doubling the width of the beam.
Then I don't know if bending resistance is the same as bending stiffness? What I’m talking about is deflection at a certain point load.
Edit: But if your formulas are correct, I am naturally wrong. (though shouldn't there be a parenthesis before the division sign?)
Then I don't know if bending resistance is the same as bending stiffness? What I’m talking about is deflection at a certain point load.
Edit: But if your formulas are correct, I am naturally wrong. (though shouldn't there be a parenthesis before the division sign?)
Then I would recommend a study!
Bending resistance is the quantity that affects strength, i.e., the stresses caused by the load.
The moment of inertia affects stiffness, i.e., deflection.
PS
Parentheses are not necessary in expressions that involve only multiplication and division.
DS
Bending resistance is the quantity that affects strength, i.e., the stresses caused by the load.
The moment of inertia affects stiffness, i.e., deflection.
PS
Parentheses are not necessary in expressions that involve only multiplication and division.
DS
I'll read up a bit when I get the chance.