Calculate strength in support for roof beam?

[Rockhard Lindgren]

I have six standing ceiling joists (60x150mm) in the boiler room / workshop in the basement of a split-level house, which means I have to duck every time I go there. Instead of breaking up the floor, I thought about cutting into the joists.

I'm considering taking six or twelve 3 mm flat bars, 100 mm wide and as long as the joists (as the width of the boiler room). Bend them 90° along the middle and then screw them into the ceiling with M8x80 straight through the metal plate and joist, after which I can cut away the wood in the joists so I can walk upright in the room.

What do you think of such an idea?

 

[GoForIt]

If I understand you correctly, you want to remove 50mm from the height of the roof beam?

Then I think you will get significantly increased sway in the floor..

 

[Rockhard Lindgren]

If I understand you correctly, you want to remove 50mm from the height of the roof beam?

Then I think you will significantly increase the sway in the floor..

I want to remove about (75-)100 mm in the joists but at the same time "secure" with the metal profiles as I mentioned.

 

[GoForIt]

It will not work to remove 50-75% of the beam and replace it with flat/angle iron..
Considering the dimension of the beams, I suspect they have a fairly substantial span..

 

[justusandersson]

It will not work. The only option is to replace the existing beams with others made of better material (e.g. glu-lam) and better dimensions. Without knowing the current beams' span and strength class and the load on the floor, I still think you can reduce the beam height to 100 mm. Whether it is worth it is another matter.

 

[Rockhard Lindgren]

A slightly different idea... same same perhaps..

5-6 mm thick flat steel bar, 75 mm high and 2820 mm long (the width of the room). One flat steel bar with these dimensions on each side of the roof tiles (a total of 12), with M8x70 straight through, 500 mm between each, four 8 mm holes in each beam.

That's quite a bit of metal for reinforcement... and you would think it should correspond to the wood being cut away...

 

[justusandersson]

It is the amount of material in height that is most important. Buy glulam beams 140x225 (homogeneous quality) and split them in half and replace the existing ones, and it will work.

 

[claesborjesson]

I have six standing roof rafters (60x150mm) in.

What do you think of such an idea?

My brother did something similar, he removed the load-bearing walls in the basement completely, installed steel beams in the attic, and cables that support the ground floor.

I don't think it's a good idea to mix two different materials wood+metal, no structural engineer wants to calculate on bent sheets AND wooden beams.

The best solution is to remove the wooden beams completely and replace them with steel I-beams.
It's easy for a structural engineer to translate, for example, a six-meter wooden beam into a corresponding I-beam.
This definitely gives the best ceiling height.

To get the steel beam into place, you can either make a hole in the outer wall and slide it into place or make the beams in 2 parts with a bolted joint in the middle.

/Claes