Beam sizing.

[vandame]

Hello.

I wanted to ask for tips regarding installing a beam after tearing down a load-bearing wall. What is best? Glulam beam, steel beam? Or would it be sufficient to use two, for example, 45x195 and set them on edge and prop them up?

The house in question is 1 & a half story, and the wall to be removed is 3.9 meters. There is no wall on the upper floor parallel to the wall to be removed.

Does anyone have an idea of what type of beam might be sufficient? The man who inspected the house suggested the latter option, but could it be enough? That would be great!

I’ll try to upload two pictures below to give a sense of the layout.
Lower floor = The wall with the wavy line is where the wall will be removed, and the blue line is where a new wall will be installed.
Upper floor = The dashed line is where the current wall on the lower floor is today.

Thankful for any answers!!

 

[MathiasS]

Steel beam is not an option for me because it's difficult to handle, hard to work with, hard to screw in place, hard to find, etc.

45x195 will look like a banana after a couple of years, forget that option unless an engineer says it's viable.

Glulam is perfect. Available for purchase "cheaply" on blocket, relatively easy to handle, easy to attach and work with, etc.

If you don't plan to seek help from an engineer, then you just have to go all out in terms of sizing.

Otherwise, you can look in this thread for tips on how to do it (unfortunately, the image links broke during the forum's conversion a long time ago, so you'll need to paste the image links yourself, the images are still there):

http://www.byggahus.se/forum/byggma...-miniprojekt-hal-i-baerande-vaegg-bilder.html

Four meters is quite long, so I would use a heavier beam than the one in the pictures. Maybe not wider, but taller. The supports can be built the same way.

 

[vandame]

"45x195 will look like a banana after a couple of years." Even if I take, for example, 3 pieces and glue and screw them together on the high edge? I understand that glulam is the best, but as usual, you want to go the easiest way, but the most important thing is not to cut corners. Mathias, you say that I should rather place a higher than a wider beam than yours, does it make much of a difference in load-bearing capacity if you go for a wider beam, for example, 115mm, and keep the same height, 225mm? I prefer it not to stick down too much.

 

[MathiasS]

Gluing and screwing of course improves the situation, but regular lumber becomes warped just by its own weight after a few years, so I don't believe in that solution, not for a 4m span anyway. Maybe someone who builds professionally can comment as well.

It is significantly better to increase the dimension in height rather than in width. I don't remember the exact ratio, but it's quite substantial.

On the other hand, maybe something like 115 225 is enough.

 

[hempularen]

I suspect you need to input more than 225 in the height of the beam.

We are currently working on an additional floor. The designer has installed 2 steel beams HEA160, the span of the beam is about 5m. And there is about 4 meters span from the beam to each outer wall, those joists are 220 high. The reason for 2 beams is more due to collision with a staircase than pure structural integrity issues.

According to the designer, it wouldn't have been enough with a glulam beam that was 220 high. In our case, the beams are recessed into the floor structure, so they don't extend downward, they are completely invisible.

 

[imported_Byggaren]

I understand that glulam is the best, but as usual, you want to take the smoothest path, yet the most important thing is not to cut corners.
Mathias, you say I should rather use a beam that is higher rather than wider than yours; does it make much difference in load-bearing capacity if you use a wider beam, e.g., 115mm, and keep the same height, 225mm? Preferably, I don't want it to protrude too much.

It is impossible to answer your question with certainty without doing a comprehensive load calculation, including the roof truss's impact on the floor structure.


A rectangular beam that is higher than one that is lower but wider is always stronger because the formula for bending stiffness is: bxh^2/6. Therefore, width doesn't have as much impact on stiffness as height does, since the latter term is squared.

For example, take a 45x220. That gives you 363 cm^3 in bending stiffness.

If you take a 45x195, it gives you 300 cm^3. To reach 363 cm^3 with maintained height, you would need to use a 57 thick beam.

Three glued and nailed together 45x195 only provide 855 cm^3 in bending stiffness. The same stiffness is achieved with a 110x220.

I also don't agree that a steel beam is always more troublesome to install. Steel has much higher strength than wood, allowing the profile to be made significantly slimmer and thereby lighter.

Wood weighs about 500 kg/m^3. Steel nearly 800,000 kg/m^3. A difference of 1:1600.

But wood only withstands about 15 MPa/mm^2 compared to steel's approximate 200 MPa/mm^2. A difference of 1:13,333, based on the best quality (glulam vs. structural steel class S 355 J2 G3).

And in a beam, it is almost invariably the deflection that becomes the determining factor. Steel is less yielding than wood due to its higher strength.

To achieve the same load-bearing capacity in steel as in three nailed together 45x195, you only need 64 cm^3 in steel. That is, an IPE 140 weighing 12.9 kg/m against 13.15 kg/m for three 45x195.
_________________
The Builder

 

[MathiasS]

Then I don't agree that a steel beam is always more troublesome to install. Steel has a much higher strength than wood and the profile can therefore be made significantly slimmer and become lighter.


_________________
Byggaren

It is a completely personal preference based on my own ability to work with steel vs wood. I also find it easier to go to the store and order glulam than to get hold of a piece of iron (it's not just "going to the junkyard"). So, a very subjective view. I understand that steel is a better choice from a structural engineering standpoint in many cases.

Moreover - interesting numbers, h^2 was what I was aiming for but couldn't remember exactly.

 

[Faidros]

Steel has a much higher strength than wood and the profile can therefore be made significantly slimmer and thus becomes lighter.

Wood is, for example, significantly stiffer and stronger than steel, relative to its own weight.

From a perhaps not entirely impartial source:
http://www.trainformation.se/LitiumDokument20/GetDocument.asp?archive=3&directory=1028&document=6908

 

[imported_Byggaren]

Wood is, for example, significantly stiffer and stronger than steel in relation to its own weight.

From perhaps not an entirely unbiased source:
[link]

That can probably be accurate. It often depends on the context. Larger wooden constructions can also be improved through steel reinforcement.

The largest wooden structure I have been involved in designing, bidding, and delivering to (circa 1965) was a timber warehouse for a sawmill in Juotseno, Finland. 3-joint frames with 96 m in free span, steel-reinforced with square steel (diagonally positioned), 6 m in cc distance.

The concrete guys couldn't even get their pre-stressed frames to support their own weight. Steel was also not popular with the Finns due to fire protection requirements and corrosion tendencies.

It ended up being 'our' IAS-beams instead.
_____________________
The Builder

 

[JanneL]

When I look at your drawings, I become puzzled. Doesn't a load-bearing wall usually run down the middle of the house? On the left side, with the hallway, living room, and bedroom, it looks as I would expect. On the right side with the kitchen, dining room, and bedroom, I don't understand how the floor joists are situated. If I understand correctly, you now have a maximum span of 5.8 m when you measure through the kitchen and dining room. When you've removed the wall to the bedroom and built a new wall by the kitchen, you will have about 5.8 m from the other direction. A natural question then is: Doesn't the floor upstairs bounce?
Thought that occurs to me: Are the floor joists running in the other direction? Or is the wall upstairs a special construction that helps support the floor joists since it seems to be in the middle of the house?
I'm not a carpenter, just a happy amateur.

 

[vandame]

Thank you for all the answers!
I am on Moelven's website where you can calculate beams yourself (although they might not consider the weight of any trusses?? but still fun), and what I wonder about there is if I can include the new wall that I am going to put up in their calculation if it is made sturdy? The open area becomes smaller then.

Where can you get hold of steel beams? nearest metal workshop?

 

[vandame]

janneL. I'm not really following now (a bit too late for me), but that's why I was planning to set up a beam to prevent this. Or how do you mean?

 

[JanneL]

Assuming that the side with the entrance is the long side and the side past the kitchen, dining room, and bedroom is the gable?

 

[vandame]

JanneL. Yes!

I'm starting to think more and more about the possibilities of using a steel beam. But what dimension is required for it to handle the same load as a 66x315 glulam beam? (According to Moelven's dimension table, it should be sufficient). I was at a metal workshop here in town and saw beams outside, but unfortunately, I didn't have anything to measure with, and the company was on vacation, so I couldn't ask either, but it might be good to know for next time. Can the supports be made in the same way as when using a glulam beam? Grateful for answers.

 

[Kempa]

I had installed an I-beam (steel) in 355 quality, and if it had become visible, I would have clad it with some lighter boards where I would have placed plugs over the screws to make it look like a solid wood beam. My niece clad a steel beam in her house in that way, and it turned out really nice.