Loft steels

[Brightspark69]

Evening chaps (and maybe chapesses)

Long time lurker first time poster, so please let me know if I’m doing this wrong or in the wrong section.

I have these plans for loft conversation beams. (Photos hopefully attached)

I’m struggling to work out what RL2 and RL4 is all about.
This is a ‘30s bungalow and I believe we sit in the internal skin, where there’s a wall plate.






Regards. Bs

 

[Brightspark69]

Sorry chaps, I was just reading back and realised I should have posted the calculation.
Focusing on RL2 and RL4, any ideas what they are and what they do?

 

[^woody^]

They look like something to do with the dormer cheeks. The "R" designations implies "roof" and the other beams "f" implies "floor"

Crap drawings though to mix the two levels up if so. Is there no section? Can't you ask whoever drew them up?

And the calcs are out of Superbeam, so not a proper engineer.

 

[Brightspark69]

This is to be a gable wall (going from a hip) and the dormer sits further in, there it says 100 x 100 sw post.

There is a section but the steels are not shown on it.

What confuses me more, is RL2 is 1.4m long, no R1 bearing, but R2 bearing is 200x100 ‍

I have made contact with the guy who drew it, but as it’s been a while since having them done (we put it on the back burner for a bit) I’m not holding out much hope.

 

[tony1851]

What puzzles me is why have 9 steel beams in a loft?

It just looks over-engineered - not in a 'belt-and-braces' way, but simply too much steelwork. Are there so few load-bearing walls at ground floor level?

RL 2 and RL 4 each support 'timber gable', with RL 2 carrying the additional point load from F6. Why two timber gables? R4 might be redundant? If F6 was moved to the right, you probably wouldn't need the steel beam R2.

 

[Brightspark69]

That was my initial thoughts, so I’m glad an expert has brought that up too.

The only supporting wall in the bungalow is the central one, the one that F1 and F2 meet.

Not really sure what f1 and f2 are for.

F3 and F4 are split as well as being different sizes. They seem small compared to photos of other builds that I’ve seen. I know all builds differ but I’ve followed a couple of builds in my area.

 

[tony1851]

F1 and F2 appear to be primary beams to support beams 3 and 4, and 5 and 6 respectively. That is why they are heavier sections than the other beams.

 

[^woody^]

On the face of it it's been badly designed. Without seeing the rest of the drawing its hard to interpret, but it smacks of a BCO foreigner which has not been designed or thought about, but just hashed up to satisfy building regulations. Never mind actually reading the drawing to work stuff out or actually build the thing, oh no it only needs to pass building regulations.
As previous, no proper structural engineer would use Superbeam.

 

[Brightspark69]

Thanks for the replies chaps.
I have attached an image of the whole plan.
So as I understand it, it’s been badly planned and just very much over engineered with a ‘that’ll do’ attitude.

 

[tony1851]

A better pic; the fact that it's a double dormer makes all the difference.
If the hatched wall between the lounge and bedroom is the only load-bearing wall, it begins to make a little more sense.

F1 and F2 are major beams which split the span for the remaining beams so that they are no bigger than necessary.
The only small issue I would raise is that F1 and F2 appear to put a considerable load on the end of the load-bearing wall? (though the drawing might show this has been addressed - writing not too clear).

 

[Brightspark69]

Sorry, I should have put the full drawing up in the first instance, but didn’t think it would be for my original question.

Yes, the bearing of F1 and F2 is a concern.
That wall is the only load bearing wall. All the others are built straight off of the floorboards.

There is no mention of the 2 beams being bolted together, just sit on a bearing plate on top of the wall.
The wall plate on top of the wall is 3” so each beam will only have 1.5” bearing!

Not sure how a 750mm bearing plate is meant to be fitted


img src album

 

[tony1851]

Just have them overlapping side-by-side rather than butting up end-to-end.