Loft conversion RSJ question

[5teves]

Hi

For a loft conversion with a dormer I'm contemplating to start soon, wondering if the following would be possible.

I will need to install two RSJ'S, one in the front just above the existing joist and one rear and one at the ridge.

They span approximately 6.5 meters in the length and will sit from the party wall to the gable end.

The question I have is, would it be possible to have these rjs's in two pieces and have them either spliced or welded together?

I want to install the RSJ'S before opening up the roof.

Please advise

 

[freddiemercurystwin]

Yes no problem but the joint needs to be designed by your structural engineer.

 

[^woody^]

I will need to install two RSJ'S, one in the front just above the existing joist and one rear and one at the ridge.

Are you sure you want them in two pieces?

 

[5teves]

Thanks Freddie.

Is this normal practice would you say or will it cause me any restrictions by using this method?

I already have internal stairs going onto the loft and was planning to tackle the project like this,

1, install the rsj at the front and strength the rafters by bolting the specified timber to them.

2, install the rsj at the rear, and install the floor joists.

3, install the ridge rsj

4, and lastly make the hole for the dormer

Is this a viable approach?

 

[5teves]

Hi Woody,

I'm not sure yet, just asking if it's viable at this stage

 

[^woody^]

lol. Any Star Trek fans? "There. Are. Three. Lights."

 

[tony1851]

It's perfectly feasible to have the beams in two pieces, connected with a splice.
But as fmt pointed out, they have to be designed. Typically, they have top and bottom plates bolted to the flanges with pre-drilled holes.
There are also web plates needed.
The bolts have to be special 'friction-grip' bolts, which firmly clamp the plates together.
Welding is not a good idea because site-welds are not as reliable as shop welds; also there is the fire risk, particularly in a roof void.