Loft Conversion Steel Beams or wood?

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Hi guys, I was hoping I could get some advice from those experienced in loft conversions.

I'm looking to convert my loft next summer (saving up at the moment) and was looking to do most of the work myself. My main concern or area i may need to get someone else in is in terms of fitting steel beams to start of the main structural work.

The loft space is 6 meters from part wall to party wall.
outside front wall to outside back wall is 7.5 meters long
the heigh in the loft space from the loft beams to the top of the highest point of the roof is 5.5 meters (its pretty high)

The rooms I make will have sloped roofs, not looking to make any dormers.

Now as any main support steel beam will need to be about 7.5 meters long, could anyone advise on what I need to look for in terms of size, height of beam and how these are to be fitted?

Would using wooden beams be more practicle and if so what sizes should I consider?

Due to the size of the loft space i'm looking to have 2 bedrooms and a small bathroom with a toilet.

Any advise will be much appreciated

Thanks in advance.
 
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Is there a supporting wall in the middle?

Assuming there is you could put in a 2 piece steel beam from party wall to party wall at the front and back and fit timber joists from them to the centre wall. You timbers would probably be spanning about 3mtrs so maybe 8 or 9x2.

If you don't have a wall in the middle you would need more steel.

I'm DIY'ing a loft conversion at the minute and that's how the architect (who I now think is a @@@@) designed it on our drawings. Our beams were 6.06mtrs long and sat on 3 padstones, 2 either side and 1 just off centre. They were calculated to have the loft floor, bedroom ceiling, timber dormer, flat roof etc... At 203 X 102 and 23 or 25 kg/mtr. They hold a timber floor that spans 3.0mtrs to another centre wall. 4 of us managed to lift the beam in through a bedroom window and into position. That was only possible because we only have one party wall, otherwise we would have needed a join on it.
 
On that span, I think you'd be looking at something like one of the 254 deep beams because of deflection issues.
You can have them cut in two or even three sections, with spliced joints bolted together on site - the beam doesn't have to be one long piece.
 
Is there a supporting wall in the middle?

Assuming there is you could put in a 2 piece steel beam from party wall to party wall at the front and back and fit timber joists from them to the centre wall. You timbers would probably be spanning about 3mtrs so maybe 8 or 9x2.

If you don't have a wall in the middle you would need more steel.

I'm DIY'ing a loft conversion at the minute and that's how the architect (who I now think is a @@@@) designed it on our drawings. Our beams were 6.06mtrs long and sat on 3 padstones, 2 either side and 1 just off centre. They were calculated to have the loft floor, bedroom ceiling, timber dormer, flat roof etc... At 203 X 102 and 23 or 25 kg/mtr. They hold a timber floor that spans 3.0mtrs to another centre wall. 4 of us managed to lift the beam in through a bedroom window and into position. That was only possible because we only have one party wall, otherwise we would have needed a join on it.

Hi, thanks for the reply.

Unfortunately there is no support wall in the middle so the steel beams would have to span the entire distance wall to wall. So in a bit of a dilemma as unsure how to go about this
 
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On that span, I think you'd be looking at something like one of the 254 deep beams because of deflection issues.
You can have them cut in two or even three sections, with spliced joints bolted together on site - the beam doesn't have to be one long piece.

Would I be needing two of the 254 deep beams as their are no support walls in between or would I need more?

Also with the beams cut into 2 peices, would this not weaken them when bolted back together?
 
It would be designed to be strong as a 1 piece. I think the cut them at 1/3rd so the joint isn't in the middle.

Without a central support it might end up being deeper than 254.

There are online beam calculators that you can play around with.
 
you need to get this designed by an engineer, he will design it in steel or timber whichever you desire however the sizes needed for each material might make the choice for you. But there are options, many years ago when I was starting out I worked for a guy who had a loft company, he was a structural engineer by trade and everything was timber, some big timbers, bolted timbers , ply box beams you name it
 

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