How many props for a flat roof support?

[Chunkytfg]

I realise the answer to my question has many variables but please bear with me.

Okay so i'm looking to take out the internal walls of my horrible extension and I know the roof will need Props to support it once the walls come down.

Basic dimensions are that the space is a 6.6m wide and 5.5m deep. but an L shape

The roof is a felt flat rood from the early 90's with fibreglass insulation between the joists.

The joists run across the back of the house across the 6.5m span with an internal wall at aprox 3.3m in the centre and around 3.5m long. This in one of the walls coming down.

There is then a random corridor approx 1m in from the edge running front to back along the 5.5m depth. The ~3.5m joists run across this wall seemingly not being supported by it as the ends are on the outside wall. This corridor wall is also coming down.

The wall that has the 2 ends of the 3.5m joists meeting in the middle is about 3.5m long. Our plan was to prop either side of the wall with 3 or 4 props with 2 scaffold boards running the length of it. so 6/8 props total

Then the wall thats seemingly not needed we were going to prop another 4 over the full 5.5m length again with boards to spread any load that a be there.

How does that sound? Assuming you've managed to follow my ramblings that is?

I appreciate that its not going to be a simple answer but I was hoping that fact all i'm propping up is half the flat roof with nothing above it and not an actual upstairs it might be the kind of question that is fairly easy to answer

 

[Chunkytfg]

i'm guessing you either need pictures as my description is rubbish or no one wants to even take a guess for me? Lol

 

[HERTS P&D]

Or they think this is a complete wind up, as why wouldn't you hire some props????????????????

Andy

 

[Chunkytfg]

Huh?

Regardless of the source of the props the question is how many am I likely to need and does my idea sound right?

 

[HERTS P&D]

Sorry, wrong thread.

Andy

 

[Chunkytfg]

Haha yeah i'd rather use too many than some convoluted method of getting round using any at all!

All i'm trying to do is clear the currently unused extension so it's a bare shell while i've got some remaining leave left this year before the proper build starts next spring.

 

[SpecialK]

Best off putting some pictures up...

 

[Chunkytfg]

Okay so lets see if this helps.

The wall between the 'family room' and the 'bedroom' is the supporting wall. I've pulled down a couple of sections of ceiling either side of it and the beams both clearly cross over and sit on this wall.

The wall that creates the corridor between the kitchen and the bedroom is the wall I suspect is not supporting anything.

The supporting wall has the joists overlap so the ones from the kitchen side only just pass over the wall but the ones from the family room side overlap into the bedroom by about 300mm. Would one line of props just on this overlap be okay or would it be best to support both sides so each set of joists have there own supports?

 

[SpecialK]

Its not something I have attempted before but I would be using props on both sides and something on the floor to spread the load like a scaffold board. Use large timbers near the ceiling to prop a few joists at a time?
What are you replacing the wall with?

Okay so lets see if this helps.

The wall between the 'family room' and the 'bedroom' is the supporting wall. I've pulled down a couple of sections of ceiling either side of it and the beams both clearly cross over and sit on this wall.

The wall that creates the corridor between the kitchen and the bedroom is the wall I suspect is not supporting anything.

The supporting wall has the joists overlap so the ones from the kitchen side only just pass over the wall but the ones from the family room side overlap into the bedroom by about 300mm. Would one line of props just on this overlap be okay or would it be best to support both sides so each set of joists have there own supports?