So, I'm hoping to get these Ledgers up in the next week or so. My current plan is to get 9x2 ripped down to 206mm (my local Timber yard is happy to do this and I'm happy with the cost) and hang the Top Chord (47mm) of the 253mm Posi from it. That would give me a level finish above and below. Is this a bit OTT?!

 

Should I be installing Ledger all round, even on the side walls? Or does the ceiling/floor just oversail the short gap to the wall?

Are you plasterboarding directly onto the underside of the joists, a good method is to counter batten the joists in the opposite direction with 75x25 this allows you to get the plasterboard to fall on timber all the time and gets a good flat ceiling. 

If you do this then you won’t need to cut the ledger board down as much. 

 

Obviously you need the height in the rooms.  

41 minutes ago, Mulberry View said:

plan is to get 9x2 ripped down to 206mm 

It's good to make use of these, and well done the merchant for encouraging it.

Be aware that the timbers are may distort due to the new imbalance of grain and stresses. Not a huge reduction so maybe not much twist.

If so, you can probably straighten them with substantial noggins / dwangs.

2 hours ago, Russell griffiths said:

Are you plasterboarding directly onto the underside of the joists, a good method is to counter batten the joists in the opposite direction with 75x25 this allows you to get the plasterboard to fall on timber all the time and gets a good flat ceiling. 

If you do this then you won’t need to cut the ledger board down as much. 

 

Obviously you need the height in the rooms.  

 

My Architect had planned a service void in the ceiling, which I had planned to omit, not because I need the space,  but more because it wasn't needed due to being able to run services in the Posis. However, you make a good point with the Plasterboard. I haven't even thought that far ahead to be completely honest.

 

I had begun to consider Resilient Channel if I were to counter batten, which I'd seen someone mention in regards to sound transfer. Any thoughts on this?

 

Speaking of Plasterboard, would you just use one layer? Or something else?

 

I do like the idea of putting a service void in the ceiling below an air-tight barrier at roof level though, so will be looking at this in due course too.

 

Thanks for your help as always.

As an aside, I have managed to coerce my SE to agree a fixing solution of 2no M16 @ 800 centres cast into the concrete, this was achieved with the use of Toothed Timber Connectors behind the timber. I will post pictures of the way I'm tackling fitting the Ledgers pre-pour in case it helps others. Of course the pictures will be different and, for some, more amusing if my method fails. 🤣

Your metal web joists are obviously metal and should therefore be fire protected.  Double standard board or single fire proof board.  The pink papered one.  Can't remember it's proper name.

 

You could potentially fix a 4x2 to the non joist walls to carry the edge of the plasterboard.  Saves battening the whole ceiling.

 

 

On 01/12/2023 at 12:54, Mulberry View said:

As an aside, I have managed to coerce my SE to agree a fixing solution of 2no M16 @ 800 centres cast into the concrete, this was achieved with the use of Toothed Timber Connectors behind the timber. I will post pictures of the way I'm tackling fitting the Ledgers pre-pour in case it helps others. Of course the pictures will be different and, for some, more amusing if my method fails. 🤣

How did you get on with this? Very close to this point also...Cheers