Posh loft - new floor questions

[monty77uk]

See attached pic ....

Red = walls (all solid either steel supported on 1st floor or all the way to ground)
Blue = Ceiling joists
Green = Ceiling binders where the ceiling has a large span

I've selected 8x2" C24 timber based upon the spans I need.

3 options as far as I see it.

- Go 90 deg to the joists so I can go above the existing ones and leave the binders in place. It's a hip roof on all sides so I won't be able to sit them on the wall plates so a couple of 12mm bolts through the existing roof rafters will support them at the end, and they'll rest on internal walls at the other end

- Go with the joists bolting them to the existing ones, ceiling binders can go as they won't be required due to increased rigidity. Should be able to get some meat on the wall plates and also bolt through rafters, again they would rest on the walls at the other end

- Go with the joists but keep the old/new separate to avoid any pressure on exiting ceiling/joists. Not sure what I'd do about the binders though

2 seems easiest and I much prefer having something sitting on the wall plates - am I missing something as to why that's not possible?

Thanks!

 

[freddiemercurystwin]

What are you doing?

 

[monty77uk]

What are you doing?

Office / storage ... will be putting a velux in too and insulating rafters etc.. as phase 2.

 

[freddiemercurystwin]

Stair going in? Any Building Control involvement?

 

[monty77uk]

Stair going in? Any Building Control involvement?

No stairs, decent ladder. No BCO.

 

[monty77uk]

OK so I went option 3. By the time I raised the new joists a little (to avoid any contact with the ceiling) there wasn't much meat left to bolt to the 4x2s and I just thought it better to leave them as undisturbed as possible.

The new joists sit nicely on some 4x2 that sits on the wall plate and internal wall and I trimmed around the first chimney using joist hangers. Some things I discovered:

- Drilling through rafter ends/joist is nearly impossible with a standard drill due to clearance between the rafters, angle drill arrives today
- Noggins will need to be 5" tops to clear the top of the existing ceiling joists
- I have a bee/wasp nest in the corner of the eaves
- It's hot in a loft this time of year

For the ceiling binder I intend to hang the centre of it from a rafter while I cut and install the new joists then I'll strap it all together (old to new) to support it. Having looked at how the binders are laid in the loft at least 2 ends don't sit properly on anything so I suspect they've not been doing a great deal anyway.

Progress pic attached anyway, be gentle, first time I've done this.

 

[monty77uk]

Started a projects thread in case it helps someone in the future, or prevents someone making the same mistake(s)

//www.diynot.com/diy/threads/loft-to-office-conversion.437497/