Hi I'm looking to take down my kitchen ceiling and open it up to the rafters on the pitched roof that has double Roman tiles, I want to put in roof windows, it's around 4x2.5, I'm a bit confused because it has double joists, one set seems to be part of the roof truss and the other has the plasterboard fixed to it, it seems overkill to me or am i missing something?

You have rafters holding the roof tiles etc. the lower framework is there to fix the plaster board to. The vertical pieces could well be supporting the roof, is there a wall below that point?

You will need to remove the whole roof structure and start again 

tiles off, rafters off, ceiling down ceiling joists down. 
 

then you wil need all new rafter done to the correct spec for that span, the rafters either side of the roof windows will need to be doubled up to take the load. 
it will all need fixing down correctly, as you have removed the ceiling joists which are acting as a support for the roof and to stop it spreading. 
 

if you just remove the ceiling joists you will end up with your roof tiles sitting in the kitchen. 

53 minutes ago, Russell griffiths said:

You will need to remove the whole roof structure and start again 

That's right. the roof is supported on these vertical timbers. 

There are probably ways to not start again by reinforcing the rafters, but its not easy or cheap.

 

This all looks like new work, and nicely done too. No insulation?

can you explain the background to this ambition?

is there a kitchen beneath or is it a shell?

Hi thanks for your replies, there is a kitchen underneath, the roof was done before we moved in, the ceiling is quite low compared to the rest of the house so we're trying to open it up.

No insulation installed which explains a couple of things (cold and damp).

I might go down route of installing the roof windows and putting (roof chutes?) like in the picture.

That looks like the answer.

3 hours ago, markc said:

You have rafters holding the roof tiles etc. the lower framework is there to fix the plaster board to. The vertical pieces could well be supporting the roof, is there a wall below that point?

Hi there's no wall below that point, I thought they would just fix the plasterboard to the roof truss instead of installing an extra set. I'm guessing it's a structural thing.

1 hour ago, saveasteading said:

That looks like the answer.

The joist centres are 400mm, if I cut one out for the square, how many adjoining joists should I brace the cut too?

57 minutes ago, orbital said:

how many adjoining joists should I brace the cut too?

Not just that but the joists and rafters will be taking double the load and need duplicating.

That's all I'm saying, as you now need a formal  design and you will need building regulation approval.

Thank you all for your advice, it's very much appreciated. 👍