What is the correct way to frame a roof light when working with existing joist spacing?

[WillH83]

Good morning all,

 

I was hoping someone may have encountered this same issue…

 

I am installing roof lights into an existing roof structure so I will be keeping the joists and existing deck. For the openings I will double the joists either side and add double headers as per normal. However, due to the spacing of the joists, the doubled joists will still be too wide for the upstand so I will need to add an extra length of timber between the two headers to support one side.

 

I have discussed with BC and they were also unsure how best to proceed as it seems that you should not add additional fixings into headers….  I have exhausted TRADA / BR approved docs etc in search of a solution but have not managed to come up with anything useful.

 

Any advice would be greatly appreciated!

[ToughButterCup]

For those of us who 'see' better in drawings or images, could you sketch it for us - then maybe photograph it and upload it please? thanks.

[bassanclan]

Choose the correct size rooflight for your rafter spacing?

[Redbeard]

Do you have purlins? IIRC in a similar position we just inserted 2 (doubled-up, to keep BCO happy) new rafters sat on the exg purlins above and below the desired roof-light position and noggin-ed (header-ed) accordingly.

[WillH83]

Thank you for your input so far

 

@ToughButterCup A good idea thank you - I have added a quick sketch which I hope clarifies the issues!

@bassanclan That was plan A but unfortunately every combo / of roof light size seems to end with the same issue... 

@Redbeard that seems a good solution but no purlins here!

 

I can only assume that this is a fairly common situation when retrofitting into older properties, surely there must be a solution that keeps the BCO happy!?

[bassanclan]

On the left you have doubled up the joist on the right you could just add two new joists doubled up.

 

Is this a flat roof?

[Mr Punter]

1 hour ago, bassanclan said:

On the left you have doubled up the joist on the right you could just add two new joists doubled up.

 

Is this a flat roof?

 

+1

 

Just make sure you have double timbers (minimum) all round.  Looks like you should add a timber sandwiched to the right of the red one.

[WillH83]

Good morning all,

 

@bassanclan unfortunately that idea did not land with the BCO as they are concerned about adding additional hangers to the doubled headers.... I also suggested just adding new doubled joists at one side but the BCO said that they must be fixed to the existing joists hence we are back where we started! and yes it is a flat roof so really shouldn't be this challenging....

 

@Mr Punter I would have assumed the same but it seems that the BCOs are forever looking for new reasons to exist!

 

Thank you all for your thoughts so far -  if anyone could point me to the correct part of TRADA or other approved docs which may shed some light on this it would be greatly appreciated!