Korniche roof lantern upstand thickness

[wolfram]

The korniche guide says to have the upstand 69mm wide. I have built mine with 44mm PSE frames filled with 25mm kingspan and 18mm OSB internally bracing them. It is externally lined with 11mm OSB - it is 55mm wide, which fits the korniche lantern eaves rails exactly (with the 6mm overhang).

I'd like to keep it this way, so it lets the most light in and I like the look of the OSB framed by the PSE. I could tack 15mm ply onto the inside to bring it up to 70mm thickness. Question is, do I have to?

the roof lantern is 2m x 2.2. The upstand is 195mm high

Its a garage build, so no plasterboard on inside.

Phil

 

[freddiemercurystwin]

Probably because typically you'd have plasterboard on the upstand internally which would increase your 56 to 69.

 

[wolfram]

Probably because typically you'd have plasterboard on the upstand internally which would increase your 56 to 69.

Thanks for the reply - that's my thought. No structural strength to plasterboard. However, all the videos I've watched they are using 3x2 then facing with OSB and plasterboard. That would make the up[stand 95mm ish wide. mine seems quite strong, but I guess the weight of the glass and the possible wind forces are making me wonder...

 

[freddiemercurystwin]

If I were drawing up such a detail for a client nowadays the upstand would be constructed with 4x2's and have insulation on the outside too so would probably be around 165mm thick.

 

[wolfram]

If I were drawing up such a detail for a client nowadays the upstand would be constructed with 4x2's and have insulation on the outside too so would probably be around 165mm thick.

as korniche state 69mm then I guess the extra thickness is for extra insulation, not strength?

 

[freddiemercurystwin]

I'm sure yours will be fine.