Bay Windows Structural Post

[RichA]

I have ordered timber casement windows (Engineered European Redwood) for a square bay window; these come with corner posts that will be bearing the weight of the flat bay roof.

The builder is requesting a specification was 97mm x 97mm C16 timber posts.

The window installer tells me the 90mm posts are structural (to the extent they casn hold another floor above), and that they exceed C16 as they are laminated in 4 layers.

I am at a bit of an impasse; does it ring true that a 4-layer laminated Engineered European Redwood post should be sufficient for a 3m x 0.6m bay window roof?

Thanks.

 

[tony1851]

The installer is correct in that laminated timber is stronger than plain; it is also dimensionally more stable. But as well as compressive strength, slenderness is also important as whichever timber is used, its load-carrying capacity is reduced as the column increases in height.
But for an ordinary bay window (1.5 - 1.8m high?), the 90x90 glulam would be fine.

 

[RichA]

Thanks, that's great; the windows are 1500mm high.

 

[Notch7]

I make timber windows, I wouldnt have any qualms about it.

Engineered timber used for jounery is going to far exceed C16.

Joinery softwood is constructed with almost knot free redwood. Gluam whitewood is usually rated C40.

Dont forget the posts also are fixed to 2 window frame jambs ceeating a larger section.