Lintel in Gable Cavity Wall for new First Floor Doorway Information, help and advice on many architecture, self build and design problems and issues

[jr2981]

Hi,

i am looking to add a new 1st floor doorway through the old gable end wall of my house into an extension, this will involve setting of a 1.2 long cavity wall lintel to give a 900mm opening. I've been reading the BS5977 standard for lintel loads to determine what loads i need to consider and as this is on the 1st floor i think i only need to consider the roof, masonry and self weight of lintel, the latter two are easy but calculating the roof loads is very confusing, has anyone completed calculations for a similar scenario??

[arbco]

In a gable it's unlikely that the floor or roof (except a purlin) will impose any loads. Suggest two box lintels or concrete lintels will be ok as it's only a small opening.