Question

why is a small gap left behind the walls while mounting a girder for roofing

Answer 1

A small gap is left behind the walls while mounting a girder for roofing usually one end of the iron structure is fixed and the other end is allowed to expand during summer season because it comes to its own place in summer.

Answer 2

Hope this will help you :

A small gap is left behind the walls while mounting a girder for roofing usually one end of the iron structure is fixed and the other end is allowed to expand during summer season because it comes to its own place in summer.

Thanks