Sliding patio door on floor joists

[grm40]

Sometime in the past a bay window was removed to create an opening for a conservatory. There is no door in the opening and I would like to put a patio sliding door in. The problem is the joist run 18 inches into the area before the concrete starts meaning I only have joists to install on underneath 

Can this be done? 

[nod]

Yes

[grm40]

Can you explain please? Is this common practise? 

 

[markc]

No difference putting door in on joists or concrete … apart from concrete is a little more difficult fixing to.

[grm40]

Thank you