Can you frame the floor like this

[Vilseiviken]

I am going to insulate my glassed-in patio. Among other things, on the ceiling of the uninsulated attic. There are currently 45x75 joists with a span of 180 cm and cc60. I need to increase to a total of 220 cm insulation. Can you extend the 75 joists with an additional 145 cm on the old ones by notching and attaching to the existing cross beams? Or should you lay the 145 ones "across" with cc60?

 

[Tompafix]

I will insulate my glass-enclosed patio. Among other things, on the ceiling of the uninsulated attic. There are currently 45x75 framing boards with a span of 180 cm and 60 cm on center. I need to increase the insulation to a total of 220 cm. Can the 75 boards be extended with an additional 145 cm on the old ones with notching and fastening on the existing cross beams, or should the 145 boards be placed crosswise with 60 cm on center?

I don't quite understand, is it a ceiling you're going to insulate that you have access to from an attic?
Pictures help to understand

 

[Vilseiviken]

The cabin has an attic where the insulation for the living area is located on the upper side of the ceiling. Above the glazed outdoor room, there is no insulation at all. The intention is to insulate with 20 cm and then lay a floor to use the space for cold storage. The problem is that the framework right there (70 mm) is too weak to walk on. I am looking to increase the load-bearing capacity of the future attic floor.