Is it possible to plane down wooden beams by 1/3 and compensate 1/3 on the width?

[yehor]

I have a timber joist 100x160mm cc60 where I want to lay dovetail plate along with underfloor heating and Sylomer strip. The problem is that there are two inward-opening doors leading to a balcony that I can't do anything about. Dovetail plate, underfloor heating, concrete, and Sylomer require 64mm. To open the doors flawlessly, I need to plane down ~44mm.

The current subfloor is 22mm raw plank. Can I glue/screw these to the side of each joist to compensate for the planing? Or is much more needed?

 

[Karrock]

100*160 is quite coarse, but unfortunately, it's the height that contributes the most. You can't start calculating it without knowing the span. You also have the option to add more studs between the existing ones. Your current experience of whether the floor is stable or bounces is also relevant.

 

[yehor]

100*160 is quite rough, but unfortunately, it's the height that contributes the most. You can't start calculating it without knowing the span. You also have the option to add more studs between the existing ones. Your current experience of whether the floor feels stable or springs is also relevant.

The span is 3300mm and the current floor feels "rock solid"

 

[Karrock]

Short and good span!
45*145 in C24 quality cc 300 is sufficient according to the wood guide app "lathunden". Having every other 45*120 and every other 100*120 cannot be far off from that. Can't the doors be cut a little at the bottom?

 

[yehor]

Short and good span!
45*145 in C24 quality cc 300 is sufficient according to the wood guide app "lathunden." Having every other 45*120 and every other 100*120 can't be far off. Can't you cut the doors a bit at the bottom?

Thanks!

Unfortunately, they are PVC balcony doors

I'm currently investigating if I can cast 10mm over the underfloor heating instead of 20mm, does anyone know why 20mm is recommended? Also, the current damping mat is 7mm, planning to replace it with 3mm.