essence pour solive et montage

Bonjour

Je désire faire un 1/2 etage dans une vielle maison. La moitié pour 2 chambres et l'autre pour une mezannine.

Pour cela je dois poser des solives. Il y a 2 possibilités apparemment pour poser ces solives.


Plan initial.
 <                                          10m                                                                  >
________________________________________________________________________________
|    ^                                                        i                                                        |
|                                                               i                                                       |
|                                                               i                                                       |
|                                                               i                                                       |
|    6m                                                      i                                                       |
|                                                               i                                                       |
|                                                               i                                                       |
|                                                               i                                                       |
|                                                               i                                                       |
|                                                               i                                                       |          ___v______________________________________ i______________________________________

                                                                 <       1/2 etage  - 5m ou 5.50m    >

Solution 1 : une série de poutres de 6m20 en 100x300 avec entraxe de 50cm toutes dans le même sens

 <                                          10m                                                           >
                                                                                    >50cm<
_____________________________________________________________________________
|    ^                                                        i         i          i           i        i           |
|                                                               i         i          i          i         i          |
|                                                               i         i          i          i         i          |
|                                                               i         i          i          i         i          |
|    6m                                                      i         i          i          i         i          |
|                                                               i         i          i          i         i          |
|                                                               i         i          i          i         i          |
|                                                               i         i          i          i         i          |
|                                                               i         i          i          i         i          |
|                                                               i         i          i          i         i          |          ___v______________________________________ i_____ i_______i______i_______i_______

                                                                 <  1/2 etage  - 5m ou 5.50m    >





Solution 2: 2 grosses poutres de 6m20 en 300x300 et une série de poutres de 5m (ou 5.5m) en 50x150 avec entraxe de 50cm.


 <                                          10m                                                                  >
________________________________________________________________________________
|    ^                                                        II                            II                            |
|                                                               II                            II                           |
|                                                               II----------------------------II---------------------------|
|                                                               II                            II                           |
|    6m                                                      II                            II                           |
|                                                               II----------------------------II---------------------------|
|                                                               II                            II                           |
|                                                               II                            II                           |
|                                                               II----------------------------II---------------------------|
|                                                               II                            II                           |          ___v______________________________________ II__________________ II____________________

                                                                 <       1/2 etage  - 5m ou 5.50m    >


Questions:

Quelle est la meilleure solution (je prefere la 1 pour des raisons d'estetiques et de hauteur). ?

Quelle essence dois je utiliser?


Merci.

Bien cordialement.

FD