  In the quest of why there should be a single transition temperature in a
multi-gapped system like Fe-based materials we use two band model for
simplicity. The model comprises of spin density wave (SDW), orbital density
wave (ODW) arising due to nested pieces of the electron and hole like Fermi
surfaces; together with superconductivity of different pairing symmetries
around electron and hole like Fermi surfaces. We show that either only intra or
only inter band pairing is insufficient to describe some of the experimental
results like large to small gap ratio, thermal behaviour of electronic specific
heat jump etc. It is shown that the inter-band pairing is essential in Fe-based
materials having multiple gaps to produce a single global $T_c$. Some of our
results in this scenario, matches with the earlier published work
\cite{two-band-prb}, and also have differences. The origin of difference
between the two is also discussed. Combined intra-inter band pairing mechanism
produces the specific heat jump to superconducting transition temperature ratio
proportional to square of the transition temperature, both in the electron and
hole doped regime, for sign changing s$^{\pm}$ wave symmetry which takes the
d+s pairing symmetry form. Our work thus demonstrates the importance of
combined intra-inter band pairing irrespective of the pairing mechanism.
