Looking for a bit of advice/guidance regarding a rotting floor.

[HoobleDooble]

Hi everyone. I bought a traditional terraced house 7 years ago, shortly after I moved in I realised the front room floor was dropping and, on closer inspection, is completely rotten.

I've been burying my head in the sand as I was totally broke at the time, but have recently come into a bit of money and want to get it fixed ASAP before I wake up on morning to find my sofa, tv etc underground.

The problem is I haven't a clue who I should be calling, would it be a job for a local builder, or do I need a specialist? Also, unlike the front room, the back of the house is concrete-floored, would I be possible/better to have the front void filled in and concreted, or is it worth a new wooden floor if the houses either side may have the same issue (the end-terrace house to the right definitely has the same problem, the left side has been empty for 30 years)?

Any advice practical or legal would be gratefully received, thank you.

We found our front room floorboards to be riddled with woodworm, so dp treated the joists and laid new floorboards. I think the total cost came to just over £100, however he is a skilled labourer (electrician by trade).
I would have though either a builder or carpenter would be your best bet as the joists will need checking.
We opted not to have concrete put down, as Victorian houses are built to 'breathe' and require ample airflow under the floorboards. We had to open up blocked airbricks an all sorts.
HTH

More concrete could cause damp problems?

Like puffy we have also had extra air bricks put in, we don't have rotting floor but it needed more airflow.