Raising the floor level

Hi

I'm about to start work updating my kitchen which will involve knocking out a wall (non load bearing) between the kitchen and utility room. Once this is done i'll have a problem with the level of the floor. My utility room is 4 inches lower than the kitchen. My two questions are:

1> How do i raise the floor 4 inches to match the existing kitchen floor?

2> The utility room has a door at each which leads to the front and rear
gardens respectivly. Would i have to remove the doors and frames
and trim them by 4 inches so that they match the new floor height and
then refit them?

Thanks in advance......Jason

Is it a timber or concrete floor? Any damp problems?
If concrete, build it up with a floor screed (a dryish sharp sand/cement mix laid, levelled and tamped to compact). Best to lay a DPM under.
If timber, fix 3x2 through the boards into the existing joists, then lay new boards on top. Make sure there is ventilation under and around the floor.

You will need to take out your frames and raise them to the required level. This could be quite a job...

Could you not rehang your doors so they open outwards

Ok then, to answer a few questions...

The utility room is a concrete floor, as is the kitchen. There are no current damp issues and all appears to be in good condition.

I could rehang the doors to swing outwards but that would mean there is a step up into the utility room. Is this acceptable??

After looking at the comments it has raised another question.

1> Would it be ok to raise the floor using timber rather than screed?
I intend to tile throughtout so astheticly it would look all the same but
structurally one half would be concrete and the other half of wood!!

Thanks in advance

Jason.