thanks for the message
with regards to the floor ....on the width of 3.6 m i used a middle joists to add a bit of strength and remove some of the springyness.
the only dpc was where the timber was incontact with the concrete piers as it was far enough the ground to allow for good airflow.
we used kingspan under the office part of the floor, but the rest was fibre glass because of the cost....quite often homebase or b&q have it on offer ie
£3 / 1200 width roll so the insulation for this cost about 20 quid instead of a few hundred
it is messy to use sometimes but what i sometimes do is make the frames on the floor with 1 side clad then put the insulation in cover with breather membrane and batten then upright it that way .saving alot of hassle......on a pent roof we do the same ie make a couple of roof slabs and lift then on.
hope this helps