Creating hole in wall to fit new FD door & casing

Sorry - I think I have posted this in wrong section. Not sure how to remove? Have now re-poste din the 'Building' section. Apologies.

Hi all

First post - but long time reader.

I am renovating my house. Been doing it for a few years now;

Had an extension built by pros whilst I have been DIYing a loft conversion, digging out ground floor for wet UFH, removing a chimney breast, moving walls, new gas elec and water supplies, the list goes on etc. Dont worry - its all with architects plans, planning permission and building control apps. I can post more details about the project in general another time (if anybody is interested).

For now I have a quick question - my loft conversion requires me to lower all ceilings on first floor to create sufficient head height in attic. Not an issue, have put in steels and removed old ceiling, will be hanging the new joists for attic shortly. As I was lowering ceilings, which also involved lowering some internal brick walls, I decided to replace the old 1960s wonky lintels over the doorways with new ones at a nice level head. I also widened a few of the doorways to have new 762mm doors (they needed changing for FD30 ones as well).

Anyway. I have set the lintels at 2030mm from floorboard level; working on the basis of a 1980mm door plus, say 40mm thick FD door casing, leaving me approx 10mm gap to jiggle around with. However, I didnt leave anything to accomodate the gap for floor covering (carpet and underlay etc).

So, my questions please

1. How thick is carpet and underlay usually?
2. Will I be ok to trim the bottom of the door to accomodate the carpet?
3. What size opening do you usually leave in the brickwork for a doorway? (I did 2030x850)
4. Will I have to also cut down the door casing to fit?
5. Can I get a thinner FD door casing, say 30mm? to create some more space?
6. Apart from probably making a bit more work for myself, have a 'dropped one' here?

Thanks folks

Matt

I would not worry about it. Doors are generally made so you can safely take an inch or so off the bottom so you should have no trouble finding suitable doors that will give you this flexibility. I don't think your thinner frame idea is a good one as it could lead to future problems if the wood is imperfectly seasoned or whatever. I think you normally source the doors and frames before doing the brickwork so you can brick up to the actual frame or a former of the same size.