In message , jonathan
writes

Hi,
We've fitted a fully glazed floor to ceiling porch on the house and now
want to fit a new front door which is now inside the porch obviously.
We like the design of some internal doors - veneered oak planking style
- to get the same design in external door spec is several hundreds of
pounds more.
The question is, can we use the internal door version and comply with
building regs (door thickness would be 34mm'ish not 44mm as existing
door), insurance etc.
Is the only reason external doors 44mm is insulation value? or is it
something more?

How secure is this porch? If it would be relatively easy to get into
you'd be better installing a proper external door on security grounds
alone.

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Si