conservatory problems

[dannyday5821]

i am prosess of having a conservatory installed

the frames for the windows have just been put in. but i have noticed there is at least a one inch gap between the bottom of the frame and the wall.

they are suggesting this should be filled in...but should this gap even exist in the begining?

[buildersmate]

Err no.
So what are the frames sitting on, then?

[dannyday5821]

nothing! apart from some blue plastic theyve stuck underneath it - id be best emailing you a photo is that okay so you can get a better look...

is that okay by you?

[buildersmate]

Not really - unless you can post it somewhere.

So brick retainer wall / dwarf wall wasn't high enough, so the frames were put on 'blue plastic', the frames sit on that, and the roof structure sits on the frames?
If that is what they are proposing, it really isn't very clever.
Even if UPVC, the whole structure weighs quite a bit.
Is the plastic solid (so won't get compressed) or cellular.
Is it continuous along the length of the windowframes?
Why can't they use wood (if the frames are wood) or acquire a matching UPVC spacer that looks if it was supposed to be there all along?
If you are not happy you really need to make it clear to them now so they don't do any more construction until they agree an appropriate solution.
It clearly wasn't designed like it.