Price of a room extension? Is this expensive?

[anonymoosy]

Hi...this is the first time I will ever have extended a property. I want to have a medium size dining room added to our house. Room for a 8 seater table and a bit of extra sitting space. Flat roof, off the shelf lantern window for the ceiling. There doesn't seem much point going down the conservatory route as one of the long sides would look onto a wall. Nothing fancy - plain white walls etc...
I'm just wondering if any of you have had a room added to your property and how much it cost. I've been quoted £75/£80k by the architect/engineer and this quite shocked me, so would love if you might share what kind of costs you paid. I'm in the South, outside of London.

My friend had to full back of her house extended by a few metres, with a new kitchen and wet room from about £30k. We are in the se so that quote is ridiculous.

PineConesAplenty I’m intrigued, why do builders quote high if they don’t want the job? It would certainly help us make sense of a few of the (mad!) quotes we’ve had recently. I may be being naive but I had thought if they didn’t want the job they’d just say?!

If they don't want the job so quote a ridiculously high price, either they won't get the job because the price is too high or someone might agree to go ahead with their ridiculous price so they will get paid way above what the job is worth so it's a win-win situation for them!

We are in Cambridgeshire and currently getting quotes in.
Part of our work is a simple 1storey extension at the side of the house
1 builder has quoted 15k
The other 30k.
It’s 2m x 5m in size.

But getting builders interested is a nightmare

We had a kitchen/diner extension 3 years ago 3m x 5m with large patios doors and huge side window including kitchen/floor etc was £35k but my husband laboured for them every Friday and he fitted floors.