Conservatory to Extension - ball park cost

Forestduncan

Evening all,

We've decided to take the plunge and replace our old, leaky 6m by 4m conservatory with a single story extension and knock through the back of the house to the dining room to create a new kitchen/dining living space. I wondered whether anyone had an idea as to possible ball park costs for the build itself. We've started talking to an architect so will get all the designs / building regs / structural plans sorted ahead of any proper building quotes but I just wanted a rough idea as this will be a huge development and I don't want to get too far in and burn up loads of cash before I get any nasty surprises.

Some points to mention:

- The foundations for the conservatory were 1000mm deep by 600mm wide (according to the plans signed planning and building control) and the architect thinks they'll be fine, so we're working to those & assuming that we won't need new ones digging
- We're assuming a flat roof construction with 3 dome windows in
- Looking at aluminium bi-fold doors c3000mm
- it's a lean-to conservatory, either side of it has a brick wall already built
- knock through opening to the existing dining room (external wall) would be c3.5-4m

So I guess the big difference/assumption to the norm is the fact that we'll be looking at building on the existing foundations, which will he,p keep costs down.

Oh, and we live in West Sussex

Any thoughts welcome

System

best person to advise is the person thats seen it and knows what the design is...

glasgowdan

And when the foundations are found to be insufficient...?

I'd say somewhere between 20 and 40k, depending on how fancy it all is!

seashore22

The final price of ours was £32,000 and that included:

Knocking down conservatory and getting rid of old foundations.
The new foundations were extra deep because of an adjacent retaining wall.
New extension - just over 3m x 4m.
Large upvc window and large upvc french doors - coloured and wood grain effect.
4 velux windows in a pitched roof.

The price rose slightly because the builders had a hell of a job digging out the old and slightly unconventional foundations - extra labour, extra time and extra skips.

Having said all that our quotes varied considerably, so giving you a ball park figure is next to impossible.
,

DRP

40k to remove 4.5 x 5.5 conservatory and replace with extension on same footprint.

The vaulted roof (dual pitch with 4 velux) increased the price over a flat or lean-to.
We have no access (terrace) therefore took a bit longer, more labour costs.
Also built a utility with toilet.

Kitchen and flooring took it to 50k.

Forestduncan

Cheers everyone. I realise that there is more than a whiff of "finger in the air" to what I'm asking. I'm a bit twitchy given that we're right at the start of this process and this is a huge commitment for us.

In my cautious state I've allowed for £40k for the extension, bi folds and knock through plus another £10k for the architect / specialists fees.....and a further £15k if we hit trouble (and kitchen/flooring as separate cost.)

Hopefully I'm not too far off the mark!

Davesnave

I wanted to do this, but when I worked on the roof of my bungalow the scaffolding showed me just how much sunshine I'd lose to the living room with anything solid-roofed, so I've replaced the conservatory.

I know there's a lot of conservatory dislike on this forum, but for me, just like the north-facing kitchen, it really works.

From costings of the plans I originally drew up, I'd say yours are realistic, barring an something unknown cropping-up.

Rain_Shadow

I've just done a similar project. demolished a 7m x 3m glass roofed area and replaced with a 9m x 3m vaulted roof room with two veluxes, under floor heating etc.etc. Also knocking through into the dining room with double glass pocket doors and relocating the gas boiler plus a few other minor things. I got no change at all from £60k inc VAT and then there was the cost of the new kitchen on top at £34k.


Expensive but well worth it.

mishkanorman

We've knocked down a garage and added a kitchen / lounge which is 7m x 5m, a new front entrance and hall 2.5m x 2.5m and a downstairs shower room 2.5m x 2.5m.
We encountered no problems and the total build cost, from a non vat reg builder who charged labour only, came to 40k. We then spent another 25k on kitchen and all associated white goods/flooring/furniture/bathroom/Skips (many, many skips)/fees etc. There was no major structural work on the original building as we only knocked through the side of a doorway.

The only thing that may change your plans is we were told flat roofs are a strict no as far as planning is concerned, I dont know if you require that for your plans however.

Silvertabby

It sounds like you are committed to an extension rather than a new conservatory, but if this helps anyone else...

Our 16 year old conservatory was basically sound - just a bit of 'pinking' on the outer door and a couple of windows needed changing as the seals had gone. We looked at replacing our polycarbonate roof with glass, and the £5K quoted was more then we were willing to pay to put on an old conservatory. We were then quoted for new windows and a door on top of the existing brickwork, which was less than we expected. We were going to go ahead with that option until the chappie said that we shouldn't rush into blinds as the new tinted roof may be enough for our east facing conservatory. That wasn't an option, as we kept the blinds on one side permanently down for privacy. That lead to the suggestion that we had a plain brick wall on that side instead of windows, which actually brought the price down. I then had a vision of 3 types of brick - the original house, the original conservatory, and the new brick. To cut a long story short, we ended up knocking the whole thing down and building a conservatory/orangery cross on the original foundations. The cost was just under £10K for the total rebuild, plus a further £800 for real stone flooring.

Clive_Woody

We are also in W.Sussex and had a 4x5m extension done, single height, pitched roof with 4 velux windows, double doors to the patio, plus some internal alterations including bi-folding doors to close off the dining room and the original opening widening and the beam raising. We also had to have 6 foot deep foundations as we have big oak trees close to the house. Decorating was included as well as new wood flooring.

Our extension cost just over £36k, which included architect and engineer fees :money:

http://www.architects-hertfordshire.co.uk/view-project/rear-extension-to-replace-conservatory-10/