Help with early budget cost comparison to rear extension

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Hi, looking for some help obtaining very ball park budget costs comparisons for the rear extension we are planning.

We have developed a number of different options and was hoping for some experienced individuals to help advise on the estimate cost differences between them.

The attached image shows internal and external view of the extension with the various different types of roof. Looking for comparison between the following:
V1 - lean too with gable, split bi-fold doors
V2 - Full gable with 2 bi-fold doors
V3 - Flat roof with 2 bifold doors
V4 - Full lean too with 2 bifold doors

The extension is 9 x 5m (40m2).

Any questions please ask.

Thanks
 

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At 5m you are unlikely to get a pitch that would support roof windows unless you had a flat roof near the house.
 
What is the height from dpc to underside of 1st floor windows.

at first glance most of those options are non starters due to lack of height.

Have you considered a flat roof with a lantern?
 
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What is the height from dpc to underside of 1st floor windows.

at first glance most of those options are non starters due to lack of height.

Have you considered a flat roof with a lantern?

Its approximately 4m. The house is an old 1920 build with high ceilings. The models have been produced on Archicad so are to scale. The pitched and lean too houses are between 15 - 18 degrees.
I am aware that we would need a steel frame in order for these to work.
 
It’s only a guesstimate really, building prices are crazy at the moment.

Flat roofs tend to be a bit cheaper, but if you want lots of skylights you may find the saving is marginal as you could end up needing more steels.

Re the pitched roof - The Marley Wessex tiles I put on my house work from 15 degrees, but the style may not be in keeping with your existing roof. Also don’t forget you’ll need to consider the height of lead flashing (75mm minimum), so from the base of your exterior windowsills upstairs minus the flashing height will be your maximum height unless you want to make a more complicated roof.
 
As it involves kitchen and lots of glass 2k/m2. So 80k. Add to that the fact that the rest of the house will feel old after the new extension so will need updating, another 20k. 100k in total.

I'm not bitter! honest... :)
 
It’s only a guesstimate really, building prices are crazy at the moment.

Flat roofs tend to be a bit cheaper, but if you want lots of skylights you may find the saving is marginal as you could end up needing more steels.

Re the pitched roof - The Marley Wessex tiles I put on my house work from 15 degrees, but the style may not be in keeping with your existing roof. Also don’t forget you’ll need to consider the height of lead flashing (75mm minimum), so from the base of your exterior windowsills upstairs minus the flashing height will be your maximum height unless you want to make a more complicated roof.


Thank you, will take that on board
 
As it involves kitchen and lots of glass 2k/m2. So 80k. Add to that the fact that the rest of the house will feel old after the new extension so will need updating, another 20k. 100k in total.

I'm not bitter! honest... :)

haha I like your way of thinking!!
 

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