Extending upwards. Rough cost?

[Freaklikemeee]

Can anyone tell me how much they paid for extending 'upwards' (including raising or replacing a roof?)

I've seen £2k per square metre quoted for regular extensions but I'm not sure if extending upwards is cheaper or more expensive.

I'm assuming the foundations of the building will be OK (if not I won't be able to do it anyway).

The property is in SW England near Bristol.

What do you mean exactly? A loft conversion? Extension over garage? It is usually cheaper per sqm to build on top of an existing building like a garage because you don't have the cost of groundworks and oversite.

(The House Builder's Bible is good for costing things)

I had a guy recently tell me that it's a huge job to raise the roof. He ball parked 40-50 but I think that's probably on the low end

RoseGarden Yes it would be a major loft conversion (requiring planning permission). My existing loft is just a very pointy storage space accessed by a ladder.

I would be looking to add on approximately 20ft in height to the building's walls to faciliate a two-storey room where the existing loft is, then put the roof back on top of that to have a cathedral ceiling...

I will check out that book you recommended—many thanks.

Or, built a flat roof with a roof garden on top.

Whoops—I meant to say the flat roof is my second idea. So rather than raising the roof it would be a whole new roof.

Chinny Did your chap happen to say whether a new roof is cheaper than trying to raise an existing roof?

That’s a massive job.

It’s a great idea but I’m wondering why nobody does it, it’s probably hugely expensive to fix the foundations.

A friend had to get her foundations redone and it costing 150,000 just for the foundations to be made safe.

Anyway the best of luck!

This picture will give an idea of what I want to do. The red lines would be the new walls.

3luckystars £150k just for the foundations!? Eeek!

The building was built in 1880 and is made of stone so I was hoping the foundations would be ok. Wishful thinking perhaps!

The foundations might be ok, sure you won’t know unless you find out!!

Good luck with the quotes, it would double the size of the house so might be worth it.

If it’s so old though it might be protected?

I am being very unhelpful I’m sorry!!

There are loads of people on here that will know all about this so I’ll just keep chatting here until the knowledgeable ones arrive!

So it’s currently a 2 story and you want to make it a 4story , is that correct?

Thanks for the chat!

It's currently a 3-storey house and I want to turn it into a 4-storey house.
The existing 3rd storey is more like an attic, really—it has very low sloped ceilings due to the roof angle so by raising the roof it would also enable me to raise the ceiling on the 3rd storey rooms and enlarge them by a few ft on each side. (Hope that makes sense!)

The building is old but not listed, so hopefully would get planning permission!

Ok so the current third floor is a tight angled attic, I understand now.

I found an article on it here, if you have a look a time the comments below it says this can be called a ‘top up build’

www.thejournal.ie/housing-2795409-Jun2016

Hello again, I found another article here while we are waiting for t’others. Maybe they are on a break. Hopefully they will show up soon.

www.telegraph.co.uk/finance/personalfinance/investing/11776649/Ive-made-500000-by-building-a-third-storey-on-my-home.html

Thanks for the articles! I didn't realize it was such a "radical" idea! There have been a few previous threads about raising roofs for loft conversions.

Article 1 says that houses built after 1945 will have adequate foundations, so I might be out of luck right off the bat. For some reason I assumed older properties would have better foundations as they're more solidly built. Will have to look into that more.

I would be okay on the character front though, as mine is one of the shortest houses in the immediate area, plus a whole bunch of new 4-storey townhouses have gone up right across the street.

He didn't say much as he couldn't commit with out drawings etc but it wouldn't be adding anything to the walls but just putting on a higher roof with wider trusses

Watching this as I would like to do something similar, but just in the very early 'dreaming' stage!

What do you do first? Or should I say, in which order would you do the following?

Get building's foundations assessed
Pre-planning meeting with planning officer
Get architect to make drawings
Apply for planning permission
Get builders' quotes
Get permission from freeholder (my building is a leasehold)
(Have I left anything out?)

We are looking at doing something similar though at a smaller scale. We are adding a new storey to bungalow, so it becomes like a detached house with smaller loft space. Planning was granted as house next to us would still be higher than our extended bungalow and there is good space around bungalow to not cause reduced light to anyone. I was also hoping that build cost per sq meter should be less than a ground floor extension, but it is coming to similar number as groundfloor. There is no ground work to do so we save cost on that but the cost of whole new pitched roof with truss etc gets added to the cost.

We've just done an upwards extension. Except we turned a (sort of) bungalow into a 2 storey.

Our 1930s foundations were v shallow (and in clay) but we were able to avoid any costly underpinning/piling by building the extension in timber-frame/slate roof.

It's worked out about 2700 per square meter. Although: we effectively had 2 rooves plus a new bathroom and new windows in some other rooms that aren't part of the extension included in that price.

Take those off and it was roughly 2300 per square m. SE (not London).

I should add that includes decorating and carpet, planning, building regs, architect, and exterior weather boarding and rendering. So reckon 2k is a decent estimate for something unadorned. Although it will definitely depend on those foundations!

Nitw1t,

Is there any advantage/disadvantage of timber vs blocks? We are getting mixed opinions from builders.

mum2015 What are the builders saying? It might come down to planning permission, as in whether it fits into the style of the existing houses on the street?

Is there a reason you needed a whole new roof? I thought they could recycle/reuse the existing roof trusses etc.

Is a pitched roof more expensive than a flat roof?

@mum2015 for us it was just because it was lighter than blocks so we could go up on our 1 foot foundations. Also our main contractor has a carpentry background, so think he just preferred it! Cost is similar, I think.

What's involved in checking the foundations? I have an added complication as I only own the 1st and 2nd floors of my maisonette—the ground floor is owned by someone else.
The ground is paved all around the house so would they be able to check the foundations?
The house is made of stone with extremely thick walls and was built in late 1800s, if that is relevant. I doubt I would get planning permission for a wooden extension.

Thank you Nitw1t. One builder was completely against timber saying it doesnt provide noise insulation. Other builder is saying he could do it in timber or blockwork based on foundations. We ourself arent much concerned about noise as such as we are in a quiet area anyway.