I Took This “Upside Down House” Idea and Tested the Real Costs
CARL Architect
97,212 views
NEED HELP WITH YOUR OWN HOME?
I offer two ways to work with me:
HOME IMPROVEMENT WORKSHOP
A private live online design session where we talk through your home, test possibilities and draw over your plans together.
https://www.carldesign.co.uk/home-imp...
RECORDED DESIGN REVIEW
Send me your plans, photographs and up to three focused questions. I’ll review everything and send you a personal recorded response explaining what I see and what you could explore.
https://www.carldesign.co.uk/recorded...
Both services are suitable whether you already own the property or are considering buying it.
In this follow-up to the Upside-Down House concept, I take the original idea and price it properly.
Original Design Video here: I Had to Turn This House Upside Down to Ma...
Download the CAD floor plans here: https://subscribepage.io/uTEokH
In the first video I explored whether flipping a tiny terraced house upside down — with bedrooms below and a roof-terrace living space above — could actually work. This video goes a step further and looks at the real-world implications:
• How planning might view a roof terrace
• What structural changes would actually be required
• How much storage can realistically be built into a small house
• And, crucially… how much it might cost
I speak to a structural engineer about the roof and ceiling implications, and to a builder I’ve worked with for over 10 years to arrive at a budget cost for the project.
The costs are broken down into broad elements (roof, services, kitchen, bathroom, terrace etc.) before being pulled back together into a single figure — because that’s how projects like this are typically priced in reality.
This is design refinement, not a first sketch. Big ideas don’t arrive fully resolved — they’re tested, questioned, adjusted and costed as they develop.
💷 Costs & assumptions
Costs shown are UK (South of England), 2025
Figures include VAT
Pricing assumes one builder undertaking the full job, not individual trades priced separately
Built-in furniture such as pull-out drawers, nook beds etc. are assumed to be DIY or bespoke joinery, and are not included
A base “like-for-like refurbishment” cost is discussed to show what you might spend even without the upside-down concept
⚠️ Important disclaimer
This video is for information and discussion only.
Cost figures are indicative budget estimates, not quotations
Structural discussion is general advice, not site-specific engineering
Do not remove ceilings, alter roofs, or undertake structural work without professional advice specific to your property
Planning outcomes vary by location and authority — nothing shown guarantees consent
Always consult a qualified architect, structural engineer, and builder before carrying out any work.
20 Comments
No allowance for stripping out, skips, waste disposal.
I work in construction and have a tame builder mate who installed a similar sized kitchen for me including appliances for £7.5k......in 2000!
Mark thinks there will be no need to allow for recoving the roof. You will need to at least do a major overhaul but there is a 90% chance a complete strip and recover will be required. You will need scaffolding for the roof works which will need to be stripped before the steel is craned in, insulated, velux rooflights and new guttering and down pipes. You might get new slates for £6k but to think you will get it all done for that is insanity. At least double it.
No allowance for any works to the stairs.
The cheapest LVT flooring (luxury vinyl tile) is £30/ m2 excluding delivery, surface preparation (ply on an old Victorian planked floor) and laying. Mark only allows £40 all in. Not a chance
5 new UPVC windows will cost £4k to install. You have a structurally glazed Crital door and structural glazing to the bedroom, 3 external doors, a large double sliding door onto the terrace, and 4 internal doors on the ground floor. Structural glazing is silly expensive. You need to budget £10k for this.
You quote £3600 for flooring and decs with flooring being £40/m2. The building is approx 100m2 excluding the roof terrace so that is £4k there alone with nothing left for decs. New electrics will need chasing in and walls will need replastering. You won't achieve the smooth finish your 3d renderings show unless you hack off and replaster throughout. Even reskimming will cost £500 / room. You make no allowance for that.
No allowance for external redecoration or repointing, or works to the small garden area or shed.
If the contingency of £7k includes fees then the party wall award on both neighbours will be a minimum of £3k (ex VAT) if there aren't problems.
To do this properly this is a £100k job any day of the week.
I Took This “Upside Down House” Idea and Tested the Real Costs
CARL Architect
97,212 views
NEED HELP WITH YOUR OWN HOME?
I offer two ways to work with me:
HOME IMPROVEMENT WORKSHOP
A private live online design session where we talk through your home, test possibilities and draw over your plans together.
https://www.carldesign.co.uk/home-imp...
RECORDED DESIGN REVIEW
Send me your plans, photographs and up to three focused questions. I’ll review everything and send you a personal recorded response explaining what I see and what you could explore.
https://www.carldesign.co.uk/recorded...
Both services are suitable whether you already own the property or are considering buying it.
In this follow-up to the Upside-Down House concept, I take the original idea and price it properly.
Original Design Video here: I Had to Turn This House Upside Down to Ma...
Download the CAD floor plans here: https://subscribepage.io/uTEokH
In the first video I explored whether flipping a tiny terraced house upside down — with bedrooms below and a roof-terrace living space above — could actually work. This video goes a step further and looks at the real-world implications:
• How planning might view a roof terrace
• What structural changes would actually be required
• How much storage can realistically be built into a small house
• And, crucially… how much it might cost
I speak to a structural engineer about the roof and ceiling implications, and to a builder I’ve worked with for over 10 years to arrive at a budget cost for the project.
The costs are broken down into broad elements (roof, services, kitchen, bathroom, terrace etc.) before being pulled back together into a single figure — because that’s how projects like this are typically priced in reality.
This is design refinement, not a first sketch. Big ideas don’t arrive fully resolved — they’re tested, questioned, adjusted and costed as they develop.
💷 Costs & assumptions
Costs shown are UK (South of England), 2025
Figures include VAT
Pricing assumes one builder undertaking the full job, not individual trades priced separately
Built-in furniture such as pull-out drawers, nook beds etc. are assumed to be DIY or bespoke joinery, and are not included
A base “like-for-like refurbishment” cost is discussed to show what you might spend even without the upside-down concept
⚠️ Important disclaimer
This video is for information and discussion only.
Cost figures are indicative budget estimates, not quotations
Structural discussion is general advice, not site-specific engineering
Do not remove ceilings, alter roofs, or undertake structural work without professional advice specific to your property
Planning outcomes vary by location and authority — nothing shown guarantees consent
Always consult a qualified architect, structural engineer, and builder before carrying out any work.
You can now work with me in two ways:
→ Talk it through with me in a live Home Improvement Workshop:
https://www.carldesign.co.uk/home-improvement-workshop?utm_source=youtube&utm_medium=pinned_comment&utm_campaign=services
→ Send me your information and receive a personal Recorded Design Review:
https://www.carldesign.co.uk/recorded-design-review?utm_source=youtube&utm_medium=pinned_comment&utm_campaign=services
Both are designed to help you get unstuck and understand what your home could become—whether you already own it or are considering buying it.