Turning conservatory into an extension.

fandyman

Hi,

I wonder if someone has experience as when I contacted my council they did not know and told me to research online (I know - it's bad but I think they are not obliged to give advice over the phone?).

I have an old rotting conservatory with a polycarbonate roof that is opened up to the living room and does not meet building regulations at the moment. I would like to replace the old glazing and doors with new modern glazing improving the U values and also replace the polycarbonate roof with a new lightweight tiled roof with no windows. I was quoted with such roof having U value around 0.15 which should meet building regs.

I've heard somewhere (could not formally verify online yet) that to be qualified as an extension (apart from meeting the insulation regs for floors, dwarf wall and roof) the amount of glazing that remains has to be maximum 25% of the space's floor area.

Now, I am not sure if the 25% is counted as just the conservatory floor area or the entire room which includes living room area as well.

Would anyone be able to advise as this will tell me whether I will be able to achieve the effect I want (turn the existing conservatory into extension by just replacing the polycarbonate roof with a solid lightweight tiled roof with insulation and replacing the doors/frames like for like with modern glazing; I am pretty sure the dwarf wall and the floor is already insulated to meet building regs).

Appreciate any post on this,

Thanks

fandyman

Also - anyone knows what the building regs tell about this particular case and can point me to a link?

TELLIT01

Glazing being a maximum of 25% of the floor area seems unlikely.  A house down the road from us had an extension built with bifold doors the full width of the extension.  On that basis the extension would have needed to be about 25 feet deep (4 x the height of the bifolds) and it's actually 15 feet deep.

When we had a lightweight solid roof fitted to our conservatory we were told it then fully complied with building regs and we could remove the doors from the house to the 'conservatory'.  We have no plans to do so.

Doozergirl

It's such a grey area and with regulations ever tightening, I wish someone would address the elephant in the room. 

The regulations applicable should really be those for a new extension because a conservatory sits outsides of the rules like an outbuilding.  

You may get away with converting it and applying that way, like a garage, but would still have to prove adequate insulation in the floor, walls and ceiling.  

I don't think Building Control would be keen to hand out certificates on the conversion of a conservatory, which is why I don't think you can get a straight answer from the Local Authority. 

You could speak to an Approved Inspector - basically private building control.  Because they run like a normal business they have to provide something approaching customer service.  

ThisIsWeird

When we had our extension designed a few years back, it had ~4m bi-folds, two windows, and two sky lanterns. I recall the Archi pondering the 25% rule, but she explained you could subtract any existing house glass that would be covered, so that in our case included the ext house door, and any house windows that would also be enclosed by it.
As said above, it's a bit grey, and I think the BCO concerned will have an input too. They may advise, for example, adding insulation elsewhere in the house to compensate, if it's needed. I got the impression that our BCO was 'open minded', and would listen to 'reason'. And reason included explaining that it would be nuts to fixate on the amount of glass proposed, when the rest of the 1930's build was freezing...
How long do you plan to live there? If fairly long-term, I have to say that I would just do this, and forget BC.*
That's my personal take. If you, instead, do this 'properly', will they expect you to check and upgrade the foundations, for example? I know I could DIY that sort of con-conversion with no practical issues, and achieve an effective and efficient room with an 'e' value meeting or exceeding the majority of homes, and for a small fraction of the cost of having to start again with an extension.

But I cannot possibly suggest you do this...

*Yes, there could be issues when it comes to sell, but really? If it's a cosy, dry, attractive, easy to heat room, then no rational buyer will be put off. Any arguments, you just tell them they can always reinstate the ext house doors.

FreeBear

fandyman said: Would anyone be able to advise as this will tell me whether I will be able to achieve the effect I want (turn the existing conservatory into extension by just replacing the polycarbonate roof with a solid lightweight tiled roof with insulation and replacing the doors/frames like for like with modern glazing; I am pretty sure the dwarf wall and the floor is already insulated to meet building regs).

Unless you were present when the walls were built and the floor slab installed, you have no way of knowing for certain that these elements are up to spec. Building Control would certainly want to see evidence that there is sufficient insulation on top of foundation depth/width and floor slab construction.

The best thing you could do is install an exterior grade door between the house and this conservatory (outbuilding). Then budget to demolish and build a proper extension with full BC oversight.

fandyman

Btw, in case someone was wondering the build reg rules on this are here:

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1133079/Approved_Document_L__Conservation_of_fuel_and_power__Volume_1_Dwellings__2021_edition_incorporating_2023_amendments.pdf

Section 10: New elements in existing dwellings, including extensions