Sunrooms And Conservatories
Sunroom Construction Belfast
Whether your sunroom is exempt from building control turns on how much of its roof is glass. CSW builds both kinds across Belfast, and settles which one you are having before the design is fixed.
Solid Roof Or Glass Roof Changes Everything
The word sunroom does a lot of work in Northern Ireland and it hides an important distinction. In the building regulations a conservatory is defined by its glazing: not less than three quarters of its roof area and not less than half of its external wall area in translucent material. Hit that and it can fall inside an exemption. Miss it, most obviously by putting a solid tiled roof on it, and it is an ordinary extension in the eyes of your district council, with everything that follows from that.
This is not an academic point. The single biggest trend in Belfast sunrooms over the last decade has been replacing glass or polycarbonate roofs with solid insulated ones, because the old ones were unbearable in July and freezing in January. That is a completely reasonable thing to want. It just moves the room out of the exemption and into full building control, and it is a great deal cheaper to know that at the design stage.
We build both. A properly detailed glazed conservatory that is genuinely usable in a Belfast spring, and a solid roofed garden room built to extension standards that you can sit in on a wet November evening. What we will not do is build the second one and let you think you got the first one's paperwork.
Glazed Conservatories
Built to satisfy the roof and wall glazing proportions, with a proper dwarf wall, insulated base and doors that thermally separate it from the house. The traditional option, and still the cheapest per square metre.
Solid Roof Sunrooms
An insulated tiled or panel roof with rooflights for daylight. Warmer, quieter in Belfast rain and usable all year, but treated as an extension for consent purposes rather than as a conservatory.
Roof Replacements
Taking a failed polycarbonate roof off an existing conservatory and replacing it with an insulated one. Popular, transformative, and a change worth checking with building control rather than assuming it is like for like.
Why CSW For A Sunroom
The Base Is Built Properly
Most failed conservatories in Belfast failed at the base. Proper foundations, insulated floor build up and a damp proof membrane rather than a thin raft on soft ground.
We Settle The Route First
Glass roof or solid roof decides your consent position. We establish it before the design is fixed rather than after the frames are ordered.
Built For This Weather
Belfast gets wind driven rain from the west for months. Detailing at the junction with the house is where sunrooms leak, and it is where we spend the time.
Joinery In House
Doors, frames and any internal fit out made by our own joiners, so the sunroom reads as part of the house rather than a kit bolted to the back of it.
Groundwork Included
Levels, drainage and the ground it sits on are our work too. A sunroom put onto ground nobody investigated is a sunroom with a cracked floor.
Garden Put Back
Because we do landscaping as well, the paving, levels and planting around the new room are finished as part of the same job.
Where A Sunroom Sits In The Regulations
Sunrooms have the clearest and most misunderstood exemption in the Northern Ireland building regulations. The definitions below come from the Building Regulations (Northern Ireland) 2012. They are general guidance rather than a ruling on your design, and your district council's building control service decides your case.
What Counts As A Conservatory
The regulations define a conservatory as a part or extension of a building attached to it and having a door giving access from the attached building, with not less than three quarters of the area of its roof and not less than one half of the area of its external walls made of translucent material.
So it is a measurable test, not a matter of what the brochure calls it. A room with a solid tiled roof does not meet the three quarters test no matter how many windows are in the walls, and it is treated as an ordinary extension.
- Three quarters of the roof area, and one half of the external wall area. Both, not either.
- It has to be attached and have a door giving access from the house.
- Adding rooflights to a solid roof does not usually get you anywhere near three quarters.
The Thirty Square Metre Limit
Class 8 of Schedule 2 covers extensions in the form of a conservatory, a porch or a carport. The floor area limit for a conservatory or carport is thirty square metres. For a porch it is only five square metres, which is much smaller than most people picture when they say porch.
Thirty square metres is roughly six metres by five. A generous sunroom, but not unlimited, and the area is measured for the sunroom itself rather than for the room it opens into.
- Meeting the glazing test but exceeding thirty square metres takes you outside the class.
- Exemption from building control is not exemption from planning. They are separate consents.
- Where the sunroom is not exempt, it is designed and approved as an extension from the outset, which is not a problem, just a different job.
Thermal Separation Where It Is Not Exempt
Where a conservatory is not exempt from the regulations, it must have effective thermal separation from the dwelling. The separating walls, doors and windows between the house and the conservatory have to be insulated and draught proofed to at least the same standard as the same elements in the existing dwelling.
In practice that means you keep a real external quality door between the house and the sunroom rather than knocking through into one open space. It is the requirement people most want to design out and the one that most often decides whether the room is a conservatory or an extension.
- Removing the separating door is usually the point at which a conservatory becomes an extension.
- Extending the house heating system into it has the same effect on how it is treated.
- Decide early. It is a design decision, not a finishing decision.
Planning And The Ground Beneath
Planning is separate and is decided by your district council under the Planning (General Permitted Development) Order (Northern Ireland) 2015. Where an Article 4 direction applies to your street those rights have been removed, and Belfast City Council has made such directions, Malone Park being a published example.
There is also a drainage question that catches people. If a public sewer runs behind the house, the NI Water protected strip is three metres or one and a half times the depth of the sewer, whichever is greater, and building over or near one without prior consent is an offence under Article 236 of the Water and Sewerage Services (Northern Ireland) Order 2006.
- Sunrooms go on the back of houses, which is exactly where Belfast sewers tend to run.
- Where building near a non critical sewer is the only option, the application goes to NI Water on form SBO A236.
- Listed buildings and conservation areas need checking before the frames are ordered.
Getting A Sunroom Right In This Climate
The Base Nobody Sees
The commonest reason an older Belfast conservatory is cold, damp and cracked is that it was built on a base that was never designed for it. Soft ground, a thin slab, no insulation and no damp proof membrane. You cannot fix that afterwards without taking the room off.
We dig out, take away soft material, and build a base with proper foundations, insulation and a membrane. It is invisible, it is a meaningful part of the cost, and it is the difference between a room you use and a room you store bicycles in.
The Junction With The House
Sunrooms leak where they meet the existing wall, and Belfast gets months of wind driven rain from the west to find any weakness. The flashing, the cavity tray above it and the way the roof abutment is formed are the whole job.
We would rather spend an extra day on that detail than come back to a damp patch on the inside of the original wall in February. Doing it properly also protects the existing house, which matters more than the new room.
Heat, Glare And Actually Using It
A fully glazed roof is spectacular in April and punishing in July, and cold enough in January that the door stays shut. That is the honest experience of most older conservatories here, and it is why solid roofs have taken over.
The middle path is a solid insulated roof with well placed rooflights: most of the daylight, a fraction of the heat swing, and a room that is genuinely usable through a Northern Ireland winter. It costs more and it changes the consent position, and for most families it is the right answer.
Replacing An Existing Conservatory Roof
Swapping a tired polycarbonate roof for an insulated panel or tiled one is one of the best value jobs we do. It changes how the room feels immediately.
It is not, however, a like for like repair. The new roof is heavier, so the existing frames and base have to be capable of carrying it, and taking the roof below the three quarters translucent threshold changes how the room is classified. Both are worth establishing with your council before the old roof comes off.
How A Sunroom Job Runs
Decide Glass Or Solid
The first real conversation, because it decides the consent route, the cost, and whether the room is usable in January. Everything else follows from it.
Check The Ground And Drains
Levels, ground conditions and where any public sewer runs. Sunrooms go on the back of the house, which is where Belfast drainage tends to be.
Consents
Either confirming the design sits inside Class 8, or making a proper building control application as an extension. Planning too where the property or the street requires it.
Base And Drainage
Dig out, foundations, insulated floor build up, membrane and any drainage alterations. The stage that decides whether the room lasts.
Frame, Roof And Abutment
Structure up, roof on, and the junction with the existing house flashed and trayed properly. Then glazing and doors.
Finish And Landscape
Internal finishes, floor, electrics where wanted, and the paving and levels outside made good so the room opens onto something finished.
Frequently Asked Questions
What actually counts as a conservatory in Northern Ireland?
A measurable test rather than a description. The regulations define it as an attached part or extension with a door giving access from the house, with not less than three quarters of its roof area and not less than half of its external wall area in translucent material. A solid tiled roof fails the roof test regardless of how much glass is in the walls.
How big can a sunroom be before it needs building control approval?
Class 8 of Schedule 2 to the Building Regulations (Northern Ireland) 2012 sets the floor area limit for a conservatory at thirty square metres, roughly six metres by five. Exceed that and the exemption does not apply even if the glazing proportions are met. A porch under the same class is limited to just five square metres.
Does a solid roof mean I need building control approval?
In practice, yes. A solid roof takes the room below the three quarters translucent threshold, so it is not a conservatory for these purposes and it is treated as an ordinary extension. That is not a reason to avoid a solid roof, it is simply a different application and a different specification from the start.
Why do I have to keep the door between the house and the sunroom?
Where a conservatory is not exempt it must have effective thermal separation from the dwelling, with the separating walls, doors and windows insulated and draught proofed to at least the standard of the same elements in the existing house. Removing that door is usually the moment the room stops being a conservatory and becomes an extension.
Can I replace my old polycarbonate conservatory roof?
Yes, and it is one of the most transformative jobs we do. Two things to establish first. The new insulated roof is heavier, so the existing frames and base must be able to carry it, and taking the roof below three quarters translucent changes how the room is classified. Both are worth raising with your council before the old roof comes off.
Will a glass roofed conservatory be usable in a Belfast winter?
Honestly, not comfortably. A fully glazed roof loses heat rapidly and swings hard the other way in summer. That is the lived experience of most older conservatories here and it is why solid roofs with rooflights have taken over. We would rather tell you that at the quote than have you discover it in January.
Is there a drainage issue with sunrooms specifically?
Often, because sunrooms go on the back of the house and that is where Belfast public sewers tend to run. NI Water's protected strip is three metres or one and a half times the depth, whichever is greater, and building over or near a public sewer without prior consent is an offence under Article 236 of the Water and Sewerage Services (Northern Ireland) Order 2006.
Why do old conservatories get so damp?
Nearly always the base. A thin slab on soft ground with no insulation and no damp proof membrane will be cold and damp for its whole life, and there is no fix short of removing the room. It is the part of the quote nobody looks at and the part that decides whether you use the space or store things in it.
Where do sunrooms usually leak?
At the junction with the existing house, where the new roof abuts the original wall. Belfast gets months of wind driven rain from the west and it finds any weakness in the flashing or the cavity tray above it. Getting that detail right protects the existing house as much as the new room, which is why we spend the time on it.
Do I need planning permission for a sunroom?
Sometimes, and it is a separate question from building control. Permitted development for a dwellinghouse comes from the Planning (General Permitted Development) Order (Northern Ireland) 2015 and is decided by your district council. If your street is under an Article 4 direction those rights are removed, and listed or conservation area properties need checking before frames are ordered.
More Building & Construction From CSW
Get Your Free Quote Today!
Tell us how you want to use the room and in which months, and we will tell you whether you want glass or solid and what that means for the approvals. No charge for the visit and no obligation afterwards.
- Call us: 07703 433214
- Email: Cswbuild@gmail.com
- Location: Belfast, Northern Ireland