On conservatories

The conservatory industry exists in its own little bubble. It’s obviously related to mainstream building, to home improvements and the world of extensions, but it is the province of specialists who, by and large, don’t do much else. There are over 200,000 new conservatories built in the UK each year — that’s a phenomenal number, more than the number of new homes being built.
The question is why? There are one or two things that conservatories have going for them which can make them a very cheap way of gaining extra space. One is that they very rarely require planning permission. Another is that they very rarely require building regulations. Thus the two big administrative heavyweights, designed to send us bonkers, are, at a stroke, banished from the world of conservatories. You can just go and order one and you don’t have to bother with red tape. Of course, Britain being what it is today, there are numerous exceptions to these rules. “Very rarely” doesn’t mean “never.”
You don’t need planning permission if the conservatory falls within the permitted development rights of the house. For a look at what these might be, type "PD Rights" into the search field and follow the link. If your house has already used up its PD rights or hasn’t got any, then you will need to apply for PP.
The situation with building regs is rather more complex. Most conservatories don’t need to trouble the building control department but there are some aspects of conservatory building which will come into the building regs ambit, forming a nice grey area (shall I? shan’t I?). To avoid having to apply for building regs:
• the floor area must be less than 30 sq m (though it’s only 8 sq m in Scotland)
• the conservatory must not form part of the ‘heated envelope’ of the house – i.e. there must be separating doors
• the roof is at least 75% glass or polycarb sheeting
• the walls are at least 50% glass or polycarb sheeting
• the conservatory must all be at least 1m from the garden boundary
• it must be at ground level
Now that does cover the great bulk of bolt-on conservatories, but it might not cover yours. But even if your planned conservatory falls outside building regs, you are still required to comply with the safety glazing directives (in Part N of the building regs) and also if you have any electrics installed, it becomes a notifiable event, if not carried out by a competent electrician who can sign it all off against his insurance. There is also potentially a nasty little problem to do with conservatories being located under means-of-escape or egress windows, which some local authorities seem to be more concerned about than others. This is a complicated area because first-floor windows have only had to be egress since 2002, so it cannot logically be applied to the 98% of the UK housing stock that was never built with egress windows. It is the sort of grey area where you might want to think about installing mains-operated smoke detectors in the house, which is in fact the single most effective fire safety measure you can make to an existing dwelling.
There is no requirement for conservatories to be double-glazed (unless you want to build one in the Irish Republic). However, if you want to make the conservatory a “walk-through” feature with no dividing doors, then the price you have to pay is that the conservatory will be assessed as part of the normal living space and it will have to meet exacting energy efficiency standards, which will certainly include double glazing.
Why bother?
So much for red tape. The bigger question is, why bother to fit a conservatory at all? If you like gardening, why not build a greenhouse? If you like light, why not build an extension with lots of glazing? If you like sunbathing, why not buy a timeshare in Tenerife? Or a sunlamp? Why are there 200,000 conservatories added onto existing homes each year? Could it be that, for most people, it’s seen as a cheap way of getting an extension? Yes, I think it just might. For whilst there are the odd aspirational companies around like Amdega who sell a very upmarket product at prices way in excess of normal extensions, the great bulk of the conservatory market is made up of the sort of thing you can pick up at Wickes for under £2,500. It’ll be built-up off a brick plinth, itself built-up of pretty minimal foundations, and it’ll be stuck onto the back of the house with a few screws and the roof will have a stuck-on flashing connecting it to the main house. If it leaks, it’s really not a disaster, and if there is a little subsidence, then that won’t really matter that much either. In fact, this sort of conservatory is a throw back to how we used to build in days of yore, and how they build shanty towns today in Brazil. Bash it up – it’ll do.
Now it’s easy to be sniffy about this sort of building, but it does have a place. If you haven’t got a lot of dosh and your house is just too cramped, then a bolt-on uPVC conservatory may be just brilliant for you, especially as you don’t have to be bothered with the boys from the council crawling all over your house. You know it’s never going to feature on Grand Designs, so what?
The upmarket options
There is a yawning gulf between these bolt-on plastic extensions (95% of the market) and the beautiful one-off designs you see in the magazine adverts. An up-market conservatory will cost rather more to build than a conventional extension. There is a surprising correlation with the kitchen market where you can easily put in a fitted kitchen into a modest house for under £3,000, but the top of the range can cost more than ten or twenty times as much. For a start, if the conservatory design tips into the zone where you have to have building control involved — and it will if it is large or there is no thermal break between the house and the conservatory — then the full weight of the energy efficiency regs comes into effect. This loosely means that glazing to have a maximum U value of 1.8, which translates as argon-filled, low-e coatings and large air gaps. The cost of the glazing jumps from around £25 per sq m up to over £80 per sq m, which makes it more expensive than conventional walling or roofing materials. Having spent all this money, you then have to think about having a very cold space in winter (do you provide heating?) and a very hot space in summer (blinds? ventilation?). You can, of course, choose to not use your conservatory when it’s either too hot or too cold or too dark, but that’s an awful lot of times for a room that’s so expensive to build, and it makes little sense when you consider the size of the initial investment.