Planning your DIY PVCu conservatory

Adding a conservatory to your house is considered to be a permitted development, not needing an application for planning permission, subject to the limits and conditions listed below.

• No more than half the area of land around the “original house”* would be covered by additions or other buildings.
• No extension forward of the principal elevation or side elevation fronting a highway.
• No extension to be higher than the highest part of the roof.
• Maximum depth of a single-storey rear extension of three metres for an attached house and four metres for a detached house.
• Maximum height of a single-storey rear extension of four metres.
• Maximum depth of a rear extension of more than one storey of three metres including ground floor.
• Maximum eaves height of an extension within two metres of the boundary of three metres.
• Maximum eaves and ridge height of extension no higher than existing house.
• Side extensions to be single storey with maximum height of four metres and width no more than half that of the original house.
• Roof pitch of extensions higher than one storey to match existing house.
• No verandas, balconies or raised platforms.
• On designated land* no permitted development for rear extensions of more than one storey; no cladding of the exterior; no side extensions.

For your information
The permitted development allowances described here apply to houses not flats, maisonettes or other buildings. View guidance on flats and maisonettes here .
Where work is proposed to a listed building, listed building consent may be required.

* The term “original house” means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so.

* Designated land includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.

DO

• bear in mind that manufacturers often quote ‘inside cill’ sizes. This is roughly equivalent to inside of the outside skin of bricks in a cavity wall, which is neither the indoor floor size, nor the outside wall size
• your homework. You are likely to find there is a lot more to the subject than first meets the eye. Plan the size and the style that will be right for your property and purpose. Quite apart from the technicalities we suggest you start by taking some leisure trips out to garden centres and show sites. Why not stop for lunch somewhere and make light work of doing your research?
• go direct to the specialists and avoid the ‘we do everything’ superstores.
• research all the polycarbonate roofing sheet variations such as subtle effects, and most importantly, shading and heat reflection. Conservatories can get very hot and bright; so consider as a minimum a roof sheet that puts ‘sunglasses’ on your conservatory. Often choosing clear polycarbonate is probably the biggest mistake you could make.
• try and go to where the trade buys from for bits and pieces like fixings and sealants and trims, etc. Take a tube of silicone sealant for example, in a superstore at a silly price of around £7 a tube, whereas you can buy online from say Screwfix for around £2. Valuable savings can also be made on power tools and just about everything else you might need by ‘buying right’.
• make sure you take account of the requirements of drains and down pipes etc., and local soil and weather exposure conditions.
• make the new conservatory floor height end up the same level as the floors in of your home.
• remember that just as people at parties always seem to end up in the kitchen, when you have your new conservatory they will probably all end up there instead. Experience has taught us that although many people regret buying a conservatory too small, people who choose more space than they expected to use are extremely pleased that they did.
• think it all through “plan your buy – and buy to plan” and don’t EVER buy there and then on impulse, particularly from a superstore where the so-called ‘special offer’ ends in a few days. It may seem a bargain at that moment in time, but may well turn out not to be all you expected had you done more homework. For example you may find that the model on ‘such a good deal’ turns out to have inferior ‘twin wall’ 10mm polycarbonate roofing instead of the now minimum standard of 16mm triple wall, etc.

Don’t

• worry too much if your conservatory faces North, South East or West. A North-facing conservatory can be fine, and can also be used all year round if you plan for it. On the other hand, a South or West-facing conservatory needs special considerations with ventilation, solar roofing properties and blinds, as it will be bright, and get HOT.
• make the mistake of thinking a certain size “will do us”. Lay canes or a hosepipe out on the size and shape you are considering. Then put a chair inside and imagine. Remember, when you have your new cane three piece, the small table, maybe a little television, plants and whatever, it will very soon fill up. It’s a bit like cupboards, have as many as you like, you will always fill them up and not know how you could possibly cope with smaller storage space! Buying a conservatory half as big again does NOT cost half as much again, as you have already ‘bought’ one end. Think about it, a normal conservatory usually has two sides and a front, extend the two sides to make it longer, and the cost of the front is not increased. In such an instance only the roof and sides cost more, and this saving applies to the groundwork as well. Bigger pro rata always becomes better value for money, with the smallest conservatory being the most expensive per square foot.
• pick a Victorian style conservatory just because it looks ‘pretty’, and a great many people make this mistake. For the same money you can get all the good looks of a stylish roof, with the pretty, decorative and fancy top, and as a bonus, a lot more space for your money by going for a ‘square’ Georgian / Edwardian style. The chopped off corners of a Victorian style will waste you a lot of indoor useable space, and because of the complication of manufacture will be the most expensive per square foot of useable space.
• take it for granted that your immediate neighbours won’t mind. ‘Green Eyes’ syndrome can be a funny thing, so get them on your side at the outset before any problems arise such as ‘it makes my room dark’, I didn’t realise it was going to be so big’, and ‘it is closer to my fence than I expected’. If you can get your close neighbour to be happy for you, it might help avoid bad feelings, and possible other problems.
• underestimate financially. You need to budget for extras such as: drainage, skips, paving, flooring, blinds, furniture, and heating, etc.
• think that it will be as easy as the Lego or Meccano you were so good at as a child, and remember Murphy’s Law which states “if it can go wrong it will go wrong, and the more inconvenience and disruption it could cause, then the more likely it is to go wrong”.
• plan a dwarf wall that will be too high to be able to enjoy the view of the garden from inside your new conservatory, when you are sitting down. Eight Bricks above indoor floor level is about 600mm (2ft) and is a popular height; and we suggest you even consider seven bricks as possibly the optimum.

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