We're thinking of attaching something to the back of our house to extend the living area, and can't decide whether to install a conservatory or a single-storey extension.  So here are some thoughts about conservatories, seen in the Daily Telegraph this week:

1 Use 
List the ways you'd like to use your conservatory as they will all affect the final design.  Do you want to entertain, relax, garden, propagate or all these?  Is it to be an all-year-round room?  
These affect the design, construction, layout and proportions, not to mention where the conservatory would be best sited.

2 Design
You want to end up with a well-proportioned conservatory and it's important to provide an effortless link between 'inside' and 'outside'.  
This is the stage to choose what you're going to put inside the conservatory and the layout of those items.  Consider the views from the conservatory and areas best for light.  
Traditionally it was thought that the style of conservatory should echo the style of your home but now it's considered that a contemporary design  often makes minimal impact and so is preferred.

3  Aspect

A south-facing aspect may seem the obvious choice, but the sun's rays become magnified and can burn plants through glass.  Also, air becomes hot and dry, and environment that no person or plant enjoys, so blinds will be an essential addition.


4  Glazing
A conservatory relies on its glass to operate to capacity.  Solar-controlled glass can help minimise the temperature of the room and control glare.  
In a north-facing conservatory, low-emissivity (low-E) glass will reduce heat loss.  
Architecturally speaking, lanterns and coloured glass can create interest, but best to try and avoid fussy effects or, for example, replicating the details of your property's windows.  
Keep things simple as a conservatory is essentially a glasshouse in its own right, not an extension of your house.  
Aim to ensure complete transparency whilst looking out.  Neutral glass won't reflect furniture, to allow a clear view, and a wonderful link to the landscape beyond.

5  Ventilation
To ensure a comfortable atmosphere it's important to have a well-designed ventilation system, although with British weather it's unlikely that air-conditioning will be really necessary.  
Roof vents are essential in releasing a build-up of hot air.  Low-level air can be drawn in through doors or low vents, with hot air rising naturally to be released through roof venting to provide cooler atmosphere.  There are manual or automatic systems, the latter of which are very useful for busy people - or for keen gardeners.  But beware, if they malfunction and stick the rain may get in or your plants may fry!


6  Temperature

The temperature at which you heat your conservatory is perhaps the most crucial decision in terms of how you will use it.  

Your choice is not just about people - temperature dictates the plants that you grow.  Heating a conservatory year-round to the same temperature as your house (59F-70F/15C-21C), will limit your plants to the tropical spectrum.

Unheated conservatories are ideal for overwintering citrus and borderline-hardy plants, especially if you cover them with fleece.

Even if you don't heat your conservatory it should be usable for about nine months of the year, providing you dress suitably for it.  We used to have our lunch in the conservatory nearly every day of the year, donning fleeces in the winter months to enjoy our soup, bread and cheese.

7 Planning regulations

Generally, most conservatories are within permitted development rights, so long as certain size and height conditions are met.  

If you life in a conservation area, Area of Outstanding Natural Beauty, national park or a World heritage Site there are further conditions.  

Visit the planning portal (planningportal.gov.uk) for the full list of conditions or check with your local authority.

Many specialist conservatory designers and manufacturers will deal not only with design, manufacture and installation but also any planning permissions.

Some very interesting points are raised here, now I'm off to do the same investigation re having a brick extension.  I understand that even if planning permission is not needed for an extension, that building regulations are necessary. 

Something not covered here is the relative cost of a conservatory compared with a brick-built extension - and how much value, if any is added to the property.

According to the moneysavingexpert forum (http://forums.moneysavingexpert.com/showthread.php?t=317959)the cost of building a single storey extension is about £1,000 per square metre.  So for our proposed 4m x 2.5m extension that should work out at about £10,000, plus extras such as planning and building regs.