Conservatory planning, construction and problems

Conservatories are a relatively simple and cost effective way of extending your home. There are so many styles available to choose from, in different materials such as timber, aluminium or uPVC. The more luxurious your choice and size or conservatory, the more the price will vary and so will the range of problems that may occur.

We often receive calls from people asking for advice on their decision to build a conservatory. Do they need a party wall agreement, or planning permission? Are there certain building regulations to follow? And we also get calls from people when things have gone wrong and their conservatory has problems.

Here, we explain the common questions about building a conservatory and highlight what to look for when things aren’t right.

Common conservatory questions

First, Planning. Adding a conservatory to your house is considered to be permitted development. You don’t need to apply for planning permission, subject to certain limits and conditions which are listed on the planning portal.

The next logical question is ‘Do I need a Party Wall agreement for a conservatory?’

Well, is your conservatory being built on the boundary line or near a neighbour’s building? Are you excavating near your neighbour’s property? If so, you may need a party wall agreement. Take a look at our Party Wall pages for more information, and if you’re still unsure, give us a call.

Problems with conservatories
Is your conservatory being built on the boundary line or near a neighbour’s building? If so, you may need a party wall agreement.

Which leads nicely onto building regs. As far as these are concerned, a conservatory is defined as ‘a building that has not less than 75% of its roof area made of translucent material and not less than 50% of its total wall area made of glass or translucent material’. If it doesn’t meet these criteria then it will need building regulation approval. However, most conservatories built at ground level and that are less than 30 square metres in floor area can be exempted, unless:

  • there are internal doors between the house and conservatory; and/or
  • the main house heating system extends into conservatory.

Don’t forget, if you are making a structural opening between the house and the conservatory then this will need building regulation approval. Building regs rules will also apply to any electrical works and glazing, but usually these will be self-certified by the tradesmen if they are members of a competent persons scheme – usually NICEIC for electricians and FENSA for glazing.

Conservatory construction considerations

There are some construction issues to bear in mind when building a conservatory, though your installer should be fully aware of these.

One thing you really should consider is the materials you use in the construction of your conservatory. Different materials affect the light, temperature and maintenance – take time to think about this and talk with your installer. It might be worth spending a little more to get the finish you truly desire. For example, in terms of light and solar heat gain (how hot it will get when the sun shines), you might consider using thermally efficient glass in your new installation. It’s more expensive, but it helps keep a conservatory cool, usually with a special coating on the outside to reflect light. Using glass for the ceiling, instead of polycarbonate can also help, as well as ensuring there are plenty of window openers.

How fussy are you about clean windows? It can be more difficult to clean the windows on your house above your conservatory. You may want to consider this before building. Can you, or your window cleaner, access those top windows to keep them clean once a conservatory is built? You can have your conservatory roof finished in self-cleaning glass (but it costs more).

You should also consider use of snow guard on gutters above a conservatory. The last thing you want is a build-up of snow in your gutters above and for them to break, crashing down on top of your conservatory.

The conservatory will need a base and foundation so expect some ‘dirty’ building work. It’s not just a case of attaching it to the side of your house. There will be digging, concrete, hardcore and cement, before the brickwork commences. And if you need to excavate for a foundation next to a garden wall or near your neighbour’s conservatory or house then party wall rules might apply.

Depending how your conservatory is built it will need ties in the roof. If it’s very wide, or has heavy glazing in the roof then the ties will help prevent the base of the pitched roof pushing outwards. Many conservatories have a tie bar anyway to offer roof support.

Always consider the most appropriate form of guttering and rainwater drainage. What are the gutter arrangements at the abutment to the house? Where does rainwater flow? Will it connect with the water drainage system of your house? Make sure this is clear and that you use a reputable company who know what they are doing. We’ve had many clients call us with water leakage problems where gutters are inappropriately or incorrectly fitted.

Post-build complications

So, once you have your beautiful conservatory built, there are some common conservatory problems you many encounter. There will always be settlement so don’t be too upset if after it has been plastered and you’ve decorated it all with your stunning cornflower blue, then small cracks appear. Building needs a lot of water and this will dry out, especially when the conservatory gets warm and this too causes cracks.

However, settlement can be caused where the base or slab is not properly formed. This can cause movement between the house and the conservatory. The conservatory may move separately to the house, but in unlucky circumstances it might pull the house itself causing structural problems there. It’s important to make sure that the base is of proper depth. We think it should have at least 200mm of hardcore with sand over before thinking about a damp proof membrane, insulation, a concrete slab and possibly a screed. If the slab and excavation is less than 350mm deep, then you should be concerned. A wall foundation will need to be at least 600mm deep. Different ground conditions will need different slabs and footings.

You can experience water penetration, especially at the abutments of the main wall and conservatory. We would recommend proper lead flashing, not flashband (a self-adhesive flashing tape often used in cheap conservatories), in order to prevent this.

Doors can become misaligned, or start jamming. This is often caused by the fluctuation in temperature and they may need some simple adjustments, but it can also depend on the budget you had for the doors. Unfortunately, the less you spend the more likely this type of problem will occur.

Leaking roofs are a common problem with conservatories. The usual cause is a failed seal, or the air vents. They’re easy to repair. Just contact your installer if it’s still under warranty, or seek the help of a professional to get it fixed.

And finally…

Make sure that whatever you do, you have your conservatory fitted by a Glass and Glazing Federation installer and that you have a decent warranty with it. Always read the small print.

If you do discover a fault, or have any problem with the conservatory, the first thing you should do is contact your installer. But if they are unhelpful or dispute the complaints on their workmanship, a Chartered Surveyor may be able to help you get the resolution you need.


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