Originally appeared in Homelife, February 2012

Picture the scene – the carpenter has finished clearing away his tools, your furniture has just been delivered and you sink into an easy chair with a glass of chilled chardonnay to admire your new conservatory like a modern day Kubla Khan – when suddenly there is a knock at the door. There stands your rather difficult neighbour clutching a sheet of paper demanding you remove 'the carbuncle of a conservatory immediately'. The stuff of nightmares? Perhaps – if you do not fully understand what you may or may not do with your own property there is a real risk that all your hard work, patience and money could go to waste.

For example, have you considered the position of the extension in relation to the boundaries to your land, or are you about to build in breach of a restriction? When you purchased your property your lawyer or conveyancing manager should have discussed the boundaries of the property with you. You should therefore have a reasonable grasp of where the boundaries to your land are located.

However, over and above the location of the boundary line there may be additional factors to consider such as whether you have an obligation to leave a 'relief' (that is to say an offset) between the boundary to your land and any construction on it. This means leaving at least 16½ inches (1½ Jersey feet) between your new construction and the boundary line. In a case where your neighbour owns the existing boundary enclosure with its own relief, this will mean that there will be a distance of 2'9" (3 Jersey feet) between the existing enclosure and your new construction.

It is worth bearing in mind that if your contract of purchase confirms a right for you to join onto a neighbour's wall then you are not obliged to leave a relief. In addition, your contract of purchase may indicate that a wall is party owned in which case you may build up the boundary wall.

It is important to bear in mind that it is not only the foundations of a construction which may breach a relief. The relief applies to the whole construction including the gutters, downpipes and fascia boards which overhang the relief.

There are also restrictions as to where windows may be placed in relation to the boundary. Unless your contract of purchase gives permission for the placement of a window within three Jersey feet (2'9") of the boundary, a neighbour may force its removal and blocking up if it is placed within that distance. It is usual when a new estate of houses are sold off for the appropriate provisions to be made for the houses and windows to remain as constructed but these provisions would not necessarily cover any extensions to the property.

There may also be restrictions in your contract of purchase on where you may build on your land. For example, it is not unusual for contracts on an estate of houses to restrict construction on the front facade of the houses in order to maintain the design integrity of a development.

If you find you have constructed an extension in breach of a relief or other restriction then you would need to approach your neighbour (or potentially the original developer of the estate) and ask them to be party to a contract to give their permission for the offending structure or window to remain.

Often problems with construction are only discovered when a party is selling their property and there might be a delay in the completion of a sale, whilst the vendor's lawyer negotiates with a neighbour to arrange for the appropriate contract to be passed. At the very least you could wind up paying their legal fees and might even end up paying your neighbour additional compensation to have them consent to the extension remaining.

In short, therefore, we strongly recommended that anyone considering an extension to their property look carefully at their contract of purchase and contact a lawyer to discuss their proposals before they submit any plans for approval. Otherwise your 'stately pleasure dome' could end up being a 'home from hell'.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.