Q We live in a top-floor flat in a terraced house in South London. Most of the neighbours have already converted their attics into an extra bedroom by putting in stairs and dormer windows. Our lease says that we own the loft above the flat. Can we do a loft extension?

A The general principle is that a lease of a bare piece of land includes the right to use the airspace above. A leaseholder is entitled to stop people putting up adverts, telephone wires or scaffolding over their property. It has even been suggested that such a leaseholder can use the whole of the space from the centre of the earth to the heavens - but there is case law which says unequivocally that the leaseholder cannot stop aircraft flying overhead. This rule obviously cannot apply entirely to leases of flats without some amendment. However, the Court of Appeal applied the general principle to a loft conversion of a top-floor flat in North London in the case of Davies v Yadegar. The court decided that the lease (which specifically included the roof and roof space) also included the air above Mr Yadegar's flat and that he should be allowed to put in dormer windows.

However, there are three things that you will have to be careful about before you go ahead. First, you will have to be 100 per cent sure that your lease includes the roof as well as the loft space. Where there is a block of flats, the roof usually will not be included in the lease of any particular flat - it will usually be owned by the freeholder. In such a case, the leaseholders of the top-floor flats usually will not have the right to extend upwards. The Court of Appeal in the Yaxley case specifically cautioned that its decision applied only where the leaseholder owned the roof.

Secondly, most leases do not allow alterations that involve changing the outside of the property without the freeholder's permission. If consent is required, the Landlord and Tenant Act 1927 says that the freeholder can object only on reasonable grounds - but you must still ask for permission first.

You also need to check whether planning permission is needed. Failure to obtain planning permission can not only lead to action by your local authority but it will also almost certainly be a breach of the terms of your lease as well.

The writer is a barrister at Tanfield Chambers. E-mail your questions to: property.consumer@thetimes.co.uk

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