Thinking of Adding a Shed or Garage to a Cross Lease Property? Read This First

Adding a garage, carport, or extra living space can be a great way to improve your home. But if your property is held under a cross‑lease title, the process is more complex than it first appears. Before you pick up the tools or speak to a builder, it’s important to understand how cross‑leases work — and what’s required to avoid costly mistakes.

What is a Cross‑Lease, really?

A cross‑lease property is one where several owners jointly own the underlying land, while each owner also leases their individual home (known as a “flat”) from the other owners. These leases are typically for very long terms — often 999 years.

Most cross‑lease titles come with a flats plan, which shows:

• The footprint of each flat, and
• Defined areas of exclusive use (for example, a backyard that only House A may use).

There is often also a common area, such as a driveway or shared parking space, which all owners use together.

Occasionally, a flats plan does not clearly define exclusive use areas. In that case, apart from the land directly under the homes, everything is treated as common property. While this is less ideal, it does not automatically mean the title is defective.

Why alterations are tricky on a Cross‑Lease?

The key thing to understand is that any structural alteration to a cross‑lease property affects all owners’ interests in the land. Because of this, changes usually require consent from multiple parties — not just council.

If you want to add for example, a garage, shed, or even a second dwelling, you will usually need:

1. Written consent from the other cross‑lease owner(s)
2. Any required council or building consent
3. Your lender’s consent, if the property is mortgaged
4. An updated flats plan, prepared by a surveyor and registered on the title (in many cases)

Skipping any of these steps can cause serious problems later.

Does the type of structure matter?

For example, adding a sunroom or enclosing a porch or extending the existing flat usually changes the external dimensions of the building. Where the external dimensions of the building are altered, you will need all the consents set out at points 1-4 above.

Detached buildings: is it any easier?

Sometimes — but not always.

If you are building a stand‑alone garage or shed that is:

• Not connected to the flat, and
• Does not increase the footprint of the flat shown on the flats plan

…then you may not need to update the flats plan, provided all other required consents are obtained.

However, if the new garage is connected to the flat, or alters the dimensions shown on the existing plan, an updated flats plan is required.

The risk of a defective title

One of the biggest pitfalls with cross‑leases is creating a defective title.

If alterations change the external dimensions of the flat and the flats plan is not updated, the title becomes inaccurate. This often only comes to light when the property is being sold — at which point:

• A purchaser may refuse to settle
• Banks may decline lending
• You may be forced to commission a new survey and update the title under time pressure

Updating a flats plan later can be expensive and time‑consuming, especially when neighbouring consent is no longer easily obtained.

 The takeaway

Making external improvements to a cross‑lease property is absolutely possible — but it requires planning, consent, and the right professional advice. What seems like a simple garage today can turn into a major legal issue tomorrow if the title is not kept accurate.

If you’re unsure whether your proposed work will affect the flats plan or require consents, it’s best to get advice before construction begins. That small step can save you significant stress, cost, and delay in the future.

This article is current as at the date of publication and is only intended to provide general comments about the law. Harkness Henry accepts no responsibility for reliance by any person or organisation on the content of the article. Please contact the author of the article if you require specific advice about how the law applies to you.