Party Wall
Apr 30, 2024

Party Wall – Roof Terrace

There is growing popularity in building onto roofs to create an outdoor space: a process that’s different compared to loft..

There is growing popularity in building onto roofs to create an outdoor space: a process that’s different compared to loft extensions.

Putting the leaseholder rights and freeholder costs into perspective

The right to extend onto a neighbouring roof depends on the lease wording. Flat owners usually don’t own these spaces unless they pay a premium to the freeholder. When no premium is required, you’d just have to cover the cost of a licence to alter. However, if there is a premium then it’s calculated on “marriage value”, which is like loft extensions but easier. This means you will need a valuation.

Premium Calculation

  1. Existing Valuation less
  2. Proposed Valuation less
  3. Build costs and professional fees, equals out to be
  4. Profit: 50% - 50%

Valuing Challenges

Unlike lofts, there isn’t much sales data for flats with or without terrace extensions.

This means valuers would have to make subjective uplifts based on existing value and experience. Not only do flat owners have to worry about licensing themselves but also party wall agreements and potentially paying a premium to the freeholder.

Just like Loft Extensions?

Just as we’ve mentioned earlier, legally extending onto roofs are similar processes when compared with loft extensions. It involves considering rights within leases and making calculations with some subjective assessments too! So if you ever need help or want more information on party wall regarding loft extensions and roof terraces feel free to contact our team of chartered surveyors.