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Do I need to worry about the height of my lantern roof?

Do I need to worry about the height of my lantern roof?

We're writing this blog post about the height of lantern roofs because this query came up with one of our customers recently. 


Aluminium lantern roof

Our customer, who was in the Manchester area, was building a flat roof extension on her semi-detached property. As part of the planning permission and building regulations process, the extension could not be higher than 3 metres tall. This is normally due to neighbour privacy concerns as well as the blocking out of natural light. Both valid reasons. 

For whatever reason, the customers' builder had built the extension a little bit higher than the customer was expecting it to be. So, when it came to sourcing her lantern roof, the customer was quite rightly questioning how high the lantern roof would be to ensure that her new extension would not go over the maximum height limit.

We took the sizes from the customer and went to our manufacturers requesting the specific height from the underside of the eaves beam to the highest point of the ridge. The sketch below demonstrates how the height of the lantern roof is determined. By inputting the width and length as well as the angle of the lantern roof, 25 degrees in this case, you can obtain the overall height of the lantern roof. In fact, for both our Korniche roof lantern and our Atlas roof lantern the vast majority are 25 degrees.


Once we had confirmed this millimetre height to our customer, she went back to her builder and was relieved after working out that after taking the timber up stands into account, there would be a spare 200mm before the maximum height of 3 metres was reached. 

This meant there was no issue and the lantern roof could be ordered.

If you have any queries about your extension and need more information, the government's Planning Portal website is a good place to start. We are also happy to help wherever we can. 

You can call us on 01622 380 121 or email us at