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Class C – other alterations to the roof of a dwellinghouse

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What does the legislation say?

Permitted development

Any other alteration to the roof of a dwellinghouse.

Development not permitted

C.1 Development is not permitted by Class C if—

(a) permission to use the dwellinghouse as a dwellinghouse has been granted only by virtue of Class M, N, P, PA or Q of Part 3 of this Schedule (changes of use);

(b) the alteration would protrude more than 0.15 metres beyond the plane of the slope of the original roof when measured from the perpendicular with the external surface of the original roof;

(c) it would result in the highest part of the alteration being higher than the highest part of the original roof; or

(d) it would consist of or include—
(i) the installation, alteration or replacement of a chimney, flue or soil and vent pipe, or
(ii) the installation, alteration or replacement of solar photovoltaics or solar thermal equipment.; or

(e) the dwellinghouse is built under Part 20 of this Schedule (construction of new dwellinghouses).


C.2. Development is permitted by Class C subject to the condition that any window located on a roof slope forming a side elevation of the dwellinghouse must be—

(i) obscure-glazed; and

(ii) non-opening unless the parts of the window which can be opened are more than 1.7 metres above the floor of the room in which the window is installed.

Our Views on Class C

Class C is a relativity open permitted development allowance that provides for the installation of rooflights and the removal and replacement of rooftiles. The allowance is self explanatory with little room for interpretation or variation.

How to Use Class C

Class C permitted development should be explored first before engaging with a planning permission and as with other permitted development allowances it is best practice to seek a lawful development certificate.

*Correct at time of writing.

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