Category: Design
Prepared by Eng. Ahmed Fathy, Projects Manager ·
Definition
The roof annex is rooms and services built on the top floor's roof in villas. Under current residential requirements it may not exceed 70% of the floor below including stairs and lifts, and is set back at least 1.5 m from the floor edge facing streets.
Why it matters on a project
It adds a room, lounge or suite for less than a full floor, but needs good thermal insulation because its roof faces the sun directly.
Measurement and pricing
Counted in the built-up area in square metres and priced like other floors, allowing for top roof insulation.
Worked example
A 280 m² first floor: maximum annex area 280 × 70% = 196 m² including the stair.
Common mistake
Sizing the annex as a share of the plot instead of the floor below, or without the street setback, so the permit is refused.
Frequently asked questions
Can the annex be let as a separate unit?
The rules allow it under conditions, including one extra parking space.
Does the annex need special insulation?
Its roof needs good thermal and waterproofing because it is the top surface facing the sun.
Related terms
- Building coverage ratioThe share of the plot area that each floor may cover.
- SetbackThe required distance between the plot boundary and the building line.
- XPS insulation boardsRigid thermal insulation boards that absorb almost no water.
- ParapetA low wall around a roof or terrace.
Read next
Does your project need architectural design and construction drawings? Send the drawings or a short description and we reply within one working day.
Service detailsRequest a quote