Planning Permission

You will not normally require any planning permission to install roof lights or skylights, this is because the permitted development rules, already allow for roof alterations so long as they follow these conditions:

  • An alteration to a project should be no more than 150mm from the existing roof plane.
  • No alteration is to be any higher than what the highest part of the roof is.
  • Any side facing windows are to be obscure-glazed; any opening should be 1.7m above the floor.

Building Regulations

It may appear to be obvious for some people, but planning permission and building regulations are two entirely separate things. Even if planning permission for a rooflight/skylight installation isn’t required, building regulations can’t be ignored. Any building or structural modification work, by law, must comply with building regulations.


A rooflight is a window that is addedto a pitchedor flat roof. When having a sky/roof light installed, it will usually require the structure of the roof being altered, to create an opening. People usually have skylights installed to give more light to a rooms or space within their home. Approval under building regulations will generally only be required for the installation of a new rooflight for any of the following reasons:

  • The roof will need to be able to take the weight of the new skylight, If the roof can’t do this, then it will be required to be strengthened.
  • Any skylight that is installed, will need to show that it has enough insulation against any heat loss, for example; that isis energy efficient.
  • If the skylight is close to a boundary, the fire performance of the skylight will need to be taken into consideration.


When you have a skylight installed in a roof, it generally entails cutting part of one or more of the roof’s rafters or joists away. The ends that have been cut will need to have new support introduced –this can normally be accomplished by joining two pieces of timber together, which go across the new opening.

The adjacent rafters or joists to which these trimmers are fixed may also need to be strengthened as they will be supporting the load transferred from the cut rafters or joists.  This strengthening can be achieved by fixing a new rafter or joist to them which must also run the full length.

Weather Proofing

Once a skylight has been installed, the edges (which is where the skylight meets the roof), will require weather proofing, this includes the glass of the rooflight itself too. This is commonly carried out by using lead flashing.


The room that the skylight is installed in, will need to be ventilated.Ventilation can be achieved by using the skylight for both rapid, and background venting.

Why not get in contact with an expert at Ultrasky today, one of their team will guide you through the process of getting your home installed with skylights. Think of all the benefits it will bring into your home.

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