Velux Windows in Battle

Fitting a Velux window into a slate roof is very similar to the way you’d install it in other roof types. All roof windows, whether a Velux-branded one or not, will come with detailed instructions for you to follow if you want to have a go at fitting it yourself. But here are some brief instructions to give you an idea of what’s involved in installing a Velux window into a slate roof:

1. After you’ve removed the Velux window from its packaging, remove the sash (the part that opens) from the frame, according to the manufacturer’s instructions.
2. Next, you need to prepare the opening for the window. You can often cut through the felt, remove one of the battens from under a slate, then slide all the slate tiles into the roof space. You should then make the cut 40-60mm wider than the window, cutting away roof timbers then replacing them with more around the opening to strengthen it.
3. The roof window’s bottom brackets need to be installed on one of the existing battens for the slate roof. One of the slate courses should line up 105mm below the top edge of the batten you use.
4. Then, measure from the top edge of the batten upwards to the height of the window plus 45mm. This is where the top installation batten should be installed, with an overhang of 100mm on each side.
5. Remove the course of slates below the window, trim any excess felt and fold it over the surrounding timber. This helps with waterproofing.
6. Add the insulation collar according to the Velux window manufacturer’s instructions.
7. Place the frame in the opening, adding the brackets according to the instructions. You’ll find that lots of roof windows have pre-drilled holes to make it easy for you.
8. Replace the sash and line up the hinges. Take a look at the opening at the bottom between the sash and the frame – it should be even along the entire width. Remove the sash again to fix the upper brackets according to instructions.
9. Add the underfelt collar for your roof window as instructed by the manufacturer, then replace any slates at the bottom. You might need to cut them to size.
10. Next, add the flashing according to the instructions, along with any parts that are not yet attached, including the hood section and top flashing piece.
11. Replace all the slates around the window, allowing 60-100mm of space between the course of slates above the window and the top of the window to allow for rainwater drainage. Then replace the sash into the frame again.
12. Add the vapour barrier on the inside of the window using the screws provided, then tape it to the existing vapour barrier to prevent moisture from reaching your roof structure.

And that’s it! If you think that sounds a bit complicated, ask a roofer or window installer to fit your roof window into a slate roof for you. You’ll get a better finish and you can be sure that you won’t get any leaks from a botched installation.

In general, no – you don’t need planning permission for a Velux window. The Planning Portal says that you don’t need to apply for planning permission to install a roof window if the following conditions are met:

• A roof window must not protrude more than 150 millimetres above the existing roof plane
No roof window or any other alteration can be higher than the highest part of the roof or stand out above the roof ridge
• Side-facing windows must have obscure glazing to protect privacy of neighbours and, if they open, they must be 1.7 metres above the floor of the room in which they are installed

You don’t need to apply for planning permission for a roof window because they are covered under permitted development rights. However, if you’re a leaseholder or you live in a building where your local authority has made an Article 4 Direction, you will have to apply. Usually, an Article 4 Direction is made when you live in a conservation area where any external home improvements could affect the character and look of the area. Luckily, there are special Velux windows that are designed to be more likely to be accepted by your local planning authority. They’re called conservation windows and, although there’s still no guarantee that they will be accepted, they are designed to look more traditional. Even if you don’t need planning permission for your roof window, you still need to follow any relevant building regulations for your local authority. The most important parts for Velux windows are section J and section L of building regulations, which refer to energy efficiency, thermal insulation and fire protection.

A Velux window is a brand of roof window, but the brand is so popular that people often use the name to describe the entire type of window. They are windows that are installed at the same orientation and ‘in plane’ with the surrounding roof, and they’re usually installed at a minimum of a 15-degree pitch. You can buy roof windows that offer completely frameless internal views for a really clean look in your loft conversion, while some come with built-in shutters.

Velux windows aren’t to be confused with rooflights which usually refers to a glazed unit that’s installed on a flat roof. It might also mean a window that’s been installed on a pitched roof out of plane with the level of the tiling.

People also confuse roof windows with skylights, which normally can’t be opened or closed and are usually smaller than Velux windows. Skylights, therefore, only let daylight into the room whereas roof windows also help with ventilation.

If you’re using your loft as a room in your home rather than simply for storage, you must have a roof window installed. Skylights won’t be enough as they don’t allow for ventilation. It doesn’t have to be a Velux window – it can be any type of roof window. Luckily, they tend to come in standard sizes and they must be CE marked if they’re sold as a roof window, so they should be easy to find.

It’s relatively simple to remove a Velux window, whether it’s Velux-branded or is another brand of roof window. Here is a breakdown of the steps you’ll need to take to remove a roof window:

1. Remove the sash (opening part) from the roof window frame. Usually there are screws in the hinges to loosen or a button to press and lift out.
2. Next, remove the tiles or slates from around the window frame along with the flashing.
3. Unscrew all the brackets around the window frame and lift out the frame.

It’s that simple! You can do all of this from inside your home – there's no need to climb on the roof. Removing the glass pane from a Velux window, for example if it has blown, is a more difficult job and should be left to a professional. It involves removing the sash from the roof window frame and then removing the surrounding parts of the sash to lift out the sealed unit. They will then place the new glazed unit into the sash frame before securing all the parts back onto the sash and fitting it back into the roof window frame.