Velux Windows in Waltham Cross

Velux windows actually refer to one brand of roof window, which are windows that sit in your roof space and allow light and ventilation into your loft. But how do you install a Velux window? If you’re a competent DIYer, it’s not as difficult as you might think.

You can normally install roof windows entirely from the inside, so you don’t need to get up on your roof or hire costly scaffolding. They come with detailed installation instructions, so as long as you follow them you shouldn’t have much trouble.

Before you start, you’ll need to read up on the Building Regulations and Planning Permission laws. Speak to your local Building Control department if you have any questions.

Firstly, prepare the opening by removing enough tiles or slates from the roof. There’s no need to go out on the roof – access them by cutting away the felt underneath which will give you access to the tiles and battens. Cut away one of the battens from under a tile, then you can slide all the tiles into the roof space. You’ll need to cut away the roof timbers to make the right size opening, then add more timbers to strengthen the ones that are left.

Next, remove the opening sash from the new roof window then fit the frame into the new opening using the brackets provided with the window. Then fit roof flashing between the new window and the roof so you don’t get any leaks. Then lay your tiles back in position around the new Velux window; you’ll probably have to cut some to shape which you can do with an angle grinder. Always cut them on the ground, not in position on the roof.

Lastly, fit the sash back onto the window and you’re done!

If this sounds like too much hard work, plenty of window installers will be able to help you fit a Velux window and will probably be able to provide a much cleaner finish.

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.

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.