Roof window installation with the slate flashing (SFX)

Roof window installation with the tile flashing (TFX)

Roof window installation with the universal flashing (UFX)


Unpacking the window

Take the roof window out of the packaging. Remove the side protecting cardboard, the protecting lath from the bottom frame and the small cardboard box from the top frame. Lay the window down on its side frame and carefully, fully open the sash.

Separate sash from the frame, unlocking the hinge

To install the frame, it must be separated from the sash. Locate and press the locking mechanism on left and right hinge (they should make a click). Once the hinges are released, carefully remove the sash and place it in the box or on something protective, with the top side facing the ground.

Mark place of the bracket

Fix the bracket 50mm from the corner of the frame.

Fixing the brackets

Fix the brackets to the frame. Use two screws for each bracket.

Prepare tools

Before starting to install your roof window, make sure you have the relevant safety equipment and correct tools to hand. It will make a big difference!


Once inside the roof space, you may find that your rafters are covered in plaster board or other covering. If this is the case it is important to establish the correct place in which to make a hole. By measuring from an external wall, you will be able to accurately determine the position of the window in relation to the outside.

Marking out

Once an approximate position has been determined, it should be marked out accordingly.

Pilot hole

A pilot hole should be cut out and removed to allow for more accurate measurement.

Locate rafters

By inserting a rule either side of the pilot hole, the rafters can be located and marked out.

Rafter edge

It is useful to work from the inside edge of a rafter, so as to minimise unnecessary framing out of the window.

Removing insulation

When removing insulation, ensure that you take appropriate precautions by wearing a safety mask and, if necessary, goggles.

Removing a rafter

If it is necessary to remove a rafter, it is important that you consider the structural implications of doing so. If you are uncertain, we recommend you seek professional advice before proceeding further.

The bigger picture

It is better to remove the surrounding area of boarding so that you can see the big picture.

Support below

Be sure to support the area below where you are cutting the rafter.

Support above

... and secure support beneath the top of the rafter.

Cutting the rafter

You can then mark out, cut and remove the timbers.

Framing out

Frame out the prospective opening to the correct height and width.

Don't forget

... to allow enough height for the reveals to splay back at the correct angle.


Marking out

Mark out the opening on the underside of the roof membrane. Do not remove more than necessary - you can always cut it back more later.

Removing the membrane

Cut out and remove the membrane, exposing the battens and the roof covering.

Tiled roof

If you have a tiled roof, carefully begin to remove the tiles from inside. Make sure the area below this roof area is clear to avoid injury or damage if an accident occurs.

Composite thin tile covering

If you have a composite thin tile covering, you may need to drill and cut through to make the initial opening.

Removing nails

If you have a slate covering it may be necessary to use a slate ripper to remove the nails.

Remove the tiles

Carefully remove the tiles around the hole. Make sure that the area below the roof is clear to avoid injury or damage if an accident occurs.


Height of the bottom support batten

Determine the correct height of the bottom support batten according to the installation instructions.

Set the level

Use a spirit level to set the batten.

Fasten the bottom support batten

Fasten the batten to support the window frame.

Fasten the top support batten

Determine the position of the upper support batten according to the installation instructions. Set the level and fix the batten.

Fixing the roofing foil

Cut the roofing foil, by cutting towards the corners of the hole.

Secure the roofing foil all over.

Installing the frame

Carefully pass the frame through the opening. Place the frame onto the support batten and lay flat on the rafters.

Check frame alignment

If the frame is level, fix the bottom brackets.

Alignment check

Mount the sash to the frame to check that it opens and closes smoothly.

Checking the gaps

Check the vertical gaps between the sash and the frame.

If the sash is not paralell with the frame, you can use a crowbar to set the gap.

Check if the horizontal gap is parallel at the bottom when in a slightly opened position.

If the vertical gap is not parallel, use the black plastic wedge for the top brackets. If the frame is correctly aligned, fix the top brackets (and side brackets if exist) as well.


Remove the sash

Remove the sash from the frame.

Attaching the membrane

It is important to ensure the water tightness of a roof window against the elements. It is therefore recommended that a collar of waterproof membrane is placed around the frame. First cut the four strips that will surround the frame, starting with the bottom piece.

Staple the membrane to the frame.

Loosen the batten underneath the frame to allow for the positioning of the membrane.

When fixing the side pieces, make sure you cut and tightly secure around roof battens.

Fixing the membrane around battens

Prepare the "Y" cut next to the window to fix the foil to the battens.

Fixing the top of the membrane

Fix the top piece of membrane underneath the existing roof membrane. If the roof is counter-battened, it may be necessary to remove a small section of batten in order to slide the cover piece into place.

Cut the existing membrane over the rafter to allow the top collar piece to be slid underneath. Lift up the cut piece and fix the top collar piece underneath and to the frame. Replace the existing piece and fix.


Shaping tiles

Depending on the height of the tiles and proximity to the base of the window, it is sometimes necessary (with profiled tiles) to shape the tiles underneath the window to allow the corrugated apron to sit correctly.

Cutting tiles

Measure out the desired cut point and use an angle grinder to chamfer the edges.

Install the tiles

Install the chamfered tiles underneath the window.

Install bottom flashing

Use your hand to press and smooth the apron to the contours of the tiles.

Remove and slightly bend back the top part of it to ensure a better fit of the tiles.

Put it back to its position and smooth the apron if necessary.

Fit bottom frame covering

Fit bottom frame covering with screws.

Fix side flashing

Fit the side flashing sections. Make sure the side flashing section fits in the bottom section.

Fold the flap of the bottom flashing onto the side flashing.

Fix side frame covering

Fit side frame covering. Make sure that the side frame covering fits the flaps of the bottom frame covering.

Fix side frame coverings with screws.

Fix upper frame "U" profile

Fix upper frame "U" profile with screws.

Fix top frame covering

Fix top frame "U" profile with screws.

Fix top flashing

Fix the top flashing section. It should sit tightly over the existing top window cover part.

Fasten the top flashing section using the flappers on the side cover parts.

Secure side flashing

Fasten the flashing side parts to the battens using the clips provided.

Trimming the foam

Trim the foam around the side and top flashing according to the tile profiles for a smooth and watertight fit.

Replace the tiles

Cut the tiles above the window and next to the window if necessary to ensure the distances are in accordance with the installation instructions.

Mount the sash

Mount the sash to the frame. Check if the sash opens and closes smoothly.

Job done!

That's it! You have now installed your roof window.