HOW TO INSTALL A ROOF WINDOW PRACTICAL ADVICE
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.
Once an approximate position has been determined, it should be marked out accordingly.
A pilot hole should be cut out and removed to allow for more accurate measurement.
By inserting a rule either side of the pilot hole, the rafters can be located and marked out.
It is useful to work from the inside edge of a rafter, so as to minimise unnecessary framing out of the window.
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.
Be sure to support the area below where you are cutting the rafter.
... and secure support beneath the top of the rafter.
Cutting the rafter
You can then mark out, cut and remove the timbers.
Frame out the prospective opening to the correct height and width.
... to allow enough height for the reveals to splay back at the correct angle.
Making the opening
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.
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.
If you have a slate covering it may be necessary to use a slate ripper to remove the nails.
Remove sufficient tiles/slates to allow a good working area. Don't be tempted to remove too many though - you'll have to put them back later!
Remove battens to the extent of the framed area.
Fixing the frame
Fasten a batten
After determining the correct height of the window installation fasten a batten to support the window frame.
Separate sash from frame
To install the frame, it must first be separated from the sash. Open the sash and rotate it through 180 degrees.
Unlocking the hinge
Locate and press the locking mechanism on each hinge (it should make a click) and separate the sash from the frame.
Once the hinges are released, carefully separate the sash and place to one side (store horizontally).
Installing the frame
Carefully pass the frame (with brackets fixed) through the opening. Place frame on support batten and lay flat on rafters.
Check frame alignment
If level, fix the bottom brackets.
Final alignment check
Replace the sash to test that it opens and closes properly. If it is not closing properly it is best to find out at this stage.
To make sure the frame is set properly, check the gaps at the closure of the sash. If the vertical gaps are parallel with the gap at the bottom in a slightly opened position, then the frame is correctly aligned, and the top brackets can be fixed.
A plastic wedge is supplied to pack the bracket where there is an uneven rafter.
Install the brackets
Making the frame watertight
Remove the sash
Remove the sash once more to continue with the installation. Remember to push in the locking pin on each hinge. Support the weight of the sash underneath whilst dislocating the hinges and carefully place back inside roof.
Cut the waterproof 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.
Loosen (or de-nail) the batten underneath the frame to allow for the positioning of the new collar.
Attaching the membrane
Starting with the bottom piece, slide under the batten and staple/tack to the underside of the frame.
Fixing the membrane around battens
When fixing the side pieces, make sure you cut and tightly secure around roof 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 existing membrane
Cut the existing membrane over the rafter to allow the top collar piece to be slid underneath.
Overlap the membranes
Lift up the cut piece and fix the top collar piece underneath and to the frame. Replace the existing piece and fix.