Skylights – Tips and Traps
Let there be light!
(by Designer Builder, Peter Harnischmacher of Capital Building)
Need to get some light into a dark room or area?
Just chuck in a skylight… ?
Sorry, wrong answer!
Skylights can cause more problems than they solve.
1. They are often thermally inefficient letting heat escape in winter and trapping and reflecting heat into the house in summer.
Some skylights offer double glazed alternatives but as discussed in previous musings, like double glazed windows, skylights are only 30% as good at insulating your home than correctly insulated walls and even less efficient in ceilings.
A well-sealed roof cavity is the number one defence against heat leaving your living spaces so think twice about poking holes in it!
2. Skylights (except solar tubes) are expensive to purchase and install.
‘But a roof window only costs around $1.5 K to $3 K’ you may say?
However, people often forget the associated costs that surround a skylight or roof window. The installer may charge up to $1,000, the plasterer may charge another $1,500 to install a shaft . Ideally, it needs an external blind for summer and an internal blind for winter, which could be another $3,000, you may then want to add an auto opener $1,500. Before you know it you have spent nearly $10,000 on a professionally installed quality skylight.
*Note prices are estimates and will vary with size and job type.
3. Skylights are a common source of roof leaks.
Make sure they are professionally installed and guaranteed.
What are the alternatives to skylights?
High light windows
Need to let light into a room but don’t want to sacrifice wall space?
A horizontally long, narrow window placed near the ceiling leaves you plenty of wall space, ventilation and most importantly plenty of light. It is thermally more efficient than your average skylight and cost-effective.
If you just want natural light without having to flick on a switch, solar tubes are the most efficient skylight. Their flexible duct design and relatively airtight diffuser mean you get good light without the thermal losses of your average skylight. They are also available as a ventilated version, great for small rooms without windows such as bathrooms and laundries. They are not very expensive and not too big.
Roofed windows (not to be confused with roof windows)
The ultimate skylight is the raised roof or lantern light. (see our ‘Hawthorn job’)
A design where windows pop up through the roof but are protected by their own roof, insulation and eaves.
If correctly designed and oriented they provide full shaded light in summer and reflect heat into the house in winter. When combined with auto opening windows and a ceiling fan they provide additional passive heating and cooling without running costs.
See also our “Beach shack” where the roofed light captures light into the middle of the house over the stairs and provides stack effect ventilation on demand. This is particularly effective when cool changes arrive, allowing the house to cool in about 10 to 15 minutes. The biggest downside of the roofed light is it is expensive. Expect around $20,000 depending on size and individual circumstances.
The Light Well
Used mostly in terrace design, the light well will provide light and ventilation to rooms on boundary walls and often to a number of levels.
Glass Floors only get a brief mention here and are only for those with BIG budgets. They do however work. Beware of unwanted exposure.
Roof window skylights aren’t all bad news. If they are of good quality such as Velux and they are installed correctly and placed correctly to reduce thermal loss, then they can look stunning, particularly on a clear starry night.
If you are considering the addition of a skylight to your next extension, make sure contact an experienced designer-builder who understands thermal efficiency and all the solutions for a particular situation. Call Capital Building now for a no-obligation new home / extension design consultation.