Answers
Short answers about rooflights
Short, direct answers to the questions we are asked most, grouped by the kind of unit.
Start here
One answer from each of six topics, the ones we are asked about first.
AnswerSkylight or rooflight: what's the difference?Skylight vs rooflight: the two words mean the same thing in daily use, but the regulations treat rooflights and roof windows differently.
Answer · Roof LanternsRoof lantern or flat rooflight: which suits your room?Roof lantern vs flat rooflight: which suits a deep kitchen or a narrow room, how each…
Answer · Flat Roof RooflightsDo flat roof rooflights leak?Do flat roof rooflights leak? Where a flat roof skylight leaks, why the kerb joint matters…
Answer · Roof WindowsCan a roof window go in a slate roof?Can a roof window go in a slate roof? Yes. How slates are lifted, which flashing…
Answer · VELUX WindowsCan you fit a VELUX window I have bought?Can you fit a VELUX window I have bought? Yes, after we check the size code…
Answer · Electric & Opening RooflightsWhat happens to an electric rooflight in a power cut?What happens to an electric rooflight in a power cut? Mains units hold their position, solar…
Skylights and rooflights in general
2
Roof Lanterns
2
Answer · Roof LanternsDoes a roof lantern need Building Regulations approval?Roof lantern building regulations: the 2.2 W/m2K limit, structural approval, who notifies Building Control and when…
Answer · Roof LanternsWhat glass goes in a roof lantern?Roof lantern glass explained: toughened outer, laminated inner, low-e and solar control coatings, and how a…
Flat Roof Rooflights
2
Answer · Flat Roof RooflightsWhich flat roof covering suits a rooflight?Which flat roof covering around a rooflight is best? How felt, EPDM and GRP each meet…
Answer · Flat Roof RooflightsNew flat roof, or just a new rooflight?Replace flat roof or rooflight? How to tell whether only the rooflight needs replacing, and when…
Roof Windows
2
VELUX Windows
2
Answer · VELUX WindowsDo VELUX windows need planning permission?Do VELUX windows need planning permission? Most houses can fit one under permitted development. See the…
Answer · VELUX WindowsHow long does a VELUX installation take?How long does a VELUX installation take? It depends on whether it is a like-for-like swap…
Electric & Opening Rooflights
2
Answer · Electric & Opening RooflightsDoes an electric rooflight need an electrician?Does an electric rooflight need an electrician? Mains wiring does, solar ones need no supply cable…
Answer · Electric & Opening RooflightsCan a manual roof window be made electric?Can you convert a roof window to electric? When a motor can be added, when a…
Energy Efficient Rooflights
3
Answer · Energy Efficient RooflightsWhy does my roof window get condensation?Roof window condensation: why the glass, frame or lining mists up, how to tell a failed…
Answer · Energy Efficient RooflightsWill a rooflight overheat a loft in summer?Rooflight overheating in a loft: how orientation, solar control glass, external shade and a venting window…
Answer · Energy Efficient RooflightsDoes a new roof window improve insulation?Does a new roof window improve insulation? What the U-value tells you, where an old skylight…
Misted & Failed Rooflight Units
3
Answer · Misted & Failed Rooflight UnitsWhy has my rooflight gone misty between the panes?Misty between rooflight panes means a failed edge seal on the glass unit, not a leak…
Answer · Misted & Failed Rooflight UnitsCan I upgrade the glass when a unit is replaced?Can you upgrade rooflight glass when a failed unit is replaced? Coatings, warm-edge spacers, laminated panes…
Answer · Misted & Failed Rooflight UnitsHow long does a glass unit swap take?How long a rooflight glass unit swap takes: the survey, made-to-measure glass, the fitting visit, and…
Walk-On Rooflights
3
Answer · Walk-On RooflightsIs a walk-on rooflight slippery when wet?Is a walk-on rooflight slippery when wet? How walk-on rooflight anti-slip finishes work, how grip is…
Answer · Walk-On RooflightsDoes a walk-on rooflight need a structural engineer?Does a walk-on rooflight need a structural engineer? Yes for a new opening. See what is…
Answer · Walk-On RooflightsCan scratched walk-on glass be replaced?Can you replace walk-on rooflight glass that is scratched? Yes. See when to leave scuffs, when…
Conservation Rooflights
3
Answer · Conservation RooflightsTop-hung or centre-pivot in a conservation area?Top-hung or centre-pivot for a conservation area roof window type? Neither is banned. See what officers…
Answer · Conservation RooflightsDo I need listed building consent for a rooflight?Listed building consent for a rooflight: when you need it, who decides in Sheffield and the…
Answer · Conservation RooflightsAre conservation rooflights energy efficient?Conservation rooflight U-value explained: what Part L asks of a heritage skylight, why glass beats frame…
Sun Tunnels
3
Answer · Sun TunnelsHow far can a sun tunnel carry light?Sun tunnel length and light: how far a tubular skylight can carry daylight, why bends and…
Answer · Sun TunnelsCan a sun tunnel go in a bathroom?Can a sun tunnel go in a bathroom? Yes, with an insulated tube, a sealed diffuser…
Answer · Sun TunnelsDoes a sun tunnel need planning permission?Does a sun tunnel need planning permission? For most houses no, if the dome stays within…