| Term | Definition |
| Aluminum coating | On all interior VELUX blinds, on the reverse side of the blind (the side of the cloth or slat closest to the pane) to reduce the heat gain in the room. |
| Argon gas | A colorless, odorless, inert gaseous element constituting approximately 1% of the earth's atmosphere, used in electric lamps, fluorescent tubes, and insulated glass window panes. Because argon is denser than air, it is a good insulator and is used in all VELUX skylights and roof windows. |
| Awning | An exterior blind installed on the roof side of the skylight and the best possible way to minimize heat gain through a skylight/roof window. |
| Blinds | Sunscreening accessories, such as venetian blinds, pleated shades, LightBlock shades, and awning blinds. |
| Cladding | Cladding is an exterior aluminum armor that offers protection from the elements and offers a streamlined appearance. |
| Combi-flashing | Combi-flashing refers to a flashing system that combines multiple skylights for almost unlimited design possibilities. |
| Condensation | A chemical reaction that causes water droplets to form when warm, moist air contacts a cold surface. All VELUX skylights are designed to minimize the chance of condensation by protecting the interior glass from cold, outside air with a special Low-E coating and argon gas that is vacuum sealed in the space between the interior and exterior panes of glass. |
| Controls | The way you operate the venting skylight or blind. Can be manual or electric. |
| Curb | A curb is a site-built wooden frame or pre-manufactured metal structure on top of which a curb mounted skylight is mounted. |
| Curb mounted | Curb Mounted is referring to a type of skylight that is mounted to an installer provided, site-built curb. |
| Deck or roof deck | Refers to the plywood or sheathing that covers the rafters or trusses of a roof structure. It provides the base on top of which the weatherproofing roof materials are applied. |
| Deck mounted | When you deck mount a skylight, you attach it directly to your roof sheathing. You do not build up a curb. |
| Diffused light | Not direct light - doesn't create a glare on PC/TV screens. Pleated shades diffuse the light to create a softer effect. |
| ENERGY STAR® | ENERGY STAR® is a program sponsored by the US government (EPA and DOE) that VELUX America aligns itself with to exceed current energy codes by more than 40%. |
| Exterior blinds | Blinds that are installed on the roof side of the skylight. VELUX offers exterior awning blinds. |
| Finished framing dimensions | Finished framing dimension is a reference to the measurement from backside to backside of the interior finishing material (i.e.. sheetrock, paneling, tongue and groove). |
| Fixed skylight | A fixed skylight is non-operable, meaning there is no ventilation. |
| Flashing | A weatherproofing system that connects the skylight with its surrounding roof material. VELUX flashing systems are designed to shed water without relying on sealants that can break down over time. |
| Frame | A skeletal structure designed to shape or support. The frame of our skylights and roof windows are made of Nordic Pine from new growth forests only. |
| Glazing or insulated glazing | Refers to the glass portion of windows, doors, and skylights. VELUX offers Comfort Glass, which consists of two pieces of tempered glass sealed at the edges by a stainless steel spacer and 2 durable sealants, and our ComfortPlus Glass, which features an exterior tempered piece sealed over a piece of laminated glass. Both units are filled with Argon gas and double coated with an exclusive Low-E coating. |
| Head flashing piece | The flashing component that interlocks with the skylight top cover and is placed under the roofing felt to insure proper water drainage. |
| Header framing | Structural lumber that ties two or more rafters together at the top of the skylight roof opening to form bracing for the surrounding roof structure. |
| Heatblock | Exterior awning that controls the heat coming through the skylight and reduces the heat gain in the room. |
| Identification tag | All VELUX skylights and roof windows will have a Label which explains the size for the skylight. All skylights and roof windows with a one to three digit number will be in standard dimensions, and this number must be used for ordering blinds (no additional measurements are needed). |
| Impact glass | The glass is very resistant to penetration from flying debris. Our impact glass meets the requirements for wind-borne debris protection of the IBC (International Building Code Commercial), IRC (International Residential Code), and the Florida Building Code 2001, with exception of Dade County Protocols. |
| Interior blinds | Blinds installed on the room side for the skylight (in the sash if venting or on the frame). |
| Laminated glass | Made up of bonded layers. Two panes of heat strengthened glass bonded together around a vinyl inner layer that holds the glass together if it gets broken. |
| Light shaft | Flat ceilings with an attic space between the ceiling and the roofline require a light shaft to deliver the light and view from the roofline into the interior opening. |
| LightBlock | Interior room darkening shade that can convert day to night. It will not be possible to find your way in the room, without light from sources other than the skylight. |
| LoE3 | LoE3 is a metallic coating that is chemically bonded to the glass and protects against heat gain and fading rays. Now with triple coating |
| National Fenestration Council (NFRC) | The NFRC rates windows, doors, and skylights on their overall energy performance. Its tests are independent and prescribe uniform testing parameters, which gives consumers a way to accurately compare products. |
| Outside frame | The outside frame dimension refers to the outer-most measurement of the wooden frame on VELUX skylights and roof windows. |
| Pan-flashed | "Pan-flashed" is referring to a type of skylight with insulated glass lens, wood frame and protective cladding, combined with factory installed metal pan flashing with welded corners and painted that mounts directly to the roof deck and requires roofing sealant. |
| Pitch | The angle of a roof. The angle which the roof surface makes with a horizontal plane. It is a ratio of rise to the span. |
| Rafter | One of the sloping, parallel beams that support a pitched roof. |
| Remote | Infrared remote control which via the electrical control will be able to operate the electric venting skylight or blind. |
| Roof window | Roof windows are designed to be installed within reach, such as attics, bonus rooms, and loft areas. Their sashes will rotate around, allowing the outside glass to be cleaned from inside the house. |
| Rough opening | The actual hole that is cut in the roof decking to install a roof window or skylight. |
| Sash | A frame in which the glass panes of a window or door are set. The part of a ventilating roof window or skylight that opens out from the frame. |
| Self flashing | Self-flashing units do not require curbs or additional flashing components to create a watertight seal. |
| Shades | Pleated shades, roller shades and LightBlock shades offer options for room darkening and light filtering. |
| Shaft | The section of the ceiling that projects a ray or beam of light. |
| Sill flashing piece | The sill flashing component is at the bottom of the skylight and is placed between the underglass rubber gasket and bottom frame section to provide a watertight seal. |
| Sill framing | Structural lumber that ties two or more rafters together at the bottom of the skylight roof opening to form bracing for the surrounding roof structure. |
| Step flashing | Step flashing is a system that interweaves ???L??? shaped flashing pieces with the roofing material going up the sides of our units to provide a watertight seal. No sealants that can break down over time are required. |
| Stick built | A term used to describe the conventional framing technique of building the roof structure one piece of lumber at a time. The opposite approach involves pre-engineered and factory-built truss systems that form a roof structure when put into place on the job site. |
| Tempered glass | Glass having an additional degree of hardness that shatters into small pieces rather than into large shards of glass. |
| Truss | A rigid framework designed to support a structure. |
| Underlayment | Something underlaid, as paper under shingles. Either ice and water shield or felt paper are used to wrap a skylight for insulation. |
| UV | Ultraviolet light that fades the interior. VELUX glazing in the skylight and blinds are efficient solutions to this issue. |
| Venting skylight | A venting skylight is a unit that is hinged at the top and opens mechanically at the bottom to provide fresh air and temperature control. |
| Wrapping a skylight | Roofing underlayment or roofing felt are wrapped around the skylight frame or curb to dramatically reduce the chance of condensation and provide added protection from extreme weather. |