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Home / Why Skylights / Lightwell Types

What type of lightwell is best for
your home & skylight?

The lightwell is typically a wood framed and drywall lined channel connecting the skylight on the roof to the inside of your home. Drawing light into your home from the skylight. The lightwell is usually designed by your architect based on the roof structure, and painted white to reflect as much natural light as possible.
  • The lightwell can be built in a number of configurations, based on the type of internal roof design. And lined with drywall or wood tongue and groove.
  • By understanding the design options and specifying the right lightwell you can ensure maximum light distribution – and ideal air flow if you are installing a venting skylight.


Lightwell Types Infographic


Lightwell Attic

Sloped roof, attic space, and flat internal ceiling
  • Flat ceiling with the lightwell built through the attic above. The lightwell connects the skylight on the roof to the ceiling of the rooms below the attic.
  • The light opening is in the ceiling of the top living floor.
  • The light is directed through the attic space with a lightwell. Represented by the red line.

Lightwell Cathedral

Sloped roof with a Cathedral ceiling
  • A Cathedral ceiling skylight installation is when the pitch of the roof is open to the ground floor.
  • The pitch of the roof is clad in drywall, tongue & groove wood, or exposed rafters.
  • The lightwell is only as deep as the rafters. Typically the sides are perpendicular and the top and bottom are splayed, lined with drywall or wood cladding.

Lightwell Attic Room

Sloped roof with an internal finished sloped ceiling
  • Sloped wall skylight and lightwell installation. This type of lightwell is utilized when an attic has been converted into living space. If the house is a ‘new build’ the attic space is often raised using pony walls to gain additional clearance.
  • The skylight lightwell installation is the same as the Cathedral ceiling. Except the space is not open to the ground floor, it has a floor creating a top storey room.

Lightwell Flat Roof

Flat roofs require a shallow lightwell
  • When installed on a flat roof, skylights (glass or acrylic), a roof access door, or a circular roof dome require a minimal lightwell, determined by the thickness of the roof joist, and the curb.
  • A glass skylight requires a sloped curb, slightly altering the shape of the lightwell.
  • A roof access door requires a built up lightwell to allow for sufficient clearance when a person is using the door to access the roof deck.

Venting Skylights Require Additional Consideration When Building A Lightwell- Accessibility For a Manual Venting, or Wiring for an electric venting

Lightwell Venting

  • If you are installing a manual or electric venting skylight it is important to consider the opening and closing of the skylight.
  • An electric model requires an electrician to run wiring from the mains to the wall switch and to the skylight. If you don’t want a wall switch, Columbia offers 2 remote control options.
  • A manual venting skylight is operated by a crank handle, or telescopic pole, depending on the ease of access.



A Cathedral Ceiling is when the pitch of the roof is exposed to the room below. The finishing (drywall, or tongue & groove wood) is attached to the underside of the roof rafters, following the pitch of the ceiling. The space in between the rafters is usually insulated to conserve energy consumption. Another finishing style for a Cathedral Ceiling is when rafters are exposed. A Cathedral Ceiling is not to be confused with a Vaulted Ceiling, which is typically an arch shape.

A skylight installed in a cathedral ceiling usually has s shallow lightwell, determined by the thickness of the roof rafters. Typically the lightwell is splayed at the top and bottom and perpendicular on the sides. The splayed lightwell maximizes the distribution of light and creates a beautiful architectural feature. Multiple skylights can be installed in a row, producing a dramatic visual effect that allows in a significant amount of light, perfect for a kitchen or sunroom.

Cathedral Lightwell Ceiling

  1. For the cathedral ceiling applications, the skylight is mounted between the rafters. The rafters are framed and finished (typically, drywall, tongue & groove wood, or exposed rafters).
  2. The lightwell sides are typically perpendicular, while the top and bottom can be perpendicular or splayed.
  3. Standard industry roof rafter spacing is 16” or 24” on center, however other spacing may be specified by an architect/ structural engineer, or in older houses built before today’s building codes.


This style of lightwell is built to transfer light from the skylight mounted on a sloped roof, through the attic space, to a hole cut in the horizontal ceiling of the upper floor. This type of lightwell can be splayed on all four sides, or be a perpendicular shaft, depending on architectural design and structural constraints, such as ducting. The lightwell’s lower opening should be splayed as much as possible to let in the maximum amount of natural light.

Lightwell Double Splay

Double or four sided splay
  • This type of lightwell will allow in the maximum amount of light, it distributes the light evenly through the room.
  • Depending on the roof, walls and obstacles in the attic (framing, electrics, and ducting), the lightwell can be splayed on 2, 3, or 4 sides.

Lightwell Single Splay

Single sided splay lightwell
  • In a single splayed lightwell one side is perpendicular 90° to the lower ceiling, while the side of the lightwell that is closest to the centre of the room is splayed to allow in more light.
  • The reason to design a perpendicular side is to avoid internal obstacles, or because the skylight is close to an existing structure, built in closet, or bookcases, or for aesthetic reasons.

Lightwell No Splay

No splay – a straight vertical, parallel sided lightwell

Lightwell Photo Pool

  • Lightwell Photo PoolA straight vertical shaft lightwell is most commonly used in a smaller roof, or where framing or obstacles in the attic make it impossible to splay the walls of the lightwell.
  • This style of lightwell is also used for aesthetic reasons as it creates a deep dramatic lightwell shaft, favoured in homes designed in the Modernist style.

Lightwells Built Around Obstacles

When a lightwell has to be built around obstacles, changes in roof line, or interior obstacles like a chimney – the lightwell sides can be framed with a change in angle to accommodate.

Lightwell Single Angle Shaft

Single Angle Shaft

Lightwell Double Angle Shaft

Double Angle Shaft


Lightwell Building Diagram

  • Building and finishing of a lightwell should be conducted by a professional.
  • It requires knowledge of framing, and how to tie the framing into existing structures like rafters and floor joists.
  • The framed structure is finished with drywall, or in some cases decorative wood tongue & groove. It is thin painted, or in the case of wood, stained.
  • If you are installing an electric venting skylight, you will need an electrician to run power to the skylight and the wall switch. (The wall switch is one option, Columbia offers two remote control options)
  • A manual venting skylight will require access to open or close the skylight using the crank handle or telescopic pole.



Lightwell Rigid Suntube

Rigid Sun Tube

Lightwell Flexible Suntube

Flexible Sun Tube

  • Sun Tubes do not require a lightwell, as light travels through the attic space via a rigid or flexible aluminum tube, to the diffuser lens mounted in the ceiling below.
  • The inside of the rigid or flexible tube is lined with a highly reflective surface called Miro-Silver®, effectively disbursing the light from the skylight above.
  • Columbia offers two diffusers lenses that fit into the ceiling – Prismatic or Soft White.

Lightwell Suntube Prismatic Diffuser

Prismatic Diffuser

Prismatic diffuser is made of durable acrylic. The diffuser’s surface contains several small prisms to help maximize and spread the light evenly.

Lightwell Suntube Soft Diffuser

Soft White Diffuser

Soft white diffuser is made of durable acrylic. The diffuser surface is smooth and evenly spreads a softer tone of light.