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Replacing a dome rooflight: measurements and photographs

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Safety first

Do not step on the dome or access an unprotected roof to take measurements. Leave work at height, damage inspection and work on smoke-exhaust systems to a qualified contractor. For an initial enquiry, the information and photographs you can obtain safely are enough.

Which dimensions matter?

  • Structural dimension K: the roof opening or structural dimension shown in the selected system drawing.
  • Clear dimension L: the unobstructed opening; the STELUX tables use O.
  • Nominal dimension N: the element size designation in its table.
  • Screw centres S: needed when checking replacement on an existing upstand.
  • Upstand height and shape: current condition and any change to the finished roof level.

Do not convert dimensions from memory. Mark the two measuring points for each dimension on a sketch and state the unit. Relationships differ between systems.

Which photographs help?

  • The complete element and its surroundings, from a safe position.
  • The dome-to-upstand junction and visible roofing finishes.
  • The opening from inside and any location of water ingress.
  • The opening mechanism and a readable identification label, if safely accessible.
  • Visible damage or distortion, without removing parts.

What can be retained?

An existing upstand or mechanism may be retained only after condition and compatibility checks. A new dome of approximately the same size is not proof of a correct fit. For smoke-exhaust systems, check the documented configuration of the complete device; do not substitute components arbitrarily.

When should the complete rooflight system be inspected?

Replacing only the upper dome is not always enough. A wider inspection is advisable if the problem may also involve the upstand, fixings, opening mechanism or roof junction.

  • Leaks at the junction between the dome, upstand or roof covering.
  • Cracks, deformation or corrosion in supporting parts and fixings.
  • A worn or unstable upstand.
  • An opening mechanism that does not work, is damaged or cannot be identified.
  • A change in roof insulation thickness or refurbishment of the waterproofing.
  • A missing identification label or unclear system origin.
  • A natural smoke and heat exhaust function requiring the documented device configuration to be checked.
  • Damage or changes to protective equipment around the roof opening.

These signs are not a diagnosis of the cause. They help determine whether the upstand, mechanism, fixings and roof junction should be inspected as well as the dome. A new dome does not automatically stop leaks originating elsewhere in the roof.

How is the quotation prepared?

Send your information and describe the issue: damage, leaks, insufficient insulation or a faulty opening mechanism. We then agree on any necessary inspection and the replacement or repair solution. Manufacturing dimensions and the scope of work are confirmed before ordering.

  1. Send the detailsPhotographs, known dimensions, location, a description of the problem and the required scope.
  2. We check the systemDome type, upstand, fixings, opening mechanism and identification details.
  3. Define the scopeDistinguish replacement of the upper element from wider refurbishment of the system and roof junction.
  4. Confirm the dimensionsMeasurement points, compatibility, function and final roof build-up.
  5. A clear quotationSupply and individual on-site tasks are listed according to the agreed scope.
Copy the replacement enquiry template

We need to replace [number] dome rooflights on a building in [location]. The problem is [damage/leaks/thermal insulation/opening/other]. The dome is [fixed/opening/not sure], and the existing upstand is [description or not sure]. Known dimensions are [state the dimension, measurement points and unit]. The roof [will be refurbished/will not be refurbished/not sure]. We require [supply only/supply and installation/system inspection]. We attach photographs of the complete element, upstand, internal opening and mechanism.

Frequently asked questions about refurbishment

What if the old dome has no identification label?

Send photographs of the complete element, dome profile, upstand, fixing points and mechanism, together with clearly marked dimensions. Without a label, an additional inspection may be needed; it is not safe to guess the manufacturer or compatibility from appearance alone.

What if extra roof insulation is planned?

Mention this in your first enquiry. A change in the finished roof height can affect the choice or adaptation of the upstand and the waterproofing detail.

Can dimensions be determined from a photograph alone?

A photograph without a scale is not a reliable basis for manufacture. It helps with the initial assessment, but final dimensions must be marked between specific measurement points and confirmed before ordering.

Servicing or replacement of a natural smoke and heat exhaust system is not treated as an ordinary replacement of an opening dome. Device details, documentation and the requirements of the fire safety design are needed. Read about the difference between ventilation and smoke and heat exhaust.

Prepare for a safe initial assessment
Send available dimensions, a description of the problem and photographs of the complete element, upstand and mechanism.

Send replacement details

Upstand shapes and dimensions · Send details for a quotation

Technical source: POS plastika catalogue “Svetlobne kupole in trakovi”, 2026 edition. The figures describe the specified catalogue configurations; confirm the exact build-up, dimensions and documentation before ordering.