THE DEFAULT CASE
What goes into a flat roof
A flat roof is what most of this catalogue is designed for. Three ways to get light in, and the roof usually decides which.
Dome rooflight
LK CLASSIC · LK NEO PLUS
A domed unit on an upstand. The widest size range, the most options, and the answer for most flat-roof openings.
- Sheds water and debris by its shape
- Clear or Opal glazing
- Fixed or ventilating
Use it when you are cutting or replacing a standard opening.
Browse rooflightsFlat rooflight
FDF NEO · FDF NEO PLUS
Flat rather than domed, where the profile of a dome is unwanted or not permitted.
- Flush sightline from below and above
- Different drainage detail — check the falls
- Same upstand requirement
Use it when the architecture calls for a flush finish.
FDF neoTubular system
SOLATUBE
Where the room needing light is not directly under the roof, or an opening cannot be cut where you want the light.
- Small roof penetration, large effect
- Routes through the void
- No structural opening in the ceiling
Use it when the room is internal, or the ceiling cannot be opened up.
How tubular systems workTHE DETAIL
Why the build-up decides the order
On a flat roof the rooflight is only half the specification. The other half is the upstand, and it is set by the roof rather than by the unit.
The upstand has to lift the glazing clear of standing water, give the membrane a vertical face to turn up and terminate against, carry the insulation line past the opening so the detail is not a cold bridge, and give the unit something to fix to. Which means the height you need is a function of your build-up — deck to finished surface — plus whatever your roofing specification requires above that.
This is the part that gets ordered wrong, and it is why the upstand is chosen before the dome rather than after it.
Specifying in order
- 1 Measure the clear opening in the deck, both directions, at both ends.
- 2 Measure the build-up depth — deck to finished roof surface, including insulation and waterproofing.
- 3 Choose the upstand type: PVC, steel, or thermally broken steel.
- 4 Choose the height, from those the type is made in, working from the finished surface up.
- 5 Choose the rooflight line and glazing to suit the performance the specification asks for.
- 6 Add the frames or opening gear the job needs — and check whether SR or fall-through protection is what is meant.
COMMON JOBS
Where to start, by job
| The job | Start here |
|---|---|
| Replacing a failed dome, kerb staying | Roof dome replacement |
| New opening in an existing flat roof | Measuring guide, then choosing an upstand |
| Re-roofing, rooflights coming out and going back | Choosing an upstand — the build-up is changing |
| Upgrading thermal performance | The range — LK neo plus and FDF neo plus |
| Internal room, no roof directly above | Solatube |
| Opening does not match a listed size | Request a quote |
Every one of these ends in the same place if you are unsure: send the opening measurements and a photograph.
AVOID
Three flat-roof mistakes
Ordering the dome before the upstand
The heights available change with the upstand type — PVC does 15, 30 and 50 cm, steel does 30, 40 and 50, and the thermally broken version is 50 only. Choosing the unit first can leave you with a height that does not exist for the type you need.
Measuring the build-up from the deck instead of the finished surface
The upstand has to stand proud of the finished roof, not the deck. Insulation and waterproofing come in between, and forgetting them is how an upstand ends up too short to take the membrane properly.
Assuming SR covers fall-through protection
It does not. SR is a weathering frame. Fall-through protection is a separate range — RSM LK, HDS LK, EAD LK and others, depending on the application. If the job needs certified fall-through protection, say so on the enquiry.
Send us the roof.
Opening size, build-up depth and a photograph. We will come back with the upstand, the unit and a price.
Guidance on this page is general. Where your roofing specification differs, follow the specification.