A roof lantern can completely transform a room. That dramatic flood of natural light into a kitchen extension or single-storey orangery is hard to beat. But once you have chosen your unit, the next question almost always follows: should I attempt this myself, or do I hire a professional? This roof lantern installation guide is here to help you make that decision with confidence.
Whether you are a seasoned DIY enthusiast or a complete first-timer, this roof lantern installation guide covers every key consideration - from structural requirements and Building Regulations to the honest cost difference between doing it yourself and bringing in a professional. By the end, you will know exactly where you stand.
What the Roof Lantern Installation Guide Involves?
Before you make any decisions, it helps to understand what a roof lantern installation actually requires. This is not the same as fitting a new light switch or replacing a kitchen tap. A thorough roof lantern installation guide will tell you there are several distinct stages, each carrying its own level of technical complexity.
Here is a high-level look at the core stages involved in a typical flat roof installation:
- Forming the structural opening - cutting through the flat roof deck and adding trimmer joists to carry the load safely.
- Installing the kerb (upstand) - a raised timber or aluminium frame that lifts the lantern above the roof surface and provides the weatherproofing base.
- Fitting the roof lantern frame - positioning, squaring, and securing the frame onto the kerb.
- Glazing and sealing - inserting the glass panels and ensuring every joint is fully watertight.
- Internal finishing - plastering, painting, or boxing around the roof reveal on the inside.
The Case for DIY Roof Lantern Installation
There is a genuine case for DIY installation in certain circumstances. If you are a skilled builder, or have previous hands-on experience with flat roofing, a smaller and lighter lantern unit can be a manageable weekend project. The main appeal is straightforward — saving on labour costs, which can add several hundred pounds to the overall bill.
Manufacturers of entry-level units, including some of the roof lanterns in our collection, supply detailed installation manuals written for the competent self-builder. Provided the structural opening already exists - for instance, you are replacing an old skylight with a new lantern of the same footprint - the mechanical task of fitting the unit itself is quite achievable with the right tools and a second pair of hands.
Why Most Homeowners Choose Professional Installation?
The reality is that the vast majority of roof lantern installations involve at least some structural work. As soon as you are cutting a new opening, building a kerb from scratch, or making good the flat roof membrane around a new unit, the job becomes considerably more involved.
Here are the key reasons most homeowners choose to hire a professional:
- Building Regulations compliance - any new opening in a structural roof requires compliance with Approved Document A (structure) and Approved Document L (energy efficiency). A professional installer will ensure your paperwork is in order.
- Weatherproofing expertise - a poor seal around the kerb is the single most common cause of water ingress. Experienced roofers know exactly how to dress a membrane up and over an upstand correctly.
- Warranty protection - most roof lantern manufacturers only honour their product warranties when installation has been carried out by a qualified tradesperson. A DIY fit can void your cover entirely.
- Safety - working at height on a flat roof requires proper access equipment. The risk of personal injury or accidental roof damage is real without the right precautions.
- Insurance implications - if something goes wrong after a DIY installation, your buildings insurer may not pay out on a claim.
For a premium product such as the Brett Martin Roof Lantern or the Wendland Roof Lantern, professional installation ensures you get the full benefit of the product's thermal performance. A well-installed lantern with a correctly sealed frame will perform significantly better than one where the detailing has been rushed.
DIY vs Professional: A Side-by-Side Comparison
|
Factor |
DIY Installation |
Professional Installation |
|
Labour cost |
£0 (your time only) |
£500–£1,500 typical range |
|
Structural work |
✗ Not recommended without experience |
✓ Handled correctly by a qualified tradesperson |
|
Building Regulations |
Your responsibility to arrange |
✓ Typically managed by installer |
|
Manufacturer warranty |
Often voided by DIY installation |
✓ Preserved in most cases |
|
Weatherproofing reliability |
Dependent on skill level |
✓ High — professional detailing throughout |
|
Insurance implications |
Potential claim complications |
✓ Covered in most cases |
|
Best suited to |
Like-for-like replacements; experienced builders |
New openings, first-time installations, all complex jobs |
|
Typical time to complete |
Variable - often a weekend or longer |
1–2 days for most standard installations |
Building Regulations: What Every Homeowner Must Know
Whether you go DIY or professional, Building Regulations apply. In England, any new roof opening must meet the requirements of Approved Document L, which sets minimum energy performance standards for new and replacement glazing. The current maximum U-value for a roof lantern is 1.6 W/m²K. Many of the units across our rooflight range comfortably exceed this, offering significantly better thermal performance.
If you are carrying out structural work - cutting a new opening, adding trimmer joists - you will also need to satisfy Approved Document A (Structure). For most homeowners, this means either submitting a Building Notice to your local authority or using a Competent Person Scheme installer who can self-certify their own work.
For properties in conservation areas or listed buildings, planning permission may also be required before any installation work begins. Contact your local planning authority for guidance specific to your property.
How to Choose the Right Professional Installer?
If you have decided that professional installation is the right route, here is what to look for when selecting who to hire:
- FENSA or CERTASS registration — these are government-authorised competent person schemes for glazing and fenestration work in England and Wales.
- Flat roofing experience — specifically ask whether they have experience with flat roof extensions and lantern installation, not just general window fitting.
- References and photos — ask to see previous installations. A good installer will be happy to show you their finished work.
- Written quote and guarantee — always get the scope of work and any workmanship guarantee in writing before agreeing.
- Public liability insurance — confirm they hold a current policy as a minimum.
If you would like to explore which product to specify before requesting quotes, browse our full range of roof lanterns or visit our skylights collection to find the right fit for your project and budget.
The Bottom Line
The honest answer to the DIY-or-professional question depends almost entirely on the scope of your project. If you are making a new structural opening in your flat roof, hiring a professional is simply the sensible choice. The cost of getting it wrong — a persistent leak, a voided warranty, or a Building Regulations notice — far outweighs the saving on labour.
However, if you are replacing an existing unit on an established kerb, and you have genuine building skills and the right tools, a DIY installation can absolutely be done correctly. The key is being honest with yourself about your abilities before you pick up a saw.
Whatever route you take, starting with the right product makes everything easier. All the roof lanterns and rooflights we supply are designed for straightforward installation and come with full technical documentation to support both trade and self-build customers.
