Daylight from above. A brighter, calmer room.
A roof lantern pours natural light into the centre of a space, turning dark kitchens and extensions into places you actually want to be. With slim sightlines, high-performance glazing and neat finishing, you get daylight without the glare and a room that feels “finished”, not makeshift.
We design, supply and fit across Grantham, Stamford, Sleaford, Newark, Bourne, Melton Mowbray and nearby villages.
Balanced daylight
Light drops into the heart of the room, not just from the side doors.
Slim, modern lines
Minimal bars and clean cappings for an uncluttered look.
Comfort all year
Solar control, low-e glazing and proper seals keep temperatures steady.
Great for kitchens
Brighten the island or dining table without harsh side glare.
Adds value and feel
Spaces look more architectural and feel more spacious.
If you prefer glass without the raised profile, consider flat roof lights. We can show both options at survey.
Rectangular: perfect over an island or dining table Square: centred feature for balanced rooms Twin lanterns: for larger spans or zoned spaces
• Small feature (c. 1.0–1.5m x 1.5–2.0m) • Family kitchen (c. 1.5–2.0m x 2.5–3.5m) • Large room (up to system limits; we’ll advise at survey)
• Ultra-slim profiles for maximum sky view • Minimal ridge and hip bars to keep lines light
If you prefer glass without the raised profile, consider flat roof lights. We can show both options at survey.
• Low-e, argon-filled units for low U-values • Solar control coatings to cut summer heat and glare • Warm-edge spacers to reduce condensation at the glass edge
• Laminated or acoustic glass to soften rain and outside noise • Satin/privacy glass for bathrooms and sensitive spaces
• Photocatalytic layers help break down dirt so rain washes it away
• Manual or electric roof vents for purge ventilation • Rain and temperature sensors to close automatically • Integrated blinds (manual or motorised) if you want extra shading
A good lantern is as much about the finish as the glass.
Colour-matched external cappings for a clean roofline
We visit, measure properly, look at your existing frames and talk through finishes, glazing and hardware. It’s a conversation, not a sales pitch.
You’ll get an itemised quote with the style, colour, glass spec, lead time and warranty. No vague “from…” pricing and no surprises later.
Every frame is built for your apertures. This is what keeps the installation neat and the seals tight.
We protect floors, remove old frames and glass, seal up neatly and clean down. Old materials are taken away. You’re not left with a skip.
If you ever need us, you don’t get pushed to a call centre. You speak to the same team who fitted the job.
We measure properly, check roof type and joist layout, and talk through sizes, glazing and vents.
Clear plan/elevation with spec, timelines and warranties. Any structural work or electrics are listed.
Lantern and glass manufactured to your opening for neat lines and tight seals.
Opening formed (or existing checked), upstands prepared, lantern set, sealed and finished. Site left clean.
If you need anything, you speak to the same friendly team who fitted it.
Serving Grantham, Stamford, Sleaford, Newark, Bourne, Melton Mowbray and nearby villages.







Not with the right glass. Solar control coatings reduce heat gain while keeping daylight. We’ll recommend the best spec for your aspect.
Laminated/acoustic glass and proper seals keep noise down. Most clients find it pleasantly quiet compared to old polycarbonate roofs.
Replacing or adding a lantern on a single-storey extension often falls under permitted development if size and height limits are met. Conservation areas and specific house types can vary. We’ll advise before you commit.
A warm, insulated flat roof deck or orangery roof with the correct upstand. We’ll check structure and advise on any strengthening.
Yes. Manual or electric vents are available, with optional rain/temperature sensors.
Self-clean coatings help. Occasional gentle wash from safe access keeps it clear. We’ll advise on maintenance.
Most single lantern installs are completed in a day once the opening is prepared. Larger or twin lantern projects can take longer. You’ll get a realistic schedule with your quote.
Yes. We can include lighting, switching and plastering or coordinate with your trades. Everything is itemised.
Trustindex verifies that the original source of the review is Google. I have been using Avanti for 35 years and the service and product quality is amazing!Posted on Google Will mcintoshTrustindex verifies that the original source of the review is Google. Cannot recommend Avanti enough!! Amazing service from start to finish. The whole team were friendly and professional. Great job and have told all my family and friends if they ever need a job doing, to give them a callPosted on Google Natalie BuxtonTrustindex verifies that the original source of the review is Google. We had nine blown windows, called a couple of window companies to try and get the best price and these guys were the only ones who got back in touch with us. We weren't willing to wait around so went with them and I'm glad we did. They came out, took the measurements and ordered the glass. I was advised the glass could take about four weeks which was fine. Less than a week later I got a call asking if there was any chance they could come later today to fit our new windows! They came round and had them all replaced in about an hour!! For the first time since we've moved into our house we have been able to see properly out of our window! Thank you for the professional and prompt service! I would recommend.Posted on Google Lisa KnightTrustindex verifies that the original source of the review is Google. We have this week had our windows installed courtesy of Avanti Windows Grantham. From start to finish we have had excellent service. I knew I was in safe hands when I met Richard who came out originally to measure up and quote, but to be honest everyone we have dealt with from Richard through to the fitting team have been spot on. Very professional. We did get quotes from other well known window suppliers but the out dated sales tactics and tedious process put us off. There was none of that with Avanti…. It was so easy. I would highly recommend them. I’d give 6 stars if I could👍🙏Posted on Google MARK GOODETrustindex verifies that the original source of the review is Google. Amazing firm and very professional. They’ve done a great job In replacing our conservatory roof for a solid one. Punctual everyday and end result it brilliant. Highly recommendPosted on Google George PimTrustindex verifies that the original source of the review is Google. Avanti delivers an outstanding service. I had a new glass roof fitted on my conservatory and the team also refurbished the whole conservatory and made it look like it was new. Fantastic job, exceeded my expectations. I have no hesitation in strongly recommending this company. A big thank you to the whole team at Avanti, a great bunch of guys!Posted on Google Douglas HowcroftTrustindex verifies that the original source of the review is Google. Brilliant company. Quality windows. Staff really friendly and helpful.Posted on Google Chris JonesTrustindex verifies that the original source of the review is Google. Absolutely over the moon with my windows and doors, service and fitting is top notch!! We will be having replacement windows from them in the future!!Posted on Google Toni BlakeyTrustindex verifies that the original source of the review is Google. A patio door leaked because they "forgot to put in drain holes". Ahe door got fitted by "trimming" the opening by wacking it with a lump hammer (even though the builder was on hand with a diamond saw), the windows came scratched and the external paint could be removed with a finger. I saw they hadn't sealed in the window frames and asked why not. Apparently they don't carry sealant!?!? They all got taken out and my builder rebuilt the door opening.Posted on Google Sheila and PeterTrustindex verifies that the original source of the review is Google. Tony and the team were very professional throughout the whole process. The fitters had to install all new windows and doors and have completed to a high standard. They have been very accommodating with my timescales and would highly recommend. Thank you!Posted on Google Evie English