Business Details
38 Years
experience
Your Trusted Window & Door Experts in Grantham
Avanti Windows has been serving Grantham and surrounding areas since 1988, establishing itself as a trusted name in window, door, and conservatory installations. As a family-run business, we combine decades of hands-on experience with a commitment to delivering tailored solutions that meet both budgetary and functional requirements. Our team specialises in domestic and commercial projects, prioritising security, energy efficiency, and aesthetic appeal in every installation. Backed by FENSA registration and a 10-year guarantee, we ensure compliance with industry standards while maintaining a customer-centric approach. From initial consultation to final installation, our experts provide transparent advice and meticulous workmanship.We pride ourselves on using A-rated, argon-filled glass and advanced low-emissivity technology to enhance thermal performance. Our services extend to secondary glazing, conservatory design, and custom solutions, supported by partnerships with trusted tradespeople for seamless project completion. With a reputation built on repeat business and word-of-mouth referrals, we remain dedicated to exceeding client expectations through reliability and technical expertise. Our operating hours and Grantham-based showroom offer convenient access for local customers seeking professional guidance.
Services
Windows
Doors
Conservatories
Aluminium
Composite Doors
UPVC Doors
UPVC Windows
Car Port
Box Sash
Details
- Year established: 1988
Highlights and features
- We have over 35 years of experience in window and door installations.
- Our team provides cost-effective solutions tailored to your budget.
- We offer A-rated energy-efficient windows and doors.
- Our installations meet Secured by Design police initiative standards.
- We provide a 10-year guarantee on all our products.
Associations and certifications
- FENSA
What people say
High standard
Fantastic company
Excellent fitting service
Delighted with the end result
Helpful professional service
Services
Windows
Our A-rated windows use argon-filled glass and low-emissivity technology to improve thermal efficiency while reducing external noise. Multi-point locking systems enhance security, meeting Secured by Design standards. Custom designs accommodate period properties and modern homes alike.
Doors
We install composite, UPVC, and bi-folding doors engineered for durability and security. Features include heat-welded corners, double weather seals, and custom colour options. All doors comply with insurance requirements and energy efficiency regulations.
Conservatories
From Edwardian to lean-to designs, our conservatories combine natural light with year-round usability. We handle planning permissions, dwarf wall construction, and skylight installations, backed by a 10-year structural guarantee.
Aluminium
Slimline aluminium frames provide modern aesthetics with robust performance. Available in RAL colours, our secondary glazing solutions reduce heat loss while maintaining external visual consistency for listed buildings.
Composite Doors
Our composite doors withstand extreme weather and forced entry attempts. Reinforced cores and multi-point locks ensure security, while decorative glass panels and durable finishes enhance kerb appeal without requiring frequent maintenance.
Questions
What areas do you cover?
We serve Grantham and surrounding areas within a 30-mile radius, including Lincolnshire and nearby regions.
Are your installations FENSA registered?
Yes, all our window and door installations comply with FENSA regulations for building control compliance.
Do you offer guarantees?
We provide a 10-year guarantee on all products and installations, covering structural integrity and performance.
Can you help with planning permissions?
Our team manages building regulation applications and planning permissions for conservatory and window replacement projects.
What security features do you offer?
Our windows and doors include multi-point locking systems certified under the Secured by Design police initiative.
How long does installation take?
Most window and door installations complete within 1-2 days, with conservatories typically taking 4-6 weeks from order to completion.
Reviews (4)
Debbie Norton
Jun 13, 2022
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A big thank you to Richard Tony and the team. Amazing service thoughout totally transformed our home! From the giles-norton family
Draylynn
Feb 03, 2022
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Our landlord got our old/rotten windows replaced by Avanti (Due to COVID there was a long wait for em). Friendly bunch, such a good job, clean seal work, no drafts, fitted well, cleaned up after themselves (indoor and out). Absolute 'massive' difference it's made in temperature and noise. Smashin' job, thanks Gaz and co'.
Dawn Mantle
Feb 24, 2021
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Unfortunateley we had a bit of a wait to get our conservatory roof replaced due to the Covid 19 Pandemic. But Avanti have now managed to come and get the job done. The team were brilliant on the day, courteous, professional and worked safely within the Pandemic guidelines. My husband and I are delighted with the end result, it looks amazing. Thank You Avanti. Highly reccommended!
Robert Edwards
Oct 15, 2020
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Very high quality doors, no nonsense quote provided, no pushy sales process. Excellent fitting service by professional team, I would highly recommend this company to anyone.
