Business Details
38 Years
experience
Expert Window and Door Installations in Grantham
Avanti Windows has been serving Grantham and surrounding areas since 1988, establishing itself as a trusted family-run business specialising in high-quality window, door, and conservatory installations. Our team combines decades of industry experience with a commitment to delivering cost-effective, energy-efficient solutions tailored to both domestic and commercial needs. As FENSA-registered professionals, we prioritise security, thermal performance, and compliance with modern building regulations, offering A-rated glazing systems and multi-point locking mechanisms under the Secured by Design initiative.Our 10-year guarantee reflects our confidence in workmanship, while partnerships with bricklayers, electricians, and plasterers ensure seamless project management from concept to completion. Customer testimonials consistently highlight our punctuality, attention to detail, and pandemic-safe working practices, reinforcing our reputation as Grantham's preferred choice for property enhancement.
Services
Windows
Doors
Conservatories
Aluminium
Composite Doors
UPVC
Secondary Glazing
Bi-folding Doors
Skylights
Guttering and Roofing Options
Details
- Year established: 1988
Highlights and features
- We have over 35 years of local experience in window and door installations
- Our team provides cost-effective solutions tailored to your budget
- We offer a 10-year guarantee on all installations
- Our energy-efficient windows reduce utility bills by up to 30%
- We are FENSA registered for quality assurance
Associations and certifications
- FENSA
What people say
Very professional
High standard
Friendly bunch
Excellent fitting service
Fantastic company
Services
Window Installation
Our window installations combine security and energy efficiency through A-rated argon-filled glass and multi-point locking systems. We offer UPVC, aluminium, and timber options with custom designs to match property aesthetics. All installations meet FENSA regulations and include trickle vents for ventilation compliance.
Door Installation
We supply and fit composite, UPVC, and bi-folding doors with enhanced security features including anti-snap locking mechanisms. Our doors improve thermal efficiency while maintaining aesthetic appeal, available in various colours and finishes to suit residential and commercial properties.
Conservatory Construction
From design to completion, we build Edwardian, Victorian, and lean-to conservatories with UPVC frameworks. Our packages include skylights, dwarf walls, and optional electrics, all covered by a 10-year structural guarantee and compliant with current building regulations.
Secondary Glazing
Our secondary glazing systems improve thermal efficiency by up to 50% while reducing external noise. Slimline aluminium frames with double-sealed units provide discreet insulation solutions for period properties where primary window replacement isn't feasible.
Conservatory Roof Replacement
We replace outdated conservatory roofs with insulated, energy-efficient alternatives. Our solutions include glass or polycarbonate panels with optional self-cleaning coatings, enhancing thermal performance while maintaining structural integrity and aesthetic appeal.
Questions
Do you offer a guarantee on installations?
Yes, we provide a 10-year guarantee covering all window, door, and conservatory installations as standard.
Are your windows energy efficient?
All installations feature A-rated argon-filled glass with low-emissivity coatings to maximise thermal efficiency.
Can you help with building regulations?
We handle all necessary building regulation applications and compliance certifications for your project.
Do you work during bad weather?
Our team works year-round, using weatherproofing techniques to maintain installation quality in all conditions.
How long does installation take?
Most window and door installations complete within 1-2 days, with conservatories taking 3-5 working days depending on complexity.
Are your installers qualified?
All our engineers hold relevant industry certifications and undergo regular training updates to maintain technical expertise.
