House Extensions
Belfast
Add Space, Value & Style to Your Home Across Belfast & Northern Ireland
House Extensions by DPMNI
Looking to expand your living space without moving home? At Diamond Property Maintenance (DPMNI), we specialise in high-quality house extensions in Belfast and surrounding areas. Whether you’re dreaming of a bigger kitchen, an extra bedroom, or a bright new living area, we help homeowners across Northern Ireland transform their properties with expertly built, fully compliant extensions.
From concept to completion, our skilled team delivers reliable service, clear communication, and exceptional workmanship — every step of the way.
Trusted by Homeowners, Landlords & Businesses
Why Choose a House Extension?
A professionally built house extension offers one of the best returns on investment for homeowners. It allows you to:
Increase your home’s square footage
Add functional space without relocating
Boost property value and market appeal
Design a layout that suits your lifestyle
Create open-plan areas for modern living
Avoid the hassle and cost of moving
Whether you need more space for a growing family, working from home, or entertaining, a home extension gives you the flexibility to shape your home around your life.
Our House Extension Process
We take care of everything, offering full design-and-build support or working with your architect and plans:
We manage the build from start to finish — keeping communication open and disruption minimal.
Benefits of Extending Your Home
Extensions are ideal for growing families, remote workers, hobbyists, or anyone wanting more usable space.
Types of House Extensions We Offer
We design and build a wide range of extensions for every type of home:
Ideal for expanding kitchens or open-plan family areas — rear-facing builds that add space while blending into your garden layout.
Combine side and rear extensions to dramatically reshape your ground floor with open-plan living, dining, and entertaining space.
Transform narrow, underused areas beside terraced or semi-detached houses into useful space.
Add rooms on both floors — perfect for extra bedrooms, bathrooms, or an upstairs study.
Convert or build above your garage for additional space without reducing your outdoor footprint.
Frequently Asked Questions
Prices vary depending on size, complexity, and materials. On average:
Small single-storey extension: from £20,000+
Double-storey extension: from £35,000+
We offer free consultations and fixed-price quotes.
Not always. Many single-storey extensions fall under Permitted Development. We can guide you through planning or manage it on your behalf.
Most house extensions take 8–14 weeks from groundworks to final finish, depending on weather and complexity.
Yes — we offer design-and-build packages, or we can work with your architect’s plans.
Rear kitchen extensions, open-plan living spaces, and double-storey builds with additional bedrooms tend to add the most long-term value.
Yes — our in-house team covers building, roofing, plumbing, electrics, plastering, and decorating.
Six Reasons For People Choosing Us
Experienced Team
Our time-served tradesmen are PASMA and IPAF-trained professionals, ensuring safe and efficient service.
Comprehensive Insurance
We carry £10 million public liability insurance and specialized SSR insurance for your peace of mind.
Eco-Friendly Cleaning
We use child-safe, animal-safe, and plant-safe cleaning solutions to protect your environment.
Proven Track Record
With over 1,400 satisfied customers, we’re trusted by homeowners and businesses alike.
Tailored Solutions
Every job is unique, which is why we provide a free consultation and custom plans based on your needs.
Local Expertise
We understand the unique challenges in North Down and Antrim, tailoring our services to meet the specific needs of your area.
Ready to upgrade, expand, or transform your property?
Book a House Extension Consultation Today
Ready to expand your space and improve your home? Let DPMNI’s expert builders help you design and build the perfect house extension — trusted across Belfast and Northern Ireland.
Other Exterior Cleaning Services We Offer
We provide reliable, efficient, and environmentally conscious cleaning for residential, commercial, and agricultural clients.
HouseExtensions
Add extra space, value, and function to your home with a professionally built extension. Ideal for growing families or creating open-plan layouts.
LoftConversions
Transform your unused attic into a functional, stylish living area — whether it’s a new bedroom, office, or playroom.
HouseRenovations
From reconfigurations to full refurbishments, we modernise homes with high-quality renovation services designed around your lifestyle and budget.
KitchenFitters
Upgrade your kitchen with bespoke fitting and installation. We handle everything from unit fitting to flooring, tiling, and finishing touches.
BathroomFitters
Create a functional, elegant bathroom with our expert team. We install baths, showers, sinks, toilets, and full wet room setups.
RoofRepairs
From storm damage and minor leaks to structural issues, we offer fast, reliable roof repairs for homes and commercial properties.
RoofReplacement
We carry out full roof replacements using modern, durable materials — protecting your property and enhancing its appearance.
Gutter, PVC& Fascia Fitting
Upgrade or replace damaged exterior components with our expert PVC, fascia, and gutter fitting — protecting your roofline and improving drainage.
Fencing& Repairs
Secure your property and add privacy with custom fencing solutions — from wooden boundary fencing to decorative garden panels.
Landscaping& Hardscaping
Transform your outdoor space with our tailored landscaping services, including paving, turfing, decking, garden design, and more.
IndustrialFacility Repairs
Keep your site compliant and running smoothly with responsive, cost-effective industrial maintenance and repair services.