A roof extension for an extra floor
Has your home outgrown itself, but moving isn't an option? A roof extension gives you a full extra floor: a master bedroom, children's rooms or a home office. We take care of the structural calculations, the build, insulation, staircase and finishing. One dedicated team, one point of contact and a clear price agreed up front.
A full living floor on top of your home
Structurally, a roof extension is the most far-reaching way to expand: the existing roof comes off, the structure has to carry the new floor, and everything must be watertight and warm. As a dedicated construction company in Rotterdam, we work together with a structural engineer and carry out the build with one team, quickly weathertight and neatly finished.
From a lightweight timber-frame extension to a steel structure: you receive a clear quote with a transparent price breakdown up front, we arrange the permit and the calculations, and you are left with a full, insulated floor. More space, more value in your home.
Request your free roof extension adviceOne dedicated team
Our own craftsmen, one point of contact, no miscommunication.
Clear price up front
A clear quote, with no surprises afterwards.
Guaranteed & certified
A guarantee on our work, plus CO certification, STEK, NEN 1010 and VCA.
Local in Rotterdam
Familiar with Rotterdam's homes and the local council.
Recent projects in Rotterdam and the Randstad
A selection of our completed projects. View the full portfolio for more.
What our clients say
We only publish genuine, verified reviews. Our clients' reviews will soon be shown here via Google.
What a roof extension involves
An extra floor calls for precision in both structure and finishing. We take care of the entire project.
Structural calculations
An accredited structural engineer calculates whether the building can carry the extra floor.
Timber frame or steel
A lightweight timber-frame build or a steel structure, to suit your home.
Roof insulation & covering
Well insulated and watertight, ready for comfortable living.
Fitting the staircase
A neat staircase that gives logical access to the new floor.
Window frames & insulation
Roof windows or frames with HR++ glass for light and low energy use.
Interior finishing
Walls, floors, electrics and painting, turnkey.
How we build your roof extension
A tight process in five steps, from calculation to handover.
Design & calculation
We take care of the design, structural calculations and the permit application for you.
Quote & schedule
You receive a clear quote with a transparent price breakdown and schedule.
Build & watertight
The roof comes off, the structure is placed and the extension is quickly made watertight.
Insulation & finishing
Insulation, window frames, staircase, services and the complete interior finishing.
Handover & guarantee
We walk through everything together and hand over neatly, with a guarantee on the work.
Our own team, no subcontractors
Your entire job handled by our own 20 to 30 craftsmen. Short lines, one point of contact.
One price up front, no surprises
You know where you stand from the outset. No unexpected extra costs afterwards.
1-year guarantee on the renovation
We stand behind our work and are only finished when you are satisfied.
Roof extensions in Rotterdam and across the Randstad
Rotterdamse Bouwbedrijf is at home in Rotterdam, but we build roof extensions across the whole Randstad. From Rotterdam and Dordrecht to The Hague, Leiden and Amsterdam, and everywhere in between. Don't see your town listed? Do get in touch, we work throughout the region.
And also in, among others
We work with reliable A-brands, for a durable result with a manufacturer's warranty.
Questions about roof extensions
Do I need a permit for a roof extension?
Can my home support an extra storey?
How long does a roof extension take?
Can I keep living in the house during the roof extension?
Where do you build roof extensions?
Ready for an extra floor?
Arrange a free, no-obligation consultation. We come to you, discuss the options and draw up a personal plan with a clear price.
What determines whether a roof extension is possible?
An extra floor is the finest way to gain space without giving up garden. Whether it is possible depends on the structure, the foundations and the zoning plan.
Can the structure carry it?
A roof extension puts extra weight on the existing walls and foundations. We always have a structural engineer calculate whether that is possible or whether reinforcement is needed. If there is any doubt about the foundations, no rarity in the Randstad, we carry out a survey first. This is not a step to skip.
A timber or masonry extension
A timber-frame extension is light and quick, and puts less load on the structure. A brick-built extension blends in seamlessly with the existing home. Which choice suits you depends on the load-bearing capacity, the budget and the look you want.
Permit and building height
A roof extension almost always requires an environmental permit. The council assesses it against the zoning plan, with a maximum building height, and against aesthetic (welstand) requirements. We arrange the application and the drawings, so you don't get stuck halfway.
Common mistakes
- Starting without structural calculations, risking an unsafe or rejected extension.
- Forgetting to plan the stairwell, leading to unusable space or a big loss of space below.
- Underestimating the insulation, leaving a sweltering top-floor room in summer and cold in winter.
Less drastic, but still more space in your loft? Consider a dormer. Prefer to extend outwards at the rear instead? See home extensions. If you would first like to know what is possible with your existing loft, read up on converting a loft into a full room.