CBS Renovation · attic conversions in het Gooi
We turn a storage loft into a bedroom, a study or a bathroom, with the structure, insulation, dormer, stairs and finishing in one project.
In many houses the attic is still storage space: boxes, a loft ladder and a roof that was never insulated. An attic conversion turns it into a room you use – a bedroom, a home office, a children’s room, a guest room or a bathroom – without building on or moving house.
Every attic is built differently, so we start with a survey at the house. We measure the height under the ridge, check the roof structure and the attic floor, and look at where a staircase and a dormer can go. You then receive a quotation that names the work part by part: structure, insulation, dormer or roof windows, stairs, installations and finishing.
CBS Renovation converts attics across het Gooi and the adjoining part of the province of Utrecht. The conversion runs as one project, with one contact person from the survey to handover. The dormer, the insulation and the installations are planned together, so the roof is opened once and the finishing follows on from the structural work.
Spacious fourth bedroom, fixed staircase, house fully renovated – see the project
An attic conversion involves the roof, the structure, the installations and the stairs. These are the parts we carry out, planned together as one project.
Every attic conversion starts with a visit to the house. We measure the height under the ridge and check the roof structure and the attic floor: can the joists carry a bedroom or a bathroom, and where will a staircase come up from the floor below? If the roof or the floor has to be strengthened, a structural calculation shows how. From the survey we draw up an itemised quotation, so you can see what each part of the work involves and costs.
For an attic you live in, the loft insulation goes into the roof itself rather than onto the attic floor. We insulate the pitched roof from the inside, fit a vapour control layer on the warm side and close it with plasterboard. In the 1905 house in Bussum the roof was insulated with Kingspan Kooltherm K12 and the pitched roof received 140 mm of PIR (Rd = 6.3); at Verdilaan 14 in Hilversum the roof was also insulated from the inside. Ventilation is planned in the same step.
More about insulation
A dormer window, called a dakkapel in the Netherlands, is an extension on the pitched roof. It gives the attic standing height and daylight over more of the floor, and where that is not enough the ridge can be raised. On Talmalaan 32 in Soestdijk a new dormer with a raised ridge created a spacious fourth bedroom; on Meentweg 62 in Bussum we fitted dormers and retiled the roof. Whether a permit is needed depends on the house and where the dormer goes, so we check that first.
More about extensions
Not every part of the attic needs a dormer. A roof window, or skylight, set into the slope brings daylight over the stairwell, into a bathroom or into a room where no dormer is planned. We trim the rafters around the opening, flash the window into the tiles, then insulate and finish the reveals together with the rest of the room. Existing dormers can be reworked as well: in the 1905 house in Bussum they were reinforced with extra beams and given new windows.
A loft ladder will do for storage, but a bedroom or a study calls for a fixed staircase. Its position is settled early, because it takes space on the floor below as well as in the attic. We look at the line of the existing stairs, the headroom above the treads and the landing at the top. At Kortenaerlaan 22 in Hilversum, a house we fully renovated, a fixed staircase leads to a landing on the attic floor with two bedrooms and a shower room.
A room under the roof gets its own circuit in the consumer unit, sockets where the furniture will stand, lighting and a smoke alarm on the landing. Heat comes from a radiator on the central heating or from underfloor heating; at Meentweg 62 in Bussum underfloor heating runs on every floor, with room-by-room controls. Fresh air comes through opening windows and, where needed, mechanical extract. Pipes and cables go in before the walls are closed.
More about underfloor heating
A bathroom in the attic needs a watertight floor, a drain to the soil stack and extract ventilation. In houses we have renovated, the attic holds a bathroom with a bath (Haagkerslaan 32), a shower room (Kortenaerlaan 22) or a bath with a double basin and electric underfloor heating (Neuweg 463). The finishing follows: plastered walls, floors, internal doors and cupboards built in behind the knee walls. When the rest of the house is renovated as well, the attic is finished to match.
More about house renovation
Tell us what you want to tackle. After a survey at the property you receive an itemised quotation.
+31 34 679 40 57
Attic floors in houses we have renovated, with the town and what is under the roof today.
Amstelveen, renovated in 2022: two dormers, two bedrooms and a bathroom with a bath.
Hilversum, 1957 house renovated in 2021: shower room and two bedrooms, each with a dormer.
Bussum: pitched roof insulated with 140 mm PIR, dormers reinforced, energy label G to A+++.
Bussum, built 1920: dormers fitted, roof retiled and insulated; we applied for the permit.
Hilversum, 1950s corner house: roof insulated from the inside, third bedroom with a dormer.
Hilversum, built 1957: two bedrooms with dormers, bathroom with bath and double basin.
From the survey to handover you deal with one contact person, and we coordinate the structure, the roof, the installations and the finishing, so you do not have to schedule separate trades.
After the survey you receive a quotation with the dormer, the insulation, the staircase, the installations and the finishing each on a separate line.
Our team counts 75 engineers and tradespeople, so the structural work, the installations and the finishing of an attic are in experienced hands.
We give a guarantee on the work we carry out, under the roof and in the rest of the house.
Our roots go back to 1995, and more than half of our work comes from previous clients and their referrals.
Our office is in Breukelen, at Merwedeweg 5b. From there we work across het Gooi and in the adjoining part of the province of Utrecht. Wherever the house stands, an attic conversion runs the same way: a survey at the property, an itemised quotation, and one contact person from the first visit until the attic is handed over.
That depends on the house and on where the dormer goes. The Dutch permit is called an omgevingsvergunning. We check this before any work starts. Where a permit is needed, we prepare the drawings and the structural calculation and file the application, as we did for Meentweg 62 in Bussum, a 1920 house where we also fitted dormers and retiled the roof.
It depends on three things: the height under the ridge, the strength of the roof structure and the attic floor, and the space for a fixed staircase. A low attic can gain height with a dormer or a raised ridge, as on Talmalaan 32 in Soestdijk, where that created a fourth bedroom. During the survey we measure all of this and explain what your attic allows.
That depends on what your attic needs. A dormer, a raised ridge, roof windows, insulation, a staircase, a bathroom and the finishing each affect the price differently, and so does the state of the roof. We therefore give a figure only after a survey at the house. You then receive an itemised quotation with each part on its own line, so you can see what the dormer, the insulation or the bathroom costs.
Yes. We insulate the roof as part of the attic conversion, while the roof structure is open and before the walls are finished. The work is done from the inside, with a vapour control layer on the warm side. At Talmalaan 32 the whole house was insulated during the renovation; at Meentweg 62 in Bussum the roof was insulated separately from the walls, which received PIR panels.
Yes, if the floor can carry the weight and a drain can reach the soil stack. We waterproof the floor, connect the drainage and the water supply, fit extract ventilation and, if you wish, underfloor heating. On the second floor of Neuweg 463 in Hilversum, a house we renovated, the bathroom has a bath, a toilet, a double basin and electric underfloor heating.
Yes. Every attic on this page was part of a larger renovation of the house. At Kortenaerlaan 22 in Hilversum, for example, the electrics, the meter cupboard, the boiler, all radiators, the bathrooms and the floors were renewed in 2021. When the attic is combined with other work, the installations and the finishing are planned once, with one contact person for the whole house.
Our office is in Breukelen, at Merwedeweg 5b. We work across het Gooi, in towns such as Hilversum, Bussum, Naarden, Laren, Blaricum, Huizen and Eemnes, and in the adjoining part of the province of Utrecht, including Soest, Zeist and Utrecht. We are at work six days a week, and every attic conversion starts with a survey at your home.
No-obligation quote
After a survey at the property you receive an itemised quotation. One point of contact, from survey to handover.
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