Loft conversions and dormers
A storey added or a dormer let in, without the structure below becoming a problem.
A loft conversion is the cheapest way to add a bedroom without giving up garden, and the most expensive way to make a structural mistake. Everything you put on top has to land somewhere below. In the 1970s terraced houses of Maarssenbroek the party walls were designed for it; in a pre-war house on the Straatweg, often not.
So on every loft conversion we have a structural engineer (constructeur) do the calculation before there is a price, not after the quotation is signed. That calculation costs money and it appears as its own line on the quotation, so you can see what you get for it: a set of figures the municipality accepts and against which the work is carried out.
A dormer is a different job in a different price class. There it comes down to the width, the position of the purlins and whether the roof boarding still carries. A three metre dormer on a sound roof is up in two to three days; the rest of the lead time sits in the preparation and the permit.
- What the municipality wants to see
- A full loft conversion is almost never permit-free: the building height changes and so does the appearance from the street. It needs an environmental permit (omgevingsvergunning) with a structural calculation and usually an appearance test by the municipal aesthetics committee (welstand). In Stichtse Vecht and De Ronde Venen that procedure normally takes eight to twelve weeks. A dormer at the rear is more often permit-free, but not inside a protected village area and not on a listed building.
- The staircase is half the job
- With a loft conversion the existing loft stair often becomes too steep or too short, and sometimes a fixed staircase has to go where a loft ladder was. That costs floor area on the storey below, and it is the reason loft conversions regularly fail at the drawing board. We look at it first, at the survey, not last.
- Insulation and sound
- New roofs are built up with an insulation package considerably thicker than what went in during the 1970s. That costs headroom. On a Maarssenbroek house it means a choice between insulation value and standing height, and we put that choice to you with the consequences attached rather than making it for you.
Roughly what it costs
Price ranges for this area, so you can see whether your plan and your budget meet before anyone comes round. Each line states what explains the difference between the bottom and the top of the range.
| Work | Range | What explains the spread |
|---|---|---|
| Extension, single storeyper m² of floor area, shell through to finished | € 2.000 to € 3.200 | Foundation on strip footings or on piles, how much glass goes into the rear wall, and the level of floor, ceiling and services. |
| Loft conversion, full storeyper project, terraced house | € 45.000 to € 85.000 | Whether the party walls run down to the foundation, whether a fixed staircase has to be added, and the thickness of the insulation against the headroom you want. |
| Dormer to the reareach, around 3 metres wide | € 8.000 to € 15.000 | Width and window layout, whether roof purlins have to be interrupted, and whether the roof boarding and insulation are renewed at the same time. |
| Opening in a load-bearing wallper opening, 3 to 4 metres | € 4.000 to € 9.000 | The span and therefore the weight of the steel beam, how easily it can be brought in, and how much plastering and painting follows. |
| Complete bathroomper bathroom of 5 to 8 m², excluding tiles and sanitary ware | € 12.000 to € 25.000 | Moving waste pipes, the condition of the existing floor, and whether the ventilation has to be replaced. |
| Kitchen, building work onlyper kitchen, excluding the kitchen units themselves | € 4.000 to € 10.000 | Whether a wall has to go, how far water and waste are moved, and whether an extraction duct to the outside is installed. |
| Repointing brickworkper elevation of a terraced house | € 3.500 to € 7.000 | Height and therefore scaffolding, raking out by grinder or by hand, and whether a lime mortar is required inside a protected village area. |
| Rot repair in a window frameper affected spot | € 250 to € 900 | How far the rot has gone and whether the profile can still be repaired or the section has to be replaced. |
All amounts include Dutch VAT (btw) and apply to houses in this area. They exist so you can judge whether your plan and your budget meet; they do not replace a quotation. After the survey at your house you receive a fixed price for the work as described.
How it runs, from the first phone call to handover
Nine steps. Each one states who is there, how long it takes and what you pay at that moment. On the steps where money actually changes hands, the amount is set in the heading face under "What you pay" and the step number is filled in. Handover is called oplevering in Dutch, and it is the step your contract will refer to.
Step 1: Phone call
You call, or leave a callback request. We ask about the type of work, the year the house was built, the place and roughly what you have in mind. By the end of that call you know whether this is work we take on and whether your budget and your plan meet. If they do not, we say so there and then.
- Who is there
- You and the work planner
- How long
- 15 minutes, within one working day
- What you pay
- Nothing
Step 2: Survey at your house
We come round, measure up, look in the crawl space (kruipruimte) and the loft, and assess the foundation, the structure and the connections to the existing house. For a loft conversion or a structural opening we establish whether a structural engineer (constructeur) is needed. You hear on the spot which price range is realistic.
- Who is there
- You and the site manager
- How long
- 45 to 90 minutes, within two weeks
- What you pay
- Nothing
Step 3: Quotation with a fixed price
You receive a quotation (offerte) with a fixed price for the work as described, a list of what is explicitly not included, and provisional sums (stelposten) for items you choose yourself. No figure in it is an estimate: what the quotation says stands, as long as the work does not change.
- Who is there
- We supply it, you read it
- How long
- Within five working days of the survey
- What you pay
- Nothing
Step 4: Design, calculation and permit
Only where the work requires it. Drawings, a structural calculation, and the permit application (omgevingsvergunning, the Dutch building permit) with the municipality of Stichtse Vecht or De Ronde Venen. If the permit is refused, the project stops and you pay for this phase only, at an amount stated on the quotation in advance.
- Who is there
- Draughtsman, structural engineer and the municipality
- How long
- 4 to 12 weeks, depending on the procedure
- What you pay
- The cost of this phase, named separately on the quotation
Step 5: Planning and start date
The start date is fixed in writing, with a week by week plan and the days on which it will be loud or dusty. Materials with long lead times are ordered in this phase, so the job does not come to a halt halfway through waiting for a window frame.
- Who is there
- You and the work planner
- How long
- 1 to 2 weeks
- What you pay
- Nothing
Step 6: Work starts on site
Day one: fencing, floor protection, a place to unload, and demolition. From this day there is one site manager who is your point of contact and whom you can call directly on working days.
- Who is there
- The site manager and the crew
- How long
- Day 1
- What you pay
- First instalment: 30 per cent
Step 7: Shell complete
Foundation, structure, brickwork, roof and window frames are in place and the work is wind and watertight. This is the moment you can stand in the new space for the first time, and the last moment changes are possible without demolition.
- Who is there
- The site manager walks it through with you
- How long
- Depends on the job, usually after 3 to 6 weeks
- What you pay
- Second instalment: 30 per cent
Step 8: Services and fit-out
Electrics, water, heating and ventilation are installed and tested. Then plastering, floors, tiling and painting. This phase is quiet but long; it is the phase in which people get impatient and in which the weekly plan matters most.
- Who is there
- Installer, plasterer and fit-out crew
- How long
- 2 to 5 weeks
- What you pay
- Third instalment: 30 per cent
Step 9: Handover and snagging list
We walk the work through together and write down everything you see, however small. In Dutch this step is the oplevering and the list is the opleverlijst. That list is cleared within fifteen working days. Only once every point on it is signed off does the last instalment fall due.
- Who is there
- You and the site manager
- How long
- 1 to 2 hours, points cleared within 15 working days
- What you pay
- Final instalment: 10 per cent, after the snagging list is cleared
The payment schedule
Nothing is paid in advance before work starts.
Each block in the bar is as wide as its share of the contract sum (aanneemsom). The pale block on the right is the final 10 per cent: it only falls due after handover (oplevering), once every point on the snagging list has been dealt with.
| Instalment | Share | When |
|---|---|---|
| First instalment | 30% | The day work starts on site |
| Second instalment | 30% | Shell complete, the work is wind and watertight |
| Third instalment | 30% | Services tested and fit-out complete |
| Final instalment | 10% | After handover, once every snagging point is cleared |
| Together | 100% |
The cost of drawings, the structural calculation and the permit sits outside these four instalments and is named separately on the quotation, so you can see what you would be out of pocket if a permit is unexpectedly refused. The total being paid in instalments is the contract sum, called the aanneemsom in your contract.
Questions about this work
Is my house liveable during a loft conversion?
The days on which the existing roof is opened are the critical ones. We work with a temporary cover then and plan that part for a dry spell. The storey below is unusable on those days. For the rest of the building time you can stay in the house as normal.
Do I always need a structural engineer?
For a loft conversion, yes. For a dormer, only if purlins or a truss are interrupted, which is usually the case above roughly two and a half metres wide. The cost of the calculation appears separately on the quotation, so you can see what it is instead of guessing.
What if the permit is refused?
Then the work does not go ahead and you pay only for the preparation carried out by that point: survey, drawings and structural calculation. Those amounts are stated on the quotation in advance, so you know the maximum risk before you begin.
More about this work in this area
The cost of a loft conversion varies widely because two very different jobs fall under the same name. A full extra storey on a terraced house, including structure, staircase, services and finishing, usually sits between 45,000 and 85,000 euros. A three metre dormer at the rear sits between 8,000 and 15,000 euros, depending on width, window layout and whether insulation is renewed at the same time.
In Maarssenbroek it is nearly always houses from the period 1970 to 1985, with a light roof structure on purlins and party walls in sand-lime brick. That combination suits a dormer well and a full conversion reasonably, as long as the party walls run down to the foundation. In the older ribbon development of Maarssen-Dorp, Breukelen and Loenen aan de Vecht it is far less predictable and the structural calculation carries more weight.
Reckon on eight to twelve weeks between the permit application and the first day on the roof, and two to four weeks of building time for a full conversion. A dormer takes two to three days on the roof.
Talk through your plan
Calling is quickest and takes fifteen minutes. If you would rather be called back, choose a time slot that suits you.