Extensions
Extra room at the back or the side of the house, at a fixed price before the first brick is laid.
An extension is the most requested addition in this area and at the same time the job that produces the most surprises. Rarely because of the brickwork. Nearly always because of the ground underneath, the connection to the existing house, and what appears once the rear wall is opened up.
So we do not start with a drawing but with a survey on site: the make-up of the soil, the existing foundation, where the drains run, the state of the rear wall, and the height of the garden against the ground floor. On the peat soils of Mijdrecht, Vinkeveen and Wilnis an extension is almost always founded on piles, even where the existing house sits on strip footings. Two foundations side by side that settle at different rates open a crack along the joint within a few years, and that crack costs more afterwards than the piles would have cost up front.
The price you receive is a fixed price for the work as described, including waste removal, scaffolding and protection of the existing floor. What is not included is spelled out in words, so you know where a further amount could still appear. Anything added later is meerwerk, the Dutch term for work outside the signed contract, and it always goes in writing with a price before it is carried out.
- What sets the price per square metre
- The difference between the bottom and the top of the range comes down to three things: the foundation (strip footings or piles), how much glass goes into the rear wall, and the level of floor, ceiling and services. An extension with a plastered ceiling, underfloor heating and a four metre sliding door costs around one and a half times as much per square metre as the same room with a plastered wall, a radiator and an ordinary window.
- Permit or no permit
- Under the Dutch Environment Act (Omgevingswet) an extension at the rear is in many cases permit-free, but that depends on the depth, the size of the rear garden zone and whether the house is a listed building or sits inside a protected village area (beschermd dorpsgezicht). In Maarssen-Dorp, Breukelen and Loenen aan de Vecht the last of those often applies. We check it per address with the municipality before you get a quotation, not after.
- How long it disrupts you
- A twenty square metre extension takes eight to twelve weeks on site. The first two weeks are the loudest: demolition, groundworks and piling or drilling. After that the noise moves outside. The kitchen normally stays usable until the week the opening through to the extension is made, and we plan that week with 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
Can I stay in the house while it is built?
In nearly every case, yes. The rear wall stays closed until the last moment: the opening is only made once the extension is wind and watertight. That week is the only one in which dust reaches the house, and we plan it with you in advance.
What happens if something unexpected is under the rear wall?
That is meerwerk, and it follows the same route as any other meerwerk: work on that element stops, you receive a price within two working days with the effect on the planning, and it is only carried out after your approval. We never charge an amount afterwards that you have not seen on paper first.
What about the foundation if my house stands on peat?
Then the extension goes on piles, usually screwed steel tube piles or drilled piles, because driven piles are often impossible in a built-up residential street. The extension gets its own foundation and is kept structurally separate from the existing house, so that different rates of settlement do not open a crack along the joint.
Is an extension possible on a narrow plot along the Vecht?
Usually, but access sets the price. On plots along the Zandpad and the Diependaalsedijk no crane can get in and everything goes over a walkway or through the neighbours’ garden. That is named separately in the quotation, so you can see what the location costs and what the work costs.
More about this work in this area
Anyone searching in English for the cost of an extension in Maarssen or along the Vecht runs into figures that are ten years old. The price per square metre for an extension with a normal finish currently sits between 2,000 and 3,200 euros, including foundation, shell, window frames, services and finishing. A four metre deep extension across the full width of a terraced house in Maarssenbroek therefore usually lands between 45,000 and 70,000 euros.
The ground under your house decides more of that amount than the kitchen that goes into it. East of the Amsterdam-Rijnkanaal, in Maarssen-Dorp and along the Zandpad, sand and clay lie close to the surface and strip footings are more often possible. In De Ronde Venen there is peat, and then piling or screwing in piles is the rule. Reckon on four to eight thousand euros of difference on an average extension.
Ask three things of every quotation you receive: what sits under the foundation, what happens at the join with the existing rear wall, and what is explicitly excluded from the price. Those are the three places where the amount tends to climb once building has started.
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.