Crawl Space Inspection

The crawl space (kruipruimte) is the space under your floor where you never go yourself. That is exactly where we find many of the expensive defects in Amsterdam homes: rotten floor joists, standing water, leaking sewer pipes, rusting steel beams and emergency props that a previous owner once put under the floor.

Even so, at many home inspections the crawl space is not really inspected. The hatch is opened, someone shines a torch in, and that’s it. Sometimes the buyer is told that the inspector is not allowed in “because of the Working Conditions Act” (Arbowet). That is not true. On this page we explain what the law actually says, what we find in crawl spaces, how we inspect them and what repairs cost. Everything is based on our own reports.

Nederlandse versie: Kennisbank Kruipruimte. Reviews from English-speaking clients: English reviews.

In brief

Is an inspector allowed into the crawl space? Yes. The Working Conditions Act and the Working Conditions Decree (Arbobesluit) set no minimum height for a crawl space, not 50 centimetres either. The inspector decides on site whether it is safe.
When do we stay out? When there is water in the crawl space (risk of electrocution), when dangerous gases are suspected, or when there is asbestos or material that may contain asbestos.
Why go in? From the hatch you see a few square metres. You don’t see the beam ends in the facades, the wall plates, the sewer pipes or the water at the back.
What do we find? In the 53 crawl space inspections we read through for this page, more than half reported wood rot and more than six in ten a poorly ventilated crawl space.
What does it cost you if the crawl space is skipped? Defects under the floor then play no part in the purchase. After the sale they can cost tens of thousands of euros, and there is little you can recover afterwards.
What does a crawl space inspection cost? At Premiumkeur from € 499 including VAT. You receive the report within two working days.

1. Why the crawl space matters so much

A large share of Amsterdam homes built before 1940 has a timber ground floor: floor joists with their ends resting in the facades and party walls, often with a wall plate along the wall and sometimes a supporting beam or steel girder in the middle. Below that floor is the crawl space, often with a damp soil and groundwater close by.

Wood and moisture don’t go well together. Dry wood has a moisture content of about 12 percent. If it stays wetter for a long time, fungi and wood rot get their chance. That happens slowly, and above the floor you only notice it when the floor starts to bounce, slope or creak. By then the damage is usually extensive.

That is why the crawl space matters so much to a buyer. Replacing a floor is no small job: the home has to be emptied, the kitchen and bathroom often partly come out, and in an owners’ association (VvE) the members have to decide on the costs. In our reports we see amounts from a few hundred euros for extra ventilation to tens of thousands of euros for a new floor.

2. What we find in crawl spaces

For this page we read 53 separate crawl space inspections from our archive in full, from 2017 up to and including 2023. They cover 37 homes and buildings in Amsterdam and 16 in the region. This is what the reports said:

A poorly ventilated crawl space (too few, too small or blocked vents): in more than six in ten.
Wood rot or brown rot in floor joists, beam ends, wall plates or supporting beams: in more than half.
A floor or joists that sag, have subsided or are losing their load-bearing capacity: in about half.
Woodworm (usually mild, sometimes active): in more than four in ten.
Leaking, broken or badly installed sewer pipes or drains: in about three in ten.
Rusting steel beams or girders: in more than a quarter.
Water on the floor of the crawl space or visible groundwater: in at least a quarter.
Fungus or brown rot, sometimes confirmed, sometimes suspected: in about a quarter. We only report dry rot (huiszwam) when we actually see it.
Emergency props, jacks, blocks or wedges under the joists: in about one in five.
A gas pipe that is corroded or not installed according to the rules: in almost one in five.

An honest note: a separate crawl space inspection is usually requested when there is already a doubt. For example a bouncing floor, damp, mosquitoes or an earlier inspection that raised questions. So these figures don’t mean that half of all Amsterdam floors are rotten. They do show which defects are there when you look properly.

Our archive of almost 3,000 of our own reports contains more than 140 crawl space inspections. On top of that, we inspect the crawl space at every building inspection where there is one.

3. “The Working Conditions Act doesn’t allow me in the crawl space.” Is that true?

No. Buyers hear this regularly, but it is not in the law. The Working Conditions Act and the Working Conditions Decree say nothing about a minimum height for a crawl space. Nowhere does it say that you may not enter a crawl space lower than 50 centimetres. That is why Fred Tokkie calls it “the crawl space excuse” (de kruipruimtesmoes): a reason that sounds legal, but isn’t.

So what does the law say?

In article 3.5g (in Dutch), the Working Conditions Decree covers work in spaces where there is a risk of suffocation, intoxication, poisoning, fire or explosion. If you can expect the air in a space to contain such substances, an employee may only enter if an assessment shows that it is safe. That is about the air in the space, not about its height.

In an ordinary crawl space under a house, that is usually not the case. There are exceptions: a leaking sewer pipe can release sewer gas, and on peat soil marsh gas can come out of the ground. If it smells of sewage or gas, nobody goes in.

And the 50 centimetres?

That doesn’t come from the law. It does appear in the general terms and conditions of several other inspection companies that we have read: there the crawl space is only viewed from the hatch, or only entered if it is dry and at least 50 centimetres high. Sometimes only if a second person is present. That is the companies’ own choice. They are free to agree on it that way, but it is not a legal rule, and it means that a large part of the crawl space often goes unseen.

The industry itself also expects low crawl spaces. The health and safety catalogue Working in crawl spaces (in Dutch) of the installation and insulation industry is a guideline, not a law, and you may deviate from it with good reason. The catalogue gives 80 centimetres as the preferred height, but also sets rules for existing crawl spaces lower than 60 centimetres: there you may work for at most one hour at a time. Working in lower spaces is simply provided for.

When is a crawl space dangerous?

Water. If there is water in the crawl space, we don’t go in. Water and electricity (cables, a submersible pump, lighting) is a life-threatening combination. The catalogue also mentions the risk of drowning if you are taken ill.
Dangerous gases. When sewer gas, gas or other dangerous air is suspected, as described above.
Asbestos. If there is asbestos or material that may contain asbestos, we don’t go in and we report it.
A floor that is giving way or an access that is too tight. Then we look for another way in: a different opening, a robot or an endoscope.

The inspector decides on site whether it is safe. That is how it works for the roof as well.

4. Looking from the hatch only: what do you miss?

From a hatch you see the soil and a few joists directly below the opening. With a strong torch you can see a few metres further, but always at an angle, with pipes and joists in the way. What you usually don’t see:

The beam ends in the front and rear facade. That is where wood rot starts most often, because the facade passes on moisture.
The wall plates along the walls and the supporting beams in the middle.
The sewer pipes. They often run to the front facade and leak precisely at the joints.
Water and rubble at the back, and emergency props that a previous owner put in.
The strength of the wood. You can only judge that by touching the wood, probing it or doing a drill test. That can’t be done from the hatch.

It works both ways. In one of our cases (see case 6), after an earlier inspection from the hatch only, it turned out that just the wall plate near the front door was affected; the rest of the floor was sound. You only know that once you have been inside.

How often does it happen? In the inspection reports by other inspectors that we have seen in our work, mainly for second opinions, more than four in ten stated literally that the crawl space had only been viewed from the hatch. None of those reports said that the inspector had gone into the crawl space. A note: people mainly ask for a second opinion when they have doubts or are unhappy. So this is not a sample of all inspections in the Netherlands.

5. What it costs you if the crawl space is not inspected

For you as a buyer, it doesn’t matter why an inspector doesn’t go into the crawl space. The result is the same, and it almost always goes like this:

You have the home inspected because you want to know what you are buying.
The crawl space is not inspected, or only from the hatch. The report then says something like “not inspectable” or “limited access”.
Rotten joists, a leaking sewer pipe or water under the floor are therefore not in the report. They play no part in the price negotiation or in the condition precedent (ontbindende voorwaarde).
The purchase goes ahead.
Months or years later the floor starts to bounce or sink. Then it turns out to be a matter of tens of thousands of euros.

A few examples. At the owners’ association in case 1, two earlier inspections had skipped the crawl space; repairs were estimated at € 60,000 to € 80,000, around € 15,000 for each member. In 2023 the investigative journalism collective Onderzoekscollectief Spit followed us for six months and described a ground-floor home in Amsterdam-Oost. At the earlier inspection there had been no access to the crawl space, and repairs were put at about € 4,800. The hatch turned out to be under a doormat, the joists were full of brown rot, and repairing the floor cost the owner around € 45,000. In another house, an earlier inspection came to just over € 5,900; after our inspection in the crawl space it was around € 25,000, and the buyers decided not to buy.

Why there is little you can recover afterwards

From the inspector. The general terms and conditions often largely exclude the crawl space. It is hard to blame the inspector for something that didn’t have to be inspected. In some terms and conditions, defects for which “further investigation” was advised are also excluded from liability. Spit found eighteen court cases over four years on rechtspraak.nl in which buyers sued their own inspection company. The buyer did not win a single one.
From the seller. The seller has to disclose known defects, but as a buyer you also have a duty to investigate (onderzoeksplicht). With an old house you are expected to allow for wear and for defects that you can’t see straight away. That is exactly why you have it inspected. We don’t give legal advice on this.

So the risk under the floor ends up with you after the purchase. A full inspection of the crawl space is the way to find out before you buy.

6. How independent is your inspector?

Many buyers are recommended an inspector by the estate agent, sometimes by the mortgage adviser. Those are parties who only earn money if the sale goes through. An inspection that brings expensive defects to light does not help them.

Onderzoekscollectief Spit and the weekly De Groene Amsterdammer looked into this in 2023 in The small print of the home inspectors (in Dutch, by Bram Logger). What they described:

Estate agents often refer buyers to inspectors with similar general terms and conditions: only assess what can be seen with the naked eye, not on the roof and not under the floor.
With some inspection companies, the estate agent receives a fee for every inspection he brings in. The buyer usually knows nothing about it.
Former inspectors spoke of three or four inspections a day, a report within a day and repair estimates that were not allowed to come out too high.
A professor of financial ethics called such mutual fees undesirable, because the client has no insight into them.

Spit found no evidence of secret agreements between inspectors and estate agents to deliberately disadvantage buyers. They did describe an earnings model that suits the inspector and the estate agent, while the buyer pays if something turns up later. Bram Logger talked about his research in October 2025 on Villa VdB on NPO Radio 1 (in Dutch).

So our advice is simple. Choose an independent inspector yourself, not one recommended by the selling or buying estate agent or your financial adviser. Ask in writing whether the inspector pays or receives fees for referrals, and whether he goes into the crawl space. Premiumkeur does not inspect on behalf of sellers, does not work with estate agents and puts its independence in writing in the order confirmation.

7. How we inspect a crawl space

If the crawl space is easy to reach, we go in. That applies to a crawl space inspection and also to a building inspection. What we do:

Look and feel. We follow the joists into the facades and party walls and assess the beam ends, wall plates and supporting beams.
Drill test. With a small drill we check whether the wood is hard. If it is rotten, the drill goes in without any effort.
Moisture measurement. We measure the wood with a moisture meter. Dry wood is around 12 percent; above that we start looking for the cause.
Sewer pipes, other pipes and ventilation. Is anything leaking, is the gas pipe in order, how many vents are there and are they open?
Photos. Every finding is in the report with a photo, so that you and your owners’ association can see for yourselves what is going on.

If we can’t get in

If the crawl space is very low, less than about 20 centimetres, we use a robot with a 4K camera. It drives under the floor and films the joists. With a lot of rubble or obstacles the robot doesn’t work well. Sometimes we look through a small hole in the floor with an endoscope, or we advise an extra crawl space hatch. At one apartment building we had a new hatch made this way and then inspected the part that had been out of reach before (case 2).

We are honest about it too: not every crawl space can be reached everywhere. Of the 53 inspections we read, a quarter could only be done in part, because the space was too low or because of rubble, sand or insulation between the joists, and a few times only from the hatch or with a robot or endoscope. What we couldn’t see is then stated in the report. That way you know where you stand.

8. How serious is it and what do repairs cost?

Costs vary widely. A few examples from our reports, with the amounts as they were in the report at the time (including VAT, price level 2018 to 2021; expect them to be higher now):

Drilling extra vents with grilles: about € 300 to € 600. With a ventilation unit with a humidity sensor: € 1,100 to € 1,500.
A layer of shells on the crawl space floor (schelpenbed): € 1,500 to € 2,000.
Renewing the sewer pipes in the crawl space: € 600 to € 1,800.
Splinting an affected wall plate: around € 800. Repairing a few floor joists: € 2,000 to € 5,000.
Treating or renewing rusting steel beams: € 600 to € 1,500.
Fumigating against woodworm: around € 1,000.
A complete new ground floor: in our reports € 15,000 to € 40,000, depending on the surface area and what is on top of the floor.
Serious cases, where the whole ground floor has to be emptied: € 60,000 to € 80,000.

Based on our practice in Amsterdam (price level 2025): repairing a crawl space with dry rot or brown rot easily costs around € 25,000, and replacing all floor joists € 50,000 to € 80,000. These are indications. Price factors are the surface area, access, whether the kitchen and bathroom have to come out, the floor finish and whether the repair is done together within an owners’ association. Always ask for several quotes.

When do you need a specialist?

With sagging joists, emergency props or a sunken floor, a structural engineer is needed before any repair. If there is dry rot, it first has to be treated properly. If a sunken floor goes together with cracks in the facades, we also advise having the foundation checked, with a foundation investigation.

Premiumkeur does not carry out repairs itself and does not recommend contractors. That keeps our advice independent.

9. Case studies from our reports

Six crawl space inspections in Amsterdam. Addresses and names have been left out.

Case 1: all floor joists rotten, Amsterdam-Oost

Situation. An owners’ association in a five-storey building from 1906, February 2019. At two earlier pre-purchase inspections the crawl space had not been inspected. The hatch was in the stairwell and easy to find.

Findings. Severe wood rot, brown rot and dry rot. The ends of most floor joists were so badly affected that the drill went in without effort; one beam end had almost completely crumbled. There was more than 10 centimetres of water on the floor of the crawl space. The floor had sunk considerably in several places.

Advice. Renew all floor joists, preferably with concrete beams, install ventilation and first find out where the water was coming from. Estimated cost € 60,000 to € 80,000, probably around € 15,000 for each member of the association.

Why it matters. This is exactly what you miss when the crawl space is skipped.

Case 2: a new hatch made the difference, Plantagebuurt

Situation. An owners’ association, building from the early twentieth century, June 2020. At two earlier inspections part of the crawl space had been out of reach. A new crawl space hatch was made.

Findings. When extra vents were drilled in the rear facade, a hole had been drilled into the PVC sewer pipe. Every time the kitchen sink was emptied, water ran into the crawl space: thousands of litres. The joists were damp but not rotten. No dry rot.

Advice. Repair the sewer pipe, install a ventilation unit with a humidity sensor so that the wood could dry, and check again after six months. According to the inspection, only three joists needed renewing.

Why it matters. The cause was only found once the whole area could be reached. And it turned out to be less serious than feared.

Case 3: too shallow to go in, De Pijp

Situation. A ground-floor apartment in a building from 1888, February 2021, combined with a foundation investigation. The crawl space was too shallow to enter.

Findings. Even from the hatch it was clear that the floor joists were severely affected by wood rot. A water pipe could be heard leaking. With the floor levelling survey we measured height differences of more than 70 millimetres on the ground floor and first floor.

Advice. Renew all floor joists and have the foundation investigated further. The estimated total cost, including possible foundation repair, came to as much as € 240,000, partly to be shared with the upstairs neighbours.

Why it matters. Even when you can’t get in, measurements and a good look from the hatch tell you a lot. But then you write in the report what you have not seen.

Case 4: steel jacks under the floor, Rivierenbuurt

Situation. An apartment on the raised ground floor in a building from 1935, March 2021. Inspection with the robot.

Findings. Floor joists under the hall, living room and dining room had sagged because they could not carry the weight of the walls above. A previous owner had put steel jacks under them, standing on a loose concrete ground cover that can itself subside. Under the bathroom there was an active leak, some dry rot, and the bathroom extractor blew into the crawl space.

Advice. Have a structural engineer calculate how to strengthen the floor, have the dry rot treated soon and fix all leaks. Repair costs at least € 30,000.

Why it matters. Jacks are an emergency measure, not a solution. From the hatch you often don’t see them.

Case 5: a bouncing floor, Amsterdam-Noord

Situation. A detached house from 1920, May 2020.

Findings. The beam ends at the side facades and the supporting beams were affected by moisture; the floor was losing its load-bearing capacity. Earlier repairs had been done badly, the piers were unstable, there was probably active woodworm, and the steel gas pipe was badly corroded. Ventilation was insufficient and there was a thick layer of mould on the party wall.

Advice. In case of a renovation, replace the timber floor with an insulated concrete beam-and-block floor (broodjesvloer), otherwise targeted repair. In addition ventilation, a layer of shells, a pressure test of the gas pipe and new sewer pipes. Costs according to the report € 14,790 for repair or € 36,690 for a new floor.

Why it matters. A crawl space rarely has just one problem. Moisture, ventilation, wood and pipes are connected.

Case 6: a second opinion with a reassuring outcome, Amsterdam-West

Situation. An owners’ association, building from 1906, March 2019. At an earlier inspection the crawl space had only been viewed from the hatch.

Findings. We went about five metres into the crawl space and did a drill test in several joists. There were shells on the floor and the crawl space was dry. Only the wall plate near the front door was affected on the underside, by moisture from the wet soil against the facade. The other joists were hard and dry, no woodworm.

Advice. Splint the wall plate (about € 800) and, as a precaution, drill two vents in the front facade (about € 300 plus grilles).

Why it matters. A good inspection also prevents needless panic and needless costs.

10. What you can do as a buyer

Before the inspection, ask every inspector: will you go into the crawl space, and how far? What do you do if that isn’t possible: a robot, an endoscope, an extra hatch?
Read the inspector’s general terms and conditions. If they say the crawl space is only viewed from the hatch, or only from a certain height, you know what you do and don’t get.
Ask the seller whether the crawl space hatch is clear. Often there is laminate or carpet over it, or a cupboard on top.
Check whether the report says per part what was and wasn’t seen. “Crawl space not accessible” is an important remark, not a side note.
If you are buying a ground-floor apartment or a home in an owners’ association, ask for the minutes and the long-term maintenance plan (MJOP). The crawl space and floors have often been discussed there before.
Hire your own independent inspector, and don’t simply go along with an inspector recommended by the estate agent.

More about the building inspection in the Premiumkeur Amsterdam knowledge base. You can request a crawl space inspection via the page kruipruimte-inspectie (in Dutch) or by phone.

Frequently asked questions

Does the Working Conditions Act stop a building inspector from entering the crawl space?

No. The Working Conditions Act and the Working Conditions Decree set no minimum height for a crawl space. The Decree (article 3.5g) only covers spaces where there may be a risk of suffocation, poisoning, fire or explosion. The inspector decides on site whether it is safe.

Where does the 50 centimetre rule come from?

Not from the law. That height appears in the general terms and conditions of several inspectors and in some industry agreements. The health and safety catalogue for the installation industry even sets rules for working in crawl spaces lower than 60 centimetres.

When does Premiumkeur not go into the crawl space?

When there is water in it, because of the risk of electrocution. Also not when dangerous gases such as sewer gas are suspected, or when there is asbestos or material that may contain asbestos. Where possible we then use a robot or endoscope, and the report states what we could not see.

What do you do if the crawl space is too low?

Below about 20 centimetres we use a robot with a 4K camera. With a lot of rubble it doesn't work well; then we sometimes look with an endoscope or advise an extra crawl space hatch.

What does a crawl space inspection cost?

At Premiumkeur from € 499 including VAT. You receive the report within two working days.

What does it cost to replace rotten floor joists?

In our reports from 2018 to 2021 a complete new ground floor cost € 15,000 to € 40,000. Based on our practice in Amsterdam (price level 2025), replacing all floor joists costs € 50,000 to € 80,000, and repairing a crawl space with dry rot or brown rot easily costs around € 25,000.

How do I know if my crawl space is too damp?

Signs are a musty smell in the house, a floor that bounces or creaks, mould at the bottom of walls and lots of mosquitoes. Dry wood has a moisture content of about 12 percent; a moisture measurement in the crawl space gives certainty.

Does a layer of shells help against damp?

A layer of shells reduces evaporation of moisture from the soil. It only works well together with enough ventilation and without leaks. In our reports it costs € 1,500 to € 2,000.

Why don't all inspectors go into the crawl space?

The general terms and conditions of many inspectors say that the crawl space is only viewed from the hatch, or only from a certain height. Inspecting a crawl space properly takes more time and equipment. In 2023 Onderzoekscollectief Spit also described that many inspections come in through estate agents, who only earn money if the sale goes through. So choose an independent inspector yourself.

Can I hold the inspector liable if he did not inspect the crawl space?

That is difficult. If the crawl space is excluded in the general terms and conditions, it is hard to blame the inspector. Onderzoekscollectief Spit found eighteen court cases over four years in which buyers sued their own inspection company, and the buyer did not win a single one. We don't give legal advice.

Videos and sources

On the Premiumkeur YouTube channel you can watch our inspectors at work, in crawl spaces too.

Sources: the figures and cases on this page come from Premiumkeur’s own crawl space inspections (2017 up to and including 2023, 53 reports). Addresses and names have been left out. The amounts are as they were in the reports. External sources: Working Conditions Decree (Arbeidsomstandighedenbesluit), article 3.5g; health and safety catalogue Working in crawl spaces of the installation and insulation industry; general terms and conditions of other inspectors as published on their websites; Onderzoekscollectief Spit and De Groene Amsterdammer, De kleine lettertjes van de woningkeurders (10 May 2023); NPO Radio 1, Villa VdB (27 October 2025). Reference date: October 2026.

Read also: Mold and damp Amsterdam, Basement Inspection, Balcony Inspection and Diensten en tarieven (services and rates, in Dutch).

Contact details Premiumkeur Amsterdam

Premiumkeur B.V., Heiligeweg 30, 1012 XR Amsterdam
Phone: +31 20 773 6842
Email: premiumkeur@gmail.com
KvK 81106130

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