Prefab House Pollutants: Pollutant Testing in Old Prefab Houses

With older prefab houses (Fertighäuser), the topic of pollutants matters: formaldehyde from chipboard, wood preservatives such as PCP and lindane, asbestos-containing façade panels and the typical musty smell caused by chloroanisoles characterise numerous houses built between 1960 and 1990. Anyone wishing to buy or renovate a used prefab house should know these substances, have targeted measurements taken and weigh up the remediation routes. This guide shows which pollutants matter and when, how an independent pollutant test works, and what to look out for when buying.

Which pollutants lurk in an old prefab house

These pollutants are typical of their construction period: from the 1960s to the 1980s, wood was chemically protected as standard, chipboard off-gassed formaldehyde, and fibre-cement panels contained asbestos. An overview of the lead pollutants:

The exact combination differs depending on the manufacturer and construction year. Anyone wishing to renovate an old prefab house will find the suitable sequence and the energy-related measures in the guide prefab house renovation.

The chronological context is important: formaldehyde was mainly an issue in the 1960s and 1970s through urea-based adhesives and today usually only off-gasses weakly — but can increase again through moisture or heat. PCP and lindane were routinely used as wood preservatives into the 1980s; they are chemically very stable and therefore still detectable even after decades. Asbestos is found primarily in fibre-cement façade and roof panels as well as in adhesives and seals up to the early 1990s. Chloroanisoles, finally, only form over time as breakdown products of the wood preservation — which is why the typical smell often only becomes clearly apparent decades after construction. This chronological logic helps to roughly classify the risk of a specific house, but is no substitute for a measurement.

Health and smell: why chloroanisoles are so relevant

It is precisely the smell that brings many buyers and residents to a pollutant test. It arises when wood preservatives are broken down into chloroanisoles by moisture and micro-organisms. Since the smell comes from the building fabric, airing helps only briefly. Well-founded information on indoor pollutants is provided by the German Environment Agency (Umweltbundesamt).

Pollutant testing: how the measurement works

The process of a reputable pollutant test in 2026 involves several steps:

Cost of a pollutant test

Relative to the possible remediation costs and the purchase price of a house, the test is a small but decisive expense. It saves you from unwittingly buying an expensive legacy problem — or, conversely, from avoiding a house on a vague suspicion that turns out to be uncontaminated.

Finding an independent expert

Make sure to assign sampling and remediation separately: whoever measures should not also sell the remediation. You can find publicly appointed and sworn (ö.b.u.v.) experts via the IHK register of experts, neutral advice from the Association of Private Builders and from the Builders' Protection Association. How construction-accompanying quality assurance works during a subsequent renovation is described in the guide prefab house construction supervision.

Remediation routes: from encapsulation to demolition

• Formaldehyde: remove sources or clad vapour-tight, supplemented by controlled domestic ventilation with heat recovery.
• PCP / lindane: remove contaminated timber or encapsulate it effectively and separate the interior from the burden.
• Chloroanisoles (smell): dismantle the odour source or seal it off with tested barrier layers.
• Asbestos: only professional removal in accordance with TRGS 519 by authorised firms.
• After every remediation: schedule a control measurement to verify success.

A decisive point: after sealing and insulating, the natural air exchange decreases. Anyone who leaves a formaldehyde or chloroanisole source in the house and at the same time makes the envelope airtight can even increase the indoor burden. That is why controlled domestic ventilation with heat recovery is part of almost every pollutant remediation. Energy-related and pollutant remediation must therefore be planned together, not one after the other.

Since pollutant and energy-related renovation interlock, you should plan both together. You will find the sequence, costs and funding in the guide prefab house renovation. For the accompanying supervision of the executing firms, the guide prefab house construction monitoring provides support.

Checking a used prefab house before buying

Before buying, specifically check the construction year, manufacturer's system and smell — and, if in doubt, have measurements taken before you sign. A sensible sequence:

• Clarify the construction year and manufacturer's system — the years 1960 to 1990 are especially sensitive.
• During the viewing, watch out for a musty, mouldy smell (an indication of chloroanisoles).
• Commission the pollutant test by an independent expert BEFORE the purchase contract.
• Equip the purchase contract with a right of withdrawal or reduction in the event of a relevant burden.
• Realistically offset the remediation costs against the purchase-price advantage.
• Work through a new build as an alternative if the burden turns out to be high.

If you would rather build new than buy a contaminated old building, compare modern, low-pollutant models via our manufacturer comparison and the house catalogues. For the legal protection of the new build, the guide checking a prefab house contract helps. How a new-build purchase works overall is described in the guide buying a prefab house.