Ventilation Inspection Reports and Intervals: OVK Guide

A ventilation inspection under Sweden's OVK rules (obligatorisk ventilationskontroll) produces two things: a signed protokoll for the building owner and a copy for the municipal building committee, plus an intyg posted visibly in the building. Ventilation inspection reports and intervals are set in Plan- och byggförordningen (PBF) chapter 5 and Boverket's BFS 2011:16 (OVK): every 3 years for schools, pre-schools and care premises whatever the system, every 3 years for blocks of flats and offices with balanced FT/FTX ventilation, every 6 years for those same buildings with natural (S), extract (F) or extract-with-heat-recovery (FX) systems, and a first inspection only for one- and two-dwelling houses with FX, FT or FTX. One- and two-dwelling houses with S or F systems are exempt. The rest of this guide turns that legal duty into a repeatable, priced, scheduled job.

What OVK is, and its equivalent outside Sweden

OVK is a recurring legal inspection attached to the building, not to a contract. The owner must have it done on time by a certified inspector (funktionskontrollant). The municipal building committee (byggnadsnämnden) supervises, holds the register, and can issue an order backed by a fine if the owner lets it lapse.

If you work outside Sweden, the closest analogues are structural rather than identical. In the UK, TM44 air-conditioning inspections run on a five-year cycle for systems over 12 kW. In New Zealand, mechanical ventilation is a specified system on a compliance schedule, inspected annually by an IQP for the Building Warrant of Fitness. The pattern is what matters commercially: a legal duty on the owner, a fixed clock, a named competent person, a report that goes to an authority, and defects that someone has to pay to fix.

Ventilation inspection intervals by building type

The intervals below come from PBF 5 kap. and Boverket's OVK regulation. The clock runs from the date of the last inspection, not from the date the defects were cleared.

The system letters decide the interval, so read them on site. S is natural stack ventilation with no fan. F is mechanical extract only. FX is extract with heat recovery. FT is balanced supply and extract. FTX is balanced with a heat exchanger. Getting F versus FT wrong on a 1970s block flips the interval between 6 and 3 years and can put you outside your own certification level.

Who is allowed to sign the report

Only a personally certified inspector, certified by a body accredited by Swedac, at one of two levels:

• Behörighet N (normal): S, F and FX systems in any building, plus FT and FTX in one- and two-dwelling houses.
• Behörighet K (qualified): everything, including FT and FTX in blocks of flats, schools, offices and care premises.

Certifications are time-limited. Check your own expiry before you promise a customer a three-year cycle: a lapsed certificate makes every protokoll you sign in the meantime worthless.

What the OVK protokoll must contain

Boverket's regulation requires a protokoll for every inspection, and the building-committee copy makes it a public act. Treat it as a document a lawyer might read three years from now. It needs, as a minimum:

• Property designation (fastighetsbeteckning), address, and the owner's name and contact details.
• The inspection date and the type: first inspection (första besiktning) or recurring (återkommande besiktning).
• The inspector's name, certification number, level (N or K) and certification expiry.
• Each ventilation system identified individually. One building can hold several aggregates with separate verdicts.
• System type and installation year per aggregate, because a recurring inspection is judged against the rules that applied when the system was built, not against today's BBR.
• Measured air flows against design flows, per aggregate and where relevant per room or flat, with the instrument used and its calibration date.
• Whether operating and maintenance instructions are present in the building.
• A verdict per system, approved or not approved, and the anmärkningar in plain language, each tied to a specific location.
• Proposals for improving energy performance without worsening the indoor climate. This is a legal requirement, not a nicety, and it is the single most skipped field on the form.
• The date the next inspection falls due.
• Signature.

Two copies then leave your hands the same day: one to the owner, one to byggnadsnämnden. The owner also gets an intyg showing the date, the result and the next due date, to be posted in a visible place in the building, usually the entrance or by the letterboxes.

The reference-flow trap

If you cannot find the design flows, you cannot cleanly declare a pass. The general residential baseline in BBR is 0.35 l/s per m² of floor area and at least 4 l/s per person; flows may be reduced when nobody is home but never below 0.10 l/s per m². Use that as a sanity check, and write down which reference you compared against. An inspector who measures against an invented target has produced an opinion, not a report.

Turning anmärkningar into a priced remediation quote

This is where ventilation firms leave money on the table. The inspection gets billed as a small fixed job, the defect list is emailed as a PDF, the owner does nothing, and three years later someone else does the remediation. The fix is to write every anmärkning in a form that can become a quote line before you leave the car park.

Sort defects into three buckets as you find them:

1. Blocking. The system fails without it. Fan not running, flows below design, fire damper function unverified, ducts that cannot be cleaned, no instructions. These go on the quote as one bundle: the work required to reach an approved OVK.
2. Deferred. Real but not failing. A worn belt, a leaking filter housing, a bearing that will not survive the next cycle. These become a service agreement or a scheduled visit.
3. Energy. The proposals you are legally obliged to make anyway. A heat exchanger running well below its rated efficiency, permanently over-ventilated flats, a fan pinned at full speed. These become a separate optional section on the quote with a payback story attached.

Each defect line needs four fields: location, what is wrong, what corrects it, labour plus material estimate. Write them on site, in the same app, on the same job. If a line cannot be priced because an aggregate has to be opened up, say so and price the investigation instead of guessing.

Handing over the report and the plan in the same visit

A visit that ends with a PDF sent later is a visit you have to sell twice. A visit that ends with a signed report and an accepted plan is a booked job. A workable sequence:

• Run the inspection on a digital protokoll template that mirrors the fields above, so nothing is missing when you close the job.
• Photograph every anmärkning as you record it and attach the photo to the defect line. A photo of a taped-over supply grille closes more work than a paragraph does.
• Generate the protokoll PDF and the intyg on site. Hand the intyg over physically and show the owner where it goes.
• Convert the blocking bucket into a quote in front of them, with a labour price they can sign. For private homeowners in Sweden, ROT is 30% of the labour cost with an annual per-person ceiling shared with RUT, so the net figure on screen is materially lower than the gross. Check the current ceiling at Skatteverket.
• Book the remediation visit before you leave. A held date converts better than a follow-up call.
• Set the next OVK date the moment the protokoll is signed: inspection date plus 3 or 6 years, minus a 90-day lead so the reminder gives you room to schedule.

That is the shape a field system should support: a protokoll template you build once, measurements and photos captured offline in a basement with no signal, a quote with the ROT deduction already calculated and signed electronically on the spot, and the next inspection sitting in the planner as a dated obligation. In OdinTask the protokoll, the quote and the scheduled follow-up are one job record, so nothing gets re-typed at a desk that evening.

The compounding part: a book of buildings

One OVK inspection is a small invoice. A hundred buildings on a known clock is a business. Every protokoll you sign writes a dated obligation into the future, and you already hold the flows, the photos and the defect history.

Track per property: system types and aggregate count, last inspection date, verdict, next due date, open defects, whether the intyg is posted, and who the current owner is. Ownership changes are the leak that kills the renewal, so verify the contact at every visit. When a due date is nine to twelve weeks out, the follow-up writes itself: last time we found X, it is due again on Y, here is a date.

Why OVK inspections fail

• Air flows below design, usually from filters, blocked grilles, or a fan speed someone turned down to stop a draught complaint.
• Missing operating and maintenance instructions, common in buildings that have changed hands.
• Ducts that cannot be inspected or cleaned because access hatches were built over during a refurbishment.
• Kitchen extract connected to a system never designed for it, after a flat renovation.
• Heat exchangers fouled to the point that the recovery is nominal.
• No verdict recorded per aggregate, so the protokoll cannot be acted on. That is a report failure, and it is yours.

The regulation hands you a recurring reason to be in the building and a legal document listing work someone has to pay for. Treat the protokoll as the start of the job, not the end of it, and OVK stops being a low-margin errand.

Want the protokoll, the priced remediation quote and the next inspection date on one job record? Start a 14-day free trial or see the pricing page.