Regulations and sources
Every calculation default that ships with PirtoCAD comes from a named source, such as a decree, a guideline, a table or a manufacturer's catalogue, or is marked as PirtoCAD's own default. This page lists the checks that work in the PirtoCAD window and what each one is based on.
How PirtoCAD handles values
Limits and coefficients are not hidden inside the program. You can see them and their sources, and you can change most of them.
The source is shown
The Calculation values view (Laskenta-arvot) shows every value's unit, the value in use and where it comes from, and the shipped default with its sources. In a system's Properties, each limit is shown with its source and clause, for example YM 1009/2017, section 20, or RakMK D2 2003, clause 4.1.1.4.
You can change a value
Type a new value and press Enter. The project uses it from then on, and the change is one undo step. A value that cannot be used, such as a negative pressure, is not stored: the previous value stays and the row gives the reason.
A value for one system
The view opens from the gear button in the Calculation panel or from the Limits heading (Raja-arvot) of a system. Where the calculation reads a value per system, you can give one system its own value. The other systems then use the project value.
- When a minimum tightness class rests on PirtoCAD's own reading of the decree, the explanation says so and marks the reading as unverified (varmistamatta).
- A proposal never replaces your own values: a room airflow you entered is kept, and the program tells you that it differs from the proposal.
- Some values are still read directly by the drawing tools and cannot be changed yet. Their field is greyed out, and the row says so.
- Guides and guideline cards are recommendations, not binding regulations. The tables on this page mark them as guidelines.
Ventilation checks
These checks work in the PirtoCAD window, and each has an automated test that runs it through the user interface.
| Check | Source and clause | Where it appears |
|---|---|---|
| Supply and extract airflow proposal by room type | FINVAC ry sizing guides (guidelines, not regulations). Dwellings: guide to ventilation sizing in residential buildings (2019), table 2, based on Decree YM 1009/2017. Other spaces: mainly the FINVAC guide to ventilation sizing in non-residential buildings (2017 and 2019 editions). Compared with the former building code RakMK D2 2012, tables 1 to 11. Where both give a value, the stricter one applies. | Room Properties: the proposal names its source document, and the change made with Apply (Käytä) is one undo step |
| Minimum duct tightness class | YM 1009/2017, section 20(1): at least class B, and at least class C where the extract air contains significant impurities other than those from people. Classes A to E are defined in section 19. PirtoCAD requires class C for systems carrying contaminated or hazardous extract air and for extract air class 4; where this rests on PirtoCAD's own reading, it is marked as unverified. A system with no class set is checked as class B. | System Properties. A class below the minimum appears in the Problems panel (Ongelmat) as Tightness class below the minimum. |
| SFP limit by building permit application date | New buildings: YM 1010/2017, section 30 (1.8 and 0.9 kW/(m³/s)). Earlier permits: the limit in force on the application date, RakMK D2 2003 and D2 2010 clause 4.1.1.4 or RakMK D3 2012 clause 2.6.1.1. Renovation requiring a permit: YM 4/13, section 5. | Calculation panel and the system's Limits |
| Duct air velocity limit in the residential sizing profile | LVI 30-10333 Acoustic design in residential buildings (guideline card, not a regulation), table 4 | Duct Properties: the limit, its basis, its level and its source |
The permit application date and the basis (new building or renovation) are set in the Calculation values view. SFP is estimated at the duty point from the unit's published fan power and marked as unverified; the value measured at commissioning is what counts. If the permit was applied for before the first SFP limit came into force, the current limit is shown for comparison only.
New energy performance decrees (YM 868/2026 and 869/2026) take effect on 1 January 2027. Their values come to the program in a data update; until then it uses the sources above.
Piping checks
| Check | Source and clause | Where it appears |
|---|---|---|
| Water pipe velocity and size | RakMK D1 2007, appendix 2 (sizing of water installations): nominal flow rates, selection of connection pipes (table 4) and velocity limits. D1 is no longer binding, but the current Decree YM 1047/2017 has no sizing tables, and its guide still refers to D1 appendix 2 for water pipe sizing. PirtoCAD marks every sizing value from D1 as unverified. | Problems panel with fixes; Size water pipes (Mitoita vesijohdot) in a water pipe's Properties, whose change is one undo step |
| Drain size from the fixtures' nominal flow rates | Uponor property drainage handbook (Kiinteistöviemäröintikäsikirja) 2015, chapter 6 (guidance, not a regulation), checked against RakMK D1 2007, appendix 4. Where the sources differ, the stricter value applies. | Problems panel with fixes; Size drains (Mitoita viemärit) in a drain's Properties |
Regulation checks for construction, electrical and diagrams are not on this list yet. Checks in progress are listed below.
Coming
These are in progress. Some already work as commands or exist in the program in unfinished form, but none has been tested in the PirtoCAD window yet:
- Room heat load from the building data
- Heating pipe sizing and radiator valve balancing
- Final circuit checks and cable sizing
- Vent pipe checks
- Calculation of natural ventilation and radon systems
- Transfer air at fire doors
Ventilation and calculation values
- Tightness classes of positive-pressure duct sections under section 20
- Sound level duct by duct
- Ductwork leakage allowance
- A flag on a value that is less strict than its source
The designer is responsible for the results
PirtoCAD's defaults and calculations support the designer. A calculation is only as good as its input data, and the designer is always responsible for checking the input data, the default values and the calculation results.
Proposals are a starting point for the design. The designer decides the final values.
An empty Problems panel only means that the current checks found nothing. It does not mean that the design has been reviewed or that it meets the regulations.