U-value, HWB and sound insulation: what OIB guidelines 5 and 6 require
Piloti names every limit with the element and position it applies to, for sound insulation with the pairing of uses, and sets your U-values against it in a check table, row by row.
In short
U-value requirements are in OIB guideline 6 and apply per element and position, such as against outside air, ground or an unheated space; sound insulation is set by OIB guideline 5 for elements between two units of use. Piloti settles the edition and new build or existing, cites the limit to the clause and checks your values as a table with a result per element.
What Piloti delivers
- U-values as a check table
- One row per envelope element: actual value, limit with ≤, source, result.
- The HWB as a key figure
- A given value against the limit, with the energy efficiency class named.
- Sound insulation per pairing
- A check table with the pairing in the first column, such as flat to flat or flat to shop.
- New build and existing side by side
- Where both are possible, the requirements stand side by side as tabs until the project is classified.
Why the number says nothing without the element
A U-value limit depends on the element and on what the element adjoins. The same wall has a different requirement against outside air than against an unheated basement. Pass on the number without element and position and it may be applied to the wrong element. With sound insulation it is the pairing: the values apply to an element between two particular units of use, and the pairing decides the value.
The edition moves especially fast here. OIB guideline 6 has a 2025 edition, adopted on 29 August 2025. According to the OIB overview (as of July 2026), it applies in Vienna since 15 July 2026 and in Tyrol since 16 July 2026, not yet in the other states. The 2023 edition of guideline 6 was binding in Vienna, Lower Austria and Carinthia according to the OIB overview (as of September 2025); elsewhere the 2019 edition generally still applies. The state’s transition rules are decisive.
And most of these questions concern refurbishment. Existing buildings, extensions and major renovations trigger different requirements than new build, and a new-build requirement applied to a refurbishment is the typical wrong answer.
How Piloti works through the question
- 01
Settle new build or existing
If the project records it, Piloti works under it. If not, and it makes a difference, that is the one question, and it comes before a new-build requirement is cited.
- 02
Pin down the edition in the state
Piloti names the version of the guideline binding in the state and cites to the clause.
- 03
Assign element and position
Every requirement appears with the element and its position, and for sound insulation with the pairing of units.
- 04
Compare given values
Give a U-value from your element catalogue or an HWB from the energy certificate, and Piloti sets it against the requirement, with a result per row.
What Piloti needs from you
- The state, and whether it is new build, extension or refurbishment.
- The elements with their position, and their U-values if you have them, for example as an Excel sheet.
- For an HWB question: the energy certificate or the calculated value.
- For sound insulation: the uses on both sides of the element.
Good to know
Piloti does not calculate the heating demand; it says which requirement applies and how a value from your energy certificate compares. The energy certificate and sound insulation evidence stay with building physics. Where a guideline refers to a standard, Piloti names it, and you look up the text under your licence.
Questions
Which U-values does OIB guideline 6 require?
The guideline sets maximum values per element and position, for new build and for major renovation. Which table applies depends on the edition your state has declared binding. Piloti names the value with element, position and a citation to the clause.
Is the 2025 edition of OIB guideline 6 in force yet?
According to the OIB overview (as of July 2026), in Vienna since 15 July 2026 and in Tyrol since 16 July 2026, not yet in the other states. There the 2023 or 2019 edition applies, depending on what the state has declared. Transition rules are in the state’s building-technology rules.
Can Piloti calculate the HWB?
Your building physics software calculates the HWB for the energy certificate. Piloti names the requirement with a citation, sets the calculated HWB against the limit and names the energy efficiency class.
Where are the sound insulation requirements?
In OIB guideline 5, in the edition your state has declared. The values apply to elements between two particular uses, so the pairing belongs in the answer. Where the guideline refers to standards, Piloti names them.