What Do Insulation Values Mean on a Sectional Door? U and R'w Guide

Two abbreviations keep appearing in technical specifications: U and R’w. Both attach a measurable value to the word “insulated”, but a panel value and the performance of a complete installed door are not the same thing. In this article we explain how to read these numbers using the published technical values of the NORMTOR industrial sectional door.

Read the documented value step by step

1. Define the requirement: temperature separation, sound expectation or both.
2. Check whether the document describes a panel, a specific test door or the complete door offered.
3. Record model, size, revision and the unit exactly as printed together.
4. Check windows, wicket doors, perimeter seals and joints against the quotation scope.
5. Do not turn an incomplete or ambiguous unit into a definite value; request current scope confirmation through the dealer.

U-value: How fast does heat escape?

The U-value (thermal transmittance) expresses the heat flow through one square metre of a building element for every 1 K temperature difference between its two sides. The lower the value, the lower the heat transfer. The REV04 English panel line prints 0.604 k (W/m²). The unit is ambiguous; verify the current manufacturer declaration before using this as a definite panel or complete-door U-value.

That does not mean the complete door returns the same figure at every size. Overall installed performance is affected by the opening dimensions, panel joints, windows or a wicket door, perimeter seals and installation details. In cold-chain and climate-separation applications, the panel value and project configuration therefore have to be assessed together.

R’w value: How much sound stays inside?

R’w is a single-number indicator used to express apparent sound-reduction performance in the field. Alkur’s technical documentation publishes R’w = 26 dB for the 40 mm panel. The figure supports comparison, but the facade, junctions, flanking paths and installation conditions mean it cannot by itself guarantee the sound level in an adjacent space or the environmental-noise outcome.

The structure behind the number

These are panel values published in Alkur’s technical documentation. The density of the polyurethane core, the bond of the steel skins and the tongue-and-groove edge geometry all work together. Seals are part of the equation too — if threshold and frame tightness degrades, the panel figure no longer describes the complete installed door.

How much does it matter in which project?

On an internal partition door the U-value can be secondary; on an external dispatch facade or a cold-store entrance it sits at the centre of the decision. A specification should not copy the panel value alone: it should also state the door dimensions, window and wicket-door options, perimeter tightness and installation detail.

Evidence record for comparison

Field to record from the document	Why it is needed
Model and revision	Prevents mixing products or editions.
Panel / sample / complete-door scope	Identifies the construction covered by the result.
Value and original unit	Prevents deriving a definite U-value from a missing unit.
Size and accessory configuration	Shows whether quotation and evidence concern the same door.
Document type and pending confirmation	Separates a specification clause from tested performance.

Keep “required performance”, “documented scope” and “pending information” separate in the completed file. Site measurement, installation and building acoustic/thermal calculations belong to the relevant project teams; Alkur does not conduct site surveys. The ambiguous REV04 heat-transfer line is not entered as a verified whole-door U-value in a bid comparison.