Calculating Door Sizes & Understanding Door Frames

Instructions on calculating door sizes and frame sizes. How to work out clear opening sizes or reveal sizes or hole in wall sizes or door sizes if you only have one of these dimensions. 

How to work out clear opening sizes or reveal sizes or hole in wall sizes or door sizes if you only have one of these dimensions. 

For a fire rated door:

•  Add 4mm to the door width to get the reveal width

•  Add 80mm to the door width to get the overall width

•  Add 8mm to the door height to get the reveal height

•  Add 46mm to the door height to get the overall height

•  Subtract 50mm from the reveal width to get the clear opening width

•  Subtract 25mm from the reveal height to get the clear opening height

For a non-fire rated door:

•  Add 6mm to the door width to get the reveal width

•  Add 82mm to the door width to get the overall width

•  Add 10mm to the door height to get the reveal height

•  Add 48mm to the door height to get the overall height

•  Subtract 30mm from the reveal width to get the clear opening width

•  Subtract 15mm from the reveal height to get the clear opening height

* Height calculations do not include allowance for flooring

Calculating Door Sizes Downloads

Door Size & Door Frame Measurement Guide

Blank frame order form – electronic

Blank frame order form – printable

For more information on Spartan door frames then please contact us.

Fire Resistance Level and Fire Ratings

The term “fire rating” is very broad and can be misinterpreted and misused. Under the Building Code of Australia, the correct terminology is fire resistance level or FRL. While fire rating plays a part in the various parts of a FRL, the two are not the same or interchangeable. When it comes to a FRL, it is important to understand what the different components are, how they are determined and the role they play in passive fire protection, particularly in fire doors.

FRL Explained

The technical expression of an FRL is:

Structural adequacy/integrity/insulation or SA/INT/INS

• Structural adequacy is defined as the measure of a tested assembly to be load bearing, or carry a predetermined load, during fire conditions. This measure is generally relevant for wall systems and not door & frame systems. Door & frame systems are said to have no load bearing ability.
• Integrity is the measure of a test assembly to restrict the passage of flame and hot gasses. It does not measure smoke leakage.
• Insulation is a measure of the temperature rise on the non-exposed, or non-fire side, of a fire resistant separating barrier.

The passing value is determined by the number of minutes in which there is no failure when tested in accordance with AS 1530 Part 4 fire test criteria.

So when you see the fire resistance level expressed as 60/60/60 it means that each element passed for that number of minutes.

SA = 60 minutes INT = 60 minutes INS = 60 minutes

Fire Testing

The fire testing is conducted by taking a test specimen, representative of what will be used out in the field, and subject it to standard time versus temperature heating conditions and a standard pressure differential.  The test measures the above elements of SA, INT, and INS to establish a FRL.

Failure Criteria

AS 1540 Part 4 outlines the passing deviations for the three categories and describes how to test each element.

Structural adequacy fails when the test specimen collapses or when the maximum rate of deflection exceeds prescribed limits.

Integrity fails when one of the following occurs:

• There is continuous flaming on the non-fire side of the test assembly
• Through gap into the furnace exceeds the prescribed sizes
• Ignition of the cotton wool pad test

It is typically the duration of integrity that is mislabeled “fire rating”. If a door had a fire rating of two hours, it is because the integrity portion of an FRL tested at 120 minutes, ie -/120/30. Note the structural adequacy is shown as “-” as doors and frames don’t have any structural adequacy.

Insulation fails when the thermocouples, or temperature measuring devices on the non-fire side of the test assembly, exceed the prescribed limits.

Click on the link to find out more about Spartan fire rated doors or check out this cool video showing a Durasteel Blast Doors pass a 4-hour integrity test.