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What is “STC”?  Glass & Glazing contractors have become more versed with this metric as it relates to their product offerings as open floor plans incorporating glass become more prevalent:

“STC” stands for Sound Transmission Class

STC ratings are a way to measure and compare how much sound is stopped / absorbed by any given product / material.  STC ratings are used for windows, wall assemblies, doors and some constituent materials.

The STC rating is the average amount of noise stopped at 18 different frequencies, measured in decibels. STC ratings are a logarithmic scale similar to the earthquake Richter Scale, which means each escalating number is significantly higher in performance than the previous number.  It is a non-linear scale.


One US glass manufacturer who has published STC ratings for their various product types are the high-performance glass experts at Viracon.

Viracon Acoustical Glass is made from combinations of various glass types along with acoustical window frames to help you effectively reduce sound transmission from airplanes, trains, vehicles and other unwanted noises. The performance data below applies to an insulating unit. Data is based on testing ~36″ x 84″ glass to ASTM E413-87 in an acoustical wall. Glass size and glazing system will affect STC rating. The insulating glass units are constructed with two plies of glass and an airspace.

The STC (Sound Transmission Class) rating is a single-number rating system for interior building partitions and viewing windows used to categorize acoustic performance.

The OITC (Outside-Inside Transmission Class) rating is used to classify acoustic performance of glazing in exterior applications.


Calculating Wind Loads on Buildings

by Steve Sanko on 8/12/2013

When structural engineers and architects collaborate during the design phase for buildings or structures, one of the most important factors requiring consideration is the velocity and imposed load of wind on the building and the constituent components (such as doors and windows). When calculating these loads, there are several factors that need to be considered.  Some of these factors are not as intuitive as one might think.

The geographical location of the building is the most important factor that should be considered when calculating wind loads. Buildings located on plain flat surfaces face more pressure than those located in a covered neighborhood where the flow of wind in highly obstructed. Similarly, if a building is located on a hill top, it will face more wind pressure than the one located at the bottom. Another consideration which is important is whether the building is located in a hurricane prone area or not.

The wind pressure on different surface areas of a building vary to a large extent depending on several factors. Places where airflow is disrupted are exposed to higher pressure, including the corners and the overhangs of roof; therefore, complex architectural designs must account for these surface area variations of wind pressure on a building.

When determining wind pressure, an important factor that needs to be considered is the direction of the wind. If the wind is blowing against a building surface it is called “windward” pressure which acts in a positive direction.  Negative wind pressure or “leeward” pressure, is generated while winds blow away from the surface in question. Depending on the usual direction of airflow in an area, it can be determined whether the building will have to face negative pressure or positive pressure.

This indicates the pressure created inside a building due to wind sucked inside through wind ports made in the building. Depending on these ports and the direction of airflow, the internal pressure can be positive and negative as well. The pressure coefficients for internal pressure also need to be accounted for during the construction of a building and its components.

Combined together, all these factors give a measure of design pressure, which is the product of all these different pressures a building is exposed to. Using this design pressure as a basic element, architectural designs for building walls, doors and windows are created accordingly.

A handy technical reference which does a great job at summarizing the differences between the “old” ASCE code and the latest ASCE 7-10 code, is the white paper – “Changes to the Wind Speed Maps and Wind Design – 2010 Florida Building Codes” as provided by Building A Safer Florida, Inc.  While this resource is written for and intended to serve as a summary for structural engineers, there is much information contained that can serve the “non-technical” reader.  The basic behavior of these wind load calculation parameters have been summarized below for the casual reader.  You don’t have to be a structural engineer in order to understand how wind loads effect the building components many manufacturers must design for – particularly in the high-velocity hurricane regions of South Florida.

Dash Door’s full-time professional structural engineer is available to provide technical support services as they relate to all products and wind load resistance.


It is often times difficult to get a “500 mile high” view of trends in the automatic door community.  It is a community of regional distribution channels and considerations.  In 2004, AAADM (The American Association of Automatic Door Manufacturer’s – conducted an influential study / survey which helped to fill in the blanks in terms of driving trends and consumer attitudes as they pertain to automatic doors in various building types.


The following white paper is offered as a resource to facility managers and building owners, to serve a baseline guide of consumer expectations of automatic entrance availability in your facility.


Research: White Paper: Automatic Door Trends Through the Eyes of Consumers and Key Buyers/Specifiers

Many of our clients get frazzled when our customer service reps bring up the dreaded question – “What is the handing of your door?”  The “handing” of a door refers to the direction that the door swings.  It’s important to understand the correct handing of an opening when ordering locks, exit devices, frames, doors or other “handed” hardware.  Even in our own office, there are multiple “methods” used between the old-school staff in our Service, Glass & Glazing and Contract Hardware groups.  In short – it is not and does not have to be a complicated thing.  The downloadable reference chart below can be used as an aid in communicating proper door handing when ordering product or service.


First off – The hand of a door is determined from the “secure” side of the door. The secure side is the side from which you unlock and enter (the “key side”).


Determine if the door is to be opened by pushing away from you or pulling towards you.  Which side are the hinges on as you are viewing the door?

If the hinges are on your Left side, and the door is pushing away from you, it is a Left Hand (LH) Swing.

If the hinges are on your Right side, and the door is pushing away from you it is a Right Hand (RH) Swing.


If the hinges are on your Left side and the door is pulling towards you, it is a Left Hand Reverse (LHR) Swing.

If the hinges are on your Right side and the door is pulling towards you, it is a Right hand Reverse (RHR) Swing.

Doors which swing out (Outswinging doors) are reverse bevel doors.


Double doors typically have an Active Leaf and and Inactive Leaf.

The Active leaf is the leaf upon which the locking hardware is installed and is used most often.

The Inactive leaf is the leaf which typically stays closed with flush bolts or surface bolts and is opened when a larger opening is needed.

It is certainly common to also have two Active leafs in the case of a pair of doors with each leaf having a panic device or push/pulls.  These doors would be handed either LH/RH or LHR/RHR.


If the door on the left side is to be active, and the door is pushing away from you, it is a LH Active Opening (LHA).

If the door on the right side is to be active, and the door is pushing away from you, it is a RH Active Opening (RHA).

If the door on the Left side is to be active, and the door is pulling towards you, it is a LHR Active Opening (LHRA).

If the door on the Right side is to be active, and the door is pulling towards you, it is a RHR Active Opening (RHRA).


Some a pair of double doors have leafs which swing in opposite directions. This is called a Double Egress opening.  The handing will be LHR/LHR or RHR/RHR.  Typically both door leaves are active.


Door leafs with exit / panic devices installed are ALWAYS handed as a reverse bevel door (LHR or RHR).


Again- door handing does not have to be a complicated matter.  Use the above information and the downloadable chart below to demystify the process.


 Dash Door – Door Handing Chart

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