EXAC - STC rating UPDATED ACTUAL
Exam Questions and CORRECT Answers
What is the STC rating? - CORRECT ANSWER - Sound transmission class
What is the required STC rating according to National Building code for residential dwelling
Unit. - CORRECT ANSWER - STC rating of 50.
What is ASTC - CORRECT ANSWER - STC rating describe the performance of the
separating wall, floor / ceiling assemblies.
ASTC Rating take into consideration the performance of the separating assemblies and flanking
transmission path.
So for the occupant point of view ASTC rating is a more accurate account of sound transmission.
the selection of sound- absorbing material had major effect - is this statement true or false -
CORRECT ANSWER - false -The type of sound-absorbing material has a relatively minor
effect on the ability of the wall to control sound. There are clear benefits associated with
increasing the spacing between studs and resilient channels - the farther apart they are, the better
the sound reduction.
provide STC consideration with the use of Rigid Versus Non-Rigid Connections Between Layers
? - CORRECT ANSWER - When the gypsum board in a wall is solidly fastened to the
wood studs on both sides, much of the sound is transmitted through the studs.
- It is thus important for the two wall surfaces to be supported independently from one another in
order to control sound transmission. This can be done by fastening the gypsum board on each
side of the wall to different lines of studs (i.e., by using staggered or double wood-stud
arrangements) or by supporting one side of the wall on resilient channels.
, Resilient channels used on one or both faces of single rows of stiff studs - wood studs or
loadbearing steel studs - also help to overcome peripheral transmission through header and sole
plates.
Adding resilient metal channels to one face of a single row of studs improves sound reduction
considerably, allowing sound-absorbing material in the cavity to be effective.
With asymmetrical (1x2) constructions, it did not matter which side the channels were placed on
- the STC ratings were not affected.
Load-bearing steel studs behave in much the same way as do wood studs, but lightgauge non-
load-bearing metal studs are flexible enough to reduce sound transmission through the material,
and provide about the same sound reduction as wood-stud walls with resilient metal channels on
one face
what is the STC requirement for assemblies in Dwelling unit - CORRECT ANSWER -
STC 50
What is the STC requirement for separating dwelling unit with the elevator shaft or refuse shaft -
CORRECT ANSWER - STC 55 minimum
What is the STC requirement for dwelling unit with secondry suite - CORRECT
ANSWER - the joist spaces in the floors should be filled with sound absorbing material on
150mm thickness
-stud spaces are filled with sound absorbing material
-have resilient channels spaced at 400 to 600 O/c
-having 12.7 Gypsum board on both sides.
The overall STC requirement is 43
The overall ASTC requirement is about 40
Exam Questions and CORRECT Answers
What is the STC rating? - CORRECT ANSWER - Sound transmission class
What is the required STC rating according to National Building code for residential dwelling
Unit. - CORRECT ANSWER - STC rating of 50.
What is ASTC - CORRECT ANSWER - STC rating describe the performance of the
separating wall, floor / ceiling assemblies.
ASTC Rating take into consideration the performance of the separating assemblies and flanking
transmission path.
So for the occupant point of view ASTC rating is a more accurate account of sound transmission.
the selection of sound- absorbing material had major effect - is this statement true or false -
CORRECT ANSWER - false -The type of sound-absorbing material has a relatively minor
effect on the ability of the wall to control sound. There are clear benefits associated with
increasing the spacing between studs and resilient channels - the farther apart they are, the better
the sound reduction.
provide STC consideration with the use of Rigid Versus Non-Rigid Connections Between Layers
? - CORRECT ANSWER - When the gypsum board in a wall is solidly fastened to the
wood studs on both sides, much of the sound is transmitted through the studs.
- It is thus important for the two wall surfaces to be supported independently from one another in
order to control sound transmission. This can be done by fastening the gypsum board on each
side of the wall to different lines of studs (i.e., by using staggered or double wood-stud
arrangements) or by supporting one side of the wall on resilient channels.
, Resilient channels used on one or both faces of single rows of stiff studs - wood studs or
loadbearing steel studs - also help to overcome peripheral transmission through header and sole
plates.
Adding resilient metal channels to one face of a single row of studs improves sound reduction
considerably, allowing sound-absorbing material in the cavity to be effective.
With asymmetrical (1x2) constructions, it did not matter which side the channels were placed on
- the STC ratings were not affected.
Load-bearing steel studs behave in much the same way as do wood studs, but lightgauge non-
load-bearing metal studs are flexible enough to reduce sound transmission through the material,
and provide about the same sound reduction as wood-stud walls with resilient metal channels on
one face
what is the STC requirement for assemblies in Dwelling unit - CORRECT ANSWER -
STC 50
What is the STC requirement for separating dwelling unit with the elevator shaft or refuse shaft -
CORRECT ANSWER - STC 55 minimum
What is the STC requirement for dwelling unit with secondry suite - CORRECT
ANSWER - the joist spaces in the floors should be filled with sound absorbing material on
150mm thickness
-stud spaces are filled with sound absorbing material
-have resilient channels spaced at 400 to 600 O/c
-having 12.7 Gypsum board on both sides.
The overall STC requirement is 43
The overall ASTC requirement is about 40
