Unit 5 - Sound Insulation in Practice.

Question 1

What is Robust details

Answer 1

A Robust Detail, for Part E of Building Regulations, is a separating wall or floor construction which has been assessed and approved by RDL.

In order to be approved, each Robust Detail must:

• be capable of consistently exceeding the performance standards given in Approved Document E of the Building Regulations for England and Wales
• be practical to build on site and be reasonably tolerant to workmanship

Question 2

SI requirements in Schools

Answer 2

BB93 stipulates minimum airborne sound insulation performances between spaces based on source activity noise and the receiving room noise tolerance

The performance standards are specified in terms of DnT(Tmf,max),w, the weighted BB93 standardized level difference.

• On site performance taking into account flanking and poor workmanship

When considering two different, adjacent room types, the sound insulation requirement should be considered in both directions, and the highest specification adopted

Question 3

SI in healthcare

Answer 3

HTM08-01 defined SI requirements for health care settings

• The noise sensitivity of adjacent spaces are used to establish the sound insulation requirement.
  
  • confidentiality is also considered
    
    • spaces requiring high levels of confidentially the required sound insulation value are set according

Question 4

SI in office

Answer 4

BS8233

• cellular office layouts the minimum acceptable sound insulation between two offices is about D**w* = 38 dB.
• Where privacy is important the minimum sound insulation should be D**w* = 48 dB

Where the indoor ambient noise level is low it may be necessary to design for higher insulation values.

speech will be audible but not intelligible if Dw* + *LA > 75 dB,

where Dw is the weighted level difference between rooms, and LA is the indoor ambient noise level in the receiver room

Question 5

what are Flanking Paths

Answer 5

Flanking paths are any route other than through the separating element that sound passes from one space to another.

The sound insulation from a structural flanking path is related to size of the element and how much it transmits sound through its structure

Question 6

SI limitation due to A continuous 70mm deep flanking concrete slab

Answer 6

A continuous 70mm deep concrete floor below a separating wall.

Dw between the two rooms would be controlled by the flanking through the concrete floor once the sound insulation goes above about 40 dB Dw.

A Dw of 45 dB can be achieved with a concrete floor construction of 120 mm thick,

A floating floor is required for requirements greater than 55 dB Dw

Question 7

flanking solutions for floating screed

Answer 7

If a partition is constructed directly onto a floating screed on thermal insulation then the screed must be split on either side of the partition.

The head of the partition must be completely sealed to the roof or ceiling construction, which can often be a trapezoidal shape, making sealing a complex detail

Question 8

Issues with workmanship

Answer 8

A common workmanship issue is using incorrect materials for the partitions

Question 9

how to improve workmanship as a designer

Answer 9

Designers can assist with improving this issue by

• aiming to keep the number of different partition types to a minimum
• keeping the thickness and density of plasterboard similar throughout
• clearly identifying on drawings which partitions are located where.

Question 10

workmanship checklist

Answer 10

On site checklists are provided for the different partition systems.

• list the construction elements and important acoustic features,
• required for robust details registration

Question 11

General tips for workmanship

Answer 11

Partitions should be installed following suppliers instructions, with suitable junction details followed.

Holes for penetrations should be tightly cut around services and the apertures suitably sealed.

Correct fixing lengths should be used for systems with resilient bars

• if incorrect fixings are used these can be accidentally fixed directly into the framework and bridging the isolation

Question 12

workmanship for cavity walls

Answer 12

Care needed that mortar fully fills the joints and that the blockwork is tightly built around services and steel work before being suitably sealed.

When constructing cavity masonry walls it is essential that the correct connecting ties are used and that the mortar does not bridge the cavity due to mortar falling onto the ties

Question 13

Improving Sound Insulation dependants

Answer 13

The amount of improvement will depend on the performance of the basic structural element to which the layer is applied.

A single sheet of plasterboard on battens may make a considerable improvement to a poorly constructed timber floor but make little difference to a concrete slab

Question 14

INSUL

Answer 14

used for predicting the sound insulation of walls, floors, ceilings and windows. The programme estimates the sound reduction index in 1/3rd octave bands for different construction types.

The software applies the basic theory of sound insulation along with more complex models and research to give predictions that are generally within 3dB of actual measurements.

Complex constructions the margin of error is greater and the predictions should be used with some caution.

Question 15

BASTIAN

Answer 15

Reducing the sound insulation of buildings following the methodology of BS EN 12354.

The sound reduction of the elements used in the models can be input from test data, predicted using INSUL or taken from the product library provided with the software.

A key feature of the software is that it predicts the sound insulation through each flanking path.

• it is possible to identify if the sound insulation is being determined by a particular flanking element or by the performance of the separating partition.