From the Executive ...
Sound proofing and acoustic work
October / November 2014

Location:
First floor - Seomra Spraoi, opposite the staff room
Ground floor: two resource rooms directly below

Contractor: Big Bear Sound Ltd.
Contact: Michael Browne (Managing Director)

Introduction:
The three rooms mentioned above are situated one (the Seomra Spraoi on the first floor opposite the staffroom) above the other two (the resource rooms directly below on the ground floor) in the newer part of the building. The problem was not with this configuration but the fact that these three rooms were more interconnected than was desirable in an educational environment. Due to shortcomings in their construction, activities in one room were severely disrupting teaching activities in the other two due to the airborne and impact transference of noise from any of the three rooms to the other two.
The work has been commissioned to radically improve the working and learning environment in all three rooms. To give you an idea of the extent of the problem, children moving about in the Seomra Spraoi generated such impact noise that it disturbed any work going on in the rooms below, the noise akin to that generated by a set of industrious carpenters. In addition while teaching in one resource room, any activity in the other was hampered by the high level of airborne noise transference. In reality, it was as if there was no partition between the rooms and the two teachers were competing in the same space.

Project goals:
Part one: to reduce the noise transference (impact) from the Seomra Spraoi on the first floor to the two resource rooms directly below.
Part two: to construct an acoustically treated wall between the two resource rooms in order to reduce the noise transference (airborne) between the two and create two interconnected yet independent workable rooms.

The table below details the TGD-021-5 recommended airborne and impact sound insulation ratings between teaching spaces. The sound insulation ratings are designed to ensure a high level of privacy between teaching spaces as well as mitigating the potential for noise disturbance in noise sensitive areas.

Airborne and impact sound insulation requirements between teaching areas

Sound insulation test results
Sound insulation tests were undertaken on 9 October 2014.
The results of the airborne sound insulation tests undertaken on the partition and floor constructions are summarised as follows:

Partition & Floor Airborne sound insulation tests

A review of the measurements shows that the existing partition airborne sound insulation is 30dB less than the recommended 45dB DnT,w performance.
The measured floor airborne sound insulation is 6dB less than the recommended 45dB DnT,w performance.

Impact sound insulation tests undertaken on the floor construction

A review of the measurements shows that the existing floor impact sound is 17dB greater than the recommended 60dB LnT,w performance.

Floor upgrades

Analysis of the test results indicates that the airborne and impact sound insulation performance is relatively poor. The following remedial works were:

• Increase the floor stiffness to improve the low-frequency sound insulation performance
• Install independent ceiling to improve the airborne and impact sound insulation performance

Partition Upgrades

• increasing the partition mass layers and the resilient connections between the layers

Glazed panel (existing, allows a visual connection between the two spaces)

• recommended that this is kept to a maximum area of 4sq.m.

To provide levels of sound insulation consistent with the main stud partition, a double glazed unit is recommended with the following glazing configuration:

• 10mm toughened glass - 100mm cavity - 12.76mm laminated glass

Door (existing, required linking the two rooms to allow supervision by staff)
The presence of a door in the partition will limit the overall level of sound insulation. As this door will not be heavily trafficked, the most cost effective method to achieve high sound insulation in this instance is to install two doors in a single frame to act in series. The doors leaves should be spaced a minimum 75mm apart.

Works undertaken:

• Light fittings removed and electrical connections made safe
• Strip out existing timber paneling and counter-­‐batons
• Remove two existing layers of 15mm fire line plasterboard
• Re-enforcement of existing structure by installing bridging pieces between all of the existing Joists at measured intervals
• Install additional blocking where existing joists meet the RSJ spine along the center of the room
• Acoustically treat the diagonal steel bracing everywhere it intersects the existing joists
• Strengthen joist where notches have been cut for the diagonal bracing
• Reinstall two layers of Fire line plasterboard
• Prop the existing floor with 2no Acrow Props (temporary adjustable props) to allow load test on the first floor
• If deemed necessary a steel post to stiffen up the floor will be installed and buried within the width of the new stud wall
• Construction of new acoustically treated dropped ceiling by installing new suspended ceiling - Joists totally independent of the existing ceiling structure to contain Rw3 100mm Rockwool, two layers of sound block plasterboard and sealed with acoustic sealant
• Remove existing sliding door and rail system
• Remove Iroko paneling and save to be reused where needed
• Install new stud partition with acoustic treatment and new door opening
• Reinstate existing timber paneling and counter batons
• Reinstate light fittings
• Painting where required.

Costings

Please click the following link to read the in depth
RMDS Sound Insulation Assessment