Careful design and good workmanship are very important when trying to avoid sound test failures. Reasons for failing a sound insulation test between dwellings usually fall into three categories:
1. Incorrect acoustic design (materials specification and/or detailing).
2. Incorrect acoustic material supply or changing the design on site.
3. Poor workmanship during the installation stage.
Potential Problems with Walls Floors
- Underweight walls (external/internal). This is often because light weight blocks have been used.
- Floating isolated screeds bridged (gaps in resilient layer).
- Continuous concrete slabs & concrete planks, screeds beneath cavity masonry walls which allow flanking from plot to plot.
- Underweight or poorly isolated ceilings.
- Joists to shallow with insufficient stiffness.
- Attic rooms in roof – poor detailing due to site constraints.
- Poor detailing for ceiling penetrations of down lighters, speakers etc.
- Dry-lining dabs bridging to isolated screed causing flanking.
- Skirting boards bridging to isolated screed causing flanking.
Potential Problems with Walls
- Underweight coursing blocks – these should never be used on blocks of flats.
- Flanking over walls via profiled floor slab.
- Poor/weak head design to non-loadbearing walls.
- Narrow cavities.
- Bridged cavities (mortar droppings or other debris).
- Incorrect wall ties (non-acoustic) or mortar accumulation.
- Poor/weak head design for folding acoustic doors.
Potential Problems with Walls Floors & Walls
- Incorrectly installed resilient bar systems (incorrect screw length or positioning).
- Insufficient validation of material properties/performance.
- Curtain walling – poor detailing (e.g. at mullion and transom interfaces).
- Build sequencing interfering with best practice/detailing.
- No allowance for onsite construction in comparison to laboratory construction i.e. you should usually take off 5dB for onsite construction.
If you require sound testing on your project, help with the acoustic design on your project or you are unsure of your existing site construction and/or need some friendly acoustic advice then contact us.