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Floor Soundproofing - Joist caps

Floor soundproofing with absorbalay

If you're looking to reduce impact sound while maximising airborne sound reduction with minimal floor build up we would recommend acoustic caps over the tops of each joist. Then replacing your existing walking surface with flooring grade chipboard, and for higher performance, a layer of Tecsound membrane. This option will keep to a minimum floor height increase.

With this solution we are attempting to maximise the mass of the floor to reduce airborne sound transmission while dramatically improving the foot fall sound being generated from the floor. The coupling of the resilience layer provided by the acoustic joist strips and the high mass of the chipboard and Tecsound is a powerful combination in reducing airborne and impact sound transmission.

Acoustic joist caps are unsuitable to use under floorboards, which need mechanical fixing ( see solution 3). This solution is creating a floating floor. In terms of impact attenuation achieved and cost and ease of fitting this solution it offers a cheaper and more effective alternative to solution 3 which incorporates the use of expensive metal hangers.

For customers looking to insulate noisy pipes please see our acoustic pipe wrap.

Key Features of Joist cap

50mm x 50mm x 50mm

This product, used upside down, can also provide the resilient layer required for customers to make up their own resilient battens. We recommend 50 by 100mm battens 

If the product is used in this manner, on a concrete floor, impact improvements in the order of: :
  • Delta L w22dB with a standard batten 
  • Delta L w24dB with a deep batten can be expected. 
Robust Details only require an improvement of Delta L w17dB

If the product is used in this manner, on a timber floor, improvements in the order of: 
  • Delta R w+C; tr14dB and 
  • Delta L w20dB can be expected. 
Robust Details only require an improvement of: 
  • Delta R w+C; tr13dB and 
  • Delta L w15dB

Sound proofing basics

When it comes to soundproofing your floor , it is important to establish what you are trying to achieve. Are you trying to stop noise from below reaching you, or are you trying to eradicate your impact noise passing down to your neighbours?

In practice, most people are aiming at stopping the sounds from below traveling upwards.  Many products on the market boast great soundproofing credentials (particularly rubber mat or underlay solutions) but the figures quoted are almost always referring to a reduction in impact sound and are of very little use in identifying how much airborne sound is being reduced.

Understanding Performance
At the foot of the page you will see a performance table. The total performance which is normally quoted on most sites refers impact sound only. However if you are worried about sound rising from below you should only consider the airborne sound number ( which is rarely quoted)

We also give an indication of acoustic performance uplift. Remember that every 10dB of performance uplift corresponds to roughly a 50% improvement in the performance of the floor. So 20dB would indicate a 75% improvement over and above the original floor.

Important Note*

As a consumer comparing different products from different companies is very hard. While we talk about improvement in decibels in all our tables many other companies will state a single figure for their products which is often in excess of 40 or even 50db. It is really important to understand that these figures invariably refer to the performance of a whole floor ceiling structure, and this will include a standardised floor and ceiling that will already be quite well soundproofed. 

There is no single product in existence, to our knowledge that will provide in excess of 40 dB when added to a standard floor ceiling divide ( plasterboard ceiling and wooden floor).

In an attempt to level the playing field we are taking a standard ceiling 12mm plasterboard a void and 18 mm floor boards as our base case. We reckon that this has an acoustic performance of about 34 dB Rw ( airborne). The final column of our table gives an indication of we believe our system might achieve in Rw ( simple airborne performance) terms.

An important word about regulation E ( the sound test required for conversions). 
We have a dedicated regulation E web site The figures in the above tables do not take into account Ctr corrections so do not attempt to create an off the shelf solution for regulation E

What do these dB numbers mean in real terms ?
What do these dB Figures mean in practical terms? In simple terms a 10dB improvement equates to a 50% reduction in sound you hear, 20db equates to 75% and 30dB to 87.5%. However this is not the same for all frequencies. This is just an average performance across all frequencies, and higher frequencies will perform better than lower. Learn More

Comparing our products with others:
Please note that the figures that we provide refer to improvement over the average floor as opposed to the performance data of the product in isolation. By this we refer to products that can be lab tested in a way that the product is tested on its own, which can give little indication how it performs in situ,(i.e. on your floor)

This is a very important distinction to understand and is confusing to a lot of people. Almost all our competitors will state the performance of the product either in isolation or include the existing floor construction within their numbers. This will exaggerate the true benefit of their products. For more information click here. This is particularly the case with laminate underlays.

A Key to the table terms above? We compare the following key issues.

  1. Floor height gain - How much floor height will rise as a result of soundproofing
  2. Labour intensity - How long will the job take? In general lifting all the floor boards will add dramatically to the time required to complete the soundproofing you can think of lifting 3 of 5 boards ( see on line instructions for further details) 
  3. Typical Airborne uplift - This gives you an idea about how much airborne sound your stopping coming up from below ( or from above) TV / Talking that kind of thing. The bigger the number displayed the better the performance. THIS IS THE KEY THING to worry about if your soundproofing from neighbour noise downstairs 
  4. Typical Impact Uplift - This gives you an idea about how much impact ( footfall) sound your stopping going downstairs. The bigger the number displayed the better the performance. Again this is only important to you if your neighbours are concerned about your footfall.


Key Points:

  • An excellent alternative to a floating floor
  • Fast, easy and effective floor soundproofing
  • A solution that significantly improves impact and airborne sound
  • Online calculator will work out your exact requirements
  • Soundproofing kit delivered to your door in 48 hours


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Replacement Soundproof Chipboard Floor Sound Insulation performance table

Floor Depth Gain Total system Performance airborne Typical Airborne Improvement Typical Impact Improvement
Acoustic Mineral Wool, Joist caps, Cement impregnated chipboard 12mm 57 dB 19 dB 22 dB
Acoustic Mineral Wool, Joist caps, Chipboard Tecsound 50 Upgrade 12mm 53 dB 15dB 23 dB
Acoustic Mineral Wool, Joist caps, Chipboard Tecsound 70 Upgrade 13mm 55 dB 17dB 23 dB

Compare all our floor solutions here.

*Please note figures stated for total system are based on a a timber joist ceiling floor construction with 200mm joist. The figures are Lab figures and are Ctr corrected. So are not comparable to regulation E Systems. The improvement figures state improvement over a regular timber floor and plasterboard ceiling.

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