Category Archives: Sound Proofing

Plumbing Update

Water Switch On.

I finally switched on the water supply to the house and then checked the compression connections on the gravity based system for leaks. The reason for using the gravity based system was to keep everything as simple as possible,  consume the lowest amount of energy and have a system that would be low in maintenance cost.  All the joint connections were brass compression fittings and I used a pipe called  “qual-pex” .  I insulated the cold and  hot water pipes for both the rainwater and the calorifier tank.

Gravity Tank 

I installed a  separate gravity tank for the toilets that will be fed from the rainwater tank in the garden eventually. I need to design a control unit to pump rainwater when required and operate from the mains to flush out the gravity tank at regular intervals. At the moment it is connected to the fresh water supply for testing.  This tank was mounted 2.71 metres above floor level.  Nylon washers were placed inside and outside of the tank brass connections fittings.

Storage Tank Connections








What worked for me in relation to the toilets was an 1/2 inch pipe that ran a distance of 15 metres approximately with a storage tank base to floor height of 2.71 meters and this enabled the cistern to fill in approximately 1 minute 45 seconds.

Lessons Learned

  • When tightening compression fittings- a good bit of advice is always leave room for an extra turn on the thread. In this way if there is a leak one can tighten the compression joint further.
  • On the calorifier connections use Jet Blue Plus paste or similar paste and check it is suitable for potable water.
  • The longest run was approximately 20 meters of 1/2 qual-pex and this  supplies enough pressure for a “natural” water flow at the furthest away sink outlet-I also removed the filter in the outlet of the tap to further increase the water flow.
  • Certain isolation On-Off valves have bore diameters that are smaller than the diameter of the pipe bore further reducing the capacity of the water flow. Visually check before purchase.
  • Check that the taps and shower fittings are designed for a gravity system. I used a tap that had a minimum operating pressure of 0.1 bar from the Grohe range (1 metre height of water is = 0.1 bar).
  • I was unaware of what an air lock can look like . In one case no water flowed and in another case I had a constant trickle of water with no air gurgling. To get rid of the air lock I used a small 5 litre pressure sprayer with a silicone hose on the end.Pressure Sprayer




  • Use copper inserts instead of nylon on “qual-pex” when trying to get gravity to work in your favour . They have a wider bore (see below).
Qual-Pex Inserts Copper and Plastic
Copper versus Plastic Inserts









Toilet Cistern

As most of the inlet valves on toilet cisterns are now designed for high pressure they come with a restriction devices and sometimes a filter. For use on the gravity system I removed these.

I plan to filter the water at the feed end of the water supply.  Both the toilet storage tank and the calorifier storage tank (supply’s the hot water) are within the thermal envelope. This means that the tanks will not freeze but this brings other issues to be dealt with, such as noise from filling and potential condensation. I installed rockwool insulation around the tank to minimise temperature differences of the indoor air and reduce the noise of water filling the tank as I have no attic space.

The original toilet had a bottom inlet valve made with plastic threads which proved difficult to install.

Cistern Inlet Valve


I did have problems with the original cistern valve where I cross threaded the plastic connection (which resulted in a leak) as one finds that space is limited under a toilet/cistern (see below).

Toilet Cistern with Penny valve for turning water off and on at the toilet.
Toilet Cistern Connection









Another problem I had was I could not get it to operate correctly from the gravity tank. To solve the above I replaced the inlet valve with a Jollyfill telescopic Wirquin brass inlet valve and removed the high pressure device.

Wirquin Bottom Inlet Valve









When I installed  the inlet valve the connection leaked between the rubber seal and cistern. I removed it and placed silicone above the rubber seal. The silicone cured the problem.


The gravity flow rate proved too low for the shower valve temperature control to work so plan B was acted on. I installed a 1.5 Bar 250w pump to raise the flow rate.

It is a Salamander RP50PT pump (45.5 dBA) . It cost €200 including postage. I am impressed with the low non-intrusive noise it generates. It comes with small sound isolating pads. One can roughly equate a 3dBA increase with twice the loudness.

Another factor to take into account when selecting  and sizing a pump for one, two or three shower units is that the power usage approximately doubles when one selects a 0.5 bar increase for this range of pumps.  So If one is sizing for the use of 3 showers being on at the same time (using one 3 bar pump) and only one  shower is on then one will be using 1000 watts of power most of the time . I feel it is more energy efficient to install separate pumps and in this way one uses the least amount of energy most of the time and the pump will also be quieter as noise increases also with each 0.5 bar of pressure.

Shower Pump


Plaster Board Finish

Wall Finishing and Fire Compartmentalisation


The golden rule is-avoid sanding as much as possible by ensuring that the knife finish is smooth at the edges and as close to a final finish as possible.  If one had to do this manually with a sanding block and pole it would be a tough job.

Thankfully over the years people have been improving the tools. I was lucky enough that the builder loaned me his sanding machine.  I just needed a hoover to manage the dust which was picked up free on the free cycle web site. The sanding machine looks like the following:

Sanding Machine
Flex WS 702VEA

Even though the above Flex machine makes the job easier and faster it still is a physical job especially when working overhead.  The hoover was not designed for the above but it worked out OK once the bag and filters were cleaned regularly.

I would suggest safety glasses when working overhead and a face mask at all times.

Technique for Sanding Used

The joints had a second coat of plaster and then a touch up coat was used to remove any edges and at the same time look for and fix any imperfections on the butt finishes (where two boards are joined with no taper edge) or tapered edges. USG 3 Sheetrock (see previous blog) was used for the second and third touch up coat.   I would not recommend the Gyproc joint filler for the second and third coat as it is primarily used for the first coat and it does a great job. When dry the finish is very hard and it would be difficult to sand. There is a Gyproc pro finisher but I found the Sheetrock product very economical and easy to work with for the second and third coat compared to other options.

I used a 150 grit sand paper on the Flex machine and left it at speed 4.   I was expecting that the sand paper would get blocked up but this did not happen. I was advised and found it very important to sand the edges of the joints and ensure that one does not stay too long on the edges as the paper on the plaster board could be damaged.  A light sand in the centre of the joint is how I finished each joint.

Sanding Joint Filler
Edge Sanding of Plasterboard












I also found it necessary to manually inspect the wall after the electric sander as one is too far away from the wall with the sander to spot imperfections. I made up a hand sanding block for this with a wood fibre board angled to get into corners.

Home Made Sanding Block












The angled  wood fibre board worked out better for me than dedicated sanding blocks and I used a pre-used sanding disc from the electric sander.

Self Build
Wood Fibre Board as a sanding block.












Plasterboard Corners

I experimented with the wall corner finishes on whether a sharp edge or rounded corners worked out better. The sharp edges looked like that shown in the top image below and the rounded corner is the image below that. If I was doing it all again I would use the rounded corners as I feel it looks better.

Plasterboard corner finish straight edge. Note dust still on one wall.



Rounded Corner

Fire Compartmentalisation

Typically with internal wooden stud walls there may be gaps between rooms at floor level or vertically. For this reason one may want to ensure that fire compartmentalisation is addressed (a previous blog covered this in detail). In order to do this I have chosen a B1 rated fire foam for the floor gaps. It also has a secondary benefit of reducing sound travel between rooms at these gaps. The foam I used was Olive PU-476.  The price varies and the best value I found in Ireland was at National Seal Systems in Dublin. I also bought intumescent water based fire sealer for small gaps around the edges of the distribution board and vertical uprights where one partition  meets another.

Self Build











Acoustic and Fire Design

Fire and Acoustic Isolation

Having recently come across a best practice guide for Electrical installations and their effect on the fire performance of buildings I have decided to change  the approach to the fire/acoustic isolation between rooms. I will now install Rockwool flexi 50mm in the 100mm partition walls and Rockwool flexi 100mm in the 140mm partition walls .

Electrics before insulation
Partition before Insulation with Wiring
Partition wall with Rockwool installed

From an acoustic perspective I was advised that it is better to install the Rockwool in the centre of the partitions rather than touching one or other side of the plasterboard as this limits the sound transfer.

The Electrical Safety Council best practice guide deals with Electrical installations and their impact on the fire performance of Domestic premises at this link when one is building a home. A summary is as follows but the full document is worth reading for any self builder.

  • Fire containment in the event of a fire
  • The need to prevent fire from passing through holes in all elements whether solid or lightweight is addressed.
  • Electrical Equipment is identified that has a direct and significant influence on the fire performance of an element.
  • Partial Penetrations –those that reduce the fire performance of part of the wall/ceiling or floor.
    Full Penetrations-such as ducts and fans that go through both elements of a wall/ceiling/floor.


Internal Partitions and Soundproofing


The internal partitions were recently installed.

Passsive House
Passive House Build

Solutions now need to be planned to minimise noise between some of the rooms. The effort one puts into this needs to be balanced with the fact that there will be a 10mm gap under the doors for the air to circulate when using heat recovery.  I might install a supply and extract outlet in the important rooms in order to minimise noise. How much noise will travel in these ducts is for another day.

Proposed Method

All the air gaps (wall to floor gaps, sockets, switches and service cavity) around the partitions need to be filled.

I will fill the ceiling and wall gaps of the service cavity with rockwool (see below).Perimiter Insulation

The method to reduce the noise I am considering for the walls is a product that uses a dampening material between two sheets of plasterboard. One of these products is Green glue and the other is Quietglue pro.  The solution appears to perform very well and I feel it is the simplest method. I plan to take  extra measures between the study and living room such as including rigid insulation (Rockwool RWA45 but I note the insulation costs €37 in Ireland and £13 in England (more research required) .

The performance values used to measure the sound proofing in America is called STC (Sound Transmission Class) and is measured in decibels (dB) against 16 different frequencies. If the sound level was 80dB in one room and the measured sound level in the other room had a  STC of 37dB the sound reduction would have a figure of STC 43.

STC only calculates the dB levels down to a frequency of 125 Hz. One needs to be aware that low frequency sound can exist from drums , traffic and an additional solution may be required.

The performance test data of the Green Glue can be found here

If one was to use one layer of green glue with an extra sheet of plasterboard one would achieve a STC value of 43 for a 4 inch wooden stud wall with 24 inch centres.

If one was to use 4 inch block this would achieve a STC of 44.

Filling a standard 4 inch wooden stud wall (with 16 inch stud spacings) with fibreglass and using plasterboard on each side achieves a STC of around 39. If one increased the stud spacing to 24 inches and filled it with insulation then the STC value would be 46.

If one was to leave out the insulation on a standard wooden stud wall one would achieve a STC value of 34.

A good source of information on sound proofing is at USG (Gypsum)

Robust Airtightness

In locations where the partitions meet the airtight membrane I am using Solitex Plus (see below -blue material). If one used only the airtight membrane it can easily be damaged.

Passive house
Solitex Plus