Tag Archives: Self-Build

Air tightness Test-Passive House 0.22ACH

Self Build air tightness test -0.22ach with a volume of 603 m3 @ 50 pascals. 

When one is building to a performance standard the day of reckoning is the airtight test. The reason for this is that when one is pumping fresh air into the house using a Heat Recovery System, rather than relying on simple multiple holes in the wall, it becomes important to control where the fresh air is coming from and where the heat is going.

Airtight Test
Airtight Test







If air is leaking in or out around windows /doors/walls or other gaps in the building fabric then heat is lost and moisture problems in the form of mould can arise or else give rise to damage to the building fabric.

The pressure 50 pascals equates to a 20 mile per hour wind which is not too untypical in Ireland. So if one opts for the Irish  building standard (a minimum standard) this equates to the air in the house changing/leaking 7 times a hour when a wind blows at 20 miles per hour. No wonder people block up the hole in the wall vents .

  • The current Irish building standard  require 7 air changes  per hour (ach) also called leakage at 50 pascals  typically with no heat recovery system As a guidance heat recovery manufactures recommend 3 Air leakages per hour to ensure that the heat recovery system can push fresh air into the house and recover heat leaving the house through its own system rather than through gaps in the building fabric.
  • The passive house standard for a new house requires 0.6 Air changes per hour (ach) at 50 pascals to ensure the heat recovery system works efficiently, ensure that occupants receive the correct amount of fresh air and minimise building fabric damage.

The passive house test differs from the Irish test because it must include pressurisation and depressurisation and use the volume as set out per Vn50 (EN13829).

The Test

Gavin O Shea from Greenbuild was hired for the job.  He is certified/audited by the National Standards Authority of Ireland (NSAI).

The preparation for this entailed sealing all cable ducts and the inlet and outlet pipes for the Heat Recovery System. One also ensures that the shower and sink outlet traps are full of water. The overflow outlet for two water tanks were not sealed off. I did consider a duck valve but it was not in place at the time of the test.

Air Tight Test
Airtight Test









The test using the Irish method gave a result of 0.181 m3

Gavin O Shea calculated that the equivalent size hole that equates to a result of 0.22 ach is approximately 65.25 cm2 (@50Pa) or a hole 81mm x 81mm if all of the leaks present in the dwelling were concentrated into one hole. That is about a tenth of an A4 sheet of paper.

The results of the air tight test can also help determine the selection of the  Heat Recovery System. If the airtight test is lower then more options are available when selecting a unit.

From my research a passive house standard Heat Recovery Unit will cost more because it needs to be independently tested by the Passive House Institute using their test method. Heat Recovery manufactures have also the burden of putting the unit through national tests or international tests with the end result being the customer pays more.  One has also the option to select a non passive house certified unit for a passive house but when calculating the performance value one needs to account for this in the PHPP software with a 12% reduction below the manufacturers performance claim.

If one wants to view certified Heat Recovery Units one can find and sort them at the following link.  One can see for example at this link the capacity (Column- Air Flow Range) that these units have as it is important to select a unit that is oversized for your particular self build. I would compare it to selecting a mini car to tow a caravan up a hill compared to using a larger car. The small car will struggle from an efficiency and noise point of view while the larger car will be quieter and more efficient at the require flow rates.  I will do a separate post on how I selected our Heat Recovery Unit.











Having carried out some DIY painting in the past I decided this time I would invest in good tools as this was going to be the biggest job to date. This first entailed selecting a brand whose painting equipment is rated highly.  I selected tools from the Wooster product range.

There are a few essential tools.
    • The Pole (I selected a 4 to 8 foot adjustable pole called the Wooster Sherlock GT extension pole ). This tool has a few good features such as snap on paint roller head, an extension that snaps in set positions, a tool to fit screw type paint rollers. A substantial rubber hand grip that made the job easier . The highest point of our ceilings are 3.6 metres and this version allowed me to reach the ceilings directly from the floor. Narrow hallways that are less than the length of the pole plus the roller would make it difficult to use this pole length.











  • Rollers– I selected a 3/8 inch nap (pile depth)  for the plasterboard because of its smooth surface and I tried a 9 and 14 inch roller called the pro-doo-z. The Nap determines the amount of paint applied and the paint texture of the wall surface . The 3/8 inch gives a fine finish. If one used a 1/2 inch nap the roller can hold more paint but the texture is different. After trying the 9 inch and 14 inch roller my preference was to use the 14 inch roller as I found it easier, faster and more stable because it is supported at both ends (see below). I would be tempted to try the contract rollers that are supposed to be faster the next time but the finish may not be the same. One can select the right roller from the web site link Wooster Rollers. 
        • Cutting In– A very useful and time saving tool was the Wooster hand-held Pelican kettle .
          Pelican Kettle

          It is available with liners to make it easy to change colours.  It has a section to hold a cutting in brush and a mechanism to hold a small roller. Both of these are necessary in order to end up with the same wall surface texture as the main roller for example around switches and sockets. I used non diluted paint for the cutting in process. One needs a mini roller also for the Pelican holder.

        • Brush– The cutting in brush I used was the Silver tip wooster 2 inch model. I never owned a high quality brush before and it is working out great.
        • Tray/Kettle-I tried the Tray and the Kettle. My preference is the 25 litre Kettle with replaceable liners. I initially bought a Kettle with no liners and the washing out of the tray or kettle at the end of a days painting is time consuming and  non environmental as one must wash the inside completely . Comparing this to using a liner that one can dispose of in the bin. I know at the end of the day it all is non environmental but using plastic liners keeps everything clean and saves time.
        • Safety Glasses and peaked cap -While painting the ceiling it is a vital item.
        • Fresh Air– While the paint is wet the smell is stronger so ensure that your rooms are very well vented. As I am painting in the winter the house temperature has dropped to approximately 9 degrees.
        • Paint-I used Dulux paint as it has a good reputation for quality.
        • Cling Film-In order to keep the brushes and rollers clean I wrapped them in clingfilm overnight. The roller lasted a week and I did not notice any problems even with this amount of time . One just took of the clingfilm and started again with no cleaning required. It also reduces waste.

Technique I used for painting

First Coat– For the first coat on the plasterboard I mixed the paint to a 3 to 1 ratio  (one litre of water to 3 litres of paint) as advised.  By diluting the paint for the first coat it is supposed to allow the paint to get a good bond with the paper finish on the plasterboard. I did not use the traditional wet plaster method on the walls. The paint also needs to be mixed in a separate container. One requires a 1 litre container to carry out the measuring. I experimented with a lower ratio of water and I could not see much of a difference with the Dulux matt white paint on the bare plasterboard only that with two paint coats undiluted the finish looked better . If the walls were wet plastered in the traditional way then the water mix appears to be vital.

I started out using the paint brush and mini roller for the first cutting in but later on I just used the paint brush for the first cut and then used the paint brush and mini roller for the second cut in order to finish with the same texture as the 14 inch roller.

Self Build Painting
14 Inch Roller

After watching numerous methods and comparing the comments I think the following is the best I have come across to date  and having used the ideas it it all makes sense. With Youtube I found one has to watch about ten videos and then decide who is doing it right. Below may help.


Imperfections .

When the first coat of paint is applied it often identifies small imperfections in the plastering. When this happens let the paint dry and fill the imperfection with USG or Gyproc ready made joint filler. When this has fully dried sand it by hand and repaint it with a few coats. This method worked for me.


Geopathic Stress Lines and other Energies

Before the foundation began we had the geopathic stress lines on the plot checked out and any other energies that were on the land in its use over the centuries.

With this information the geopathic stress lines were identified in one future bedroom. The bed was moved to combat this and the other energies cleared.

My understanding is that the geopathic stress lines are like naturally occurring magnetic fields that run under the ground and for this reason we felt it was easy to minimise the risk by knowing about them if they existed on the plot and dealing with them at this stage of the self build.

For example some say there is no evidence that pylons and mobile phone masts can damage your health but we decided not to take a risk by building on another one of these issues known as geopathic stress lines. We are also addressing potential risks from other energies such as mains electricity, wi-fi etc. For example one person may be susceptible to hay-fever, a particular food allergy, mobile phones etc and another not.

Like all these things there is no way to be sure how one might be affected.  I think some people are more susceptible and we will try and design these potential risks out of the self build for this generation and the next generation who chose to live in the house.