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Air Tightness Testing

Contact - 01323 841488 or 07867 960711
or Email info@uk-building-assessments.co.uk

Air Tightness Testing


Air Leakage Testing

Why is an air test needed?

Gaps and cracks in the building fabric are often difficult to detect simply by visual inspection. Air leakage paths through the building fabric can be tortuous; gaps are often obscured by internal building finishes or external cladding. Where a dwelling has been pressure tested, this value is used in the SAP DER calculation. 

Air Permeability Testing

What is Air leakage?

Air leakage is the uncontrolled flow of air through gaps and cracks in the fabric of a building (sometimes referred to as infiltration or draughts). This is not to be confused with ventilation, which is the controlled flow of air into and out of the building through purpose built ventilators that is required for the comfort and safety of the occupants.

Air Tightness Testing


Building Regulations

Part F of the building regulations for Ventilation in domestic dwellings is now being actively enforced . There is a requirement to test and certify the validity of flow rates in new builds, to ensure performance is in line with current legislation. The Government has SAP (Standard Assessment Procedures) in place for air tightness testing, setting standards buildings must comply with to be energy efficient.

About Us

Air Tightness Testing, Air Leakage Testing, Air pressure Testing


Having been in the energy business since 2007, our gained knowledge puts us in an exceptional position to supply support and advice for all your Domestic or Commercial needs. 

Air testing services form part of the requirement for SAP and SBEM As Built Certification. Air permeability testing is a mandatory requirement under Building Regulations Part L for all new houses and large extensions (25%+ of existing). The air permeability rate that a dwelling requires is determined by the SAP evaluation but should be less than 10a/c at 50pa. In most cases, it is becoming more common for air leakage rates of less than 5 a/c at 50pa as Building Regulations becomes more stringent.

We will provide you with Air Tightness Testing engineers in who can carry out the level of test you require to comply with current legislation. Engineers who can deliver air leakage rates of less than 3m3/(h.m2), which is a requirement on many Code 4, 5 and 6 dwellings.

Legislation

Regulations on air leakage testing

Air Tightness Testing is a requirement for all new buildings, whether residential, commercial or public,  under Part L of Building Regulations. It forms part of the SAP calculation for new homes and part of the SBEM calculation for any building that isn’t residential.

Part L of the Buildings Regulations requires that all non domestic buildings which have a gross floor area greater than 500m2, be subject to mandatory air permeability tests. For domestic dwellings a representative sample of houses (in a development) must be tested. 

The Building Regulations detail a maximum permitted threshold for the air pressure test of 10 m3.h/m2. More often than not, this relatively generous air leakage rate is superseded by a target value detailed within the building’s respective SAP Calculation (Domestic) or SBEM Calculation (Commercial) as a result of the measure air leakage rate having a direct impact on the buildings calculated carbon emissions.

Part L1A is the part of building regulations that is concerned with conservation of fuel and power in new dwellings. 

Failure to comply with part L1A of Building Regulations can lead to a large fine and potential court action, so it is important that all standards are met, in order to achieve the necessary pass certificate for the property.


How is an air tightness test
carried out?




To complete an air tightness test, the engineer will need access to an empty dwelling. The engineer will need access to an external door (approximate size 2.1m high x 0.9m wide) and an electrical supply within 25 metres of the doorway.

 A large fan will be put in an expandable door frame, which goes into an external door in the house, normally the front door. All other external doors and windows will be closed and all internal doors kept open.

All controlled ventilation openings will be sealed with polythene sheet or self-adhesive tape during the test. These include mechanical ventilation fans, window trickle vents and open flues/chimneys.

The fan will then typically depressurise (although you can also perform a pressurisation test) the house to a pressure of at least -50Pa. An anemometer reads the internal pressure, external pressure and the strength that the fan has to work at to create that pressure difference. Readings are taken at different pressures, and along with other factors such as barometric pressure and temperature, fed into software which calculates air leakage.

It is important for the engineer to accurately calculate the building's external envelope before arriving on site. 

The score is shown as metres cubed (m3 ) of air lost, per hour, per metre square of building envelope (Floor area, walls area & roof area).

What does air leakage affect?

Energy Performance of Buildings Regulations

The air leakage affects the building's performance and is one of the key areas in meeting Building Regulations Part L or exceeding these standards for low carbon buildings, Code for Sustainable Homes and BREEAM. Making a building air tight reduces the amount of fuel needed to heat it, which in turn reduces the CO2 produced, reduces your carbon footprint and your energy bills.

How can I improve the air tightness of dwellings?


1. Refer to the Communities and Local Government accredited construction details.
2. Seal any gaps where pipes and cables pass through the building envelope.
3. Seal any gaps around windows and doors.
4. Drylining is notoriously susceptible to air leakage. Ensure that the plasterboard is continuous (i.e. there are no holes behind fitted units, sinks/baths, etc). When drylining directly on to an external wall the plasterboard should be mounted on ribbons of plaster or adhesive around all the edges rather than dabs. Ensure the joints between boards are sealed and the plasterboard is correctly detailed at joints, corners, reveals and window sills.
5. Draught strip all windows and doors.
6. Draught strip any loft hatches.
7. Seal holes around light fittings and pull cords in the ceiling. If the light fitting is not airtight then install an airtight box over the light fitting in the ceiling void.
8. Ensure there is a good seal around boiler flue pipes. 

When Do I Need an Air Tightness Test?

Report Advice

An air tightness test is completed towards the end of the construction process, in order to meet Building Regulations/Standards. The integrity of the structure must be complete prior to the test. Testing is typically performed post second fix. All major penetration to walls and floors must have already been made. On top of this, you’ll need:

1. All service penetrations sealed
2. Trickle vents installed
3. Loft access hatch in place
4. Plumbing complete with water in the traps
5. Seals fitted on external doors
6. Electrical outlets fitted 

The results of the test are used within SAP and SBEM calculations, and can influence a new buildings overall energy rating.

How Do I Pass an Air Tightness Test?

Providing a Professional Service

While we will never guarantee a pass, the engineers who are doing the testing, will do as much as they can to help you. There are a number of common air leakage areas in a property. If you address all of these, you give yourself a good chance of passing the test.

If a test is not passed first time, the engineer will help you out as much as he or she can within a fair time frame. If you ensure you have tubes of mastic and expanding foam with you on the day, our engineers can point the air leakage areas during the testing. If they are small enough to fix at the time, we’ll wait and re-test the property, doing our best to ensure a pass first time.

Why is testing for Air Tightness Important

Testing for air tightness is not just a legal obligation, it ensures dwellings are fit for use. An air tightness test is an indicator of how much air is leaking out, and therefore how much heat is escaping from a particular dwelling. A lack of attention to air leakage can result in:

Dampness and/ or rising damp
Excessive heat loss
Increased heating and energy bills
Drafts
Reduced comfort for those living inside the property



As a landlord or house builder, this would expose tenants and residents to unsatisfactory living conditions and as a developer; these unwanted consequences could make all the difference when it comes to selling or renting a development.


How long will the Air Tightness Test take?

The actual test (after set up) is usually completed in well under one hour on the average size domestic building. During this period no personnel should enter or exit the building. It is preferable that the building is unoccupied.

We will let you know how long we expect the test to take on more complex buildings.

Different levels of
Air Leakage Testing

Tester Levels

There are different levels of air tightness testing, established from the size and complexity of a building. An overview of each is provided below:

Level 1: Air Pressure Testing for single dwellings and other smaller non-dwellings up to 4000 m³ gross envelope volume, typically tested with a single blower door fan.

Level 2: Air Pressure Testing for simple and complex buildings larger than 4000 m³ gross envelope volume. This does not include large and complex, high rise (LCHR) buildings, and phased handover/zonal buildings.

Level 3: Air Pressure Testing for LCHR buildings, phased and zonal handover buildings.

What information do we require prior to a site visit?


1. Floor plans and section drawings.
2. Design-stage SAP reports for each dwelling to be tested. 
3. Contact details for the site manager. 

Opening Times


Mon     8.00am-6.00pm
Tue      8.00am-6.00pm
Wed     8.00am-6.00pm
Thur     8.00am-6.00pm
Fri         8.00am-6.00pm
Sat       8.00am-6.00pm
Sun      Closed


Ring us for a quote

Tel: 01323 841488

Mobile: 07867 960 711

Email: info@uk-building-assessments.co.uk


Speak to our Energy Assessments Manager

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