Air Pressure Testing
It is a requirement under the Building Regulations 2006 Part L that new dwellings must pass an air tightness test prior to occupation.
The number of properties to be tested should be in accordance with the following table:
|No. of instances of dwelling type
||No. of tests to be carried out on each type
|4 or less
||One test of each type
|Greater than 4, but equal or less than 40
||Two tests of each type
|More than 40
||At least 5% of each type, unless the first 5 units pass, when the frequency can be reduced to 2%
Purpose of an air tightness test
All buildings require some ventilation in order to dispel moisture and pollutants etc. and provide combustion air. This ventilation is usually in the form of trickle vents, extract fans, cooker hoods and air conditioning systems.
The purpose of the air tightness test is to identify and quantify un-controlled air losses. These losses often occur from gaps around waste pipes, ill fitting windows and doors, and loft hatches etc.
Un-controlled air loss not only wastes energy but causes draughts which can result in discomfort to the occupants.
The air tightness test gives an indication of the quality of the construction process, since poor workmanship will adversely affect the test result.
Air testing procedure
The air tightness test consists of placing a suitably sized fan in a temporary screen which is placed into a suitable external door opening.
Internal and external temperatures, along with barometric pressure and wind speed are recorded.
The fan, which can be controlled by computer or manually, is run at various speeds to adjust the pressure inside the building, with the readings recorded at various pressures. The computer then calculates the air leakage of the building.
The test will show how much air is leaking through the structure and whether the overall result meets the Building Regulation requirements.
In order to carry out an air tightness test and provide a full result we require the following to be available at the time of the test:
- SAP Design air pressure test figure
- Electricity supply
- Water supply to enable traps to be filled
- Area of floors, walls and roof (we carry out an on-site survey to determine these quantities)
The air tightness test, which is carried out to ATTMA requirements, should only be performed on completed buildings, i.e. they must be ready for occupation or at a stage where the envelope along with all plumbing, electrical, heating and ventilation installations are complete.
If the building fails the initial test we will provide information to the contractor to assist him in improving the result. We will re-test the property within one hour at no additional cost. However, should this test also fail will have to reschedule the test for another time, at an additional cost.
Why Terry Holmes Consultants?
We have considerable experience of carrying out air tightness tests on domestic and commercial buildings. Our staff would welcome the opportunity of discussing your requirements with you.