Air Tightness Testing
Air tightness can only be verified by a relatively non-intrusive test, by a competent testing company. Irrespective of Building Regulations requirements, pressure testing provides benefits to clients, as it will help us to make buildings more energy efficient, cost effective and comfortable – and benefit the environment.Test Procedure
Air tightness testing is carried out in accordance with the procedures detailed in ATTMA TSL1 and ATTMA TSL2 (free downloads from this website) and BS EN:13829 (2001).
ATTMA TS1 describes how to carry out the test and the analysis required to determine the air permeability. Air permeability is expressed as volume flow per hour (m3 h-1) of air supplied to the space per square metre (m-2) of envelope area for an internal to external pressure difference of 50 Pa ie zz m3 h-1 m-2 at 50 Pa.
The test involves connecting a fan, or a number of fans, to a suitable aperture in the building envelope and pressurising it over a range of pressure differences. The fan speed is increased in steps up to a maximum and then decreased in steps. Air volume flow rate through the fan (equal to the air leaking through the building envelope) and the pressure difference across the building envelope are recorded at each fan speed. In calculating air permeability, corrections are made for temperature and barometric pressure.
Preparation
Before the test is carried out, ventilation systems must be sealed. Sealing can be achieved with plywood sheeting or plastic sheeting and strong adhesive tape. Drainage traps should be filled.
While the pressurisation test is being carried out all external doors and windows must be closed and secured to avoid them being blown open.
Internal doors must to be wedged open during the test to avoid them slamming shut. The fan unit will create draughts in the building. Lightweight objects and paper near the fan unit should be removed or covered to avoid them being blown about. Fixtures and furniture will not be affected.
Practicalities
Access in and out of the building during the test will not be possible (unless there is an emergency and a need to evacuate the building). The test will take approximately 30 minutes. Site workers can remain in the building during the test, or will have to remain outside until the test is complete. There are no health risks to site workers who remain in the building during the pressure test, however there may be some discomfort due to cold draughts and some noise from the fan.
