Air Tightness Testing issues

Through our regular on site air tightness testing, we come across 4 main air tightness testing issues for failure:

  • Behind kitchen units
  • Bathrooms
  • Service ducts
  • Plasterboard on mortar dabs (most common method of lining walls, but can be done better)

Many drawings by architects show common areas to seal around windows, doors and wall and roof junctions for example. But rarely show where to seal when connecting the kitchen waste to the soil pipe and sealing to the plasterboard fixed behind kitchen units.

if we look at each in more detail, hopefully we can pass on our experience to help you and your site managers achieve confidence in the results required and concentrate on the getting the build completed.

One of the main issues is the void between the blockwork and the plasterboard. The blockwork is generally not sealed. Holes appear in the mortar and the void between the plasterboard and blockwork acts as a plenum for air movement through the building fabric.

Please click on the link below for guidance with plasterboard on to dabs when adjacent to SVP pipes (generally behind kitchen units and in bathrooms where a skirting board is not installed)


This is the most common area for leaks in our experience

Why is it a problem?

  1. Air leaks through the blockwork mortar joints into the void between the blockwork and plasterboard. This acts like a plenum for air movement.
  2. The base of the plasterboard behind kitchen units IS NOT SEALED or finished with a skirting board. This is because the kitchen installers no not want to scribe the kitchen units over the skirting board.
  3. The kitchen waste drains behind the kitchen units and connects to the main drain, often in the corner.Really trick to seal around this unit. And the soil & vent pipe (the main large vertical drainage pipe) often runs up through the loft so pulls in air from a lot of different areas.

What can be done:

  • Connect the drainage up.
  • Wrap the SVP in mineral wool to reduce heat loss and slow down air movement.
  • Ensure the plasterboard to the walls is taken down to the floor and has a full horizontal and vertical mortar dab behind the
  • Form a boxing frame in timber.
  • Use Pro-clima ROFLEX pipe grommet or a fire collar to seal the top of the SVP so air does not leak from the loft space

Need further advice for air tightness testing?

We have in house and on-site expertise for helping to improve air tightness and pass the air tightness test and move on to finish your property.

Just get in touch.


Download the right specification for your project

Do you have a project in mind, configure your specification here.

Learn More