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30 Aug 2016 - Much tape doesn't mean much airtight

A new house recently tested had to be tested on 3 visits to get it to a relatively good standard of about 3.5 m3/hr.m2 - the first test being outside of the 2011 Part L requirements of at most 7 m3/hr.m2.

Three of the noticeable things about this house:

  • Lots of tape - in fact at least 7 different tape types from 4 different suppliers
  • Lots of membrane - 3 different types
  • Fair bit of expanding foam - much of it not doing its job
So it is a reminder that lots of materials doesn't mean good airtightness - workmanship is key.

numerous types of tapes
numerous types of tapes
2 Types of membrane
Various membranes
Inconsistent foam
Example of foam sprayed in, but not expanding as much as the worker expected
- plenty of gaps left
foam missing from area
Example of total loss of foam - this is looking upwards,
the foam may have fallen down after application

06 January 2016 - 2015 in Airtightness

Just for interest: the best and worst tests of the year in 2015

Best Air Permeability test Worst Air Permeability tested - New build Worst Air Permeability tested - Existing
1 0.13 9.87 20.33
2 0.22 9.02 12.72
3 0.30 5.98 11.28

The readings are in m3/hr.m2.

And if you are eagle eyed, you will see that yes, just 2 new homes didn't pass the airtightness test at a Building Regulations level, at least on their first run at it.
The Building Regulations Level is a mximum result of 7 m3/hr.m2.

But of course, a much larger number of new builds had self imposed targets of much less than that, and they did not all reach their there's another metric to measure this year....

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