DoctorJez, cool photo. He fixed it by sealing the downstairs skirting to the floor, sealing the tops along the gable walls and the other two sides by lifting the upstairs floor. It might not be the best, but was the easiest and the house is probably 90%+ of where it should be. Made a huge improvement to comfort and heat loss, so he is happy.

Doctor Jez - you got it - though I must admit there was a hefty clue in the name. You are correct of course - relying on the inner plasterboard skin to provide the air barrier is not the way to go. BUT... I've worked on sites where properties that hadn't been pressure tested (most, of course) had developed this fault and the owners first noticed the draught, rather than the gap. Prior to carrying out the repairs (quadrant beading at that time) held a lighter to the gap, seen the flame move or sometimes even be blown out, because the primary air barrier was ineffective (poor sealing at various points, such as around joist ends, cavity closers etc, and also, as you say, that all-important top floor ceiling/wall junction. My point is this - It's all very well testing a percentage of properties at the 'brand new' stage - properties where a great deal of care will have been taken to ensure that the primary air barrier is sound.... In the real world, once those properties have passed the test, the remainder may not have the same care taken, and rely on the plasterboard skin. Parging coat on all externall walls? Well yes - that would make a massive difference. But then you're back to the drying out problem. The main advantage of dot and dab (probably the only one, since I'm not keen on it) is the reduction in drying out time. The other option is back to hardwall plastering - but, as I was discussing with a site manager this morning - how many plasterers are there who can still do it???

kgr

drying times for modern parge coats can be as low as a few hours after which time you can apply the plasterboard. In many cases builders are using parge coats on party walls anyway for acoustic purposes - for example Part E robust detail EMW4 which is a block-block party wall with 75mm cavity, parge coat on the blocks and plasterboard on dabs - it is the most common masonry robust detail and one of the bst performing (it is also a thermal bypass but that is another story) - so to carry on the parge coat to the external walls is only a marginal cost.

Your point on the lack of site testing is well taken and has concerned us for a long time - in particular on large devleopments where only one of each one house type needs to be tested - which on big sites means that after the initial tests on the very first dwellings no more are tested for years. The Part L 2010 consultation document tries to address this problem by penalising developers who don't test frequently with a 2 m3/h.m2 penalty on the mran measured air permeability - see below - it is section 4.8 in the consultation document which can be downloaded from http://www.communities.gov.uk/documents/planningandbuilding/pdf/partlf2010consultationvol2.pdf. Whether this stays in the regulations after the consultation is another matter.

Jez

"4.8 To comply with regulation 17C, the proposed Dwelling CO2 Emission Rate (DER)
must be no worse than the TER calculated as set out in paragraphs 4.2 to 4.6. The
final DER calculation produced in accordance with regulation 20D (see paragraph
4.9 below) must be based on the building as constructed, incorporating:
a. any changes to the performance specifications that have been made during
construction; and
b. the assessed air permeability. The assessed air permeability shall be
determined as follows:
i) where the dwelling has been pressure tested, the assessed air
permeability is the measured air permeability;
ii) where the dwelling has not been tested, the assessed air permeability
is the average test result obtained from other dwellings of the same
dwelling type on the development increased by a margin of +2.0 m3/
(h.m2) at 50 Pa;
iii) on small developments (see paragraph 5.15), where the builder has opted to
avoid testing, the assessed air permeability is the value of 15 m3/(h.m2)
at 50 Pa."

sinnerboy - with the energy penalty that comes with a 15m3/h.m2 air permeability and the 25% reduction in TER in the 2010 regs, I doubt that any small developers will avoid testing due to the additional cost for the better fabric U-values that would be required to offset the higher air permeability in order to meet the TER target. In most cases it would be cheaper to get a pressure test done. In any case, in our experience houses built by smaller developers are more airtight than those built by the big boys.

Jez

In Dublin now in this housing market - customer is king . Just recently on a multi unit development - when one guy saw a house being tested - they all wanted it . And they all got it too . Regs did not enter into it .

Dr Jez - I agree the small guy tends to build better then the mass producer - as a rule .