Air test

[nod]

I was talking to a chap yesterday 

on a large site that we have been working on for the past five years

He was air testing one of the completed properties 

I remarked that I hadn’t seen him for a while He then told me that they only test one in eight and apply the same score to the other seven

I wonder if the people who are buying realise this

[ADLIan]

Another example of lack of enforcement of the Regs! The Building Regs are very specific on the air tightness testing regime, see Section 3.17 of Appr Doc L1A, requiring testing of 3 of each house type or 50% of each house type, whichever is the less. The SAP assessor should pick this up too as a copy of the test certificate needs to be provided for each tested unit and the convention is to add a penalty of +2 to the measured value for the untested dwelling type (Section 2.9).

[Jeremy Harris]

When we were looking around for a builder we went to look at a small development of five houses that were being built by one of the frame companies we'd shortlisted.  Whilst were were being shown around one of the most complete houses by their sales guy, he was called away to make a call from the site office.  We stood chatting to a guy who was sticking airtightness tape around, and I asked what sort of result they were expecting.  He replied that it had failed the air test twice and he was adding more tape in an attempt to get it to pass.  He was clearly a bit pissed off at having to do this and remarked that he was thankful he didn't have to "do all this crap" on the other houses, as they were only going to test one of the five...

 

When builders are failing to even meet the pretty crappy airtightness requirements in Part L1A you know things are bad.

[lizzie]

I thought everyone knew it was the norm that testing was done on sampling basis.  Its the same as the building inspections thats only on sample too.  I think gas and electric have individual tests but beyond that its every so many houses per test e.g. one in 5 or 8 or whatever.

[Dreadnaught]

1 minute ago, lizzie said:

I thought everyone knew it was the norm that testing was done on sampling basis

 

Yes, appalling. When the party that has a vested interest in a pass chooses the one to be tested I think that it is a stretch to say that testing is done on a sampling basis. The sampled one clearly is not representative of all. An awful state of affairs.

[ADLIan]

The properties to be tested should be chosen by the BCO not the developer/builder - yet to see that happen!

[Dreadnaught]

1 minute ago, ADLIan said:

The properties to be tested should be chosen by the BCO not the developer/builder - yet to see that happen!

 

Would that be the BCO officer selected and paid for by the developer/builder?

[PeterW]

9 minutes ago, Dreadnaught said:

 

Would that be the BCO officer selected and paid for by the developer/builder?

 

Heaven forbid..!!! I was assured that NHBC Building Control and Warranty Services were entirely independent ........ really ...... ?

[Mr Punter]

We did seven townhouses, all a bit different.  The test guy picked one (end terrace) and tested it.  It passed easily (3.74 against 5.00 required) but I was quite surprised when he did not test the others.  Fee was £690 and the guy was on site for about 2 hours.  I imagine they just extrapolated the results over the remaining, which all got a slightly worse score.

[SteamyTea]

Here is what real scientists need to do when statistically testing samples.

http://www.kayelaby.npl.co.uk/statistical_methods_for_the_treatment_of_experimental_data/6_1/6_1.html

 

I suspect that the Chi Square is used for buildings.  Chi Square compares expected results to real real results to see if there is a difference.

So it all comes down to the expectations i.e. 1 in 10 houses will fail, will give you a different acceptable error compare to 1 in 8 failing.

 

All bollocks really as even the test houses are only dodge to get a pass.

[nod]

18 hours ago, ADLIan said:

Another example of lack of enforcement of the Regs! The Building Regs are very specific on the air tightness testing regime, see Section 3.17 of Appr Doc L1A, requiring testing of 3 of each house type or 50% of each house type, whichever is the less. The SAP assessor should pick this up too as a copy of the test certificate needs to be provided for each tested unit and the convention is to add a penalty of +2 to the measured value for the untested dwelling type (Section 2.9).

Three of each isn’t enough

This chap charges £150 per house 

and a further 50 for any others on the same day same site

So it’s not the cost that stops builders having all of them done 

[Nickfromwales]

10 minutes ago, nod said:

So it’s not the cost that stops builders having all of them done 

It is......The cost of having to do the remaining properties to a reasonable / acceptable standard so they pass  

[PeterW]

I was just typing the same response as @Nickfromwales..!!

 

Cost will be to make them compliant - and no, the purchaser won’t ever know they bought a colander until they find out the heating bills...

[nod]

18 hours ago, JSHarris said:

When we were looking around for a builder we went to look at a small development of five houses that were being built by one of the frame companies we'd shortlisted.  Whilst were were being shown around one of the most complete houses by their sales guy, he was called away to make a call from the site office.  We stood chatting to a guy who was sticking airtightness tape around, and I asked what sort of result they were expecting.  He replied that it had failed the air test twice and he was adding more tape in an attempt to get it to pass.  He was clearly a bit pissed off at having to do this and remarked that he was thankful he didn't have to "do all this crap" on the other houses, as they were only going to test one of the five...

 

When builders are failing to even meet the pretty crappy airtightness requirements in Part L1A you know things are bad.

I don’t really understand the air tests They seem like a pointless excercise 

I’ve carefully sealed all sockets Air can get in but not out But yet prior to testing the builders use baby plugs on the sockets tape one downlights tenpory tape and foam around windows and doors 

All to say the house has reached a reasonable standard of air tightness

 

Googleing airtests shows how low pricing has become 

 

Ive just had three home energy Certs done for three rentals we have 

£25 each All very detailed certs 

Though pretty simalar 

I remember people were giving up there jobs to retrain to do the these compulsory home energy certs 

With charges expected to be about £500 per property 

Now it’s like everything else cut throat 

stack them high sell them cheap

 

 

[Jeremy Harris]

1 minute ago, Nickfromwales said:

It is......The cost of having to do the remaining properties to a reasonable / acceptable standard so they pass  

 

Spot on.  This was EXACTLY the case with the well-known timber frame firm building the development of five houses that we went to see.  They were struggling to get the first completed house to pass, and it was about to have it's third air test, so it is  near certainty that the other 4 houses on the development came no where near to meeting Part L1A.  They were putting a lot of work into taping up around windows and doors when we were there in order to get a pass, which suggests that they don't normally bother to use airtightness tape on most builds.  Given that, even with a house just built to meet building regs most of the heat is likely to be lost via air leakage and drafts, then i think it's fair to say that few new builds come close to their certified energy performance.

[Nickfromwales]

Were putting more effort into this thread than the average mass builder puts into quality control. They just use good painters as thats the bit people get to see. 

[Onoff]

I've read about air testing on here, marvelled (enviously ) at some people's results and thought I understood the concept.

 

The phrase "taping windows and doors" keeps coming up. What does this mean exactly? If you need to tape to test then in real world use that tape isn't there and the results are pointless. The window / door design should surely be such that the rubber seals are in effect airtight without taping. I can half understand taping over key holes as those mechanisms might be inherently leaky but then not really. They should be the known (minor) loss points and everything else should be designed out.

[PeterW]

6 minutes ago, Onoff said:

The phrase "taping windows and doors" keeps coming up. What does this mean exactly?

 

Taping is where you apply a tape between the window frame and the brick/block/timberframe to restrict any airflow. It’s the more modern and quicker method than using foam and mastic. 

 

In frame seals should stop any air leakage between the sash and the frame. Most have double, triple and sometimes quadruple seals on high end casement windows. 

[Onoff]

2 minutes ago, PeterW said:

 

Taping is where you apply a tape between the window frame and the brick/block/timberframe to restrict any airflow. It’s the more modern and quicker method than using foam and mastic. 

 

In frame seals should stop any air leakage between the sash and the frame. Most have double, triple and sometimes quadruple seals on high end casement windows. 

 

And does that tape stay there permanently?

[PeterW]

4 minutes ago, Onoff said:

 

And does that tape stay there permanently?

 

Yes it’s behind the plasterboard and is retained. Look up Gerband for examples. 

[ProDave]

58 minutes ago, nod said:

I don’t really understand the air tests They seem like a pointless excercise 

I’ve carefully sealed all sockets Air can get in but not out But yet prior to testing the builders use baby plugs on the sockets tape one downlights tenpory tape and foam around windows and doors 

All to say the house has reached a reasonable standard of air tightness

 

 

The point is, if you build a house properly, you are not relying on the sockets to make a seal. You have an air tight layer around the inside of the house, then a service void inside that sealed envelope before plasterboard etc.  It would make no difference if my sockets were removed.

 

I work in plenty of old houses where when you remove a socket, a howling cold gale comes out, it is truly shocking that the wall structure is open to the roof or the floor to let cold air into the building fabric.

[Onoff]

4 minutes ago, PeterW said:

 

Yes it’s behind the plasterboard and is retained. Look up Gerband for examples. 

 

So the test gets done pre boarding?

[Jeremy Harris]

Our air test was done before boarding and first fix.  All the things that needed to go outside were already in place (ducts through floors and walls etc) and were temporarily covered with tape for the test.  Once cables, pipes etc were fed through the various ducts in the floor/wall etc they were sealed up again.  In my case I used balls of chicken wire (with a pull wire) stuffed down around any remaining space in ducts (after the cables etc were in place), then filled the gap with slow expansion foam, then sealed the top with airtightness tape, after trimming the foam back flush to the top of the duct.  In the case of smaller cable ducts, where I used 25mm plastic conduit through the wall, I sealed around the cables in those with silicone sealant.

 

For the air test, the house shell has to be complete, with the doors and windows fitted, and will all the insulation in place.  All our doors and windows are taped tightly to the inner vapour control board layer.  Around the windows the plasterboard is bonded to that VCL board with pink grip, sandwiching the airtightness tape in place.  The slight gaps around the outside of the door and window frames is filled with low expansion foam, and the outside of that was trimmed back and sealed with a bead of sealant.

 

There is a 45mm deep service void on the internal side of all the external walls, with vertical 45 x 45 battens on 400mm centres, nailed through to the structural frame beneath the VCL board.  The plasterboard is fixed to those 45mm battens after first fix, so all the plumbing and cabling runs inside that service void.

[newhome]

21 minutes ago, PeterW said:

 

Yes it’s behind the plasterboard and is retained. Look up Gerband for examples. 

 

I read it the same as @Onoff as @nod used the word temporary above but maybe that’s only those who are trying to cheat the system (well more than the others)?

 

1 hour ago, nod said:

prior to testing the builders use baby plugs on the sockets tape one downlights temporary tape and foam around windows and doors 

 

 

[PeterW]

14 minutes ago, Onoff said:

 

So the test gets done pre boarding?

 

Nope - can be done right at the end but fixing any issues is a nightmare once they are fully plastered. 

 

You have to consider that holes into ceiling voids such as downlights will create problems if there isn’t a air barrier above the ceiling. 

 

The BRegs standard is woeful anyway - failing it is like leaving a standard window wide open so it’s not acceptable to be failing what is already a poor standard.