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Just had the air test done and we achieved 0.6ach. This is with a temp front door albeit sealed as best we could and the Internorm sliding doors leaking like a sieve. We have one large set that did not leak at all and the two sliders joined together where atrocious. We are obviously very pleased with this result and hope to improve on that as we need to do another one at the end. 

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Pete, we got 0.6 ACH on our first test as well.  Even so, after going around the windows we found and fixed quite a few leaks on some of our Internorm seals later so we are probably quite a bit less.  A double check is well worth while, IMO.

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A great result.  I actually made mine worse after the airtest was done as I had to remove/split the airtight tape at the bottom of some windows to let out water that had come in over the top of the frame before the cladding went on.  All fixed now, mind you!

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We scraped in with 0.59.  With a temporary external door too, sealed as best they could.  Sliders leaking - couldn't stop that.  And we subsequently found two small pipes from the plant room to the outside that hadn't been fully sealed.  So could maybe have been better but its a pass and it will do nicely.  

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This particular product might not be available over here but i gues a version might be. Anyone seen it/anything similar.

 

 

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@Big Neil I've enquired but had no response from Pacific Aerobarrier regarding UK or European distribution.

 

Could be an opportunity for someone to bring this product to market here if anyone is quick off the mark. 

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4 hours ago, TerryE said:

Pete, we got 0.6 ACH on our first test as well.  Even so, after going around the windows we found and fixed quite a few leaks on some of our Internorm seals later so we are probably quite a bit less.  A double check is well worth while, IMO.

Did you actually have a second test? The guy doing the testing said we need to do another one before we will get the certificate but it seems a waste of time as I only have to fit the MVHR ducting and I will not be penetrating the airtightness membrane at all in any other place. How many tests have people had done? 

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47 minutes ago, Pete said:

Did you actually have a second test? The guy doing the testing said we need to do another one before we will get the certificate but it seems a waste of time as I only have to fit the MVHR ducting and I will not be penetrating the airtightness membrane at all in any other place. How many tests have people had done? 

One is the norm, prior to insulating usually ( if blown cellulose is the weapon of choice ).

I guess the two test argument is if you want to be sure that you haven't reduced the buildings integrity after the initial test proves 'positive'. MBC do their test once as they simply want to know that they have satisfied their part of the contract, as they guarantee the result of <0.6 so just need to be able to demonstrate that at the handover.

A second test on that pretence would only be for the homeowner to confirm that follow on trades haven't subsequently turned the house into swiss cheese.

For me, I'd HAVE to have the second test done, for my own sanity, but others may value a night out in favour of such worries.

If certification is involved then the second test may be ( with good reason ) mandatory. Certainly not a bad thing AFAIC.

 

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5 hours ago, Big Neil said:

This particular product might not be available over here but i gues a version might be. Anyone seen it/anything similar.

 

 

 

A similar product was featured on this season’s This Old House Project - the Jamestown Net Zero house. It’s in the first segment of the show.  Looks like it’s from the same supplier as the one mentioned above. 

 

https://www.thisoldhouse.com/watch/airtight-house-jamestown-net-zero-house

 

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4 hours ago, Pete said:

Did you actually have a second test? The guy doing the testing said we need to do another one before we will get the certificate but it seems a waste of time ...

 

I sent the test report to my B Insp and he was really happy with it.  The requirement is 10 and I think 14× better or thereabouts is a reasonable margin.  Don't you? :) 

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10 hours ago, TerryE said:

 

I sent the test report to my B Insp and he was really happy with it.  The requirement is 10 and I think 14× better or thereabouts is a reasonable margin.  Don't you? :) 

 

This is the first part of the reply from our Building control Area Manager after I sent in the Air Test Certificate and EPC:

 

Quote

Hello Jeremy

 

Thanks for your email, the air test and EPC results are impressive so say the least.

 

This was followed by a request asking me if I'd provide a couple of hours on site to chat to some building inspectors, planning officers etc about how we'd gone about building a house that was so much better than the requirements in Part L1A...

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1 hour ago, JSHarris said:

 

This is the first part of the reply from our Building control Area Manager after I sent in the Air Test Certificate and EPC:

 

 

This was followed by a request asking me if I'd provide a couple of hours on site to chat to some building inspectors, planning officers etc about how we'd gone about building a house that was so much better than the requirements in Part L1A...

I must admit I was really chuffed with our result especially as I know we could improve with the known leaks that need fixing. I am waiting for my B/insp to respond as to whether he wants me to have another test done as the test company said I needed another one prior to moving in which to be honest with you although I would like to improve on the 0.6ach I have other things to spend my money on. How many tests did you have done Jeremy?

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23 minutes ago, Pete said:

I must admit I was really chuffed with our result especially as I know we could improve with the known leaks that need fixing. I am waiting for my B/insp to respond as to whether he wants me to have another test done as the test company said I needed another one prior to moving in which to be honest with you although I would like to improve on the 0.6ach I have other things to spend my money on. How many tests did you have done Jeremy?

 

Just the one. 

 

IIRC the result was 0.43 ACH @ 50 Pa, so massively under the Part L1A maximum allowable.  This included some known air leaks at the door locks (easily fixed with the injection of some very thick, aerosol-applied, motorcycle chain lube) and leaks at two doors where the hinges and catches needed some adjustment (again, easily fixed, although a bit fiddly to do in the case of our French windows).

 

I'm certain our airtightness is now better than when the house was air tested, but whether this makes any measurable difference to performance is debatable.  I'm inclined to think that once you get down to below 0.6 ACH variations from changes in the wind speed outside impacting on the MVHR are probably a greater influence.  I found that when balancing the MVHR there was a pretty wide degree of variability in flow rate as the wind gusted outside, presumably due to local small dynamic pressure differences between the external intake and exhaust.  Not worth worrying about, but it was clear that this variation probably swamped any variation from air leakage.

 

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Just to endorse what Jeremy is saying, IMO the key difference in my build was that the build was airtight by design rather that by construction fix-up.  Examples here are:

  • On each floor the joists were hung off the TF panels, decked out and the next floor on panels sat on this decking.  There was a air tightness membrane wrap from the inside lower panel, out and over the joist ends and back inside and up the upper panel.  This sealed all joist ends for air tightness, so no taping up around joist ends.
  • All other interfaces were properly taped and sealed by the MBC airtightness crew.
  • None of my trades were allowed to penetrate the filled panels.  Where penetrations were require Jan and I had a standard procedure for fittting an airtight access pipe: drill through inside to out with a 1m × 15mm drill; use this hole to core out the 25mm (say) entry and exit holes; feed through the 25mm abs pipe and seal properly at both ends;  one of us then insulated and sealed the inner pipe bore when the electrician (or whoever) was done.

Our biggest residual leak by far, IMO was down to incorrect sealing in fenestration, which is fairly easy to identify and fix. 

 

One issue that we did avoid -- thanks to reading Jeremy's early posts on this -- was to place our inlet and outlet some 5m apart high on the same gable wall so we don't seem to get the gust pumping effect that some installations experience, as any wind-gusting impacts the inlet and outlet equally.   

Edited by TerryE

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Thanks for the above info chaps. I fully endorse and what you are saying Terry as we did the same and the only noticeable leak was the Internorm sliding doors. Now you know my installation has been a nightmare but on this occasion the reason for the leak is the missing trim. I went and had a look at the single sliding doors which showed no sign of leakage to try and compare the two to determine the fault. When you look at doors when they are open you will see that when closed they drop down and engage two flexible seals onto corrersponding edges and this is the problem with my large sliders in that the missing trim has a neoprene gasket on it which engages with the flexible seal on the door so I am hoping that when this turns up and is fitted it will stop the air leaks. I am gutted now as my air test would have been lower as it was sucking air like mad through the whole of the sliding door gap which is about 6m in length. I will take 0.6 any day of the week though.

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My b/insp said if the air test people will give me a certificate for the air test at 0.6 then he is happy with that. So received my cert and it says 0.56ach so happy with that, gutted I did not have my Internorm gasket in place, may have beaten Mr Harris 0.43!!

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45 minutes ago, Pete said:

My b/insp said if the air test people will give me a certificate for the air test at 0.6 then he is happy with that. So received my cert and it says 0.56ach so happy with that, gutted I did not have my Internorm gasket in place, may have beaten Mr Harris 0.43!!

I think we should all chuck a £1 in and find out :D 

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1 minute ago, Nickfromwales said:

hink we should all chuck a £1 in and find out

 

Totally up for that.

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Would that be crowd funding? The air test was £240 incl vat so when you get to £239 let me know 👍

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Ours is not the lowest air leakage amongst the builds of other members here, I'm sure.  I think there are at least a couple of people who've had air test results that were better than ours, but can't recall who they were, but the lowest of them should be the target to beat in any competition. 

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I visited a house twice during construction that achieved 0.08 ACH at 50 pa. This podcast talks all about it.

 

https://www.houseplanninghelp.com/hph183-how-to-achieve-an-outstanding-airtightness-result/

 

Their secret was the prime contractor was motivated to achieve a very good result to promote their new Passive-House building prowess commercially. They used the PH15, I-beam system and taped everything to high heaven.

 

One point to consider is that ACH is measured relative to the volume of the house. This big house also has a big basement and basements are inherently airtight. I think that the calculation includes only 50% of basement volume to compensate for this but somehow I suspect that big houses especially with basements can achieve these very low figures more easily.

Edited by Dreadnaught

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0.25 for mine. Not sure what it will be after completion but I shan't bother with a second test afterwards unless I have to, on the basis that there will be so little that I can change and the house is already warm and comfortable.

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