Aerobarrier booked for Tuesday

[Post and beam]

I have been speaking to Aerobarrier for a couple of months and took the plunge, they arrive this Tuesday to demonstrate how badly or how well a job i did of my airtightness detailing.  Anyone want to predict a before and after score?   SIPs built, 200 square metre Potton framed 2 storey. All of the airtightness work has been done by me, for better or for worse. 

[JohnMo]

1 m³/m² at 50Pa, as found by them.

[Post and beam]

Results are in. 

 

3.9 as built air permeability prior to Aerobarrier doing their thing.

 

Ended up with a figure of 1.4, so a 63% reduction.  

 

The structure surface area was calculated as 479 square metres.  I dont know how this would relate to an ACH  figure. 

[Indy]

Can I ask how much this cost?

[Post and beam]

£2k 

[Nickfromwales]

3 minutes ago, Indy said:

Can I ask how much this cost?

 

Just now, Post and beam said:

£2k 

I have spoken with AB at length, so I could better understand their processes and procedures, and the lions share of their installed cost is for time spent with site prep and hunting down any obvious faux pas; costs include masking off of all doors/windows and anything precious etc, with then a couple of hours spent for actually 'treating' the dwelling. @Post and beam, does that ring true?

 

The more I look into this the more it makes sense to do it on every project, to make a good home "great" as they say.

 

63% is a hell of an improvement, and as an advocate of "airtightness, airtightness, and more airtightness", to squeeze every drop of HR out of the MVHR, this seems like a great product/service to me.

[-rick-]

2 hours ago, Post and beam said:

Results are in. 

 

3.9 as built air permeability prior to Aerobarrier doing their thing.

 

Ended up with a figure of 1.4, so a 63% reduction.  

 

The structure surface area was calculated as 479 square metres.  I dont know how this would relate to an ACH  figure. 

 

What type of construction?

What were you aiming for (both before + after treatment)?

Did they find some obvious oopsies or is the bulk of the improvement from the spray process? Put another way how much work did the spray process do?

 

[garrymartin]

16 minutes ago, -rick- said:

What type of construction?

 

On 22/06/2025 at 13:11, Post and beam said:

SIPs built, 200 square metre Potton framed 2 storey

 

[Post and beam]

51 minutes ago, Nickfromwales said:

does that ring true?

Yes dude

[Post and beam]

27 minutes ago, -rick- said:

Did they find some obvious oopsies or is the bulk of the improvement from the spray process? Put another way how much work did the spray process do?

I think the majority of the improvement is from the spray, certainly down to the 2 figure i think. Then the guys entered the house a couple of times with spray foam fine nozzle guns to help where they could see the mist still moving towards cracks.

No big obvious issues just lots of tiny movements of air. Guys did say the builders had done a great job on the windows and doors. 

This made me feel a little better because in this case the 'builders' is me. I taped all windows and doors.

[ProDave]

Was this done on an empty house or furnished?

 

Did any of the sealing gunk (whatever it is) settle on any visible surface of the house and need cleaning off afterwards?

 

Before or after plasterboarding?

[Post and beam]

1 hour ago, Nickfromwales said:

63% is a hell of an improvement

 True, but, disappointing from my point of view. Looking at it another way it means i left them with a lot of improvement to find. So did i do an effective job with all my detailing? It certainly took a shed load of work .

[Post and beam]

2 minutes ago, ProDave said:

Was this done on an empty house or furnished?

 

Did any of the sealing gunk (whatever it is) settle on any visible surface of the house and need cleaning off afterwards?

 

Before or after plasterboarding?

House is 70% plaster boarded & plastered, not yet occupied or furnished.

Yes the 'goop' did settle on horizontal surfaces. The upper floor is a little tacky. A bit like some pub carpets back in the day.

The window sills are the only area of any concern. I told the guys not to bother covering these as they are currently primed MDF and will need sanding and painting anyway.

But the goop has not dried to a state where i can brush it off so i think sanding the window sills will be a little more of a sticky task than it might have been.

[-rick-]

5 minutes ago, Post and beam said:

But the goop has not dried to a state where i can brush it off so i think sanding the window sills will be a little more of a sticky task than it might have been.

 

Use a wide scraper. Even if it takes off some of the primer you'll save clogging a load of sandpaper.

[Nickfromwales]

16 minutes ago, Post and beam said:

But the goop has not dried to a state where i can brush it off so i think sanding the window sills will be a little more of a sticky task than it might have been.

I would try water and a dish scrubby pad doodah first, as it is a water-based product iirc?

[Nickfromwales]

25 minutes ago, Post and beam said:

I told the guys not to bother covering these as they are currently primed MDF and will need sanding and painting anyway.

......😑

 

"oops!".

 

Get it all masked people, it's in their remit/costs and saves a boatload of time.

 

33 minutes ago, ProDave said:

Was this done on an empty house or furnished?

 

Did any of the sealing gunk (whatever it is) settle on any visible surface of the house and need cleaning off afterwards?

 

Before or after plasterboarding?

They (AB) ask that you complete all 1st fix work, plumbing/electrical/ventilation etc, including any penetrations you need to make in the build fabric, ahead of their arrival.

 

Getting plasterboard on, on the inside face of the external walls, would prob be a good position to be in before getting 'sprayed' possibly with back boxes in if these are getting drilled and fixed vs fast fix boxes etc.

 

They say that you only need to foam around doors and windows, and that you don't need to apply AT tape there, and their product will do the job of sealing up without issue. I asked about longevity there, and apparently not a problem. So, you can factor in the cost of time/tape for all doors and windows, and apply that to their price tag, making it cheaper again.

 

They are in and out in a day too, which is pretty damn good.

 

They expect you to have foamed/sealed up the obvious stuff, but they do go looking on the day; I assume this is to preserve their reputation and results etc as well as to do the job with diligence.

 

I'd be happy to see the process in person, may get the opportunity soon, as I am proposing this for 2 self build clients currently.

[Indy]

Very interesting and quite a reasonable cost. I'm going for a traditional masonry build so makes even more sense to do it as the airtightness inherently will be worse than a SIPS product due to the nature of the build process. 

[Post and beam]

1 hour ago, Nickfromwales said:

I'd be happy to see the process in person

This is why i announced before hand that they were booked. I imagined at least one or two selfbuilders would have been interested.

 

5 minutes ago, Indy said:

airtightness inherently will be worse than a SIPS product

Yeah! dont bank on it. I had to do a LOT of work after the TF frame was left to me as completed. In the kitchen for example i could see daylight ( lots of daylight) out through the open eaves detail. I had no idea 'open' meant quite that open.

[LnP]

8 minutes ago, Post and beam said:

 

Yeah! dont bank on it. I had to do a LOT of work after the TF frame was left to me as completed. In the kitchen for example i could see daylight ( lots of daylight) out through the open eaves detail. I had no idea 'open' meant quite that open.

I have a quote from Potton (but we're still wrestling with planning🫤) which says "You have not advised your requirement so we will be targeting 5. We will achieve this air tightness through the external walls. Air tightness of the overall structure is a combined responsibility between the principal contractor and all trades". Actually I have advised I want better than this and they are prepared to "target" 3. Did you have any expectations about what airtightness you'd get from them?

[Post and beam]

1 hour ago, LnP said:

Did you have any expectations about what airtightness you'd get from them?

Not at the outset no. They filled in the target air tightness box with '1.5-3' and specified MVHR  as a consequence. Their chosen supplier was not credible as far as i am concerned. Prior to this i was not really aware of what MVHR  was to any meaningful level and thought of it as just another thing i had to pay for. Lots of reading up on the subject quickly brought me to realise its worth. I went with Brink for the parts.    What type of house are you talking to them about?  5 is not much of a score for them to aim for as a 'premium' supplier, i think all the major house builders would give you that figure. I am also interested to learn which level of package you are considering from them. Keith

[-rick-]

3 hours ago, Post and beam said:

Yeah! dont bank on it. I had to do a LOT of work after the TF frame was left to me as completed. In the kitchen for example i could see daylight ( lots of daylight) out through the open eaves detail. I had no idea 'open' meant quite that open.

 

1 hour ago, Post and beam said:

Not at the outset no. They filled in the target air tightness box with '1.5-3' and specified MVHR  as a consequence. 

 

All in all a good result then with aerobarrier. When I first read your post with results I thought 'not great, not terrible' but given where you started 1.4 is a good result.

[Post and beam]

4 minutes ago, -rick- said:

1.4 is a good result.

1.4, air permeability of course.  i would like to know how that relates to an ACH  number. Not a straight forward calculation i know.

[JohnMo]

1.4 is m³/h·m² .

 

You know the m² figure

 

You need to work out the house volume in m³.

 

Now you have house m² and house m³.

 

Multiple 1.4 by your m² area. You now have the air loss per hour atv 50Pa.

 

Divide your answer by your volume. That should be your ACH at 50Pa

 

 

 

[LnP]

3 hours ago, Post and beam said:

Not at the outset no. They filled in the target air tightness box with '1.5-3' and specified MVHR  as a consequence. Their chosen supplier was not credible as far as i am concerned. Prior to this i was not really aware of what MVHR  was to any meaningful level and thought of it as just another thing i had to pay for. Lots of reading up on the subject quickly brought me to realise its worth. I went with Brink for the parts.    What type of house are you talking to them about?  5 is not much of a score for them to aim for as a 'premium' supplier, i think all the major house builders would give you that figure. I am also interested to learn which level of package you are considering from them. Keith

They quoted for 0.15 U value external wall ULTIMA 90/50 (TW55/TW55) system, factory fit insulation between the studs, a VCL, a secondary insulation layer across the studs, and a service void batten. They also offer an upgrade to 0.12 U value external wall - ULTIMA 140/50 (TW55/TW55), which we would take if we go with Potton. The leak tightness they "target" is the same regardless.

I agree, 5 is not sufficient. They said we could make the target 3, but I'd have to check my notes whether they proposed a charge for that.

[Post and beam]

They do 3 basic types of house the old dormer cottage style like the gransden show house. The georgian style and the much more modern looking things. Even a passive version.  I suggest reading their terms very carefully, they have many years experience and de risk everything they say. Whatever target airtightness you end up with remember that they write ' final airtighness is down to'  .... others. If you are not taking the full turnkey package then there is so much left to do that will not be done by them that the target is meaningless. It will not be their fault when the target is not reached. I have learnt a great deal while building mine about Potton details and standards.Are you a competent DIYer or a builder yourself? There are things i might be able to help with regarding them. Where are you in the country? Keith

4 hours ago, JohnMo said: