Airtightness Test

murphy31ie

Hi,
We have scratched coated the external walls, installed our membrane in the ceiling and taped all windows and doors. We did a prelim airtest at this stage and it was running at 5 @50Pa. According to the tester once we scratch coat all the internal walls, put all the plasterboard up and skim all walls that this will come down below 3. Is this true?

delfagio

Hi Murphy,

I would be no expert on this, Mick the Man is another guy on boards.ie that is very good on this topic, but I would not be so sure that the internal walls would make a big difference to the test as these are within the building envelope and they especially wouldn't account for an additional 2ACH @50pa.

I couldn't really say if the results would drop from 5 to 3ACH by the time it's finished. I could be wrong but I would have thought at this stage it would have achieved better than 5ach. Don't get me wrong it's still meeting building regulations but it's just showing a lot of air leakage.

Did the airtightness tester look for any sources of air leaks during the test when it was hitting the 5ACH @50pa??....I would have expected him/her to look or try identify where the air leakage was coming from.

Have all your Windows and doors been sealed up with air tightness tape also? And are you a two story or a bungalow, if your a two story did you seal the first floor where it meets the external walls along the perimeter of the building?? Oh and also the ground floor joint where the external walls meet at this point around the entire building perimeter???

galwaytt

5 is not great at this stage - finishes might get it to 4. Something is awry. Where were the leaks visible during the test ??

It really should be below 3 now, and aiming for a finish of half that imho.

dos29

Got ours tested with all taping and membrane in place but only scudding on inside of cavity walls, outside finished plaster. Result was 7.
Redone after plastering and skimming inside walls, (no plasterboard), and went to 2 something, can't remember exactly.
Hope this helps.

murphy31ie

delfagio - My thoughts were also it is a bit high, I was not there for the test but my dad was, he is in the construction business. My dad and the tester went around and sealed any leaks they could find. All windows and doors have been taped, the tester did comment that the tape should have been wider than what was used by the person that taped the windows and doors. It is a two story house, we haven't sealed the first foor where it meets the perimeter nor the ground floor joint as we wanted to wait until the floor screed was poured as we were told if taped the screed poured over it makes a mess of the tape.

dos29 - I think your change is a bit different in that your external walls weren't sealed in the first test and were sealed in the second.

Calahonda52

murphy31ie wrote: »

Hi,
We have scratched coated the external walls, installed our membrane in the ceiling and taped all windows and doors. We did a prelim airtest at this stage and it was running at 5 @50Pa. According to the tester once we scratch coat all the internal walls, put all the plasterboard up and skim all walls that this will come down below 3. Is this true?

You need to tell us more about the house construction.
Whats the contract target ACH?
Is is passive spec?
do u have mhrv?
were all service ducts sealed up: waste pipes, sewer pipes esb cable to meter from board etc?

You cannot do more covering up with it at 5 and hope....

What happens if it sticks at 4 with house finished.:eek:

murphy31ie

We were not going for passive spec, were trying to get it under 3, we are installing MHRV so we would need to get the house under 3. All ducts and pipes were sealed up, the tester commented that there was a good bit of weakness were the external wall meets an internal wall but that will be sorted when the internal walls are scratch coated. I didn't know whether to believe that would make much of a difference.

Calahonda52

well then get all the internal scratching done and then test again, it will be too late if u put up the PB
Concrete places are very porous.

Have you considered a smoke test, very very revealing when u stand outside and see the smoke pi$$ing out

murphy31ie

The PB will only be on the external walls, the scratch coating of the internal walls will be done after the PB is put on. A smoke test could be a good shout in the meantime.

galwaytt

murphy31ie wrote: »

We were not going for passive spec, were trying to get it under 3, we are installing MHRV so we would need to get the house under 3. All ducts and pipes were sealed up, the tester commented that there was a good bit of weakness were the external wall meets an internal wall but that will be sorted when the internal walls are scratch coated. I didn't know whether to believe that would make much of a difference.

There's no point in covering anything with plasterboard until you know where the leaks are, so stop and fix those now. Scratchcoat and retest at a minimum.

Even at 3, you're on the border of negligible for the effectiveness of MHVR - it really needs to be better.

I still think you should be aiming to be below 2.

Calahonda52

galwaytt wrote: »

There's no point in covering anything with plasterboard until you know where the leaks are, so stop and fix those now. Scratchcoat and retest at a minimum.

Even at 3, you're on the border of negligible for the effectiveness of MHVR - it really needs to be better.

I still think you should be aiming to be below 2.

thats it in a nut shell

murphy31ie

Cheers for the advice, will go back to trying to get it tighter. The airtightness tester was not a great help so will use someone different the next time, it is just hard to find the leaks now the tester has been and gone.

MicktheMan

murphy31ie wrote: »

Hi,
We have scratched coated the external walls, installed our membrane in the ceiling and taped all windows and doors. We did a prelim airtest at this stage and it was running at 5 @50Pa. According to the tester once we scratch coat all the internal walls, put all the plasterboard up and skim all walls that this will come down below 3. Is this true?

I sincerely doubt it. The tester should have given much better advice than this. As others have said, you have some significant leakage issues which ought to be addressed now before it's too late.

All junctions need to be sealed (and I don't just mean taped as I have seen several cases where windows have been "taped" but leaked badly under pressure) including wall to floor junctions which are often missed by the inexperienced. A common problem I encounter is the wrong product (tape for example) being used in the wrong situation. Also look out for tape being applied to poor / unprepared / dirty surfaces.
How is the 1st floor constructed, timber or concrete? If timber, how are the joists supported / airtightened and if concrete, were the slabs / walls wrapped for airtightness before installation?

murphy31ie

Hi Mick,
Thanks for the info, we plan to tape/seal the wall to floor junctions (ground and 1st floor) after the screed has been poured, we were told if taped before the screed makes a mess of the tape (open to being told this is totally wrong). The first floor is solid concrete slabs not hollowcore, in a earlier tread I mentioned that we made a mistake thinking as they are solid we didn't have to wrap them. Nothing much we can do now other than tape under the slab to the wall, we probably should have did that for the test. The tester did mention also a bit of leakage was happening under the door but again that can't be sorted until the floors go in.
All info is really appreciated

Calahonda52

murphy31ie wrote: »

Hi Mick,
Thanks for the info, we plan to tape/seal the wall to floor junctions (ground and 1st floor) after the screed has been poured, we were told if taped before the screed makes a mess of the tape (open to being told this is totally wrong). The first floor is solid concrete slabs not hollowcore, in a earlier tread I mentioned that we made a mistake thinking as they are solid we didn't have to wrap them. Nothing much we can do now other than tape under the slab to the wall, we probably should have did that for the test. The tester did mention also a bit of leakage was happening under the door but again that can't be sorted until the floors go in.
All info is really appreciated

This goes from bad to worse.
What door?
how wide the gap?
why was it not taped?
where was the blower?
was this a full airtightness test or just a simple blower test?

The guys here will do the math but a 10mm gap 850 mm wide under a door at 50 will equate to a large part of the 5

murphy31ie

The side door of the house, we don't have a back door so this acts as it. The blower was at the front door and it was a full test, was not there for the test but according to my dad the tester said it was only a slight bit of leakage coming from it.

delfagio

Hi Murphy,

I know your going to seal up the 1st floor slab to the external walls on the 1st floor itself, just make sure you do this on the underside too before you do your dropped ceiling downstairs. As you won't be able to get into it again so easy after the ceiling goes in.

Also as others say make sure all toilet/shower/sink/bath waste pipes, external light/outdoor socket cables, ESB, Eircom, alarm cables, overflow pipe from attic storage tank etc that pass through the external walls are all sealed and taped too.

Definitely get a second test done again before you do any internal plasterboarding etc. It may be a few hundred euro but a drop in the ocean really compared to ripping out finishes later to try seal anything. I learned that the hard way. I let my plasterer put me under pressure to get his work done that I didn't do a preliminary airtightness test before plastering. Lesson learned hard way as I said.

A couple of things also, if you can make sure you are there the day the airtightness test is done, so if there are any issues you will be there yourself to view them or seal anything up there and then. Sometimes it's pointless the issues getting passed second hand to you. No offense to your dad or anything. It's just easier to get information first hand yourself by been there.

Here is a big tip for you. Organise with your window supplier to be on site the day the test is been done. That way if any rubber seals need replacement on leaking Windows or doors they can sort this there and then for you and it saves you getting window company out later to fix issues and then having to get another test done AGAIN ha.

Also if the window company have a guy or two on site on the day of the test, they could tighten in any windows/doors that may have air leakage. It makes a lot of sense to do this and most window companies would be happy to do that as after all it would be their snags if anything was wrong. Plus again the window company would see and get the information first hand instead of you having to pass them on the issues later and it may be hard to explain to them where or what certain issues are.

Hope this helps.

delfagio

Oh also make sure you seal up that gap at the bottom of your side door and any other door around that might be the same. If there is a gap, believe me it would be letting in a LOT of air.

As my airtightness tester explained to me....a result of 1ACH would be the equivalent of a single hole in a wall that you could fit a full box of 20 cigarettes through. A result of 0.6ACH which is Passive, would be the equivalent of a single hole in a wall that you could only fit 4 or 5 cigarettes through.

I would seal the floor to wall junctions now and do a test and you could seal them again if you wanted after the finished screeds are done. Double back-up

murphy31ie

Really appreciate the info delfagio, thanks very much for taking the time.

ht9zni1gs28crp

Im in the middle of chasing 0.5 air leak...trust me when I say the smallest of smallest holes make such a difference!

delfagio

Hi Miller,

Your CHASING 0.5ach, what ACH are you getting at present. Are you trying to get passive, meaning your at 0.65ach??

Cheers :)

ht9zni1gs28crp

delfagio wrote: »

Hi Miller,

Your CHASING 0.5ach, what ACH are you getting at present. Are you trying to get passive, meaning your at 0.65ach??

Cheers :)

Im at 1.01, I need 0.6 ACH :mad:

delfagio

Bloody hell, where was I going, my maths is terrible......I was adding 0.05 instead of 0.5.:eek:

Wow fair play Miller63. Still that is a really great result 1.01ach. I can only imagine how hard trying to find that 0.5ach difference would be.

If I finish around that mark you are at currently I will be happy. My tester reckons once I address the few airleaks we identified in the first go that he would be confident we should finish up between 0.9-1.5ach.

I would be happy with that. :)

galwaytt

delfagio wrote: »

Bloody hell, where was I going, my maths is terrible......I was adding 0.05 instead of 0.5.:eek:

Wow fair play Miller63. Still that is a really great result 1.01ach. I can only imagine how hard trying to find that 0.5ach difference would be.

If I finish around that mark you are at currently I will be happy. My tester reckons once I address the few airleaks we identified in the first go that he would be confident we should finish up between 0.9-1.5ach.

I would be happy with that. :)

Going by your description, I think you'll do better than that. ....when's the big date ?