When to do an Airtightness Test?

ninjaBob

I am at the point where we have the windows in, the roof is slated and we are currently doing all the first fixing.

When would I go about doing an airtightness test? So I wait until I have my ceilings in? Or can I do the test right now by blocking the up the various openings that we are aware of?

I don't have a finished floor or a front door (just a frame right now). I would like to do the test before we go too far so that any problems can be fixed, but I don't want to do it too early as it could be utterly pointless.

Cheers

uprising

ninjaBob wrote: »

I am at the point where we have the windows in, the roof is slated and we are currently doing all the first fixing.

When would I go about doing an airtightness test? So I wait until I have my ceilings in? Or can I do the test right now by blocking the up the various openings that we are aware of?

Cheers

Bob what are you building?, a gas chamber?, nuclear bunker?

I have never heard of an airtightness test on a building, buildings need ventilation to stop rot etc. The roof is slated, you have tyvek, felt or some membrane under them, none of these are airtight, the felt/membrane over laps by 6 inches or so, its not sealed, it just allows water to roll off according to gravity.
I think you maybe getting mixed up with insulation, which is responsible for keeping your building warm, by trapping warm air inside as best it can, but this isn't airtight either.
Your main concern is drafts getting in around windows etc I imagine, which is all part of insulating your building.

How did you plan on doing the airtightness test anyway?

edit: tut tut uprising .... you need to get informed....
to anyone reading this post, an air tightness test IS required on new domestic houses under building regulations 2008.

syd

ninjaBob

Well I went into the supplier to try and find out pricing for the HRV ducting. He asked if I had done an airtightness test. This was not something I thought would be done until the house was plastered, finished floor level was in. You would then test to see if there were any openings. (Waste Pipes, Draughts from Windows etc). With the end result being you are aware and capable of controlling the flow of air through the house.

What the supplier tried to explain as that once the roof is done, they seal of the doors and do some tests. I am unsure if this is how it's done and was just wondering when such tests needed to be done.

The supplier kinda of threw me, but he could be talking out of his ass.

archtech

uprising wrote: »

Bob what are you building?, a gas chamber?, nuclear bunker?

I have never heard of an airtightness test on a building, buildings need ventilation to stop rot etc. The roof is slated, you have tyvek, felt or some membrane under them, none of these are airtight, the felt/membrane over laps by 6 inches or so, its not sealed, it just allows water to roll off according to gravity.
I think you maybe getting mixed up with insulation, which is responsible for keeping your building warm, by trapping warm air inside as best it can, but this isn't airtight either.
Your main concern is drafts getting in around windows etc I imagine, which is all part of insulating your building.

How did you plan on doing the airtightness test anyway?

welcome back to planet earth there uprising. there is a requirement for air tightness within building under the building regulations for quiet a while now (2 or so years at this stage) . As to how air tight building should be that's another story.

sinnerboy

You will need to do a test . In fact anybody that did not have their external walls up to wallplate by 01 July 2009 - has no choice - you must do a test .

Best time is when the building is weather tight and plastered , sanitary fittings and kitchen in but before decorations , including tiling , are started . Because you are bound to find areas ( around window openings , where drain pipes enter / exit your walls ) that need to be stripped back before sealing

You should look for Q50/5 ( your tester will explain this ) if looking at HRV . Otherwise warm air will be forced out of the building , not recovered .

Google for testers

who what when

uprising i think you might be a little out of touch.

ninjaBob

Ok So I don't do it now, before I put the ceilings up? So how on earth do I guage if my Heat Recovery are effective I have been informed:

What is the air tightness you are building to? The reason for asking
this is if you are building an air tight property, i.e. less than
3m3/h/m2 then 2 units will be required. However if you are not building
to a high level of air tightness, then 1 unit will e able to service
your property.

sydthebeat

ninjaBob wrote: »

What is the air tightness you are building to? The reason for asking
this is if you are building an air tight property, i.e. less than
3m3/h/m2 then 2 units will be required. However if you are not building
to a high level of air tightness, then 1 unit will e able to service
your property

my god, did a HRV sales rep actually say this to you??? :eek:

sinnerboy

ninjaBob wrote: »

Ok So I don't do it now, before I put the ceilings up? So how on earth do I guage if my Heat Recovery are effective I have been informed:

read post 5

Juantorena

We did an initial 'suck-and-see' - pun intended - test before walls slabbed/floors poured, etc to determine if there were any major flaws in the main envelope. Best to find them then when fixes could be easily applied.

We're about ready for the full/actual test now (one paint coat on walls -stage).

sinnerboy

sydthebeat wrote: »

my god, did a HRV sales rep actually say this to you??? :eek:

Agreed Syd

OP this installer does not know what they are talking about - seek another

onq

sinnerboy wrote: »

You will need to do a test . In fact anybody that did not have their external walls up to wallplate by 01 July 2009 - has no choice - you must do a test .

Best time is when the building is weather tight and plastered , sanitary fittings and kitchen in but before decorations , including tiling , are started . Because you are bound to find areas ( around window openings , where drain pipes enter / exit your walls ) that need to be stripped back before sealing

You should look for Q50/5 ( your tester will explain this ) if looking at HRV . Otherwise warm air will be forced out of the building , not recovered .

Google for testers

Thank you for that date sinnerboy, I couldn't find it when I tried to check it.



ONQ.

ninjaBob

sinnerboy wrote: »

Agreed Syd

OP this installer does not know what they are talking about - seek another

Ok, I suppose my question has then been answered in sorts, do a preliminary test when you can still fix major issues, the do another when ready to do decor.

If anyone can recommed a HRV unit I would appreciate it.

MicktheMan

ninjaBob wrote: »

I am at the point where we have the windows in, the roof is slated and we are currently doing all the first fixing.

When would I go about doing an airtightness test? So I wait until I have my ceilings in? Or can I do the test right now by blocking the up the various openings that we are aware of?

I don't have a finished floor or a front door (just a frame right now). I would like to do the test before we go too far so that any problems can be fixed, but I don't want to do it too early as it could be utterly pointless.

Cheers

What is your air tightness / ventilation strategy? Do you have one? Your architect should be able to advise on this and also know when best to check the house before build is too far along.
If your airtightness line is along your ceiling them this would need to be done before testing, temporarily seal the other openings such as attic access holes, ventilation openings etc. Get an indicative reading and check the house with smoke for weaknesses. Use an experienced airtightness tester. I find it very useful to have the plumber and electrician present during this pretest (it is an excellent learning experience for them and also shows them you take airtightness seriously!)

fishfoodie

Related to 'when' to do an airtightness test.

Is there a risk that if you do the test at certain times in construction, you'll end up skewing the test because of things like wood drying out & outgassing inside the building envelope ?

I imagine that soon after plastering the amount of water vapour being released would be huge, but stuff like people storing their wood flooring inside to allow it to dry etc, would that be enough to mess things up ?

MicktheMan

fishfoodie wrote: »

Related to 'when' to do an airtightness test.

Is there a risk that if you do the test at certain times in construction, you'll end up skewing the test because of things like wood drying out & outgassing inside the building envelope ?

I imagine that soon after plastering the amount of water vapour being released would be huge, but stuff like people storing their wood flooring inside to allow it to dry etc, would that be enough to mess things up ?

No, the "outgassing" effect is negligable. Also, the reason for the pretest is to find weaknesses before they are covered up / decorated / fittings applied. The pretest will give a good indication of where you are wrt airtightness and if you are on track to achieving your designed/target value.

fishfoodie

MicktheMan wrote: »

No, the "outgassing" effect is negligable. Also, the reason for the pretest is to find weaknesses before they are covered up / decorated / fittings applied. The pretest will give a good indication of where you are wrt airtightness and if you are on track to achieving your designed/target value.

Yeah. Just did a quick back-of-an-envelope calculation & you'd need to convert 0.6l to get 1m3 of vapour, so if you'd need to probably keep a couple of kettles boiling inside for the entire period of the test, otherwise it'll just condense again & you'd see no effect.

Might be worth doing it for a laugh on someone