House is Too Airtight

[Newlands Ian]

Hi all

 

I'm looking for some ideas on how to get my airtightness test result up from 4 to 5. I need the result to be 5 or more in order to avoid having to replace all the internal fans and submit an amendment to the building warrant. Needs to be something that looks nicely finished and permanent, not just holes in the plasterboard which I won't get away with.

Thanks

[Big Jimbo]

What is the problem ? Are they saying that you need MVHR or something because your house is too airtight ? You could do a 100mm core drill to outside, with an open vent on both the inside, and outside.

[MikeSharp01]

11 minutes ago, Newlands Ian said:

I'm looking for some ideas on how to get my airtightness test result up from 4 to 5. I need the result to be 5 or more in order to avoid having to replace all the internal fans and submit an amendment to the building warrant.

Feels all wrong - the better the air tightness the better the insulation works and the less the house costs to run, in energy and financial terms, so better for the planet. People might, still seems wrong, suggest a reversible scheme, IE do the core drill operation suggested above, keep the cores, have the air test and then replace the cores.

[Newlands Ian]

Yep, they're not saying I need MVHR but dmev fans and 10mm gap cut at the bottom of all internal doors to allow circulation. 

 

Drilling a hole is an option but I don't really want to cut a hole in my nice new render 🙂

 

Also, the air-test guys tape up all visible vents so would have to be in a non-obvious location.

[Big Jimbo]

That's a joke. You tape everything up in order to get the best air test result you can. When you are living in the house they wont be taped up will they ? So in the bloody real world untape your bathroom extractor vents etc, and tell the twat to test the house like that. 

[Buzz]

Just change who you use to do the air test , have a word with some of the trade's used during your build and explain what you need and guarantee they will have a number of someone who can help. 

[Big Jimbo]

And don't pay you airtest person. They should not be taping anything up. Twats.

[MikeGrahamT21]

Adjust the bolts on the window openers so that they close poorly and don't make a proper seal, shouldn't be obvious and no works needed really, just an allen key

[ProDave]

Like others this is counter intuitive.  4 is a poor air test, I would be very disappointed and wanting to improve it.  but if you want a cold draughty inefficient house that is your call.

 

Get the air tester back, and instruct him NOT to tape up the vents, or peel off just enough of the tape he has put on to get the air test just over 5 and job done.

 

If I was the BCO I would not accept you making the air test worse.  I would expect you to be making the property better.  I think all it needs is the fans swapping for the sort that have a low speed constant trickle running.  Replacing those is likely going to cost less than another air test, so just do it.

[saveasteading]

35 minutes ago, Big Jimbo said:

They should not be taping anything up.

Sure about that? Airtight fabric first, ventilation second.

With lots of extractor ducts open to the world, a pressure test will force air through, gjving a poor result, so I think that taping up is correct....assuming you want to test the building for leaks, not the ducting.

[Kelvin]

8 minutes ago, saveasteading said:

Sure about that? Airtight fabric first, ventilation second.

With lots of extractor ducts open to the world, a pressure test will force air through, gjving a poor result, so I think that taping up is correct....assuming you want to test the building for leaks, not the ducting.

My understanding too but if he wants a worse airtight test then this is a way to achieve that. 
 

4 is poor even by typical new build standards. 

[Big Jimbo]

@saveasteading obviously you want the best airtest result you can achieve for your epc. But in the real world, those vents are not going to be taped up when the house is in use are they ? So in effect you are getting a false air test result. It was only a simple case of the twat saying "it's a bit to airtight, i'll take a strip of masking tape off one of your extractors. That will get you a pass" The twat was just looking for a re-visit and an extra fee. 

[jamieled]

An airtight test is meant to test uncontrolled leakage, hence why vents are taped for tests.

[nod]

I haven’t read the answers 

But should you be getting your test results down The higher the score the worse it is 4-5 is really poor 

Most of the homes I work on are looking a two

[Big Jimbo]

No bathroom extractor is going to be airtight. So taping it up for the test is fine in order to get the best result. However, cutting 10mm off the bottom of doors etc. Really ? When just one of the OP's extractors is uncovered his air leakage will rise, even when the extractor is not in use. Therefore, no need for chopping doors etc is there ? Bloke is just looking for a re-test fee.

[Big Jimbo]

6 minutes ago, nod said:

I haven’t read the answers 

But should you be getting your test results down The higher the score the worse it is 4-5 is really poor 

Most of the homes I work on are looking a two

I'm waiting for you to get below 2 @nod. I know you build in block, and do proper dot and dabbing. Go on you northern monkey (Only calling you that because you wont come down South and do my plastering) We know you can do it.

[Newlands Ian]

1 hour ago, Big Jimbo said:

That's a joke. You tape everything up in order to get the best air test result you can. When you are living in the house they wont be taped up will they ? So in the bloody real world untape your bathroom extractor vents etc, and tell the twat to test the house like that. 

The problem is that the air test guys seems to be very "by the book" and the book says tape up all the vents. It's not real world but it's the way they do it.

[Newlands Ian]

11 minutes ago, nod said:

I haven’t read the answers 

But should you be getting your test results down The higher the score the worse it is 4-5 is really poor 

Most of the homes I work on are looking a two

My issue is that building control have said either I show them an air test of 5.0 or worse, or I need to change all the fans to dmev and submit an amendment to building warrant. I'm thinking the best and most cost effective short term solution is to alter the building fabric in some way to get the result I need.

[Newlands Ian]

1 hour ago, ProDave said:

Like others this is counter intuitive.  4 is a poor air test, I would be very disappointed and wanting to improve it.  but if you want a cold draughty inefficient house that is your call.

 

Get the air tester back, and instruct him NOT to tape up the vents, or peel off just enough of the tape he has put on to get the air test just over 5 and job done.

 

If I was the BCO I would not accept you making the air test worse.  I would expect you to be making the property better.  I think all it needs is the fans swapping for the sort that have a low speed constant trickle running.  Replacing those is likely going to cost less than another air test, so just do it.

Four dmev fans, plus the cost of fitting them and then cost of an amendment to building warrant to will be significantly more than another air test.  

 

I've been living in the house since Christmas and it's super warm, definitely not draughty.

[Kelvin]

11 minutes ago, Newlands Ian said:

The problem is that the air test guys seems to be very "by the book" and the book says tape up all the vents. It's not real world but it's the way they do it.

It is the he real World as far as airtightness testing is concerned. They are testing your build fabric for leaks which you can’t control other than sealing them up. 

[Kelvin]

5 minutes ago, Newlands Ian said:

Four dmev fans, plus the cost of fitting them and then cost of an amendment to building warrant to will be significantly more than another air test.  

 

I've been living in the house since Christmas and it's super warm, definitely not draughty.

It’s warm just like any house can be warm. The issue is more your heat is escaping the building through the leaks so you need more heat input to keep it warm. 

[Big Jimbo]

As previously said by others then. crack open the window latches on a few windows. That will make your house more leaky. I would have had the bloke up against the wall outside. Covering your vents for an airtest is fine, but in the real world they will not be airtight. They will add to you uncontrolled ventilation when uncovered and not in use. You obviously got a right One for your airtest. Ask him to explain in writing why nothing has been taken into account for the fact that your extractor vent have been made airtight for your test, but wont be airtight when uncovered and will add to you uncontrolled air leakage. Was he 16 and just out of school ?

[Big Jimbo]

As you might have guessed i detest people who draw pretty pictures of things that can't be built in the real world. people who do tests without using a bit of common sense. people who work in Council planning Depts, and people who busy body on Parish Councils. All the rest i like.

[ToughButterCup]

1 minute ago, Big Jimbo said:

.... and people who busy body on Parish Councils. All the rest i like.

 

I'm wun o' they mate : bizzy bodies ... I pick up litter with my 88 year old nearish neighbour every now and then.  Ex-builder.

Full of words for the wise. Looks at our left-over Durisol, shakes his head. He's got a point.

 

[Newlands Ian]

2 minutes ago, Big Jimbo said:

As you might have guessed i detest people who draw pretty pictures of things that can't be built in the real world. people who do tests without using a bit of common sense. people who work in Council planning Depts, and people who busy body on Parish Councils. All the rest i like.

Ha! It does feel like a lot of people just want to say 'no' as a default stance. Having said that, I suppose the lesson here is that I should have planned better. I should researched the regs before submitting the first test (even though tester advised it would be fine!). Also, not sure why my architect didn't specify the dmev fans or highlight that it might be an issue. Anyway, that's water under the bridge and I just need to fix it now.