Airtightness

creedp

I have expended a great deal of time and energy getting my builder to appreciate the importance of airtightness, although I failed in my efforts to have a hollowcore membrane installed! All the time he has treated these requests with at best scepticism and at worst downright hostility.

Becasue he got great pleasure recently telling me that another house he has built has just had its airthigtness test and got a result of 3.77. He was at pains to remind me that no specific airtightness measures were taken by him for this build, e.g. windows/doors were no taped, no membranes on upstair ceilings, no sealing of holes in the external walls, etc. He more or less gloated that I was a gob****e for having spent so much time, money and effort with airtightness measures when with nothing I could have achieved 3.77.

Is this normal or in time when plaster/skim dries/cracks will the lack of membranes and tapes result in a significant deterioration in the airtightness quality of that build? If so doesn't it once again call into Q the usefullness of the BER Certs as a indicator of the heating requirements of a house with houses obtaining good results initially which cannot be sustained over time.

Any views?

sydthebeat

As him for the specification he built to to achieve a 3.77 air tightness result.

have you seen the result verified?

I cannot fathom how a house that didnt seal external holes could achieve anywhere near 3.77.

on top of this, if he treats your orders with so much disdain, do you really think hes going to pay much attention to the actual installation????

creedp

sydthebeat wrote: »

As him for the specification he built to to achieve a 3.77 air tightness result.

have you seen the result verified?

I cannot fathom how a house that didnt seal external holes could achieve anywhere near 3.77.

on top of this, if he treats your orders with so much disdain, do you really think hes going to pay much attention to the actual installation????

No I haven't seen the result but given that he didn't even know that 3.77 was a good result and asked me what did I think of it makes me think he isn't faking it!! I'll ask him for a copy and see what he says.

Bty please stop making me even less confident about the quality of the job he has done for me. I have been reduced to a quivering mess as a result of this build and I don't need someone telling me it could be worse that I had persuaded myself it is:D

Juantorena

creedp wrote: »

I have expended a great deal of time and energy getting my builder to appreciate the importance of airtightness, although I failed in my efforts to have a hollowcore membrane installed! All the time he has treated these requests with at best scepticism and at worst downright hostility.

Becasue he got great pleasure recently telling me that another house he has built has just had its airthigtness test and got a result of 3.77. He was at pains to remind me that no specific airtightness measures were taken by him for this build, e.g. windows/doors were no taped, no membranes on upstair ceilings, no sealing of holes in the external walls, etc. He more or less gloated that I was a gob****e for having spent so much time, money and effort with airtightness measures when with nothing I could have achieved 3.77.

Is this normal or in time when plaster/skim dries/cracks will the lack of membranes and tapes result in a significant deterioration in the airtightness quality of that build? If so doesn't it once again call into Q the usefullness of the BER Certs as a indicator of the heating requirements of a house with houses obtaining good results initially which cannot be sustained over time.

Any views?

Sounds like a builder who won't be in business too much longer. The quality of construction/detailing can now be measured and he hasn't copped on to this.

Perhaps we got particularly lucky but I too impressed on our guy the need for top-notch airtightness. Any of the trades that wanted to put a hole through a (SIP) wall had to run it by me first. Was there an alternative to the hole? If not minimise it, and the number of them, and seal it/them properly. He - and his trades - took this on-board really well....it became an on-going joke in fact.

And we were rewarded with a good result at the end.

Juantorena

creedp wrote: »

No I haven't seen the result but given that he didn't even know that 3.77 was a good result and asked me what did I think of it makes me think he isn't faking it!! I'll ask him for a copy and see what he says.

Bty please stop making me even less confident about the quality of the job he has done for me. I have been reduced to a quivering mess as a result of this build and I don't need someone telling me it could be worse that I had persuaded myself it is:D

Oooops, sorry.....

sydthebeat

creedp wrote: »

Bty please stop making me even less confident about the quality of the job he has done for me. I have been reduced to a quivering mess as a result of this build and I don't need someone telling me it could be worse that I had persuaded myself it is:D

not my intention at all.

I know a few well established good builders who dismiss airtightness tapes etc, but they are confident enough to offer their own solution to the issue.

what is his specification on a jamb? how does he intend to ensure its air tightness?

sas

sydthebeat wrote: »

I know a few well established good builders who dismiss airtightness tapes etc, but they are confident enough to offer their own solution to the issue.

What would their solution be without using the words silicone,caulking or mastic?

creedp

sydthebeat wrote: »

not my intention at all.

I know a few well established good builders who dismiss airtightness tapes etc, but they are confident enough to offer their own solution to the issue.

what is his specification on a jamb? how does he intend to ensure its air tightness?

I'm only joking .. but seriously I am a quivering mess after this build. I take you point re: offerring alternative solutions to achieve airtigtness for a specific aspect of the build. However, I can assure you he doesn't offer alternative solutions other than I've been building houses .......... I'm tired now and reading about the new Part L Regs coming down the tracks makes me glad that I'm not starting all over again with my incumbent builder

The only person at fault here is me and my selection process.

Gulliver

We had such problems with our builder that we decided the only way that it was going to get done correctly was to do it ourselves. He thought it was hilarious the amount of effort we put into it.

We installed the membrane, taped the windows with fleece, used bond over that to provide key for plasterer at the reveals and wallplates. We used the sealant on any holes/joints on the walls and taped any protrusions through the membrane (lights/hrv).

Moral of the story, local builders don't care about "all this unnecessary crap architects come out with" that was "never needed before". I wish I'd got someone more cooperative.

gears

sas wrote: »

What would their solution be without using the words silicone,caulking or mastic?

I think you forgot one more, the old staple of EXPANDING FOAM.....

sydthebeat

gears wrote: »

I think you forgot one more, the old staple of EXPANDING FOAM.....

yep, mentioned along side silicone.....

creedp

gears wrote: »

I think you forgot one more, the old staple of EXPANDING FOAM.....

No self respecting builder would go anywhere without a can of expanding foam hanging from his belt. If you can't fix it ..foam it:)

Poor Uncle Tom

...or the good old favourite "tin of stuff" which used to do the rounds in the 80's.

"How will I fix that?" was always followed by "use the tin of stuff"....:D

MicktheMan

creedp wrote: »

Becasue he got great pleasure recently telling me that another house he has built has just had its airthigtness test and got a result of 3.77.

Any views?

Does your builder consider this result good? I wouldn't, especially on a once off build (even if no specific AT measures were taken).

sinnerboy

creedp wrote: »

I have expended a great deal of time and energy getting my builder to appreciate the importance of airtightness, although I failed in my efforts to have a hollowcore membrane installed! All the time he has treated these requests with at best scepticism and at worst downright hostility.

Have you signed a contract with the builder ?

Do you not have a contract administrator ?

Or are you ( with no dis respect intended now at all ) - someone who did not realize that it is not wise to proceed on the basis that "builders know what they are doing" and therefore did not wish to "waste money" on professional fees during construction ?

creedp

sinnerboy wrote: »

Have you signed a contract with the builder ?

Do you not have a contract administrator ?

Or are you ( with no dis respect intended now at all ) - someone who did not realize that it is not wise to proceed on the basis that "builders know what they are doing" and therefore did not wish to "waste money" on professional fees during construction ?

Yes the 1st Q and No to 2nd

On third I would prefer to say that I am someone who wasn't aware I needed to hire an architect/contract administrator. Of all the people I know who build a house only one used an architect and that was to design a 'special' house. Bty the architect did not supervise the house build!nIn addition, I know a couple of builds from the last 4 years that did not even put insulation under the floor, screed poured directly onto subfloor. Needless to say these were signed off by professioanl engineers.

I think the building scene has moved on dramitically in recent years but peoples perceptions of the build process and especially the perceptions of many of the building professionals has not caught up. I have raised some of the well accepted norms on this forum, e.g. counterbattening roofs, roof ventilation spaces, 150mm 225mm cavities, 200mm insulation under the floor, airtightness - wrapping slabs, etc with people who are building/have built and building professionals only to be considered crazy.


In addition I think that the building professionals to whom you prefer need to make themselves more indispensible to the building process. For instance prior to commencing my build I received a large volume of material through post from all sorts of building contractors/professioanls but not one from an architect. Untill people are educated on the merits of employing this category they will continue to ignore them.

So although I accept your point re: I am someone who wouldn't waste money empoying professionals I would like to say that if the same professionals better advertised thier expertise this might not have happenend. I think if cuts both ways here.

sinnerboy

creedp wrote: »

I think if cuts both ways here.

Point taken - again I wasn't "having a go at you".

creedp

MicktheMan wrote: »

Does your builder consider this result good? I wouldn't, especially on a once off build (even if no specific AT measures were taken).

Well Mick I would have thought that given the Regs figure of 10 ach and the revised 2010 Regs reducing this to 7 ach a figure of 3.77 ach without employing any specific airtightness measures is not a bad result. I'm not saying a better one should be achieved but its hardly a bad one.

A further point here is why are the Regs so far into cloud cuckoo land here. If as Mick the Man say that a figure of 3.77 ach is a bad result then why are the revised Regs at 7 ach and yet the acceptable building details go on about airtightness tapes/membranes not to mention the cold bridging enigma!!

At least the new U values are being reduced somewhat and are not too far above std/non passive results but the airtighness measure seems to be off the wall altogether

creedp

sinnerboy wrote: »

Point taken - again I wasn't "having a go at you".

Absolutely accept that and I wasn't trying to infer this in my reply. I assure you I accept the point you make and wish I had engaged a professional. That's my point had I known the importance of employing someone in this capacity I would have done so. If I had I would be in a lot better place now

sinnerboy

Consider speaking to a solicitor to review the signed contract. It may not be too late to appoint and a Contract Administrator ( Architect / AT / Engineer ) who would have certain important authorities - inspections / quality / payments.

It's amazing how effective squeezing payments can be on improving site quality. Once the contractor gets the message that defective works affect payment things change.

But for the reasons you expressed so well , I would pick my CA with great care.

MicktheMan

creedp wrote: »

Well Mick I would have thought that given the Regs figure of 10 ach and the revised 2010 Regs reducing this to 7 ach a figure of 3.77 ach without employing any specific airtightness measures is not a bad result. I'm not saying a better one should be achieved but its hardly a bad one.

A further point here is why are the Regs so far into cloud cuckoo land here. If as Mick the Man say that a figure of 3.77 ach is a bad result then why are the revised Regs at 7 ach and yet the acceptable building details go on about airtightness tapes/membranes not to mention the cold bridging enigma!!

At least the new U values are being reduced somewhat and are not too far above std/non passive results but the airtighness measure seems to be off the wall altogether

Agree, while elemental u values have been reduced very agressively in successive part L revisions, air tightness targets were newly introduced in the 2008 at 10 and will shorly be 7. In my experience as a tester, the 10 m3/hr/m2 rarely if ever is breached even in the worst built houses and tbh 7m3/hr/m2 is still a very very badly built house.
It seems to me that the powers that be either do not understand the impact of air tightness has on the energy performance of a building or they are afraid that specifying a tight airtightness regime will introduce the (imo real) risk of excessive moisture buildup within the dwelling leading to a host of other problems down the road.

moy83

Gulliver wrote: »

We had such problems with our builder that we decided the only way that it was going to get done correctly was to do it ourselves. He thought it was hilarious the amount of effort we put into it.

We installed the membrane, taped the windows with fleece, used bond over that to provide key for plasterer at the reveals and wallplates. We used the sealant on any holes/joints on the walls and taped any protrusions through the membrane (lights/hrv).

Moral of the story, local builders don't care about "all this unnecessary crap architects come out with" that was "never needed before". I wish I'd got someone more cooperative.

What type of bond did you use over the tape at the windows and doors ? Does unibond do the trick or did you put mesh over it ? is there any of that tape that has some kind grip (maybe like sticky scrim ) that you could plaster straight over without using mesh first

Gulliver

I used gypsum bonding coat. When it was going off, I scored the face to provide a key for the plaster. There was plenty of depth of bonding to enable me to do this without coming close to the tape underneath. The plasterer then gives it a wash of unibond before he plasters it.

You could use mesh over the fleece tape and hopefully 1) the mesh won't penetrate the tape and 2) the plaster will permeate the mesh properly to the tape to make the seal.

There is another fleece product which is over twice as dear that has a plastic mesh built in. The problem was that you need to put a thin skim of plaster underneath the mesh/tape and then press it down and give it another coat. Our plasterer "didn't want to be messing with all this lifting tape business" so we went with the bond idea.

There is also stuff like Siga tape, but they all seem to be for sealing a window to a timber frame.

AMG86

You will not get 3.77 without paying attention to joints etc. You could arrange to get a preliminary test done. This would be preferable to waiting until slabbing, plastering is completed. I would look to see the actual result in the first house you referred to. How about approaching his client directly. Of course you have some trumps in your hand! You should not part with your money until you are happy at the various stages