Blower Door Test Vs Thermal Imaging?

selfbuildache

Hi all,
We've just got cellulose insulation pumped into our (we hope!) air tight, new build, house. We're aiming for low Uvalues, high BER etc.
The guy who did the insulation is telling us we only need the Blow Door test at this stage but our BER assessor is saying we won't need the Blow Door test and only need thermal imaging done.
We're ready to get going with slabbing etc. but don't want to move ahead without knowing everything is as it should be before it's too late to change but which of these 2 should we be doing - or should we be doing both??
Both these guys (insulation and BER) are highly recommended and we 'trust' and like both so we're nervous...
Any advice appreciated as this board has got us through sticky parts of this build up to now...

MarcusFenix

Thermal imaging used in the right hands should tell you all you need to know.

MicktheMan

selfbuildache wrote: »

We're ready to get going with slabbing etc. but don't want to move ahead without knowing everything is as it should be before it's too late to change

You are absolutely right to test for airtightness at this stage when you can easily and economically repair any weaknesses found. TI not strictly necessary for airtightness but can aid / speed-up the diagnosis process (in the right experienced hands of course) not to mention uncovering missing insulation. If the conditions are right, TI can be very helpful in tracing the origin of air leaks when slabbing is already done.

sydthebeat

AN AIR TIGHTNESS TEST IS A LEGAL REQUIREMENT BEFORE YOU OCCUPY THE BUILDING. iTS VERY HELPFUL TO HAVE ONE DONE AT THIS STAGE TO IDENTIFY MAJOR LEAKS BEFORE THE HOUSE IS FINISHED, THEN DO THE FINAL ONE BEFORE OCCUPATION.

(oops only seeing caps now )

the thermal imaging is much more responsive when theres a high temperature difference between internal and external, i assume your heating system is not up and running yet!!

the TI may be able to identify areas of cold bridging, it will be up to you or your designer to decide on the best way to resolve these issues.

imitation

Personally I would go for the blower test as well, I'm sure TI would pick out small leaks, but would it pick up larger systematic flaw ?. I think it would also be very useful to have an exact measure of your air leakage rate

selfbuildache

Thanks for the responses... but I'm still a bit confused. I think the answers are split between the TI and Blower Door?

Sydthebeat - no, there's no heating yet.
So, can the TI detect air leakage??

We're more nervous about our windows/doors not performing (Vs insulation) as promised as we had some really basic problems with them early on and the company had to come out and replace some of them, so I'm thinking the Blower Door Test might show up faults here better than TI?

holdfast

TI can t find air leakage, its detects temp difference. For it t work it delta T of 10 deg c to work, so if your heating is not on or working it will be hard to justify it.

Your assessor I would say is not up to much, does he shout yeha often. There are to many assessor without a base knowledge of regs or qualifications going round. They have done a three day course and now they are guru`s. get the AT test done and if your worried about insulation problems heat the house and test with TI.

sydthebeat

as holdfast states, thermal imaging does not detect air leakage, a blower door test and report will.

a thermal imaging report will show where heat is being lost through the fabric.

both test are very useful, and very different

selfbuildache

Holdfast + Syd, thanks again. I knew that about the TI - I'm just getting confused in panic!

It sounds like the Blower needs to be done at this stage really. I'm now nervous about our assessor and his advice!

I have a vague recollection of the head honcho of the cellulose promising an independent test when I followed him up with questions about settling with cellulose... it was quite a while back so I need to look up my notes. Maybe this way I can get both tests done! (Presuming that it IS a TI that's needed for testing the insulation...)

Lantus

An air pressure test at this stage would be fantastic because you can measure the facade and give it a value which can be measured against wht you specified. If it fails then the contractor can begin remedial work at a stage when he's still able too.

I would consider this an essential tool.

TI is really interesting but less 'quantative'. It cannot measure the air tightness at all. All it can do is show areas that are colder or wamer. If you have a fully sealed and heated building then you could identify cold bridges and possible areas where there is air leakage. However, without the air pressure test you wouldn't know whether you had a problem and needed to do remedial works or whether it was just a bit cool looking on the camera would you?

selfbuildache

Just a follow-up to the above post.
We got BOTH the Blower and the TI done. (Assessor was doing the blower door anyway but thought we should get TI done too - so at least I'm confident in him again! And he did us a good price on both.)
Got a great result too (0.48 if I'm writing it correctly) on the blower door test but both the TI and blower showed up cold bridges and leakages of sorts in the doors and windows which I'm now able to follow up with the company (that'll probably be another posting!)
Many thanks!