Pre-Drywall Blower Door Testing

[Ted S.]

For you guys that build homes for a living, I need to find a way to do a blower door test prior to drywall.

The homes are typical production homes or semi-customs with the insulation on the attic floor.

Let's just say I have all the details figured out for the walls and the floor, after all, we have sheathings and foundation walls there so I could technical use products like Zip Wall and can foam gaps to get the floor and walls tight.

But how do I do the attic floor? Lets just say the framer boards the second floor ceiling and creates and air barrier, the question is at that point is do you think it is possible to rough the HVAC, plumbing and electrical with this drywall in place? I would assume you would need retrofit cans, etc and the trades would probably beat it up.

What do I have to do to get this to work? I don't want to insulate up over the rafters with foam, I am working in a market where that is not cost feasible.

[David Meiland]

Re: Pre-Drywall Blower Door Testing

What about having the rockers rock the lid, then test, then have the insulators come in and the rockers finish after that. One small out-of-sequence bit of work...

[BeachBoy]

Re: Pre-Drywall Blower Door Testing

What about having the rockers rock the lid, then test, then have the insulators come in and the rockers finish after that. One small out-of-sequence bit of work...

Just be sure the inspector is ok with that sequence.

Probably won't work if you are planning on doing the Quality Insulation Installation (QII) procedure as you won't be able to get to some areas to put the insulation in right, nor for the HERS rater to check it. On the other hand, you could insulate the attic, then drywall the ceiling, as long as the insulation contractor, drywall contractor, rater, and inspector don't mind the extra site visits.

Or you should be able to staple plastic sheeting up to the ceiling temporarily.

[Dancing Dan]

Re: Pre-Drywall Blower Door Testing

Would there be access to the attic from the exterior? Or a hatch?

And don't put cans into your insulation - no wonder your dog ran away.

[Ted S.]

Re: Pre-Drywall Blower Door Testing

Good call on the inspector. I know in retail work it is not uncommon to rock one side of the wall prior to electrical sign-offs.

As for the Rater inspection, not a problem, that's how we do it now. The ceiling gets blown in at the end.

Dan, access is from a hatch, basically a very mainstream construction detail. Boring I know.

David, I think you provide a very realistic approach. One of the ideas I have considered is boarding the entire underside of the ceiling framing with polyiso. That would be done after mechanical and electrical rough by the insulator who would be also performing blower door assisted air sealing. That more of less keeps the sequence, but the cost of polyiso...fixtures and boxes would also need to be set lower, not so much a big deal.

[David Meiland]

Re: Pre-Drywall Blower Door Testing

You get some added value from the polyiso, so maybe not a bad way to go. One way or another you have to seal off the attic.

What are you going to do about vaults?

[daigie]

Re: Pre-Drywall Blower Door Testing

Hi Ted,
I do not know of any retrofit recessed lighting that can be put up to insulation and air sealed. I am a remodeler in Mass so I haven't had to deal with the blower door test yet with the new energy code. w\Why do you want to do it before all the roughs? Do you feel you have a better chance of passing before all the penetrations are in the attic? Just curious, what town is this in?

Steve

[Ted S.]

Re: Pre-Drywall Blower Door Testing

What are you going to do about vaults?

Not sure yet.

Technically, net and blow is the way to do that, however, the drywall would need to be the air barrier if it is a vented cathedral. So that means it would need to be blown, inspected, then boarded to get to where we are at with the "pre-drywall blower door test". So like many conditions, there are solutions, but there are challenges with sequence which needs to be resolved.

[Ted S.]

Re: Pre-Drywall Blower Door Testing

Hi Ted,
I do not know of any retrofit recessed lighting that can be put up to insulation and air sealed. I am a remodeler in Mass so I haven't had to deal with the blower door test yet with the new energy code. w\Why do you want to do it before all the roughs? Do you feel you have a better chance of passing before all the penetrations are in the attic? Just curious, what town is this in?

Steve

So, good info, I know there will be a challenge with the cans.

I would like to do this pre-drywall blower door test after the mechanical roughs to dial the building into code. I would assume the blower door would be run by the insulator, so just prior to the drywall makes sense. This is the time when the insulators mobilize, so they would test, air-seal, and insulate all at one time.

I received a call from the EPA today, they are reaching out to Raters in Massachusetts. I was both flattered and shocked by the call. Massachusetts is slated to adopt IECC 2012 on July 1st of 2013. IECC 2012 requires air changes of not more than 3 under blower door fan pressure.

I am convinced, having tested many homes, a pre-drywall blower door test will be a necessity to meet these numbers.

[David Meiland]

Re: Pre-Drywall Blower Door Testing

I think the 3ACH50 target is going to choke a lot of people. Window leakage is going to start to come into play, along with other stuff that isn't really the builder's fault. The last two code-required tests I've done have failed, which doesn't really carry a penalty here, but is still a little bit of a diplomatic challenge. What happens in MA when you fail the test?

[Ted S.]

Re: Pre-Drywall Blower Door Testing

If I look at a file of 100 houses, less than 5% make the 3ACH50. The ones that did make it, were typically large with finished basements. Because, well you know, large houses are energy efficient, not small houses...

Anyway, I have no idea how this is going to happen. Code right not is 7 ACH50. If you can't make that, you shouldn't be building houses.

I have had them fail (very few) and was able to fix them. One was a dislocated return air plenum. Another we fixed the missing weatherstripping at the basement door. You could get them fixed because the code is so lax. But, 3 ACH50 is far from lax, especially if it a 2000 SF run of the mill colonial. There will be no fixing that when it comes in at 5 ACH50.

You are right about the windows, something's gotta happen there. People will choke too, because the mechanical ventilation code is lacking.

But regardless, the pre-drywall blower door test has to be developed if the code is going to be met. There's just no way.

[David Meiland]

Re: Pre-Drywall Blower Door Testing

Ted, is passing the test mandatory there? It isn't here...

[Ted S.]

Re: Pre-Drywall Blower Door Testing

Yes, mandatory here. Why is it not there? Is it in some type of concurrency period?

[David Meiland]

Re: Pre-Drywall Blower Door Testing

I think the state code folks knew that a lot of builders would fail, at least on their first house(s) tested, and what are they gonna do, make you tear out the drywall and strip off the siding to air seal? That's just not palatable, so they are easing people into it with a test you're allowed to fail as long as you attempt some remedial work after failing. So far I'd say it's about 50/50 on new construction passing the standard, which is about 5ACH50.

[Ted S.]

Re: Pre-Drywall Blower Door Testing

That's kind of like duct testing. It's typically done at the end, but if it fails, what do you do? We have had a number of failed systems, but were able to go back and find the problems. It's always been marginal however, finding it has some element of luck.

So now we test at the rough until we are confident with the sub. However, duct testing will also get harder, the testing to outdoors will go away. Total leakage will only be allowed. Sorry if this jargon gets confusing to some here.

The point is, techniques developed in weatherization work will need to be practiced in new construction if these new codes are in fact adopted and enforced as they are becoming very stringent. I would assume WA will soon mandate the code, the non-passing provision will eventually go away.

A couple things I see is one, this pre-drywall blower door test, two, insulators will need to really learn air sealing, three, building configurations will need to change. We will see more conditioned basements to (among other things) get the ductwork inside the envelope and increase the volume of the house for the purposes of testing. Bigger houses do better than smaller houses.

Getting back to the question. Perhaps my intent to achieve this with a slight change in construction sequence and not much more in materials by boarding the ceiling out of sequence ain't going to make it in the end. Maybe costs are inevitable.

Maybe the right way to go is to board the ceiling with rigid insulation after the rough of mechanical and electrical, tie this air barrier into the walls and floors and test. This would give a good continuous insulation to the ceiling assembly as well. The question is now cost.

How much would it cost to do that? It is a pure add to the project. How many man hours would it take to board a 1200 SF ceiling? The terminations would need to be sealed to the top plates, etc.

If I figure $1 psf for material, plus one man day billed at $75 per hr that would be a $1800 add to the project. All that gets me is an extra continuous +/- R7, and the ability to run my test. It think it's hard sell in the production market. Especially because with an open blow attic you can get to R49 very easily with little labor. And if you do board the ceiling with rigid, you still have to open blow anyway.

Kind of thinking out loud here. I still think the drywall is the way to go, and I think it should be done at framing. The reason why is because there are also many details such as behind the tubs, kneewalls, soffits, etc which all need a similar treatment (rigid air barrier), so this all needs to be done at the same time.