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Urban Rustic: Installing an Airtight Attic Hatch

The right product and careful installation preserve the air barrier and save energy

Posted on Jun 6 2018 by Eric Whetzel

Editor's note: This post is one of a series by Eric Whetzel about the design and construction of his house in Palatine, Illinois, a suburb of Chicago. A list of Eric's previous posts appears below. For more details, see Eric's blog, .

Our attic is designed mainly to hold our blown-in insulation (a future post will go over the details), as opposed to a place for running HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. equipment, conduit for electric, or as a potential area for carving out additional storage space.

Nevertheless, in order to have access to our attic for future maintenance or repairs, I installed a well-insulated attic hatch in a closet ceiling in our master bedroom.

In keeping with Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. and Pretty Good House principles, I tried to protect the thermal envelope, even in this relatively small area, and avoid what can be a notorious point of air leakage and heat loss (i.e., the stack effectAlso referred to as the chimney effect, this is one of three primary forces that drives air leakage in buildings. When warm air is in a column (such as a building), its buoyancy pulls colder air in low in buildings as the buoyant air exerts pressure to escape out the top. The pressure of stack effect is proportional to the height of the column of air and the temperature difference between the air in the column and ambient air. Stack effect is much stronger in cold climates during the heating season than in hot climates during the cooling season.).

There were two main products I considered using for this. One was the (R-50 / without ladder). The company also has a product called the Battic Stair Cover that allows for a built-in ladder for easier access to the attic (you won’t need to drag your ladder in from the garage) while also maintaining a high R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. .

The other product I considered using was from ESS Energy Products, the . We ended up going with the Battic Door hatch, which I purchased through the Home Depot website (this saved me a trip to the store since it was delivered to site).

An Austrian company, Wippro, makes a Passive House certified pull-down hatch and ladder called the Klimatec 160. It had been carried by 475 High Performance Building Supply but is no longer available.

Another possibility is an attic ladder sold by .

I thought the Battic hatch was the better choice since it seemed like it would be a little sturdier and more durable. To be honest, once the product arrived and I unpacked it, I realized it was something I, or anyone with basic carpentry skills, could put together themselves (assuming you have the time).

Installation

Following the directions, I cut an "X" in the Intello on the ceiling between two roof trusses (and our 2x6 service core below each truss) in order to establish the opening for the Battic frame.

I folded the cut edges of Intello up into the attic for the two long sides of the Battic frame. For the two shorter sides of the Battic frame it was easier for air sealing to push the Intello down into the living area. Then I screwed the Battic frame into place.

Once it was in place, I used a mix of Contega HF Sealant and Tescon Vana tape to seal the Intello to the Battic frame (see Images #2 and #3 below).

Once the outside perimeter of the Battic frame had been sealed to the Intello, the only place left for air infiltration was where the lid would meet the frame of the Battic hatch once it was installed (more on this later when I discuss my first blower door test).

There was some additional framing required, but it was just a couple of headers between the roof trusses to add structural integrity to the two shorter sides of the Battic frame.

Since we were using a significant amount of blown-in insulation in the attic, it made it necessary to build up the sides of the Battic frame in the attic with some OSB to get the top of the opening above where the insulation would eventually stop (see Image #4 below).

After a couple of practice attempts, it quickly became apparent that raising and removing the lid once in place, and fighting to get it back down into the master bedroom closet, wasn’t worth the trouble. Instead, I built a small bench in the attic next to the Battic frame so I could push the lid up above the level of blown-in insulation (see Image #5 below). This way, the lid was safely stowed while I dealt with any issue in the attic.

It’s very easy to grab the lid off the bench and bring it back down into position while slowly walking down the ladder in the master bedroom closet to make the final connection/seal.

Consider access from a gable end

Although the installation process was fairly straightforward and headache-free for the Battic product, if I had it to do over, I think I would locate the attic access point on the exterior of the structure — for example, on the gable end of the house in the backyard.

Putting the access point above the air barrierBuilding assembly components that work as a system to restrict air flow through the building envelope. Air barriers may or may not act as a vapor barrier. The air barrier can be on the exterior, the interior of the assembly, or both. would make meticulously air sealing the entry point for the attic less important, so keeping water out of the attic would be the main goal. An additional plywood buck would’ve been necessary, replicating what I did for our windows and doors (more on this later), but I think it still would’ve been the better option overall.

Putting the attic access on the exterior of the house also would mean avoiding an ugly hole somewhere in our drywalled ceiling. No matter how nicely trimmed out, these attic access points on the interior of a home never look right to me. We’ve tried to hide ours as much as possible by sticking it in our master bedroom closet, which has worked out well, but not having one at all on the interior of the house would make for a cleaner, better solution in my opinion.

If granted a do-over, I would also add a catwalk in the attic, through the roof trusses, in order to make getting to any point in the attic much easier to navigate, when necessary in the future, while also avoiding disturbing the blown-in insulation too much.


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  1. Eric Whetzel

1.
Jun 6, 2018 2:26 PM ET

Great Work
by John Prospect

It looks like you did the best you could, when going up through a ceiling. We are trying to plan to go through a gable-end but, with a dutch gable roof, the available area will be tight. There is a minimum access hatch area required by code.

Has anyone tried to go up under a wide overhang and then through the gap made by a raised heel truss? My sketches don't seem to make this work, but it seems possible in principle if the heel is high enough.

Exterior access definitely seems to be the best option, where possible.


2.
Jun 6, 2018 9:33 PM ET

John
by Malcolm Taylor

I'm not sure the raised-heel helps much, as it will be covered by insulation leaving you about the same amount of free area as with conventional trusses. If the floor plan has a recess in the exterior walls that the trusses extend over you might fit one in. it depends on the roof pitch, but you are probably looking at a six foot (or more) overhang to make it work.

I agree - if you are going to put the hatch in the ceiling Eric has done a great job.


3.
Jun 7, 2018 5:48 AM ET

great job
by David Goodyear

Looks like a great air sealing job. Eric, keep and eye on this one when you do your blower door test. It will tell you whether or not your hatch is nice and tight. I made my own hatch. Did the blower door test and thermal imaging. There is a cool rim around the hatch way but just from thermal loss and there was no air leakage. The cool rim wasn't that surprising. its a couple of degrees cooler than room temperature but not cool enough to cause any condensation.

A catwalk is definitely a welcome addition to the attic from an acccessibility point of view. I've been up there several times now and without it would make it impossible to move around. My insulator was also quite happy. He spent most of his time on the catwalk while blowing insulation into the attic space.

I tossed around the idea of an exterior access to the attic. But gave up for several reasons including the fact that it would be hard to get a good weather tight seal at my location (high wind, lots of rain) and accessing from the gable end on a 2 storey would make attic inspection impossible for me...I'm afraid of heights!


4.
Jun 8, 2018 4:49 AM ET

Thanks Malcolm
by John Prospect

Malcolm, your point about the insulation is a good one. I contemplated having a spot where the insulation was a bit thinner, since it wouldn't be as big a compromise as a ceiling hatch. However, the heel would still have needed to be very tall (and overhang wide) or the roof pitch steep, as you say.

David, I happen to like the "Dutch" gable (or "Japanese" gable) since it provides better overhang on the end walls. The other upside is that it gives a place to stand when opening the gable hatch. I admit that heights don't bother me much, though. This is a nice article showing a dutch hip roof, although for a very different climate application:

My only concern with this design is nesting birds in the small gable ends - a location that is harder to clean.

I also like catwalks. I really wished I had one when I had to run wire for a security system through a large attic a few years ago and had to balance on truss bottom chords buried beneath blown-in fibreglass insulation.


5.
Jun 8, 2018 11:25 AM ET

Edited Jun 8, 2018 11:26 AM ET.

David
by Malcolm Taylor

Whenever I can I locate the attic access on a gable end. I had never thought of the location discouraging inspections, but of course you are right. Even if you aren't worried about heights, dragging out a ladder and unscrewing the door makes the job less appealing than poking your head through a hatch - although if the hatch were situated in my wife's closet, it would involve a fair amount of work to get to.


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