Blog Post

Access Ceilings: Replace Fixtures Without Cutting Into Drywall and Insulation

Paying attention to the various layers in a building envelope is critically important for ensuring air tightness and moisture management—and can be attractive, too.

Ducting for our HRV, electrical wiring, recessed lights, and plumbing fit into this access ceiling. Click to enlarge.Photo Credit: Alex Wilson


Air leakage and the integrity of insulation in energy-efficient houses is a huge issue—more significant than many people realize. We can have the best of intentions with lots of insulation, but if we leave it leaky or include details that compromise the integrity of that insulation the home’s energy performance can be severely affected.

Take recessed ceiling lights, for example. From a design standpoint, they’re great, since the light source is roughly flush with the ceiling and all of the mechanism is hidden in the ceiling above (in recessed cans).

In a house with an unheated attic (insulation in the attic floor—which is the ceiling of the floor below) or with an insulated, sloped cathedral ceiling (roof), if we install recessed cans into that ceiling we’ve created a significant pathway for air flow and compromised the insulation. This is the case even with recessed lights rated for “insulation contact,” those IC-rated fixtures are far better than older models that required a significant air space surrounding the lights, but they still result in significant air leakage.

Creating an access ceiling that looks good

One of the solutions to this problem is to create an access ceiling (or drop ceiling) below the air barrier of the insulated ceiling. Recessed lights can be installed in such a ceiling. Lest images of acoustic ceiling panels in commercial office buildings come to mind, rest assured that access ceilings can be done in a very attractive way.


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Tedd Benson has been doing this for years with Bensonwood homes using his OpenBuilt platform, and our designer-builder, Eli Gould, has his own access ceiling detail that he’s using in our Dummerston home. He’s using this layered, access ceiling detail on both the first floor ceiling (which is not insulated) and for a horizontal section of the second floor ceiling, spanning between the insulated sloped and insulated rafters.

Eli builds roughly square panels out of painted 1x10 shiplap boards—three boards per panel. These drop in and can easily be lifted up to access the recessed lights. On the first-floor ceiling, these panels fit into tracks formed by added beams that are both attractive and strengthen the ceiling joists.

Recessed lights are mounted in the access ceiling panels.Photo Credit: Alex Wilson


Along with installing recessed lights in these ceiling panels, registers for our Zehnder heat-recovery ventilator are mounted there as well. The ceiling cavity above the panels provides a space to run wiring, ventilation ducts, and—in some locations—plumbing. Future modifications to any of this can be made very easily.

Air tightness also depends on layers in walls

Our superinsulated wall system has seven layers: from the interior there is the layer of gypsum board; the wall cavity with fiber insulation; a taped and air-sealed sheathing layer (using Huber’s Zip sheathing) that serves as the air barrier; a layer of exterior rigid insulation on the outside of the sheathing; a layer of waterproof but vapor-permeable housewrap (weather-restive barrier); a rain screen (vented air space) formed by vertical strapping; and finally, the factory-painted wooden clapboard siding.

By keeping the air barrier in the center of the wall—with cavity-fill fiber insulation on the interior—wires can be run through the that insulation without compromising the air barrier.

Effectively insulating a wall cavity with wires running through it should be done with something other than batt insulation. Cellulose insulation (dense-pack or damp-spray), fiberglass (dense-pack or spray), or spray polyurethane foam (closed-cell or open-cell) all fill well around wires. As I described in a blog a few weeks ago, for our house we used Johns Manville Spider spray fiberglass insulation, which has an acrylic binder to hold the insulation in place.

A ceiling panel made from three sections of shiplap pine.Photo Credit: Alex Wilson


Wiring for wall outlets can also be contained in baseboard raceways. This is a detail that Benson uses with his OpenBuilt wall system—and one that Eli uses on some projects. It totally avoids running wires in the insulation, allowing easy modifications later, and it’s an ideal solution for panelized construction (in which wall panels are built in a factory and trucked to the jobsite). We considered such a system, but it would have added a lot of cost. 

With our air barrier in the middle of the wall, the cavity-fill insulation can dry to the interior, and the exterior insulation can dry to the exterior. This offers effective drying potential due to the "vapor profile," and More and more building science experts seem to be recommending this approach. We’ll find out how it worked—or someone will—in 20 or 50 or 100 years when a totally dry wall system with no rot will, I hope, be evidence of good moisture management.

Testing air tightness

We don’t yet know how good a job we have done with air sealing at our house. I’m hoping that we will end up with an air leakage rate as low as 1.0 air change per hour at 50 pascals of pressure difference (ACH50)—as measured by a blower door. That will be far tighter than the average new home being built today, but still considerably leakier than a house built to the rigorous Passive House standards—which require an air leakage rate of 0.6 ACH50.

Even if the news is embarrassing and we don’t get to 1.0 ACH50 I promise to report that here. If we don’t make it, it will likely be because some elements of our 200-year-old frame necessitated complex detailing with the sheathing layer or because we didn’t spend the money needed for the best Passive House windows and doors. But I’m optimistic.

Oh, and did I mention that the recessed cans in our access ceilings will contain LED lights? I’ll write about those in a future blog.

Alex is founder of BuildingGreen, Inc. and executive editor of Environmental Building News. In 2012 he founded the Resilient Design Institute. To keep up with Alex’s latest articles and musings, you can sign up for his Twitter feed.

Published August 22, 2013

(2013, August 22). Access Ceilings: Replace Fixtures Without Cutting Into Drywall and Insulation. Retrieved from

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August 26, 2013 - 10:14 am

As a remodeler I vote for accessible ceilings!

Things change, and things go wrong. Though cutting and patching drywall isn't that big a deal for small areas, accessible ceilings allow more wholesale changes to be made easily.

One point I would make, for those with open-truss or I-joist construction, is to be aware of a new building code provision: IRC 2012 section R501.3. 

For floors whose fire performance is less than nominal 2x10s, this new section of the code specifies either fire sprinklers for the room below, or a membrane of 1/2" gypsum (or 5/8" wood structural panels). To read the provisions (and some exceptions and modifications) there is a free copy of the code available here:

The fire performance of I-joists and open-web trusses is not as good as traditional 2x joists, which retain significant structural strength in the middle even as the outer layers char. Youtube has entertaining demonstration videos if you would like to see this effect yourself!

A complete gypsum ceiling protects the floor members in a fire. Access ceilings made of wood panels don't offer the same protection; sprinklers, solid joists, or various fire protection materials are worth considering, even in areas where the 2012 IRC has not been adopted (or isn't enforced). 

August 26, 2013 - 9:58 am

I believe I have mentioned this before, but since the topic has popped up again, I feel obliged to repeat the warning: DO NOT fill cavity walls with PU foam.

Why not? Because it prevents dampness in the outer leaf being able to be carried upward by air convection in the cavity and dissipate via the eaves.If you fill with fibrous material, the convection is impeded by both air resistance and much lower heat input but can still happen.

In UK, when PU foam injection was sold as "the best thing since sliced bread" to prevent heat loss through walls, the people who bought it rejoiced at what they saved on their energy bills. But, a few years down the line, they wept at what they had to spend out for replacement of outer leaves which had become rain-soaked and then frozen, so that the typical UK bricks crumbled and fell apart (and, of course, for replacement of the insulation with something else or reversion to the original ventilated cavity).

What is the moral? Perhaps think about paying more for foamglas or some other truly waterproof material as the outer leaf. But you would still need to think about how to get rid of moisture generated inside the house.

It makes me wonder whether these "Passivhauses" will last.