Wall jobs tend to arrive with a backstory: a homeowner had cellulose blown into the walls years ago, there's been a leak or a mouse problem or a rewire, and now it all has to come out. The first question is always whether you can get it out through holes or whether the drywall has to come off.
Here's the short version of how to remove blown in insulation from walls. If the drywall is being replaced anyway, cut it open and vacuum each stud bay from the face; it's faster and you'll know every bay is empty. If the wall finish has to survive, you can vacuum through access holes at the top and bottom of each bay, but it's slower, it rarely gets everything, and dense-packed material fights you the whole way. Which method you pick decides most of what follows.
Two ways in, and how to choose
|
Access holes |
Open drywall
|
|
|---|---|---|
|
Best for |
Walls with finishes worth saving, small sections |
Water or rodent damage, rewires, full gut jobs |
|
Speed |
Slow, one bay at a time through a small opening |
Much faster per bay |
|
Completeness |
Material hides behind blocking and in corners |
You can see the bay is empty |
|
Hose |
Reducer down to a small hose |
Full-size removal hose |
|
Repair |
Patch every hole |
Hang, tape and finish new board |
If the insulation is wet, moldy or full of droppings, open the wall. You need to see and dry the framing anyway, and a camera through a two inch hole won't tell you whether the bottom plate is rotten. Access holes make sense for dry, clean material where the reason for removal is something like rewiring a single run or swapping the fill for a different insulation.
One thing to rule out before either method: vermiculite. It was sometimes poured into wall cavities, it looks like small gray-brown or gold pebbles, and it may contain asbestos. A removal vacuum and our bags are the wrong tools for it, since no bag of this kind is HEPA rated. If a test hole turns some up, close it, have the material tested and leave the wall to a licensed abatement contractor.
Dense-pack is the reason walls are harder than attics
Attic cellulose sits loose on the ceiling. Wall cellulose was usually dense-packed: blown in at high pressure through holes until the bay was stuffed tight, so it wouldn't settle and leave a cold gap at the top. That's great for the house and miserable for removal, because packed cellulose doesn't flow toward a hose on its own. It sits there as a firm block and the vacuum just nibbles a tunnel through it.
What works is breaking it up before you try to pull it. With the wall open, a hand rake, a stiff bar or gloved hands will loosen a bay from the top down, and the vacuum follows behind. Through access holes, you're limited to wagging the hose tip back and forth to chew the material loose, or using a stiff rod to break it up first. Expect it to take several passes.
Packed material also fluffs up once it's loose, so a wall can fill more bags than its cavity volume suggests. Our free bag calculator lets you set the condition to packed: enter the wall length as one dimension, the wall height as the other, and the stud depth (3.5 inches for a 2x4 wall) as the insulation depth, then add the usual 10 to 15 percent spare.
Before you cut or drill, find the wiring
Walls hide more than attics do. Outlets, switch legs and exterior lights all run through the bays you're about to open, and older homes may have cables stapled tight along a stud right where you want to drill.
- Shut off the circuits feeding that wall at the panel and confirm them dead with a non-contact tester.
- Mark studs, outlets and switches on the wall before you start.
- Cut drywall with a shallow blade set just deeper than the board, never a full-depth saw blade.
- Look into each bay with a light before the hose goes in, and keep the hose tip moving so it doesn't snag a cable.
- Check plumbing walls (kitchen, bath, laundry) for supply and drain lines before drilling.
If you find damaged insulation on the wiring, chewed cable, or knob and tube wiring, stop and get an electrician in before going further. Removing the insulation around it is fine; pulling on the wire is not.
Clearing a bay through access holes
Locate the studs and drill or cut an opening near the top of each bay and another near the bottom. Size the holes so a reduced hose fits with a little room to angle it. Many dense-pack jobs were blown from the outside, so you may find the original plugs under a strip of siding; reopening those can save interior patching.
Feed the hose in from the top hole and work downward in overlapping passes. Then go in from the bottom hole to pull what has slumped onto the bottom plate. Don't assume a pair of holes clears the bay. Most framing has a horizontal fire block somewhere in the wall, often around mid-height, which splits the bay into two sealed compartments. If the hose stops dead partway down, that's probably what you've hit, and you'll need a hole on each side of it.
Lay plastic on the floor under every hole and keep a small container handy, because loosened material will spill out of the lower openings. Finish each bay by checking it with a borescope or a flashlight from both holes.
Clearing bays with the drywall open
When the board is coming off, cut it in sections rather than one big sheet, and let the bay's contents fall straight onto plastic where they can be picked up by the hose. Better still, cut a strip near the top first and vacuum the bay from above before the rest of the board comes down; that keeps most of the cellulose in the hose instead of on the floor.
Work each bay top to bottom with the hose and a hand rake, paying attention to the corners behind the studs, around electrical boxes and on top of any blocking. You'll be able to see when a bay is clean, which is the whole point of opening the wall.
Bags, hose and setup for a wall job
Wall removal produces fine cellulose dust and usually happens inside an occupied house, so the bag choice matters more than it does in an attic. Leave the vacuum and bags outside, and run the hose in through a window or door with the gap taped off.
For cellulose out of a wall, our PRO-400 Extra Heavy Duty is a good default: its non-woven fabric is low dust and it holds up to 400 pounds. Wall jobs also throw more hardware than attics: drywall screws, chips of board, wire staples and the odd plastic plug from the original dense-pack holes all go up the hose, so keep your usual length of hose on the bag side of the machine as a buffer. When the vacuum can't sit near the work, or the bags have to be carried through a finished house, our PRO-200 small bags hold about 250 pounds each and are far easier to walk out the front door. The full range is on our insulation vacuum bags page.
Inside, seal off the room with plastic, cover the supply and return registers, and turn off the HVAC while you work. Breathable coveralls such as our Cool-Suits keep cellulose dust off your clothes, so it doesn't get tracked through the rest of the house when you step out of the containment.
Inspect the empty bays, then patch
An empty wall is the best look you'll ever get at that framing. Before anything gets closed up, check the studs, plates and sheathing for water staining, soft wood, mold growth, droppings and chewed wiring, and fix whatever caused the removal in the first place. A moisture meter is worth having on any wall that got wet.
For access holes, cut drywall patches to fit, back them with a scrap of wood or a patch clip, then tape, mud, sand and prime. If new insulation is going back in by dense-pack, talk to the installer before you patch: they may want to reuse your holes, and patching twice is nobody's idea of a good day. Fully opened walls get new board once the bays are dry and inspected.
Get the bags in before the drywall comes down
Wall jobs go smoother when the bags are on site before the first cut, sized for packed material rather than a fluffy attic. The RAM team can help you pick between the PRO-400 for dusty cellulose and the PRO-200 for jobs where everything gets carried through the house. We ship every order free the same day, and someone picks up at 404-354-6268 around the clock.
Frequently Asked Questions
Can I use a regular wet/dry vacuum to pull insulation out of a wall?
For a single bay, maybe, but you'll be emptying the canister every few minutes and the filter will clog fast on cellulose. A dedicated insulation removal vacuum moves the material through a large hose into an outside bag, which is what makes a whole wall practical.
How big should access holes be?
Big enough for the hose you're using to go in at an angle, and no bigger. Larger holes make the vacuum work easier but every extra inch is more patching and more risk of hitting a cable, so many crews start small and enlarge only the bays that need it.
Does fiberglass come out of walls the same way as cellulose?
Loose-fill fiberglass in walls vacuums out much like cellulose, though it's lighter and usually less packed. Fiberglass batts in walls are a different job: they're pulled out by hand once the drywall is open rather than vacuumed.
Should I remove the insulation from the inside or the outside of the house?
If siding is coming off for a re-side project, going in from the outside spares the interior finishes completely. Otherwise the inside is usually easier to control, since you're at a comfortable height and can contain the dust in one room.
Is it worth removing wall insulation that's dry and clean?
Often not. Dry, undamaged cellulose in a wall can usually stay, and the disruption of removal outweighs the benefit. Removal makes sense when the material is wet, contaminated, settled badly or in the way of work that has to happen inside the wall.