What You Need to Know Before Cutting a Hole in Your Wall (Savvy’s Pre-Install Checklist)
Cutting a hole in your wall isn’t like hanging a picture frame or installing a shelf. It’s a commitment — a “we’re doing this for real” home improvement moment. And while it can seem intimidating, installing a through-the-wall AC can be one of the most satisfying and worthwhile upgrades you’ll ever make. But only if you know exactly what you’re doing.
I’m Savvy, and trust me: after helping homeowners successfully install wall units (and helping more homeowners fix the messes that happen when you skip the prep), I’ve learned exactly what matters before the saw touches the drywall.
This guide is your complete pre-install checklist — everything you need to understand before cutting, drilling, measuring, or buying anything. Let’s walk through the wall sleeve basics, structural rules, electrical steps, and the “don’t skip this” tips that save you stress, money, and repairs you never want to pay for.
Let’s do this the Savvy way: safely, smartly, and with zero surprises.
1. Wall Sleeve Basics: Your AC’s “Home Inside a Home”
Before you even think about cutting, you need to understand what a wall sleeve is — and why it’s not optional.
A wall sleeve is a metal (sometimes heavy-duty plastic) box that slides into the hole you cut in your exterior wall. It becomes the structural support container for your AC unit. It keeps the wall safe, holds the AC securely, and ensures the entire installation is airtight and weatherproof.
Think of it as a custom-designed parking garage for your through-the-wall AC.
Without a sleeve, you’d be shoving an expensive appliance directly into wood framing, insulation, and sheathing — all of which deteriorate rapidly when exposed to:
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Moisture
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Condensation
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Heat exchange
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Vibrations
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Outdoor air
And yeah… bugs. Many bugs. Trust me.
Why the Sleeve Matters
A proper sleeve provides:
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Support (prevents sagging and shifting)
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Weatherproofing (keeps rain out)
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Drainage (channels condensation outside)
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Air seal (improves efficiency and prevents leaks)
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Compatibility (designed to match specific AC dimensions)
According to Energy.gov, even small air leaks around AC installations can significantly increase cooling costs and reduce performance.
A wall sleeve prevents exactly those problems.
2. Structural Considerations — Explained Simply (No Engineering Degree Needed)
Let’s clear up the biggest fear people have:
“What if I cut into something important?”
Great question — and that’s exactly the mindset you should have.
Here’s what you need to check before making any cuts.
A. Is the wall load-bearing?
A load-bearing wall supports the roof, ceiling joists, or another floor.
Cutting into it the wrong way? Big mistake. Big repairs.
You do not want to learn the physics of home collapse the hard way.
How to tell if the wall is load-bearing:
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It runs perpendicular to floor joists
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It sits directly under another wall on the story above
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It is part of the main structural “grid”
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It’s near the center of the house
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It’s connected to major beams or foundation points
Not sure? Check your attic or basement for joist direction. Or contact a structural inspector.
Savvy Says:
“If there’s even a 5% chance the wall is load-bearing, stop and verify. Guessing is not a strategy.”
B. Avoid cutting studs — unless you know how to reframe
Through-the-wall AC units are wider than the 14.5" space between standard studs. This means you’ll likely need to cut one stud and frame a header — just like framing a window.
The International Residential Code (IRC) requires that any stud you cut must be properly supported above and below with a header and jack/king studs.
Reframing is totally doable, but not something you “wing.”
If reframing scares you, choose a wall between studs:
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Closet walls
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Walls adjoining hallways
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Walls without heavy loads
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Areas where you can confirm stud spacing or add supports
C. Watch for electrical lines, plumbing, and HVAC ducts
Cutting into a stud is one thing. Cutting into wires or plumbing is… a renovation horror story.
Before cutting:
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Use a stud finder with AC wire detection
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Access the attic or basement to inspect the wall path
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Cut a small pilot hole inside and use a borescope camera
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Turn off the circuit breaker to that wall
The EPA warns that improper wall penetrations can also impact indoor air quality, especially if insulation or moisture barriers are compromised.
Don't risk it.
D. Exterior wall depth matters
Wall sleeves typically accommodate walls between 4" and 8" thick.
Measure your wall from interior drywall to exterior siding.
If your wall is:
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Too thick, you may need a deep-sleeve model
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Too thin, you may need to build out the opening
Vinyl siding? No problem.
Brick? Tricky but possible.
Stucco? Prepare for dust. Lots of dust.
3. Electrical Needs (Absolutely Don’t Skip This Part)
Through-the-wall ACs often require:
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Dedicated circuits
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Specific voltage
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Correct amperage
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Proper outlet placement
Window units, in comparison to Through-the-wall ones, often plug into standard 115V outlets.
But many through-the-wall units use 230V systems for efficiency and power.
Energy Star emphasizes checking electrical requirements before purchasing an AC to ensure safe installation and proper function.
Let’s break it down simply.
A. Voltage: 115V or 230V?
Check the product specifications.
115V units work with standard household outlets.
230V units require:
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A dedicated 230V line
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A double-pole breaker
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A specific RECEPTACLE (they’re shaped differently)
If you don’t already have a 230V line on that wall, an electrician visit is guaranteed.
Savvy Says:
“Don’t try to DIY electrical unless you already know how to safely wire a breaker. It’s not the time to ‘learn on YouTube.’”
B. Amperage & Dedicated Circuits
Common unit requirements:
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15A
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20A
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30A
Many wall units specify a dedicated circuit ONLY to avoid overload.
Sharing a circuit with:
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TVs
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Computers
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Heaters
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Lighting
…can cause tripping or overheating.
C. Proper Outlet Placement
Your outlet must be:
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Near the AC (plug shouldn’t be stretched or strained)
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Slightly lower than the AC’s chassis
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Not behind where the AC blocks access
If the AC has a built-in heater, outlet placement is even more crucial because these draw higher wattage.
4. Savvy’s “Don’t Skip This” Tips Before Buying
This section alone has saved my clients thousands in mistakes.
Read it twice.
Tip #1: Match the AC to the Sleeve — They Are NOT Universal
Not all sleeves fit all ACs.
Not even close.
Brands often use proprietary dimensions.
Before buying:
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Check the model number
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Confirm sleeve compatibility
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Verify wall thickness
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Review drainage requirements
Many homeowners discover too late that their AC sticks out 4 inches because they bought the wrong sleeve.
Tip #2: Check Drainage Direction
Some sleeves support:
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Rear drainage
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Internal drainage
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Bi-directional drainage
This affects:
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Moisture control
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Mold prevention
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Drip patterns outside
If you live in a humid state, proper drainage is non-negotiable.
Tip #3: Don’t Install Too High or Too Low
Through-the-wall ACs should sit:
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At least 10–12 inches above the floor
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Not higher than shoulder height unless remote-controlled
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Low enough for proper condensation flow
Too high = hot air stays trapped at ceiling
Too low = poor circulation and potential splashback
Tip #4: Double-Check Sun Exposure
Installing on a west-facing wall increases heat load dramatically.
Energy.gov confirms rooms exposed to direct sunlight may need up to 10% additional cooling capacity. Choose shaded walls where possible.
Tip #5: Plan for Exterior Weatherproofing
You’ll need:
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Flashing
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Exterior caulk
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Drip edge
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UV-safe silicone
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Proper insulation
Skipping this leads to rotten studs and expensive repairs.
5. When to DIY and When to Bring in a Pro
Let’s be real:
Some homeowners can absolutely DIY this.
Others… should absolutely not.
Here’s how to know.
DIY If:
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You can confidently use saws + drills
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You understand basic framing
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You can read installation manuals
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You know how to add or modify trim
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You’re comfortable sealing exterior penetrations
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You choose a 115V unit and have a proper outlet
DIY saves $300–$800 in labor.
Bring in a Pro If:
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The wall is load-bearing
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There’s unknown wiring inside the wall
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You need a 230V electrical line
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You need a new dedicated circuit
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You’ve never reframed an opening before
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You live in a condo/HOA with rules
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Your wall has stucco or brick (harder cuts)
Hiring a pro reduces risk and ensures the AC operates at peak performance.
6. Final Savvy Checklist (Print This!)
Before cutting:
STRUCTURE
✔ Confirm wall is not load-bearing
✔ Identify all studs
✔ Locate electrical/plumbing/HVAC
✔ Measure wall depth
✔ Choose the correct wall location
SLEEVE + AC
✔ Buy matching sleeve + AC model
✔ Confirm drainage style
✔ Check ventilation clearance outside
✔ Check sleeve depth requirement
ELECTRICAL
✔ Confirm 115V or 230V
✔ Confirm amperage
✔ Confirm outlet placement
✔ Confirm dedicated circuit
EXTERIOR PREP
✔ Plan flashing
✔ Weatherproofing supplies
✔ Caulking rated for exterior
✔ Insulation materials
SKILL LEVEL
✔ Decide DIY or pro
Final Thoughts: Yes, You Can Do This — If You Prepare
Cutting a hole in your wall is a big step — but with the right prep, it’s a totally manageable project. The key is respecting the structure, understanding your electrical needs, and choosing the right equipment before you begin.
Through-the-wall units are one of the best long-term cooling solutions you can add to your home — energy efficient, quiet, secure, and clean-looking. But only if you build the right foundation for them.
In the next blog, you will know "How to Choose the Perfect Sleeve for a 10k–12k Unit (Savvy’s Guide)".
