How Scorpions and Pests Get In Around a Garage Door

This subject has been written about almost entirely by pest control companies, and their advice tends to end at the same place: replace the bottom seal on your garage door. It's reasonable advice as far as it goes. It also explains why so many households around Mesa, Gilbert and Chandler put a brand new seal on the door in April and are still finding scorpions in June.

A garage door isn't sealed by one strip of rubber. It's sealed by four separate runs — the bottom, both sides, and the header — and by the two corners where the bottom run meets the side runs. Those corners are the specific place we find still open on doors that have just had new bottom seals fitted, because the bottom seal is a door part and the side seals are a frame part, and nobody owns the joint between them.

There is no published gap dimension for a scorpion, and you should be wary of any page that gives you one. University of Arizona Cooperative Extension sets a test instead of a number: “No outside light should be visible underneath exterior doors when viewed from the inside at floor level.” That is something you can actually run tonight. Bark scorpions also climb, which is why the header matters as much as the slab. This page walks the whole perimeter, in the order we walk it.

Hands-on repair — moderate risk Involves tools and adjustment. Read the whole section before you start, and we’ll mark where to stop.

This is general guidance based on what we see on service calls — it isn’t a substitute for someone looking at your actual door. Every door is a little different, and if anything here feels beyond what you want to take on, stop and give us a call.

Start Here

What to check in the next 10 minutes

Do this at night with the garage lights on and the exterior lights off, or in the day with the lights off and the door closed. Either way you're looking for light, because light and a scorpion use the same openings.

  1. 1
    Sit on the floor inside with the door closed and the lights off

    Give your eyes a full minute to adjust — most people quit too early. Then look at the whole outline of the door: along the slab, up both sides, across the top. You are mapping every place light comes through, and you'll almost certainly find openings you had no idea were there.

    You’ll know it worked when: You can name every spot on the perimeter where light shows, rather than just the one you already knew about.

  2. 2
    Put your attention on the two bottom corners

    Where the rubber along the bottom of the door ends, and where the flexible seal down the jamb ends, there is a small triangular void. On most doors we inspect it's open. It's the single highest-value spot on the perimeter and it survives a bottom seal replacement untouched, because the two seals belong to different parts of the assembly.

    You’ll know it worked when: You've looked specifically at both bottom corners rather than at the bottom edge in general.

  3. 3
    Look up at the header seal

    Across the top of the opening there's a strip of trim with its own seal resting on the top section of the door. It gets less attention than anything else on the door and it's often missing entirely on older installs. Bark scorpions climb walls; a gap up there is as usable to them as one at the slab.

    You’ll know it worked when: You know whether your door has a header seal at all, and whether it's touching.

  4. 4
    Check where the track brackets pass through the trim

    Two or three metal brackets per side bolt through or past the stop molding to hold the vertical tracks. The seal can't run continuously through hardware, so there's an interruption at each one. Look with a flashlight from inside — these read as small bright points rather than a line.

    You’ll know it worked when: You've found the bracket penetrations on both sides and know whether they're open.

  5. 5
    Run a hand along the slab under the closed door

    Feel for dips, a cracked lip, or a spot where the concrete drops away. A seal can only follow so much contour. Where the slab is low, the seal is bridging air, and no amount of new rubber will change that.

    You’ll know it worked when: You know whether the floor under the door is flat enough for a seal to work on.

Have you already replaced the bottom seal?

This splits the page into the two groups of people who land on it.

Did you fit a new bottom seal and find that things are still getting in?
Yes — new seal, no change
What that means: Then you've done the part everyone does and the part nobody does is still outstanding. Go straight to the corners, then the sides and header. In our experience that's where the remaining path is roughly nine times out of ten, and it's why the fix appeared not to work.
Where to go next: Go to causes 2, 3 and 4.
No — the bottom seal is old or I haven't checked it
What that means: Start there, but treat it as one of four runs rather than as the job. Press the rubber with a thumb: if it doesn't spring back it has stopped compressing, which is how seals fail in this climate even when they look perfect.
Where to go next: Go to cause 1, then work around the perimeter.
The seals are all fine and I can still see light
What that means: Then the seals aren't the variable — the geometry is. Either the slab under the door isn't flat enough for a seal to bridge, or the door isn't hanging square in the opening. Both defeat perfectly good rubber.
Where to go next: Go to causes 6 and 7.

There's no version of this where you seal one run and finish. A perimeter is only as closed as its worst few inches, and the worst few inches are almost never the ones you were looking at.

Where they're actually getting in

Six openings, in the order we find them. Match what your dark-garage inspection turned up.

Even hairline of light along the slab

The bottom seal has hardened and stopped compressing. The whole width is open by a little.

Jump to that fix ↓
A triangular void at one or both bottom corners

The junction between the bottom seal and the side seal. The classic missed spot.

Jump to that fix ↓
A vertical line of light down one edge

The jamb seal isn't touching the door face — hardened, loose, or set too far out.

Jump to that fix ↓
Light across the top, or no header seal at all

The header run is missing or has pulled away. Matters because scorpions climb.

Jump to that fix ↓
Bright points at the track brackets

The seal is interrupted where hardware penetrates the trim.

Jump to that fix ↓
A lens of light over a dip in the concrete

The floor, not the seal. A threshold is the tool for this one.

Jump to that fix ↓
Gap that widens toward one corner of the door

The door isn't hanging level, and that defeats every seal on the list.

Jump to that fix ↓

The perimeter, as a system

Think of the closed door as a rectangle with four edges, and ask what closes each one.

Along the bottom, an astragal — a rubber strip sitting in an aluminum retainer channel along the door's bottom edge — is squashed flat by the door's own weight against the slab. That's compression sealing, and it depends on the rubber still being flexible enough to deform.

Down the two sides and across the header, it's a different mechanism entirely. A flexible flap mounted on trim called stop molding lies against the outer face of the door. Nothing squashes it; it just leans. Those runs are fastened to the building rather than to the door, and they're usually one continuous miterd run around the three sides.

That difference in mechanism is the whole reason the corners fail. At each bottom corner, a compression seal on a moving part has to meet a contact seal on a fixed part. The bottom seal ends at the edge of the door. The side seal ends at the slab. Between the two there is a small void, and there is no standard part whose job it is to close it. When a door leaves the factory that void is small. Add a few years of rubber shrinking back at both ends and it's a gap you can put a pencil through.

The other thing worth internalizing is how you judge whether a run is closed, because measuring it is a dead end. University of Arizona Cooperative Extension does not publish a gap dimension for scorpions in either of its relevant bulletins — the figures circulating online come from marketing copy, not research. What Extension publishes instead is a performance test: “No outside light should be visible underneath exterior doors when viewed from the inside at floor level.” Its scorpion guidance is the same idea applied to the whole opening — door sweeps “tight fitting with no gaps,” weather-stripping installed to “ensure a snug fit,” and “inspect all seals of doors including the tops and sides.” Light is the measurement. Your eyes are far better at finding photons than at judging sixteenths of an inch, which is the practical reason the test works.

Astragal The bottom rubber. Seals by compression. A door part, replaced from the end of its channel.
Stop molding The trim around the sides and header carrying the flexible seal. A building part, fastened to the jamb.
The corner void The gap where a compression seal on the door meets a contact seal on the frame. Nobody's part, which is why it's nobody's fix.
Threshold A raised bead of vinyl or rubber bonded to the slab. It gives the seal something flat to close against on a floor that isn't.

Seal one run and you've reduced the traffic. Seal all four and both corners and you've closed the route.

What each opening looks like from a dark garage

The left column is what you'll see in your inspection. Do the whole table rather than stopping at your first hit.

What you’re seeingMost likely causeHow urgentWho should fix it
Thin even line along the whole bottom edgeAstragal hardened — stopped compressing while looking intactFix this monthYou can do this
Triangular void at a bottom cornerThe junction between the bottom seal and the side sealFix this weekYou can do this
Bare retainer channel showing at the end of the bottom sealThe rubber has shrunk or slid, opening the corner furtherFix this weekYou can do this
Vertical line of light down one edgeJamb seal hardened or standing off the door faceFix this monthYou can do this
Light across the top of the doorHeader seal missing, hardened, or pulled looseFix this monthYou can do this
Small bright points partway up each sideSeal interruption where track brackets penetrate the trimFix this monthYou can do this
Curved patch of light over a low area of slabFloor contour beyond what a seal can bridgeFix this monthEither — call us if unsure
Light along a crack in the concrete running under the doorA cracked slab with a lip the seal can't followFix this monthEither — call us if unsure
Gap that widens steadily toward one cornerThe door is hanging out of level — cables or drumsStop using itCall a pro
New bottom seal fitted, same traffic as beforeThe remaining path is the corners, sides or headerFix this weekYou can do this
Everything sealed and they're still turning upThe route isn't the door — service door, wall penetrations, or atticKeep lookingYou can do this

What’s actually causing it

These are ordered the way we work through them on a real service call — cheapest and most common first, so you don’t start by replacing a part that was never the problem.

1

The bottom seal has stopped compressing

Basic check

The one everybody starts with, and it does belong on the list — just not alone.

The important local detail is that the seal fails without looking failed. Sustained heat and ultraviolet drive the flexibility out of rubber, so the astragal goes stiff while keeping its shape. Stiff rubber can't deform against the concrete, so it touches only where the slab is highest and leaves a thin, continuous opening everywhere else. We diagnose that with a thumb press and cover it fully on its own page.

Where it matters for exclusion is that this is a low, wide opening running the full width of the door — the highest-traffic route on the perimeter for anything that walks in from a warm driveway at night.

How you can tell: An even hairline of light along the whole bottom edge, and rubber that stays dented when you press it rather than springing back.

The fix
  1. Press the astragal hard with a thumb at both ends and the middle. No rebound means it's spent regardless of how it looks.
  2. Check both ends for bare retainer channel — shrinkage leaves an inch or two of empty aluminum at the corners.
  3. Replace with a profile matched to your retainer slots. A hollow bulb profile deforms further than a flat one and copes better with an imperfect slab.
  4. Fit it with the door closed, and clean the packed silt out of the channel first — that's most of the work on an older door.
  5. Reset the opener's down travel afterwards. Fresh rubber is taller, so the door now meets the floor earlier than the opener expects.
  6. Then keep going. This is one of four runs, and on its own it will not settle the question.

You’ll know it’s right when: New rubber rebounds under a thumb and, with the garage dark, there's no line of light along the slab.

Where to stop: Nothing risky in the seal itself. The one thing to know is that no part of the job requires touching the brackets at the bottom corners of the door — those carry the full pull of the lift cables and wear factory warning labels for it. The rubber slides out the end of its channel and the brackets stay where they are.
2

The corners where the bottom seal meets the side seals

Basic check

If you take one thing from this page, take this. The two bottom corners are where we find open paths on doors whose owners have already done everything the pest control article told them to.

Here's why it's structural rather than accidental. The bottom seal belongs to the door and stops at the door's edge. The side seal belongs to the frame and stops at the slab. Where they meet, one is compressed flat and the other is standing vertically, and there is no part in the assembly whose job is to bridge between them. New from the factory, the void is small enough to be unremarkable. Then the astragal shrinks back from its ends, the vertical seal stiffens and stops leaning in, and what was a slight overlap becomes a triangular hole at floor level in the exact corner of the opening.

It's also the least-observed square inch of the whole door. It's low, it's in shadow, it's behind the trim line, and everybody's eye is drawn to the long straight run in the middle.

How you can tell: With the garage dark, a small triangle or wedge of light at floor level right at the outside edge of the door — often visible on one side only.

The fix
  1. Get down at floor level inside the closed garage, lights off, and look at each bottom corner individually.
  2. From outside, check whether the astragal actually runs to the end of the retainer or stops short of it. If there's bare channel, that's the first thing to fix.
  3. Check whether the vertical jamb seal reaches all the way down to the concrete, or stops an inch or two above it. Trim is often cut short so it clears the slab.
  4. Where the vertical seal stops short, the run can be extended down to the slab — that alone closes most corner voids.
  5. A corner-specific seal block sits in the void and is compressed by the door. Fitted to the trim rather than to the moving door, it takes up what neither run reaches.
  6. Re-inspect from the dark garage after fitting anything. The corner either shows light or it doesn't, and there's no ambiguity in that test.

You’ll know it’s right when: Both bottom corners are dark from inside the closed garage, and the bottom seal runs corner to corner with no bare channel at either end.

Where to stop: Keep whatever you fit clear of the door's travel and clear of the bottom corner hardware. If closing the corner means adding material that the door has to force past, it'll be shredded within a season and it may add enough resistance for the opener to read as an obstruction.
3

The vertical seals down both sides

Basic check

The side runs seal by contact rather than compression: a flexible flap on the stop molding rests against the outer face of the door for its full height. That means the failure mode isn't wear, it's loss of set. Once the vinyl hardens it straightens out and stands away from the door instead of leaning on it, and you're left with a seal that is present, unbroken, and touching nothing.

The other failure is positional. Trim fastened into framing that has spent twenty summers drying out loosens and drifts, and a run of molding that has moved an eighth of an inch away from the door is a full-height opening.

For exclusion purposes a vertical gap is worse than its width suggests. It's continuous from the slab to the header, it's shaded, and it faces the direction dust and wind actually come from.

How you can tell: A line of light down one or both edges of the door, and a flap that doesn't want to move when you push it toward the door face.

The fix
  1. Push the flap toward the door at three heights on each side. It should have give and want to return.
  2. Look at whether the flap is contacting the door or pointing at it — a shadow line behind the flap means it isn't touching.
  3. Check the trim for movement by hand. Loose molding is a separate fix from a tired seal, and doing the seal on loose trim wastes both.
  4. Replacement strip nails or staples to the existing stop molding. Set it with the door closed so it just kisses the door face.
  5. Resist the urge to set it in tight. A seal pressed hard against the door drags on every cycle and wears a stripe in the finish.
  6. Do both sides. The shaded side is usually years behind the sunny side and doing one leaves you re-inspecting in a year.

You’ll know it’s right when: Both flaps lie against the door face along their full height with a slight bend in them, and both edges are dark from inside.

Where to stop: If a side gap is wedge-shaped rather than parallel — wider at one end — stop treating it as a seal. That's a door hanging out of square, and it's covered properly on our side gap page.
4

The header seal across the top

Basic check

The most neglected run on the door, and the one that undermines the assumption people bring to this subject.

Bark scorpions climb. They go up stucco, up block, up the face of a garage door, and they are perfectly capable of arriving at an opening seven feet off the ground. A household that has sealed the slab meticulously and left a quarter-inch gap across the header has closed the obvious door and left the less obvious one open.

Header seals fail in three ways. They're missing outright, which is common on older installs where the trim was fitted without one. They've hardened and lifted off the top section. Or the trim has pulled away from the header framing — the top run gets the least support and the most direct sun of the three.

One thing a header gap is not, here: thermal bowing. On an insulated door the two skins run at different temperatures and the panel bows toward the warmer one — DASMA calls this inherent to bonded-core sections, not a defect. Hot outside and a cooler garage bows the door outward, and the reported field symptom of an outward bow is the top section rubbing the header, not standing away from it. The inward bow that opens a gap at the top is the cold-outside case. So in Phoenix, treat a header gap as a seal or trim problem. If instead the top of your door starts scraping the header on hot afternoons and stops in cooler weather, that's the one worth reading about on our side gap page.

How you can tell: Standing inside the closed garage looking up, a line of light along the top of the door. Or you look and find there's no seal up there at all.

The fix
  1. Look up from inside with the door closed and the lights off. This is a different sightline from the one you use for the bottom and it's easy to skip.
  2. From outside, check whether a flexible strip is present along the header trim and whether it touches the top section.
  3. Push on the header trim. It should be solid — this run gets the least fastening and the most heat.
  4. Where there's no seal at all, the strip fits the same way the side runs do, and it should meet the vertical runs at both top corners without a gap at the miter.
  5. Watch the top section clear the seal when the door opens. The top of the door tilts as it goes over the curve, so contact that feels right when closed can bind on the way up.
  6. Re-check the two top corners after fitting. The miters are small openings in their own right.

You’ll know it’s right when: The top edge of the closed door is dark from inside, the seal touches the top section without dragging on it, and both top corners are closed.

Where to stop: Work off a solid ladder with the door fully closed, and don't operate the opener with anyone on a ladder near the header. The top section moves toward the header as the door starts to open, which is not a good place to have a hand.
5

The gaps where hardware penetrates the trim

Hands-on — moderate risk

A detail that almost nothing published about this subject mentions, and that we find open on most doors we inspect.

The vertical tracks are held by brackets bolted to the jamb — usually two or three per side. Those brackets have to occupy the same space the stop molding and its seal want to occupy, so the seal is either notched around them, stopped short of them, or simply run over them with a bulge and a void behind it. Every one of those is a hole in the perimeter, at a height that suits a climbing insect perfectly.

The same applies wherever anything else passes through — a keypad wire, a light fixture bracket, an old lock bar slot in the track, or the holes left behind by hardware that was removed years ago.

How you can tell: From inside the dark garage, small distinct points of light partway up one or both sides rather than a continuous line. They line up with the bracket positions.

The fix
  1. Map the bracket positions from inside by eye, then look for light at each one.
  2. Check the vertical track for an unused lock slot — a rectangular hole in the track that's open straight through to outside.
  3. Look for abandoned fastener holes in the jamb from previous hardware.
  4. Close small penetrations with an exterior-grade sealant at the trim, not on the door and not anywhere the door's travel passes through.
  5. Where the seal has been notched around a bracket, a short filler piece behind the notch closes it without interfering with anything.
  6. Don't seal, block, or pack anything that a moving part passes through. If in doubt about whether something moves, watch a full cycle before you commit.

You’ll know it’s right when: No distinct points of light anywhere up either side with the garage dark, and nothing you've added contacts a moving part.

Where to stop: Leave the track hardware itself alone. Bracket bolts sit in slotted holes and locate the track that holds the door in the opening — sealing around them is fine, loosening them to seal behind them is not. Sealing around fixed brackets is ordinary work inside a weather stripping and bottom seal replacement.
6

The slab under the door isn't flat enough for a seal

Hands-on — moderate risk

There's a limit to what rubber can do. A bottom seal can deform maybe half an inch, and that's generous. Where the concrete has a dip, a slope beyond what the seal can follow, or a crack with a lip on one side, the seal is bridging air and there is nothing wrong with the seal.

This is where a threshold earns its place, and it's the option most homeowners have never heard of. A threshold is a raised bead of heavy vinyl or rubber bonded to the slab where the door lands. Instead of asking the seal to reach down into a low spot, it raises the floor to meet the seal, and because it's bonded to the concrete it also stops water and blown dust running along the slab and under the door.

The trade-off is real and worth stating. A threshold makes a small ridge you'll feel driving over, and it can trap water and grit on its garage side if the floor slopes inward. On a floor that's slightly off, it's the difference between a perimeter that closes and one that doesn't.

How you can tell: The seal is soft and healthy, the door is level, and the light forms a curved patch over a specific area of the floor rather than a straight line.

The fix
  1. Lay a long straightedge across the opening on the concrete and look for daylight under it. That measures the problem in one move.
  2. Check whether the light pattern lines up with the low area. It nearly always does.
  3. Try a deeper bulb-profile astragal first — more squash means more tolerance for the floor, and it's the cheaper option.
  4. For anything past what rubber can bridge, a bonded threshold is the right tool. Both surfaces have to be clean and dry, which in practice means degreasing the concrete.
  5. Set a threshold where the door actually lands, not where you think it lands — mark the door's contact line on the slab first.
  6. Watch how water runs on that apron in a storm before committing, so you don't create a dam on the wrong side of the door.

You’ll know it’s right when: With the door closed the seal contacts along its full width, and a straightedge on the slab shows no daylight beneath the door's landing line.

Where to stop: If the low spot is at one corner and the door has also started to rub the jamb, this isn't an uneven floor — it's a floor that has moved. That's a different diagnosis and it's the subject of our settled slab page.
7

The door isn't hanging level, which defeats all of it

High risk — call a technician

Everything above assumes the door is sitting square in its opening. When it isn't, the seals are being asked to close a gap that changes as you move along the door, and no combination of rubber will do that.

A door hangs level because both lift cables carry it equally. If one cable has slipped, spooled unevenly on its drum, or come off, that corner of the door sits low and the opposite corner sits high, and the gap under the door tapers from one end to the other. Fitting new seals to that door produces a marginal improvement in the middle and no change at the ends.

It matters far beyond the pest question. An unevenly hung door is loading its rollers at an angle the track wasn't built for, and it's the state immediately before a door comes off its track.

How you can tell: The gap widens progressively toward one end rather than being even or localized. Often one bottom corner is visibly closer to the slab than the other, and there may be a visibly slack cable.

Where to stop: Stop cycling it and let us look. Lift cables run under the same load the springs hold, and a cable that has left its drum doesn't get put back by hand. The reason this sits on a page about pests is that we're regularly called to seal a door and find that the reason the seals never worked is that the door hasn't been level for a year — and that's the more urgent finding by a wide margin.
8

The route isn't the garage door at all

Basic check

Worth saying plainly, because we'd rather you didn't spend money on a door that was never the problem.

A garage has other openings. The service door out to the side yard, usually with a seal in worse condition than the main door's because nobody thinks about it. The gap under the door between the garage and the house. Penetrations for hose bibs, conduit, dryer vents and irrigation lines. The junction where the block or stucco meets the slab. Weep screed at the base of a stucco wall. Attic access, if the garage shares one with the house.

We're garage door people, so we'll close the door's perimeter properly and tell you honestly if we think the door isn't your route. If the door is genuinely sealed and things are still turning up, the answer is somewhere else on the building, and that's the point to get someone who does exclusion work on the whole structure.

How you can tell: The full perimeter inspection comes back dark, the seals are all soft and touching, and the traffic hasn't changed.

The fix
  1. Do the same dark-room light inspection on the service door — it's a smaller opening with the same four runs.
  2. Look at where the wall meets the slab, inside and out, particularly on the shaded side of the house.
  3. Check every pipe, conduit and vent that passes through the garage wall for the gap around it.
  4. Check the door between the garage and the house — it's the one that decides whether a garage problem becomes a house problem.
  5. Look at what's stacked against the outside walls. Woodpiles, block, pavers and irrigation boxes are harborage right next to your perimeter.
  6. If all of that is closed and the traffic continues, the structure needs someone who does whole-building exclusion. That's not us, and we'll say so.

You’ll know it’s right when: You've inspected the garage's other openings the same way you inspected the door, and you know whether the door was ever the route.

Where to stop: We don't give pest control advice beyond sealing — no products, no treatments, no recommendations about what to spray. Our part of this is the openings, and there's more of that than most people realize.

What you’ll need if you’re doing this yourself

  • A dark garage and ten patient minutes — the single best diagnostic on this page, and it costs nothing. Light and a scorpion use the same openings
  • A bright flashlight, used from outside while someone watches from inside — turns the inspection into a two-person sweep and finds penetrations the ambient method misses
  • A long straightedge — tells you in one move whether the slab is within what a seal can bridge
  • A phone camera — photograph each corner from inside in the dark; comparing before and after is how you know the fix worked
  • Exterior-grade sealant — for hardware penetrations in the trim — not for anywhere the door itself travels

Things not to do — and why

× Don't replace the bottom seal and consider the job done

That's one of four runs, and it leaves both corners, both sides and the header untouched. It's the specific reason people conclude sealing doesn't work.

× Don't inspect in daylight with the garage lit

An opening that's invisible under those conditions is perfectly obvious from a dark garage, which is exactly why UA Extension words its standard as no visible light rather than as a width. Every finding on this page comes from the dark-room method.

× Don't caulk or foam the gap between the door and the slab

That edge moves hundreds of times a year. Rigid filler tears out within days, and while it's there it can hold the door down hard enough for the opener to fight it.

× Don't pack anything into the tracks or around the rollers

Everything in a track has to keep moving freely. Material added there binds the rollers and transfers the load to the cables and the opener.

× Don't add material that the door has to force past

Anything creating real drag will be destroyed by the door within a season, and in the meantime it can add enough resistance to trip the opener's force setting — which is part of the safety system.

× Don't seal the perimeter and leave the corners

It's the one junction with no owner: the bottom seal belongs to the door, the side seal belongs to the frame, and the void between them belongs to nobody. It's where we find the path.

× Don't ignore a gap that tapers toward one corner

That's a door hanging out of level, not a seal problem. New rubber won't close it, and the underlying cause is a cable issue that gets worse with every cycle.

× Don't assume the header doesn't matter because it's high up

Bark scorpions climb. A gap seven feet off the ground is as usable to them as one at the slab, and the header is the run people check last or not at all.

Why this is a garage door subject here

In most of the country, sealing a garage door is about drafts and energy bills. Around Mesa, Gilbert and Queen Creek it's about what walks in, and that changes how carefully the job needs doing.

Bark scorpions are nocturnal, flat, and they climb — so the whole perimeter is in play rather than just the floor line. University of Arizona Extension describes how they get in without giving a dimension: “They enter under and around poorly fitted doorways, through window vents, and under exterior walls with openings.” They're also drawn toward the conditions a garage offers on a summer night: shade, a temperature drop after dark, and the smaller insects that come to the light over your driveway.

What makes it a door problem rather than only a pest problem is that our seals fail early. Rubber that would last eight to ten years elsewhere is done here in two to four, and it fails by hardening rather than tearing — so it stops sealing while still looking correct. A household can go years believing the perimeter is closed.

  • Light is the standard, not a measurement — UA Extension's test is that no outside light shows under the door when you look from inside at floor level. Nobody publishes a scorpion gap width, and the numbers you'll find online come from pest-control advertising.
  • They climb, so the header counts — Extension is explicit that you should “inspect all seals of doors including the tops and sides.” Sealing only the slab line addresses the route people picture rather than the whole route.
  • Brush or rubber at the bottom, per Extension — az1677 recommends a brush or rubber seal for garage door bottoms rather than vinyl. Its stated reason is cold-weather performance, which doesn't apply here; we mention it because it's the published guidance, not because Arizona heat argues for it.
  • Seals here fail by hardening — two to four years, worst on south- and west-facing doors, and with no visible damage to give it away.
  • Blown silt marks the path — after a haboob, look at where dust has drifted inside the closed door. It's a free map of every opening in your perimeter.
  • Slabs move — expansive soils and post-tension slabs mean garage floors in this valley shift, and a slab that has dropped at one corner opens a gap no seal can bridge.
  • Landscaping stacks the odds — irrigation boxes, block, pavers and woodpiles against the garage wall put harborage directly against the perimeter you're trying to close.

Keeping the perimeter closed

Sealing is a maintenance item here rather than a one-time project. Seven habits cover it.

  • Do the dark-garage inspection every spring and fall — all four runs and both corners, ten minutes. It's the check UA Extension actually specifies, and the only one that reliably finds an opening too small to see in daylight.
  • Thumb-test all the rubber, not just the bottom — the side and header flaps harden the same way, and a stiff flap that looks fine is doing nothing.
  • Photograph both bottom corners once a year from inside in the dark. Comparing this year's photo to last year's catches the corner opening up before anything gets through it.
  • Keep the driveway apron and the slab under the door swept — grit trapped under the seal grinds it flat and props the door up on debris at the same time.
  • Move harborage away from the garage walls — block, pavers, firewood and irrigation boxes stacked against the wall put the population next to the perimeter.
  • Don't leave the door partly open for ventilation on summer nights — a door propped a few inches gives up everything the seals are doing, at the hour when it matters most.
  • Check the perimeter again after any door work — a new seal changes where the door closes, and a door that has been re-set can leave a corner open that used to be closed.

How a perimeter opens up

It's a sequence, not a coincidence, and it explains why the obvious fix so often changes nothing.

Step four is the expensive one, not in money but in confidence — it's where households conclude that sealing a garage door doesn't work, when what didn't work was sealing a quarter of it.

What a perimeter seal call involves

We treat this as a survey first and a parts job second, because the useful part is finding every opening rather than replacing the obvious one.

What we do on a visit for this
  • Walk the full perimeter from inside with the door closed and the lights off, and map every opening
  • Compression-test the bottom seal along its width and check both ends for bare retainer
  • Inspect both bottom corners specifically, where the door seal meets the frame seal
  • Test both vertical seals and the header seal for contact and flexibility
  • Check for penetrations at every track bracket, unused lock slot and abandoned fastener hole
  • Straightedge the slab across the opening and assess whether a threshold is the right answer
  • Confirm the door is hanging level and that the gap isn't being caused by the door itself
  • Re-inspect from the dark garage after the work, so you can see the difference rather than take our word for it

You'll get a written quote before any work starts.

What drives the cost

Sealing a perimeter properly costs more than replacing a bottom seal and less than most people expect. What moves the number is how many of the four runs need doing.

  • How many runs need replacing A bottom seal alone is the smallest version. Bottom, both sides and the header is four times the material and most of the labor difference.
  • Seal strip versus whole stop molding Where the trim is sound, only the flexible strip is replaced. Where sun has finished the molding itself, it's new material around three sides. Which of those two you need is decided when the weather stripping and bottom seal replacement is measured up.
  • Whether a threshold is needed A bonded floor threshold is the answer for a slab a seal can't follow. More material, more prep, and it addresses something rubber can't.
  • Corner treatment Closing the two bottom corners is a small line item and it's the one most likely to be the reason you called. It's rarely the reason a quote is large.
  • What the survey turns up If the perimeter isn't sealing because the door is hanging out of level, that's a cable job with a sealing symptom, and it's a different conversation.

You'll get a written quote before any work starts. If the door is due anyway, our full tune-up is $39.99 — same price in every city we serve.

Still stuck? We’ll come take a look.

Same-day service is our standard across Mesa, Gilbert, Chandler, Queen Creek, Scottsdale, Phoenix, and the rest of the Valley.

Due for a check-up while we’re out? Our full tune-up is $39.99 — same price in every city we serve.

Questions we get asked about this

Where this information comes from

Serving the Valley

Where we come out

We’re a family-run shop based in Mesa, and we cover the whole Phoenix metro. Same-day service is our standard — pick your city, or just call (602) 935-9766 and we’ll find the soonest slot that works.

Not sure if you’re in range? Give us a call — if we can’t get to you, we’ll point you to someone who can.

Mesa-based · Serving the whole Phoenix Valley

Want us to just take care of it?

If you’ve worked through this and you’d rather have someone who does this every day handle it — that’s us. Tell us what your garage door is doing and we’ll come diagnose it properly.

  • Same-day service is our standard
  • Family-owned right here in Mesa
  • Straight answers — we’ll tell you if it’s not worth fixing
  • Written quote before any work starts
Due for a check-up anyway? Our full tune-up is $39.99 — same price in every city we serve, and we’ll go through the whole system while we’re there.
Mesa · Gilbert · Chandler · Queen Creek · Scottsdale · Tempe · Phoenix · San Tan Valley · Apache Junction · Gold Canyon · Fountain Hills · Maricopa · Guadalupe

Want Access to Exclusive Deals, Maintenance, and Updates?

Sign up to receive access to our latest updates and best offers.

Call (602) 935-9766 Book online