Direct answer: If a squirrel chewed your splash block extension, the usual fix is replacing the damaged downspout extension section once you confirm the water path is actually leaking or collapsing there. Start by checking whether the chewing only scarred the surface or opened holes, crushed the outlet, or loosened the connection at the downspout.
Most likely: Most often, squirrels chew the thin end or sidewall of a plastic downspout extension, leaving holes or a split that lets roof runoff dump beside the house instead of carrying it away.
Animal damage on a downspout extension looks minor until you watch water run. A few tooth marks are one thing. A chewed-through sidewall, flattened outlet, or loose connector is a drainage problem, not a cosmetic one. Reality check: if runoff is landing within a couple feet of the foundation, this is worth fixing before the next storm. Common wrong move: replacing the splash block while leaving the chewed extension or loose joint above it.
Don’t start with: Don’t start by sealing everything with tape or caulk. If the extension is brittle, crushed, or half disconnected, patching it usually fails after the next hard rain.
The extension has scrape marks or shallow gnawing, but you do not see daylight through it and it still holds its shape.
Start here: Run water from a hose into the downspout and watch the chewed area closely before deciding it needs replacement.
Water sprays or dribbles out of the chewed section instead of reaching the end of the extension.
Start here: Focus on the damaged section itself. If the plastic is thin, cracked, or opening up under flow, replacement is the durable fix.
The outlet end is pinched down, kinked, or partly closed off where the squirrel chewed it.
Start here: Check whether water backs up, spills at the top joint, or pools beside the house because the extension cannot discharge freely.
The extension is hanging crooked, separated, or leaking where it attaches, with chew damage nearby.
Start here: Check the connector and fit at the downspout first. A loose joint can look like a bad extension when the real issue is the connection.
This is the most common squirrel damage pattern on flexible or thin plastic extensions. You will usually see a wet streak, spray, or drip right at the gnawed spot during flow.
Quick check: Feed water through the downspout for a minute and watch for leaks at the tooth-marked area.
Squirrels often work the end of the extension, and once that end folds in, water slows down and can spill upstream.
Quick check: Look through the outlet end. If the opening is badly misshapen or partly closed, the extension is restricting flow.
Chewing and tugging can shift a light extension enough to open the joint at the downspout, especially after wind or mowing traffic.
Quick check: Grab the extension near the top and see whether it wiggles, slips off, or shows a gap at the connection.
Sometimes the chew marks are real, but the bigger problem is water already moving slowly because the extension is packed with debris or lying uphill.
Quick check: Lift the extension slightly and look for standing water, packed leaves, or a low spot that traps runoff.
You want to separate harmless surface chewing from actual drainage failure before replacing anything.
Next move: If water stays inside the extension and exits cleanly at the far end, the chewing may be cosmetic for now. If water leaks from the chewed area or never reaches the outlet properly, keep going.
What to conclude: Visible leakage at the damaged spot confirms the extension is no longer doing its job, even if the hole looks small when dry.
A loose top connection can mimic a failed extension, and it is a different fix than replacing the full run.
Next move: If the leak is only at a loose or cracked connection, you can focus on that joint instead of replacing more than needed. If the connection is solid and the leak is farther down at the chewed section, move on to the body of the extension.
What to conclude: This tells you whether you need a downspout connector or elbow, or whether the damaged extension itself is the main problem.
Squirrel damage that opens the wall or crushes the outlet usually does not hold up to patch repairs for long.
Next move: If the extension body is still round, intact, and only lightly scarred, you may only need to correct slope or reconnect a joint. If you find open holes, a crushed outlet, or brittle cracking around the chew marks, plan to replace the damaged extension section.
A new part will not solve much if the extension is full of debris or lying in a low spot that holds water.
Next move: If water now runs cleanly to the outlet and stays away from the foundation, the repair path is confirmed. If water still backs up or disappears into a buried line slowly, the problem may be farther downstream than the squirrel damage.
This finishes the job and confirms you fixed the actual water path, not just the visible chew marks.
A good result: If water exits strongly at the end and the area near the foundation stays dry, the repair is done.
If not: If the new extension still overflows or backs up, stop replacing parts and chase the downstream blockage or buried outlet issue next.
What to conclude: A successful test confirms the animal damage was the real failure. Continued backup means the extension was only part of the problem.
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Only as a very short-term stopgap. If the plastic is chewed through, sun-brittle, or crushed, tape usually lets go after a few wet-dry cycles. Replacement is the better fix once the damage is confirmed.
Run water through the downspout and watch the extension. If water leaks from the chew marks, sprays out the side, or fails to reach the outlet, the damage is affecting drainage.
Only if the splash block itself is cracked, sunken, or no longer catches the discharge. Many times the real problem is the chewed extension or a loose connection above it.
Then the squirrel damage was not the whole problem. Check for a clogged buried extension or blocked outlet downstream. That is when pages like /buried-downspout-clogged or /buried-downspout-outlet-clogged become the right next step.
They usually do less direct damage to metal than to thin plastic extensions, but they can still loosen joints, chew attached plastic pieces, or work at a weak connector until it leaks.
It can be. A small hole near the house can dump a surprising amount of roof runoff right at the foundation during a hard storm. If you see wet soil, splashback, or erosion there, fix it soon.