RV slide-out leaking: find the leak and fix the seals

Common symptoms

• Water on the floor at the front corners of the slide room after rain.
• Drips from the top edge of the room, inside the RV.
• Leaks only when the room is out, or only when it is in.
• Water spills inside as you bring the room in.
• Daylight or a draft around the edge of the room.
• Rubber seals that look torn, flattened, folded over or out of place.

Quick checks before anything else

• The room is all the way in or all the way out, not stopped short.
• Both sides of the room sit even with the wall.
• The top of the room is clear of leaves, pine needles and standing water.
• No seal is folded over, pulled loose or torn.
• The slide topper (the fabric awning over the room) is not sagging with water.
• Sealant at the corners of the room and around its window has no gaps or cracks.

What causes an RV slide-out to leak?

• Worn or damaged seals Keystone says weather breaks down rubber over time. Torn, flat or hard seals stop sealing.
• Debris lifting the seals Keystone says twigs, leaves and pine needles can lift the sweep seals and let water in.
• Failed sealant Gaps and cracks at the corner moldings, window and room roof let water behind the trim. Keystone calls poor upkeep the leading cause of slide-out leaks.
• Room not fully in or out If the room stops short or comes out crooked, one side never presses its seal tight.
• Water on top of the room Rain sitting on the room’s roof or on the topper runs inside when the room moves.
• Damage to the room’s roof A tear in the membrane on top of the room lets water into the room itself.

Step-by-step: how to fix an RV slide-out leak

When your RV slide-out is leaking, find out when it leaks before you buy seals. Lippert’s through-frame manuals give the key: the outside seals should press tight when the room is in, and the inside seals should press tight when the room is out. So a leak with the room in points to the outside seals, and a leak with the room out points to the inside seals and the wipers.

1. Note exactly when it leaks Write down whether water shows up with the room out, with it in, during travel, or only as the room moves. Note where: a front corner, the top edge, or the floor edge. That tells you which seal to look at first.
2. Run the room fully in or out A room that stops short never presses its seals. On a Lippert in-wall (Schwintek) slide, hold the switch a few seconds after the room stops so the motors shut off on their own. If one side sits farther out than the other, re-time it as shown in our slide-out troubleshooting guide.
3. Clear the top of the room From a ladder, use a small broom or brush to clear leaves, twigs and pine needles off the room’s roof, as Keystone advises. Look for tears in the roof membrane while you are there. Keystone says the membrane can often be patched. Clear water and debris off the top before you bring the room in.

   

4. Clean and inspect every seal Bulb seals are round, hollow rubber strips that squash flat when the room closes against them. Wiper seals (also called sweeps) are flat rubber blades that slide along the room’s sides and top as it moves. Wash them with mild soap and water, as Lippert’s in-wall manual says. Keystone does not recommend lubricants on the sweeps, because they collect dirt. Look for tears, flat spots, hard rubber and seals folded under. Fold any flipped seal back out by hand.

   

5. Check the sealant on the room Keystone says the moldings around the slide opening and every part of the room “box” should be inspected every six months for gaps, cracks and shrinkage, and resealed as needed. Pay close attention to the window in the slide and the corners. Use the same type and brand of sealant as the original, or remove all the old sealant first, because Keystone warns two different sealants may not bond. Never use silicone on the roof material, and let new sealant cure before you wash the RV.
6. Check the slide topper A topper keeps water and debris off the room while it is out. Carefree says to check that its fasteners are tight. When water pools on the fabric, Carefree says to bring the room in 8 to 12 inches at a time to dump it. If you must close the room in the rain, close it in those same short steps so the water runs off.
7. Wipe up what the seals leave Keystone notes that sweeps are not made to work like squeegees, so some water can stay on the room after rain. Wipe it with a towel. A little water on top is normal. Water that reaches the floor is not.
8. Replace damaged seals Keystone says to replace seals at the first sign of trouble, and to see your dealer for damaged sweeps. Seals differ in shape, width and how they attach, so take a piece of the old seal or the RV maker’s part number when you buy. On some Lippert SlimRack slides, a bulb seal at the top of each side channel is held by a screw, and Lippert sells a SlimRack replacement flap seal with an attached bulb.
9. Have the room’s adjustment checked If clean, good seals still leak with the room fully in or out, the room may not be pulling tight. Lippert’s hydraulic through-frame manual shows nut adjustments at the cylinder so the room seals in and out, and a sync bracket for a side that won’t seal. It says mechanical room adjustments are for certified technicians, so we leave this to a shop.

Differences by slide type

Lippert in-wall (Schwintek). Each side has its own motor. If the motors get out of step, one side stops short and its seals never press. Lippert’s fix is re-timing: run the room fully out, bring it in 8 to 10 inches, and repeat at least three times, then hold the switch 3 to 5 seconds at each end from then on. Lippert also says a wiper seal caught on the floor can stall the room.

Lippert SlimRack. The drive sits in a channel in each side wall. Lippert’s touchpad override lets you run one side’s motor alone if that side must come in farther to seal. After any override, though, Lippert says a dealer must reprogram the controller.

Through-frame and hydraulic. These rooms are set to seal by adjustments under the RV. Lippert’s hydraulic manual says 2 to 3 inches of free travel at the adjuster is normal, so play there is not a fault by itself.

When to call an RV tech

• Clean, undamaged seals still leak with the room fully in or out.
• The room sits crooked and re-timing doesn’t fix it.
• Water has reached the floor and it feels soft. See our RV slide-out floor repair guide.
• The room’s roof membrane is torn, or the leak is behind trim you can’t reach.
• Sweep seals need replacing and you are not sure of the profile.

For how the whole slide system works, see our RV slide-out repair guide.

Common questions