Truck shells or canopies allow you to cover your truck bed so you can haul items in all types of weather, or even have a dry place to sleep while you camp. They are supposed to form a seal with the truck bed that prevents water from entering. But especially in rainy climates, some truck shells can leak. What steps should you take when you first notice a leak in your truck shell?
1. Examine the screws around your windows.
Over time, these window screws can get a little loose, and water can come in between the shell and its window. Remove each screw, apply a threadlocking adhesive and re-insert it into the hole.
2. Add clamping points.
Many shells have two clamping points where the shell and the bed are held together, but it can still shift slightly. Adding a third clamp can keep the shell in the proper position and provide a more even seal.
3. Check your gasket.
If the gasket sealing your shell is too thick, and you get any movement such as when you are offroading or just driving on uneven surfaces, a wrinkle or buckle can develop along the bottom edge. That causes a gap that can allow water in. You can remove the entire gasket and install a slightly thinner type to allow for better contact.
4. Find out what type of foam is used.
Some installers use foam sealant to fill any cracks in the truck shell, and if they use the wrong type, it can eventually allow water to get through. Open cell spray foams are advantageous in some applications because they expand really well to fill all the available space; however, they are not water resistant and should not be used on a truck shell or camper. Look for a closed cell foam that is water resistant.
5. Look for an uneven surface along the bed rail.
Any dent or irregularity can lead to a leak. Take off your shell, mask off the bed rail so it doesn't get too messy and apply a silicone sealant where the shell makes contact. Carefully put the shell back on and then use sealant tape to ensure that the gap is closed. This will often solve the problem but it will require some work to remove the truck shell should you wish to replace it or take it off completely
If you continue to have trouble with water leaking into your truck shell, contact a qualified installer or the manufacturer.