How to Caulk Aluminum Siding

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Things You'll Need

  • Rags

  • Utility knife

  • Fine sandpaper

  • Paintable caulk

  • Caulking gun, if necessary

  • Coat hangar, if necessary

  • Pail of water

  • Putty knife

The need to caulk aluminum siding may be related to different factors, however the way to do the caulking remains the same. Regardless of whether you are fixing a dent, a small hole, cracks or are caulking around windows and doors, the way to apply the caulk never changes. When you caulk your aluminum siding you will be accomplishing two things. The first is that you can then paint your home and it will look new again. The second is that it will help to keep the home warmer in the winter due to fewer drafts, a huge plus in colder climates.


Step 1

Locate the areas that need to be caulked. This will vary, however, common issues that can be fixed by caulking aluminum siding are dents, small holes and cracks. For homes that are drafty this might be around windows and doors or the seams of the aluminum siding itself.

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Step 2

Prepare the aluminum siding for caulking. Make sure there is no dust, grime or dirt where you will be applying the caulk. Use a dry rag to brush away any loose paint, dirt or grime. If you are replacing old caulk around windows and doors, you will need to remove it first. Use the utility knife to separate the caulk from the siding and then rub with sandpaper until smooth. Use a rag to brush away any debris before caulking the aluminum siding.


Step 3

Pull the plunger on the caulking gun as far out as it will go if using a caulking gun. The teeth on the plunger will need to be facing upward with the trigger facing downward; this is done by just twisting the plunger. Place the tube of caulk in the gun, twist the plunger so the teeth face down and begin to squeeze the trigger until the plunger hits the tube of caulk.


Step 4

Cut a hole in the tip of the caulking tube on an angle. The hole size depends on your project and the tip shows where to cut for different sizes. It is best to start with a small hole first and then make it larger if need be. This is the same regardless of the type of caulk being used.

Step 5

Puncture the foil seal on the tube of caulk. Most caulking guns will have a wire built onto them to do this.. A squeeze tube would have a point built into the cap. If your caulk has neither of these you can use a coat hangar to puncture the foil.


Step 6

Pull the trigger of the caulking gun or squeeze the tube of caulk to fill cracks and dents. While squeezing the trigger or tube of caulk just move the tip of the tube to distribute the caulk evenly. This will take some practice, so before you start caulking siding, practice on a rag or maybe an area of the aluminum siding that is not noticeable.


Step 7

Smooth the caulk. Wet the rag and squeeze well. Wet your finger and use your finger to smooth the caulk in the crack or dent in the aluminum siding. For a larger dent you may want to use a putty knife dipped in water to smooth the caulk.

Step 8

Clean your finger or the putty knife off on a rag to remove the excess caulk. Repeat as needed until the dent or crack looks how you want it to. Allow to dry per the caulk manufacturer's instructions before painting.


Step 9

Caulk around windows or doors connected to your aluminum siding by pressing the tip of the tube into the crack and moving the tip in a straight line from one side to the other. Pull the trigger on the caulking gun or squeeze the tube of caulk as you go.

Step 10

Wet your finger and press the caulk into the gap between the window or door and the aluminum siding and pull your finger right across the gap, wiping your finger off on the wet rag as you go. Rinse the rag in the water when necessary. Allow the caulk to dry per the manufacturer's instructions before painting.


When caulking siding it is important not to use too much caulk. As long as the gaps and tiny cracks are filled there is enough caulk. When only caulking small areas, a squeeze tube should be sufficient. If caulking several windows as well as a couple doors, however, you will likely want to use a caulking gun.


When caulking siding always wait until the caulk is dry before painting. Check the forecast to make sure it won't be raining in the next couple days to be sure the caulk will not get wet before it is completely dry.


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