Refresh Your Home's Exterior: Re-Caulk House Siding

Caulking is a sealant that fills gaps, cracks, nail holes, and other similar imperfections on the surface of a house's siding. It is an important maintenance task as it prevents moisture from penetrating and causing leaks and deterioration. When deciding how to recaulk your house siding, it is crucial to consider not only where to apply the caulk but also where not to use it, as incorrect placement can cause more damage than good. This guide will provide an overview of the process, including choosing the right type of caulk, preparing the surface, and applying the caulk effectively.

Caulking butt-joints

Butt joints are where two pieces of siding meet, and they can be end-to-end or end-to-face. Caulking butt joints can be tricky because they are too small to accommodate a bond-breaker (backer rod), so the caulk can't stretch properly once applied. However, they are also too large to be left alone, as they can let in a lot of moisture from rain, snow, or sprinklers, which can cause serious and expensive damage.

The need to caulk butt joints depends on the manufacturer and the installation method used when the siding was first installed. Generally, butt joints on cedar siding should not be caulked because natural siding boards are designed to expand and contract with the elements, and adhesive can prevent their natural movement. Butt joints on cedar siding should only be caulked if they were previously caulked. Fiber cement boards are caulked only when there is no metal flashing behind them. If there is no metal flashing, the butt joint should be caulked to keep the pieces together and prevent moisture.

If you are using primed siding, you must seal all exposed cuts of siding, including those at butt joints. Butt joints that are covered with joint moulding, sealant, or factory prefinished end are considered sealed from the weather. If the siding is prefinished, the gap does not require a sealant or joint moulding when backed with a minimum of 4-inch-wide flashing, and the ends of the siding are factory-finished.

To repair buckling due to improper installation, you will need to separate the affected piece of lap using two wooden wedges. Then, slide a piece of metal sheeting behind the butt joint to protect the house wrap. Use a keyhole or reciprocating saw to create a proper 3/16" space between the two pieces of siding. Remove any sawdust, dirt, or debris from the gap. If any piece is deflecting against the side of the wall, face-nail only that area to flatten the piece back against the wall. Properly caulk and paint all exposed nail heads. Prime and seal the gap using a brush, following the manufacturer's instructions. Finally, finish the repaired area with exterior paint.

Sealing corners and crevices

Prepare the Surface:

Before applying any caulk, it is crucial to remove any old caulk, debris, or paint that may hinder the adhesion of the new caulk. Use a utility knife and a putty knife to carefully cut and scrape away the old caulk. Ensure that the surface is clean and dry before proceeding.

Choose the Right Caulk:

The type of caulk you select will depend on the material of your siding and the size of the gaps or cracks. Latex, silicone, butyl rubber, or a mixture of these ingredients are common options. Butyl-rubber is often recommended for exterior siding as it can withstand changes in temperature and repeated exposure to outdoor elements. You can also choose a caulk that matches the colour of your siding for a more aesthetically pleasing result.

Apply the Caulk:

Using a caulking gun, apply a continuous bead of caulk along the corners and crevices, ensuring that you fill the gaps completely. Work carefully and use both hands to grip the gun to avoid shaking or slipping, which may result in a messy application. Remember not to use caulk for gaps larger than 1/4 inch; instead, use a foam backing rod to provide adequate support.

Smooth and Wipe Away Excess:

After applying the caulk, use a damp cloth or towel to smooth out the caulk and remove any excess product before it sets. This step is crucial for achieving a clean and professional finish.

Allow Curing:

Once you have completed the caulking and smoothing process, allow at least 24 hours for the caulk to cure and fully dry. Refer to the manufacturer's instructions for specific curing times, as they may vary depending on the type of caulk and environmental conditions.

Remember, when caulking exterior siding, it is just as important to know where not to use caulk as it is to know where to apply it. Avoid caulking wood siding, as it can prohibit the natural expansion and contraction of the wood. Additionally, refrain from caulking the bottoms of horizontal siding sheets or the edges of tongue-and-groove panels, as this will interfere with the natural waterproofing and movement of the panels.

Choosing the right caulk

When searching for the right caulk for your house siding, quality is important. There are several other factors to keep in mind when making your decision.

Types of Caulk

Siding caulk comes in a variety of materials, including latex, silicone, butyl rubber, or a mixture of these ingredients. All of these materials have different properties and are meant to be used for specific situations.

Exterior Use

Butyl-rubber is sometimes recommended for exterior siding since it’s a specialty outdoor caulk that can withstand changes in temperature and repeated exposure to the elements. However, you can choose any exterior caulk that will bond to your siding. Just make sure to read the labels and spot-check on an unseen portion of your siding.

Color

It is possible, and for some homeowners preferable, to color-match your caulk to your siding. Some siding companies stock bespoke caulks in pre-matched colors that will go perfectly with your siding. While it is ultimately up to you to determine the color, we would recommend choosing something inconspicuous in a shade slightly lighter than your siding—avoid white unless your siding is white. Remember that your caulk color and siding won’t match exactly since caulk and siding are made from two different materials with different consistencies.

Caulking trim boards

Caulk is a sealant that fills gaps, cracks, nail holes, and other imperfections on the surface of your home's exterior. It is important to use caulk on your trim boards to prevent moisture from penetrating the cracks and joints, as well as to improve the overall appearance of the surface. Here is a step-by-step guide to caulking your trim boards:

Step 1: Prepare the surface

Start by cleaning the surface and removing any existing caulk or dirt so that the new caulk can adhere correctly. You may also want to tape the area to ensure straight lines of caulk.

Step 2: Choose the right caulk

For trim boards, it is recommended to use an interior, paintable, latex caulk. Latex caulk is easy to clean up, dries quickly, and is inexpensive. Choose a white colour if you plan to paint the trim, or a colour that matches the finished wood colour if you prefer a clear finish.

Step 3: Cut the nozzle

Cut the nozzle of the caulk tube at a 45-degree angle, about 1/8" to 1/4" away from the tip of the tube, depending on the size of the bead you want. Cutting the tip at an angle will allow you to better position the tube when applying the caulk.

Step 4: Break the seal

Use a nail, wire, or the puncture tool attached to your caulk gun to break the inside seal of the tube by inserting it into the nozzle hole. Puncture the seal a few times to ensure a smooth flow of caulk.

Step 5: Load the caulk tube

Adjust the rod of the caulk gun and insert the tube onto the frame, making sure the plunger is against the bottom of the caulk tube.

Step 6: Apply caulk to the trim

Starting at one end of the trim, place the nozzle of the caulk at a 45-degree angle where the trim meets the wall or wherever there is a gap. Pull the trigger slowly to apply pressure and move the nozzle steadily along the joint to fill the gap with an even bead of caulk. Work in sections if you have a lot of caulking to do, as you don't want the caulk to dry before you can smooth it.

Step 7: Smooth the caulk

Use your finger to smooth the caulk and create a professional-looking finish. First, dampen your fingertip with a wet cloth or paper towel. Then, lightly run your finger along the length of the bead to create an even finish. Remove any excess caulk with your finger and wipe it onto a damp cloth.

Step 8: Let the caulk dry

Once you have finished applying and smoothing the caulk, let it dry according to the instructions on the tube.

Tips:

• It is recommended to caulk before painting, as it will give you a seamless finish.
• If you are caulking around windows, be sure not to caulk the window weep holes, as these are designed to let water out.
• Do not caulk trim boards that sit on top of the siding, as this will prohibit air circulation and cause a damp environment.

Removing old caulk

To effectively remove old caulk, you'll need to follow a few important steps. Firstly, cut through the old caulk using a utility knife or a putty knife. Try to make your cut as precise as possible to avoid damaging the underlying surface. After cutting through the caulk, use your fingers or pliers to pull out the caulk gently. Be careful not to scratch or damage the surrounding area.

Once you've removed the bulk of the caulk, use the putty knife to scrape off any remaining residue. Scrape carefully and thoroughly to ensure you get rid of all the old caulk. If necessary, you can use a heat gun to soften the caulk, making it easier to scrape off. Just be cautious not to apply too much heat, as this can damage the siding or surrounding materials.

After scraping, you'll likely need to sand down the surface to create a smooth and clean finish. This step is crucial for ensuring the new caulk adheres properly. Use fine-grit sandpaper and sand in the direction of the grain if you're working on a wood surface. If the siding is made of another material, such as vinyl or aluminium, choose a suitable sandpaper grit designed for that material.

Finally, it's essential to clean the area before applying new caulk. Use a damp cloth or brush to remove any dust or debris generated during the removal and sanding process. Ensure that the surface is completely dry before you begin caulking. Additionally, you can use a primer or sealant to further prepare the surface and enhance the adhesion of the new caulk.

Frequently asked questions