Can You Put Dicor on Top of Dicor? Is It Beneficial?

Dicor is a popular sealant used widely in RV roof repair and maintenance. It is a self-leveling sealant that evenly flows across roof surfaces to seal cracks, gaps and leaks. When applied properly, Dicor forms a waterproof barrier that protects RVs from exterior damage.

The short answer is yes, you can safely apply an additional layer of Dicor sealant on top of existing Dicor. As long as the underlying Dicor is still well-adhered, adding more Dicor can help reinforce and further waterproof the roof. Multiple coats of Dicor are often used for repairs or filling deep cracks.

Applying Dicor sealant serves important protective purposes for RVs. It seals the roof from water damage, prevents leaks, fills gaps between roof components, and helps reflect UV rays. While a single application is usually sufficient, additional Dicor coatings can be added to restore an aging roof system or prepare surfaces for new roof installations. Using Dicor properly is key to extending RV roof life.

Can You Put Dicor on Top of Dicor

Can You Put Decor on The Existing Decor?

Yes, you can apply Dicor on top of existing Dicor. Begin at the back of your coach and work forward. When you find areas sealed with lap sealant, clean off the weather-darkened old sealant using mineral spirits and a rag. This blackening is actually dirt, and cleaning ensures proper adhesion for the new sealant.

You don’t have to remove all the old sealant; just touch up cracked areas. Dicor lap sealant is designed for layering. Wear disposable gloves, wipe down areas with mineral spirits, and let them dry completely. Work methodically from the back to the front of the RV, cleaning small sections at a time. Once an area is prepped, you can begin applying the new Dicor sealant while the rear sections are drying. Tape off sections as needed to avoid dripping. Carefully follow the product instructions for ideal temperature and humidity during application. Dispense the Dicor in a continuous, 1/4-inch bead, allowing it to self-level. Applying in sections works better than trying to coat the entire surface at once.

With proper prep to remove grime and ensure adhesion, plus disciplined application technique, additional layers of Dicor can be built up as needed over time. Just allow each new layer to fully cure before adding more. Patience and care will be rewarded with a more durable, leak-proof seal.

Factors Determining Whether to Apply Dicor over Existing Dicor

In most cases, you can apply a new layer of Dicor sealant over an existing layer of Dicor sealant. However, there are a few situations when you should not apply a new layer.

Condition of the Existing Dicor Sealant

The condition of the existing Dicor sealant is one of the most important factors to consider when deciding whether or not to apply a new layer.

Flexible and Adherent Dicor: If the existing Dicor sealant is still flexible and adherent, you do not need to remove it before applying a new layer. Simply clean the surface thoroughly and apply a new layer of Dicor sealant.

Cracked or Peeling Dicor: If the existing Dicor sealant is cracked or peeling, you should remove it before applying a new layer. Cracked or peeling sealant will not provide a good base for a new layer, and the new sealant will not adhere properly.

Hard and Brittle Dicor: If the existing Dicor sealant is hard and brittle, you should remove it completely before applying a new layer. Hard and brittle sealant is no longer effective and will not provide adequate protection for the roof.

Other Factors to Consider

In addition to the condition of the existing Dicor sealant, there are a few other factors to consider when deciding whether or not to apply a new layer:

The thickness of the existing sealant: If the existing Dicor sealant is more than 1/4 inch thick, you should remove it before applying a new layer. Applying a new layer of sealant to an already thick layer will only make the sealant thicker and more prone to cracking and peeling.

The cleanliness of the roof: The roof must be clean, dry, and free of debris before applying Dicor sealant. If the roof is not properly prepared, the sealant will not adhere properly.

The weather conditions: Dicor sealant should not be applied in cold, humid, or windy conditions. The sealant will not cure properly in these conditions, and it will be more likely to crack and peel.

If you are unsure whether or not you should apply new Dicor sealant over existing Dicor sealant, it is always best to err on the side of caution and remove the old sealant. This will ensure that you get a good, lasting seal and protect your roof from leaks.

Guidelines for Applying Dicor Over Existing Dicor

Before applying new Dicor over existing sealant, follow these simple guidelines to ensure a successful and lasting seal:

A. Assess the condition of the existing Dicor: Before applying new Dicor over existing sealant, evaluate the current state of the Dicor. If it is still flexible and firmly adhered to the surface, you can proceed with reapplication.

B. Remove hard and brittle Dicor completely: If the existing Dicor has become hard and brittle, it’s crucial to remove it entirely. This step ensures proper adhesion of the new sealant and prevents issues that may arise from the old, ineffective sealant.

C. Clean the surface thoroughly: Prepare the surface by cleaning it thoroughly. Remove any debris, old sealant residues, or contaminants. A clean surface provides a better foundation for the new Dicor sealant.

D. Apply new Dicor in a continuous bead: When applying the new Dicor, use a continuous bead along the intended sealing area. This application method ensures a consistent and effective seal, minimizing the risk of leaks or other potential problems.

E. Smooth the bead for a uniform seal: After applying the bead of Dicor, use a tool or your finger to smooth it out. This step helps achieve a uniform seal and enhances the overall appearance. It also contributes to the effectiveness of the sealant.

F. Allow the sealant to dry completely: Once applied, allow the Dicor sealant to dry and cure completely before exposing it to external elements. This drying period is crucial for optimal performance and longevity of the seal.

Reasons for Removing Hard and Brittle Dicor

Before applying new Dicor, it is essential to understand why removing hard and brittle Dicor is necessary for effective sealing and maintenance.

A. Adhesion issues due to lost flexibility: Hard and brittle Dicor loses its flexibility over time. If left in place, the new layer may struggle to adhere properly. Removing the old, inflexible sealant ensures better adhesion and a stronger bond with the surface.

B. Risk of crack propagation through the new layer: Hardened Dicor is prone to cracks. Applying a new layer over cracked sealant may allow cracks to propagate through the new layer, compromising the integrity of the seal. Removing the old, cracked Dicor helps prevent this risk.

C. Importance of proper surface preparation for new Dicor: Effective surface preparation is crucial for the success of the new sealant. Removing hard and brittle Dicor ensures a clean and smooth surface, providing an ideal foundation for the application of the new Dicor.

D. Achieving a uniform seal for leak prevention: Hard and uneven Dicor surfaces can lead to an uneven application of the new sealant. Removing the old, hardened layer allows for a smoother application, ensuring a uniform seal that is less prone to leaks.

E. Preventative maintenance to identify underlying issues: Removing hard and brittle Dicor provides an opportunity for a thorough inspection. This preventative maintenance step helps identify any underlying issues, such as water damage or structural concerns, before applying the new sealant.

By addressing these reasons, you contribute to the longevity and effectiveness of the new Dicor sealant, ensuring a secure and reliable seal for your RV or other applications.

Frequently Asked Questions (FAQs)

Q1. Can Dicor be applied on top of silicone sealant?

Yes, Dicor adheres well to cured silicone, so it can be safely applied over top of silicone sealants on RVs. Ensure the silicone is fully cured before applying the Dicor.

Q2. How often should Dicor be reapplied?

Dicor should be reapplied every 2-3 years to maintain maximum roof protection. Check for cracks or signs of damage annually. Reapply as needed to touch up problem areas. 

Q3. Is there a maximum number of layers of Dicor that can be applied?

There is no set limit, but 5 coats is generally the recommended maximum thickness. Too many layers can cause drying and curing issues. As long as the existing Dicor is well-adhered, additional layers can be added.

Q4. Can Dicor be used on EPDM RV roofs?

Yes, Dicor is EPDM-compatible and creates a super durable seal on EPDM (ethylene propylene diene monomer rubber) roof materials. It will not react with or break down EPDM over time. Proper prep is key.

Q5. Is Dicor environmentally friendly?  

Dicor is over 90% solids so it has low VOCs. It is free of isocyanates, harsh odors and is considered relatively environmentally friendly for sealants.


Applying additional layers of Dicor over existing well-adhered Dicor is safe and can further improve the protective seal on RV roofs. Proper surface prep and following product instructions for application temperature and thickness is vital for ideal curing and performance. Regularly inspect Dicor seals for cracks or damage, reapplying layers as needed to touch up flaws. Maintaining the Dicor roof barrier through proper inspection and reapplication helps prevent leaks, water damage, and deterioration, extending the life of the RV for years of enjoyable traveling.

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