How to Seal a Roof Without Professional Help
Give your roof an extra layer of protection
Repairing or replacing a roof can be a complex, time-consuming, and costly process, particularly if you are living in the home while work is being done. Applying a seal coat is a great way to extend the lifespan of your roof, whether it is brand new or you want to squeeze a few more years out of it.
Seal coats are an absolute must for flat roofs to prevent water from building up and leading to moisture damage later on. Applying a dedicated sealant is also important for sloped roofs, as the coating shields the surface from UV damage and improves your home’s energy efficiency. Better yet, this is a DIY-friendly job, though it is not without its hurdles. Read on for step-by-step guidance on how to seal a roof on your own.
What Does Sealing a Roof Mean?
Sealing your roof means that you install a coat of sealant. This sealant helps increase the lifespan and durability of your roof against harsh weather and UV rays. Sealants can also increase the waterproofing, fire resistance, and mold resistance of your roof.
Types of Roof Sealant
These are the most common roof sealant types available on the market:
Polyurethane
Silicone
Acrylic
Liquid rubber
Sealant tape
These products are either water-based or solvent-based. Water-based sealants are thinner and more budget-friendly, although they require more frequent reapplication. Solvent-based sealants cost more but are best for protecting your roof against severe weather.
Additionally, here are the sealant types to consider for different goals:
Increased waterproofing: rubber, silicone, polyurethane
Increased UV ray resistance: rubber, silicone, polyurethane, acrylic
Easier to install: water-based rubber, acrylic
For rainy and snowy areas: polyurethane
Small repairs: sealant tape
Cost to Coat a Roof With Sealant
Roof coating costs $0.65 to $5 per square foot, depending on the type of sealant you choose.
Preparing to Seal a Roof
First of all, this process is conducted primarily on the roof, which is not the safest place to be, especially if you are inexperienced working at heights. If you decide to seal a roof yourself, be sure to wear protective gear, use a sturdy ladder, and have a friend or family member on hand to help. Also, gather up all of your supplies and tools so you do not have to go reaching for anything later on. And make sure to purchase the right sealant type for your roof.
The last preparatory step is to climb the ladder and check out the state of your preexisting seal coat. Clear away any flaking or loose sealant with a stiff brush and brush off any rust if you are working on a metal roof. You should also remove any chunks of debris or anything else out of the ordinary, like old bird’s nests and the like.
6 Steps to Sealing a Roof
After you finish the preparatory work, move on to these six steps to seal your roof properly.
1. Clean and Rinse the Roof
You already removed debris, residual seal coat, and rust, but now it is time to give the roof a proper cleaning so the new sealant applies evenly. The best cleaning solution for the job is an etching cleaner such as trisodium phosphate, otherwise called TSP. Start by mixing around half a cup of TSP into two gallons of hot water. If you noticed some mildew on the roof during your initial inspection, add a quart of bleach to the solution and cut down the water by a quart.
Always wear protective eyewear when working with TSP. Once you are properly protected, apply the solution to the roof with a stiff brush or a sprayer of some kind. Allow the compound to sit for a while (check the TSP’s instructions for specific time details) and finish it off with a thorough rinsing with water.
2. Make Minor Repairs (Optional)
If you notice any leaks, holes, or other types of damage to the roof or specific parts of the roof, like the flashing, now is the time to make the necessary repairs. Give the roof another inspection now that it is clean to look for any damage that eluded you earlier. Grab your caulking gun and caulk seams throughout the roof. Patch up any holes or leaks with a simple roof patching kit. These kits differ in many regards, but the process typically involves applying a layer of the patching compound, adding a layer of a reinforcing grid mesh, and finishing with another layer of patch. Reinforcing grid mesh ships with roof patch kits and is a flexible mesh coating that bonds with the patch.
3. Apply a Primer Coat
This step is potentially optional, as some sealant compounds already feature a primer as one of the primary ingredients. In other words, read the instructions that accompany your sealant. If it says to add primer ahead of time, use a roller or soft roof brush to apply a layer of primer to the entire roof surface. Allow it to dry before moving on to the next step.
4. Check the Weather (and the Sealant)
Before you actually apply a coat of sealant, check the instructions and find out if there are any temperature or weather restrictions, as some compounds require specific temperature ranges and humidity levels to bind properly to the roof materials. If the weather does not comply with the sealant’s demands, put these final steps of the project on hold until the perfect day presents itself. Some sealants are not picky regarding outdoor conditions. If this is the case, move on to the application process.
5. Apply the Sealant
Now it is time to apply the roof sealant. Start by pouring a small amount of the seal coat onto the roof and using a soft roof brush to spread it into a thin and even coat. Work slowly and carefully in small sections until you have covered the whole surface of the roof with a coat of sealant.
Some people stop here, but many roofs benefit from a second coat, though only you know the specific needs of your roof. Wait four to six hours for the first coat to dry before starting on the second. When applying the second and final coat, make brush strokes that are perpendicular to the strokes you made when applying the first coat. This helps create strong and stable layers.
6. Dry and Touch Up
Allow the sealant to dry for at least six hours, though overnight is the best choice here. Once fully dried, climb the ladder for the last time to inspect your work, carrying the sealant with you. Inspect the dried coat thoroughly, looking for any areas you accidentally missed during the initial application. Touch up these spots with the sealant until you are satisfied with the results. Allow these spots to dry and, voilà, you have a newly sealed roof.
Tips for Sealing a Roof Properly
To seal your roof properly, you should first make sure you are using the right sealant type for your goals and type of roofing material. Roofing products usually specify which materials they work best on, so check the details before purchasing.
Make sure to take your time during the cleaning process, because any leftover dirt, moss, or other debris will prevent you from installing the sealant evenly on your roof.
And before you start working with the sealant, take time to cover any important landscaping or outdoor furniture around your home. That way, you will not have to worry about accidentally spilling sealant and causing damage.
DIY Roof Sealing vs. Hiring a Pro
This is a time-consuming and potentially dangerous job, as the lion’s share of work is conducted at great heights on top of your roof. The potential danger involved in this process is why many homeowners contact a local roof sealing company, as these contractors are experienced and insured for the work. However, the work itself is not terribly difficult and is appropriate for DIYers with experience in laying down paint, primer, and related materials. Additionally, a good chunk of the time commitment involves waiting for coats to dry.
If you are dead set on doing it yourself, make sure to have helpers available to stabilize the ladder and deliver important materials and tools while you are on the roof. You could save up to $1,000 by doing it yourself, as most contractors charge between $35 and $90 per hour for this type of work.
Frequently Asked Questions
This depends on the design of your roof and any preexisting issues. If you have water and puddles pooling, no matter the roof type, apply a coat of sealant immediately. Beyond that, seal a flat roof every five years, though constant rain and snow hasten this time frame to three or four years. Add a few years for sloped roofs, waiting six to eight years between applications, as water does not pool with these designs.
Roof sealant is available in a wide variety of compounds to suit different environments and roof types. The most common compound is acrylic roof sealant, which is great at deflecting UV rays. Other popular products include polyurethane, rubber, and silicone. Each type requires unique weather conditions for a successful application, so read the instructions for starting.
Hiring a pro to seal a roof costs $450 to $2,100, with an average price of $1,300. The cost fluctuates according to roof size, roof design, preexisting issues like leaks, and accessibility concerns. These costs take additional procedures into consideration, like power washing before adding a layer of sealant and patching up holes.