The Cost of Flashing a Chimney

Last Updated on December 27, 2023
Written by CPA Alec Pow | Content Reviewed by CFA Alexander Popinker

Flashing a chimney is an essential step in the process of waterproofing, and for good reason – if not properly flashed, water can infiltrate into the chimney and can lead to expensive repairs. Even if your housețs chimney has been properly flashed before, it doesn’t mean you don’t need another inspection every year or so – because from time to time there may be new leaks popping up around the chimney that wasn’t present when last inspected.

How much does it cost to replace chimney flashing?

On average, a chimney flashing job can cost anywhere from $250 to $1,000. This price really is going to depend on the type of material you have for your chimney as well as what kind of work needs to be done. The professional doing the job will also have an impact on the final bill. They will need to do their onsite assessment so that they know how much time it’ll take them before they’re able to provide an accurate estimate for the project’s total cost.

You might also like our articles about the cost of chimney cap installation, flat roof replacement, or standing seam metal roof installation.

There are many different types of metals that can be used for these purposes but galvanized steel and aluminum will usually be the most affordable option. For example, if you want to use copper (which is more expensive), it could cost up to 40% or 50% more than using standard metals such as galvanized steel or aluminum.

When you have a metal chimney with an interior stainless steel flue duct, the costs can be around $300 to $600 to have it flashed at the point where it is penetrating the roof. If your chimney is made of brick and needs new flashing, then these costs could rise up to $500-$1,500 depending on which sides need work.

For example, if you have a large multi-flue chimney and you think that it needs flashing down the sides, then it could easily cost over $1 000. The cheapest option is usually done when people are getting their roofs replaced and can range from around $150 to approximately $250.

One commenter on Angie’s List said: “I would expect most flashing jobs to be within the $250 – $400 range if it is a base flashing job.”

The average chimney flashing job could be in the $200 to $500 range, depending on your type of roof, according to Baumgardt Home Inspections, located in Wisconsin. For example, a flat built-up might cost you about between $300 and $500 for materials alone, while an asphalt sloped roof would only run you $200 to $400.

Details on flashing a chimney

It’s important to have flashing installed between your chimney and roof for protection against water seeping in. Flashing will have two-panel parts: step flashing, which goes underneath shingles and bends upward against your chimney, then counter flashing, which wraps around over top on the first part before being cut back into mortar joint near the top.

In general, contractors will first inspect the chimney’s deck around it to see if there is any damage in need of repairing. Once they’ve cleaned out all the existing flashing and assured that everything looks sound, a cricket may be built on top of your roof for ventilation purposes. The next step will be all about grinding the mortar joints to make sure that the new counter flashing is secured to your chimney. First, a water barrier will be wrapped around it followed by securing shingles on all sides and back of the chimney. Lastly, they’ll install this type of flashing with fresh mortar in place for long-lasting relief from rainwater damage.

Any extra costs to consider?

The flashing material on the roof can be customized to match whatever color your roof has. This has a higher cost in comparison with using standard materials, which is why many contractors just use materials with generic colors that are close enough to the color of most roofs.

A chimney sweep is usually done along with this process. A contractor who advertises their service as “complete” might not always cover a chimney cleaning in addition to flashing the chimney, so it’s always a good idea to ask what you will get for the money.

If you wait too long before getting a flashing repair, your contractor may find serious structural damage. Moisture can enter through the roofing material and into the attic causing significant harm to both it and other parts of your home like drywall damage or wood rot that could cost even more money in repairs if they’re left unattended for too long.

Important tips to consider

One of the best ways to prevent a chimney flash from going bad is by hiring an expert. Many contractors are not properly trained and their work will only cause more damage in the future, so it’s crucial that you hire someone who knows what they’re doing when getting this job done.

Before you hire a contractor, do your homework and ask to see examples of their work. Not only will this give you an idea if they are qualified for the job but also help them feel more confident in themselves as well. You can also ask for before and after pictures or projects completed around you to see their way of doing their job.

Flashing installation can be difficult and often requires the help of a professional. Keep in mind that even if you think your flashing is installed correctly, there are still vulnerable areas where water can enter through small gaps/cracks which need to have special urethane caulking applied for maximum protection against leakage.

Is there any way to save money?

You can save money on your home insurance bill by asking the company if they will cover some or all of the flashing. Some homeowner’s policies are designed to protect against more than just fire and break-ins; many offer coverage for storm damage too, so you should see what is currently included in your policy.

Invest in a metal that will last longer, such as stainless steel or copper. These metals are expensive but you save money over the long term because they don’t need to be replaced as often and can go for decades without needing any repairs.

If you’re looking to take on a DIY project, flashing your chimney can be done in one day and requires less than $100 in materials. If this sounds like something that interests you, the Family Handyman has some great tips for how to get started – including where to find cheap kits online.