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Ask the Carpenter: New roof? Should you replace the skylight, too?

Ask the Expert Home Improvement
AP

In my remodeling travels, I’m often asked whether you should replace skylights when you re-roof.

Skylights have a service life, and replacing them when re-roofing is the best approach. In the long run, it’s more cost-efficient, and allows you to synchronize your roof and skylight warranties. You also have the opportunity to update with new features, technologies, and coatings.

The cost

If you reuse your old ones, the cost of reflashing them is between $200 and $600 per skylight. If you replace them, the expense is $800 to $1,500, depending on the type of skylight you choose. The price difference may be the decider for you, but you should know that roofers sometimes include a disclaimer stating that they will not be held responsible for future glass-seal failures or other leaks with older skylights.

There’s a reason for this disclaimer. An asphalt roof, for example, has a life span of 20 to 30 years, depending on the type of roofing material and weather exposure. A skylight’s life span is about the same. It costs a roofer less to replace a skylight when the roof has no shingles.

The technology

Today, skylight technology is far more advanced. I like a solar-powered one with a built-in rain sensor. When it detects rain, this sensor automatically closes the unit, and because it’s solar powered, there’s no need to hire an electrician. Solar-powered skylights also come with a touch-screen, programmable remote control, allowing you to customize venting options:

■ To open and/or close at select times;

■ To open a certain amount;

■ To open or close the blinds (increasing the thermal comfort of your home).

In addition to solar-powered features, today’s skylights come with special glass coatings to keep them cleaner and protect from UV rays. Low-E-3 glass improves energy efficiency by 35 percent over skylights manufactured in the 1990s.

The tax credit

This is probably the best part, and I’ve checked this with my accountant. A new skylight is now eligible for a 30 percent federal tax credit through December 2019.

Summary

As you can imagine, not every customer will take me up on this recommendation. Some folks are re-roofing only to sell their house. By replacing your skylights when you redo your roof, you’ll save money in the long run and ensure you won’t be paying for a new roof twice. It’s cheap insurance. If you push the life of a skylight past 25 years, you’re on borrowed time.

Rob Robillard is a general contractor, carpenter, editor of AConcordCarpenter.com, and principal of a carpentry and renovation business. Send your questions to homerepair@globe.com or tweet them to @robertrobillard. Subscribe to our free real estate newsletter at pages.email.bostonglobe.com/AddressSignUp.