Join the MRA | Member Login
Find a Professional
  • Why Metal Roofing?
    • About MRA
    • Benefits of Metal Roofing
    • Compare Roofing Materials
    • Homeowner Testimonials
    • Inspiring Metal Roofing Projects
  • Homeowner Resources
    • Metal Roofing Buyers Guide
    • Resilient Housing Guide
    • Metal Roof Sustainability Guide
    • Above All Else You Need a New Roof eBook
    • MRA News
    • Member Provided Resources
    • 3rd Party Articles
    • Frequently Asked Questions
    • Preparing for Hurricane Season
  • Gallery
  • Visualizer
  • Ask The Experts
    • Energy Efficiency
    • Existing Metal Roof Questions
    • Installation
    • Is A Metal Roof Right For My House
    • Metal Roofing Benefits
    • Product Selection
    • Other
    • Archive
  • Find a Professional
Join the MRA Member Login
Sign Up Log In Add New Topic

TOPIC: Maintenance

Mildew on rafter tails and purlins

Return to Maintenance

Return to Archive

Return to Forum

This topic has been closed by the administrator. Comments are no longer accepted.
I built a new vacation home on the water in Florida three years ago. I have a Galvalume roof with exposed rafter tails and purlins. About 6 months after construction, the rafter tails and purlins became black with mildew. I thought that it was the fault of the paint job. Six months ago, I had the house repainted by a very good paiinting coontractor. He pressure washed it thoroughly and applied a very high quality paint with extra mildewside. The rafter tails and purlins have already started to mildew badly. Please let me know if you have ever encountered this problem and if there is a remedy. Thanks for your help.
Jim Hardee

5/10/2004
Share
Or copy this URL: https://www.metalroofing.com/spirit/comment/3131/find/
I assume the rafter tails and purlins are wood. Unlike Galvanized metal, Galvalume does not leach off zinc at the same rate which makes the Galvalume last longer however it does nothing to kill mildew. Galvalume does not support mildew, mold etc and providing you have a positive slow, flushes everything off with each rain. I suspect that somehow the rainwater is getting on your framing mambers. Metal on lower slopes tends to sipho water back up under the leading edge with the smooth surface. Quite possibly your builder did not install a drip edge which stops the problem. Have a look and if you have any further questions, please contact me directly with a photo.
Allan Reid
Dura-Loc Roofing Systems, Inc.

5/10/2004
Share
Or copy this URL: https://www.metalroofing.com/spirit/comment/3132/find/
I have a 70 year old house with Asbestos shingles on the roof. It has been a great roof all these years, but it starting to break-up in places now. my question is can I have a verticle metal roof installed over top of it? thanks Charlie
Guest User

5/10/2004
Share
Or copy this URL: https://www.metalroofing.com/spirit/comment/3133/find/
Thanks for your reply. The rafters and purlins are wood. I'll send you photos. The painter thinks that condensation is building up between the metal and the tails and purllins and causing the mildew. Please let me know if this is common and if there is a method of preventing it. Also, is it standard practice to prime and put a finish coat on the tops of the tails and purlins prior to installing the roof. Jim
Jim Hardee

5/11/2004
Share
Or copy this URL: https://www.metalroofing.com/spirit/comment/3134/find/
There have certainly been instances of successful installations over asbestos shingles. This is usually done either with one of the shingle, shake or tile metal products or with a vertical seam product, in which case the vertical seam product would have to be installed over battens. I suggest working with the manufacturers of products you like to determine how appropriate this type of installation for your situation. If you go to my company's website (www.classicroof.com) and click on For the Architect, you can go to our list of Technical Bulletins and download our bulletin on Roofing over Asbestos. Todd Miller
Todd Miller
Isaiah Industries, Inc.

5/11/2004
Share
Or copy this URL: https://www.metalroofing.com/spirit/comment/3135/find/
  • About the MRA
    • Member Companies
    • Leadership
    • MRA News
  • For Professionals
    • Join the MRA
    • Industry Resources
    • Upcoming Events
  • Contact
  • Subscribe
©2023 Metal Roofing Alliance. All Rights Reserved. Privacy Policy Terms and Conditions