I am the president of a patio home/condo association in Louisville, Kentucky.  Our units are now 18 years old and need to be re-roofed.  We have several men in our community who insist that we lay over the existing shingles rather than tear off and shingle.  They say the difference of the life of the roofs is two years.  We've had many, many leaks over the years.  Apparently the valleys were put in wrong.  The leaks happen mainly when we have hard rains, but they have leaked other times.  My question is, can we lay over roofs that leak?  And for 20-year shingles, is the lifespan of laid over roofs 18 years?  Thank you very much for your attention to this, and I look forward to your response.

2012 Angie\'s List Award Rooftime In CIncinnati
2012 Angie's List Awar  

Rooftime is an A-Rated Member
Rooftime is an A-Rated  
Anything that was installed incorrectly, and remains for any reason on the roof, is still there, still wrong, even when covered by new material.

If you have had a large amount of leaks over time, you should strip it down to inspect for wood sheathing damage.

Using new dimensional shingles over proper underlayment, on a solid wood deck, should equate out to a 30 year minimum roof system.

The main problem I have found when working on condo / apartment complexes is the fact that the wood deck tends to be thinner then the 7/16 - 1/2" you really need as a minimum. Shingles are measured in 10' x 10' sections we refer to as a SQUARE.

One square of typical 3-tab shingles weighs abut 285 pounds. Adding a second layer adds another 300-350 pounds in that 10X10 box area. A wood deck that is 3/8" or 5/8" will be stressed badly by this added weight. IF you get a few bad heavy wet snows, you can actually cause the deck to dip and warp from weight that exceeds the load factor.

It is ALWAYS advisable to strip a roof down and rebuild it to a better standard than the builders used.

Good Luck!  


All Answers

Answers by Expert:

Ask Experts


Dale Rooftime Shoemaker


Follow us on TWITTER: search Dale Rooftime Follow us on FACEBOOK: search Dale Rooftime Shoemaker A residential roofing specialist. Owens Corning Preferred Contractor 2010-2012 Owens Corning Top Of The House Certified 2010-2012 Velux Skylights Certified Installer 2008-09. Box Gutter craftsman. Coppermsmith / Tinner. Certified EPA Asbestos Handler GAF Master Elite Contractor ELK 2006 Roofer of the Year / Midwest Region Owens Corning Preferred Contractor-1996 Certainteed Lifetime Wizard Certainteed Shingle Master Certainteed Quality Master Angie's List Super Service Award winner: 2006-2007-2008-2009 Press Community Paper, Cincinnati's Favorite Roofer 2009


A second generation roofer, working my son into the business now! We are certified FIBERGLASS insulation installers. We sell and install PINK FIBERGLASS loose-fill and Radiant Barriers. We are Cincinnati - Northern Kentucky's "GREEN" contrcator: recycling our waste material, lowering home energy costs, improving our world one job at a time!

National Roofing Contractors Association, National Roofing Contractors Association, Midwest Roofing Contractors Association, Kentucky Roofing Contractors Association, Ohio Roofing Contractors Association, Tri-state Roofing Contractors Association, HBA-NKY, BBB, Angies List, Professional Roofers Advisory Council 10 Year Member

Professional Roofers Magazine, Slaters Journal, Press Community Paper

GAF Roof School 2005 MRCA Shingle Course 2006

Awards and Honors
Angie's List Super Service Award Winner 2006, 2007, 2008

Past/Present Clients
WLWT, Gold Star, Auto Zone, Ryans Allglass, McAlpins, Wendy's, Quick Stop,

©2017 All rights reserved.