Recently I inspected the roof pictured above. My visual inspection revealed at least three layers of asphalt shingles. Without removing each layer there was no way to be sure that a fourth lay hidden beneath. Most homeowners who opt for a re-roof do so to save money in labor costs. Under ideal circumstances, the average savings is about 25%. Those ideal circumstances include solid decking, no existing leaks, and a roof with no sidewalls or chimneys where flashing is needed. Add to that the fact that a re-roof likely won’t last as long as a new roof on solid decking and you are left with a job that could end up costing you more.
Now that we have reviewed the upside, let’s look at the downside.
- Number one: If you don’t strip off your shingles and tar paper down to the sheathing, you will never know the condition of your sheathing. Sheathing rot and water damage are common even in properly installed roofs.
- Number two: with an overlay, you forfeit the opportunity to install an ice and water-leak barrier directly to the wood decking. Without this, ice could travel up the old layer of shingles, melt and leak into the home.
- Number three: as mentioned above, flashing around roof penetrations are harder to address and can easily be compromised leaving the roof vulnerable to adverse weather conditions.
- Number four: a second or third roof adds tons of weight to the roof framing and this could be a big problem if there is significant snow accumulation.
The Final Word – all of us are used to making decisions based on the pros and cons. In this case, the answer is obvious.