Best new roof option
We are currently getting estimates to have the roof replaced on our 15 year old, two story colonial. We live in Syracuse, NY where the average yearly snowfall is 115.6". Would it be okay to have the new roof installed over the original roof? I know "roof overs" are done all the time but I worry about the extra weight that this would add in addition to the snow. The tear off would involve new flashing, rubberized leak barrier on eaves, valleys and etc. I assume that in most new construction they don't put down leak barrier. What are your thoughts? Thanks.
g iRe: Best new roof option
It's the consensus of most people in the roofing industry today that all old shingles should be removed.
The points you mention in your post are valid; not only should a waterproof membrane be put on, especially in your case where long freezing winters are almost certain to threaten roof leakage due to ice dams at the eaves and valleys, but you would also avoid the extra weight involved in multiple roof layers.
Ice dams are very common in any area where heavy snow occurs, so it is important to strip the old shingles and put on a waterproof membrane along the lower sections of the eaves; that way, when freeze-thaw cycles occur, you have assurance that you won't get any leaks inside the house that will destroy ceilings and walls.
Most new installs also include a ridge vent, if one is not already present; this is designed to work with the soffit vents and adequate attic insulation to prevent hot air from accumulating in the attic which would cause ice dams at the eaves.
The appearance of a single-layer roof looks 1000% better than you would ever get with a 2nd layer, the new flashing and neat fit makes it a pleasure to look at a new roof that will dress up the appearance of the house for many years to come.
A 2-layer roof simply doesn't have the lasting power of a single-layer installation, & it will have to be replaced much sooner; it's false economy for the homeowner to skimp on a re-roofing job and live to regret it later on down the road.
Last edited by dodsworth; 10-23-2010 at 12:07 PM.