Option # 1. So if we are to attempt to clean that roof, we would not clean it if we thought it wouldn’t last at least another 5 years, or 3 years, or whatever your cutoff would be. You would hire us to clean it and we either clean it or not depending the roofs integrity that same day. If not, then we can generate a good game plan and talk about some other options for the roof structure.
Option # 2. We could do a full on thorough inspection of the roof before we do any work, that way there are no surprises and you will know a lot more about what it needs and our opinion of how long it should last. There is a 95.00 cost for this but you will get photos of any repairs needed, will know if a cleaning is the right thing to do, and will give our ballpark opinion of how long we think it shall last.
Option # 3. You have an honest roofing contractor look at it and tell you what he or she thinks. A good one should be able to get in the attic, check ventilation and insulation, check how many layers, and give you a rough idea of what they think for the time left on it is. I know a good one who can do all of this if you need a good referral.
You can do option 2 and 3 together.