What % of shakes need to be bad before you tell the client it might need a complete re-roof and recommend a roof consultant. Not contractor.
Ken it really comes down to how much (working) knowledge an inspector has with this type of roof. As a builder I have installed wood shakes and even today am fascinated with their beauty…especially the older roofs. I am not sure what your definition of “bad” is or how you determined they were bad however most of these roofs should be around for 30 years…those that were taken from old growth trees can last 50 years or more. So you see it really comes down to the price…it would be crazy to take seasoned shakes that still have substantial life and replace them with new growth shingles that may only last 20 years. Especially taking into consideration that most people only live in a house for 5 - 7 years and are gone. To replace a whole roof can be expensive…and unnecessary.
Many factors have to be looked at before truly suggesting that the whole roof be replaced…I wont even go into the hand drive versus air gun issue which has a dramatic effect on wood shakes / shingles.
My advice for inspectors is to simply advise their client to have a professional roofing contractor(s) that deal with these types of roofs evaluate it to help them make that determination.
For the owner it will come down to cost of replacing a few shakes / shingles or doing the whole roof.
Obviously an inspector needs to use some common sense when looking at a roof that clearly has reached its life…yet unless that inspector is very knowledgeable with wood shakes / shingles my suggestion is to let someone else make the call.
Home inspectors do not recommend remedy to the defect.
In this case, the inspector brings to the client’s attention that “*more than three *(for example)” shakes were rotting and recommends that he consult with a qualified roofing contractor for advice.
Anytime I see damaged/defective shingles, shakes, etc., I recommend my client get an opinion from a Prof. Roofing Contr., experienced in that type of existing roof.
I voted “15%” in your poll. I feel that at that level of visible wear/damage (or even less), coupled with additional information from the sellers/buyers/realtors disclosure documentation, that leaks, ongoing wear, damage will continue if left unchecked. Just common sense to me, and it puts everyone involved on notice that problems are/may/will occurr.
I didn’t vote in the poll because out here in high fire-hazard San Diego, any wood roof automatically gets a recommendation for a re-roof with more fire-resistant material. Many counties in California do not allow wood roofs anymore.
OK, if you lived where there was 400 inches of rain a year (like Ponapei), what percentage of the shakes would have to be bad before you moved back to Dan Diego?
On second thought never mind. After living in San Diego, you’d have the shakes way before you hit the 400 mark. :|.)
As a rule of thumb - when I can look at a wood shake or wood shingle roof and see about 25-30% of them needing repair or replacement I will report something similar to the following:
During the examination of the wood shake roof, we noted one or more of the following conditions present: damaged and/or missing shakes; missing, damaged and/or separated ridge caps; nail pops; curled shakes; holes; rusted flashings; excessively raised shakes. These conditions lend themselves to moisture intrusion.
In our opinion, due to aging, heavy wear and damage the roof covering and/or flashings appear near or at the end of their useful lifespan. Have a competent and licensed roofing contractor read the report: review the roofing system, its accessories and their condition; and then service, repair or replace any defects or unreliable conditions as needed to properly correct them.
Should a full replacement not be needed at this time, we feel it would be prudent to budget for replacement in the near future or maintain a comprehensive warranty that would cover this building system. We also recommend verifying the insurability and acceptability of the roofing with your insurance company prior to closing escrow.
Does it matter? I have not seen a wooden shake roof that does not leak some. It is hard to get insurance on them in my area. Somebody had their head up their butts when they first thought up a wooden shake roof. Either wooden shake roofers are stupid or they laugh whenever they install on. Same goes for flat roofs without any pitch. They have no choice expect to leak.
When they look like this.