How far from the water your house actually is
Two houses in this county, built the same year to the same drawing, will not need the same roof twenty years later. The variable is the air, and it changes fast as you move west.
Three bands, roughly
On the water and the barrier communities, salt is a daily fact. Metal is the limiting part of the roof: fasteners, drip edge, valley metal and flashing reach the end of their life while the covering above still looks serviceable from the street.
Two to six miles inland, through most of West Palm Beach, Lake Worth, Boynton and Delray, the exposure is real but no longer decisive. Hardware and covering age at closer to the same rate, and either can end the roof.
West of the turnpike, through Royal Palm Beach and Wellington, salt stops being the story. Sun and the summer rain govern, and the underlayment is the limiting layer.
What changes in the quote
In the first band, coated or stainless fasteners and rebuilt rather than sealed flashing are worth what they cost, and reusing existing metal is the most common reason a new roof leaks in its first years.
In the third band that same money is better spent on a longer-rated underlayment, because nothing is going to eat the hardware before the membrane gives out.
A contractor quoting one specification for the whole county is quoting from a price list rather than from your address.
Quick answers
- I am four miles inland. Does salt reach me?
- Somewhat, and enough to matter at the fasteners. It is the band where asking the question is more useful than assuming either answer.
- Does a canal or lake count?
- Not in the same way. It is salt in the air that works on metal, and inland fresh water does not carry it.
- Can I see corrosion myself?
- Sometimes, at the drip edge and at exposed fastener heads. What you cannot see from the ground is the condition of the flashing, which is where it matters most.