After 1980, almost all roofs are concrete tiles. Before that, asphalt
composite/shingle is the most common one. You don't always need to replace the whole
roof, many people start with replacing the Water proofing aka felt paper
that's underneath the tile or shingle. It takes about $8000 for felt, and $
25,000 for both felt and roof top for a 2000 sqft house. Concrete usually
lasts 30-50ys, and composite 20-30ys depending on the quality of felt paper.
The thicker the better. Felt paper of 20lbs is the thinnest.
If your roof is shingle originally, when you replace it with concrete titles, the house top may not sustain the weight of concrete unless its structure is updated. Do not go with the light concrete that
cannot be walked on.
所以看房龄才决定要不要换。如果屋没漏但心已切，建议取中间值。Get 3 quotes before you select which company to go with, the pricing may vary 20%.