Stopgap repairs on tile roof that's lacking any underlay

We seek solution, within a modest budget, of a major roof problem. The house is a 4-story sandstone built in 1894. The roof is slanted and of tile. There is no underroofing below the tile.

During record rains last winter, there were leaks not only in the roof but at the chimney and around windows. We inspect the roof each summer and then make patches.

Short of removing the original tile and installing an underroof and then recovering, which is not within our budget, should we consider any coating for the tile? Ross McKee San Francisco

At this distance, I would have to say that the only permanent solution to the leaks on such an old tile roof is complete removal and replacement over a new waterproof underlayment. This would include new metal flashing and counterflashing, and new roof jacks and valleys. Anything less is piecemeal and temporary, and only delays the inevitable.

Another hidden expense in a complete reroofing project could be the replacement of water-damaged roof sheathing and rafters.

However, some important leaks may be stanched by new flashing and caulking around the chimney and replacement of roof jacks and other suspect metal. Leaks in the tile are bears to find and fix, since the evidence of the leak may have an invisible source 10 or 20 feet away.

Seams, ridges, valleys, cracks in the tile, all may be points to check on in a temporary patching program.

Have you had an experienced roofer inspect the roof? I would follow his advice in the matter, since on-site judgment is best.

Leaky windows are less expensive to fix. They may be repainted, caulked, or weatherstripped.

Old dwellings, while a joy, may be subject to high maintenance costs.

Almost nobody does it, but I recommend that new house owners set aside 1 or 2 percent per year of the original construction cost to defray certain future upkeep expenses.