Tarps are made of polymeric materials that are resistant to water, ice, and air. Tarps typically last up to 90 days on the roof, while those constructed of more robust materials can last up to two years. Roofing contractors recommend not keeping it for more than three months, which can lead to further issues.

The cost for roof replacement can be less when you have an overlay. With an overlay, new shingles are installed on top of existing ones. So you'll save on labor costs and disposal. That might be a good idea if the layers underneath are in good condition, including metalwork, flashing, and decking (sheathing).

If any are worn, curled, slipped or missing tiles, it's a sign your roof may need replacing. At the very least you should look to repair broken and missing tiles as soon as possible. Also, check the ridge of your roof. This should be completely straight.

So how often should you replace your roof in California? The answer depends on a few factors, such as the type of roofing material, the climate, and how well the roof has been maintained. In general, however, most roofs will need to be replaced every 20-30 years.