Homeowners who want to get the longest life out of their roof should know the signs of a bad roofing job. It’s especially important to look for these signs when you’re buying a home, so you can avoid homes that might need major roof repairs.

Plus, when you’re considering which roofing contractor to choose, you might look through their gallery of past work to decide if they provide the quality roof installation you’re looking for. If you know the signs of a bad job, you’ll know to steer clear.

Here are the signs of a bad roofing job:

1. Roof Looks Slanted

Does something just look off about the roof, but you can’t really place it? Odds are the shingles haven’t been installed straight, so the roof looks like it’s drooping or leaning. This is a serious problem, as shingles have a very specific “exposure” or distance between them. Too much space could cause a leak. Too little space and the shingles stack up too thickly for the nails, so they fall off.

2. Uneven or Bumpy Roofs

Sometimes it’s not just an optical illusion, and the roof really is sagging or bumpy. It’s possible that the roofers left many under-driven nails, causing many shingles to pop up, which increases the odds of a leak. The other, more likely problem is that the roofers didn’t install proper ventilation on the roof and now condensation has developed on the inside of the roof, causing the wooden deck to swell or droop. Most likely, the whole roof will need to be replaced.

3. Mismatched Shingles

If a home has just had a complete re-roof, the shingle color should match exactly. If they don’t then either the roofer has failed to ensure all of the shingle bundles were in the same batch, or they are using shingles from a second-class manufacturer. Either way, this roofer isn’t taking proper care in their work.

4. Woven Valleys

The valley of the roof is the “ditch” where two roof planes meet. These low spots will be exposed to the most water, so installing them properly is one of the most important tasks of roof installation. If the shingles appear woven together, then the roofer installed a woven valley, which is not acceptable by modern roofing standards. These valleys are weak and liable to leak.

Instead, you should see a small strip of metal down the valley of the roof. This installation style is called an open valley  and provides the best protection.

5. Missing Roof Accessories

A roof isn’t just about shingles, but inexperienced and unskilled roofers might think so, and neglect to add in the accessories that a roof needs to be functional, as an attempt to cut costs. Drip edges are a common oversight. They are relatively new in the roofing world but add so much protection to the edge of the roof that they’ve become necessary and even legally mandatory in some areas.

Other roof accessories that are commonly overlooked include:

  • Roof vents
  • Underlayment
  • Flashing
  • Gutters

If you notice that your roof is missing these accessories, or has any of these other signs of a bad roofing job, it’s wise to get a professional you trust to inspect the whole roof right away, so you can avoid leaks and protect your home.