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Home/Roofing/Sagging ridge line

Roofing · Structural first

Sagging visible along the ridge line

A dip in the ridge means framing rather than roofing. That is a structural assessment before it is a roofing quote.

Quick answerLook down the ridge from the ground. A dip means framing rather than roofing: rafter spread, a failed ridge board, or decking that has been wet for a long time. That is a structural assessment before it is a roofing quote. New shingles over a sagging frame won’t fix it, and may hide it.

This is most common in homes built before about 1940. Old roofs were often framed lighter than today, and decades of extra shingle layers, snow and leaks add up. The ridge is where it shows first, because it should be a straight line.

Timber framing and roof trusses on a new home under construction
Roof framing on a house under construction. A dip at the ridge points to the framing, not the shingles. Photo by Troy Mortier on Unsplash.

1Why ridges sag

  • Rafter spread. If the bottoms of the rafters push the walls outward, the peak drops. Missing or weak ties between opposite rafters let this happen.
  • A failed ridge board. The board at the peak can crack or rot, especially after long-term leaks.
  • Wet decking. Decking that has been wet for years softens and sags between rafters.
  • Extra weight. Multiple layers of shingle add load the original framing wasn’t sized for.

2How to check

  1. Sight down the ridgeFrom the ground at the gable end, look along the peak. It should be straight. A dip in the middle is the sign.
  2. Look for wavy slopesDips between rafters across the slope point at the decking.
  3. Look in the atticCheck the ridge board for cracks, rafters for splits or sagging, and the deck for stains and soft spots.
  4. Look at the wallsCracks near the top of exterior walls or doors that start sticking upstairs can go along with rafter spread.
Don’t walk a sagging roof

If the ridge or deck is sagging, stay off the roof and don’t put weight on soft areas in the attic. Get it assessed first.

3Fixing it

Do it yourself

  • Spot and photograph the sag from the ground
  • Look for stains and cracks in the attic from a safe footing
  • Get a structural assessment before roofing quotes

Hire a pro

  • Structural assessment of rafters, ridge and ties
  • Framing repairs as specified
  • Deck replacement where it has softened
  • Then the reroof, on a sound frame

Framing repairs may need a permit. Check local code and ask whether an engineer should look at it.

4What drives the cost

The price depends on the cause. Adding ties or bracing is a different job from replacing a ridge board or rafters. Decking replacement, tear-off of old layers, permits and any engineering add to it. Get the structural scope defined first so the roofing quote is built on it.

Roofing cost

Dip in the ridge line?

Talk to a roofing contractor who will check the framing before quoting the shingles.

877-360-4657

5Questions

Can a new roof fix a sagging ridge?

Not on its own. New shingles follow the frame underneath. The framing has to be fixed first.

Is a sagging roof dangerous?

It can be a sign of a serious structural problem. Don’t walk on it, and get it assessed promptly, especially before heavy snow.

Some old roofs just look wavy. Is that the same thing?

A little waviness across old plank decking is common. A clear dip along the ridge is different and needs a structural look.

Written by Jaylan Jones. I Like To Exterior Services earns a referral fee when a call connects to a contractor. See our business-model disclosure.

877-360-4657