How It Works

Select the work to be done
Let us know what project you need help with and when you need it done - we'll match you with the right pros for the job.
Compare matched pros
Verify pro credentials, read reviews, ask questions, discuss availability, and request project estimates.
Complete your project
Hire the pro that's right for you and your budget. After the project is complete, let your community know how it went.
Powered by

The Home Depot
Cabinet Contract Flowers Lightning Paintroller Teardrop Toolbox Pin Cross Search Search Arrow Thin Arrow

Why is My Roof Sagging?

Pro Referral > Home Guides > Roofing > Why is My Roof Sagging?
Why is My Roof Sagging?

If you roof seems to be sagging inwards, you need to contact a roof repair contractor quickly. Under no circumstances should you step on the roof, as the underlying rafters may have rotted and the roof may give in under your weight. If you have experience with roofs and want to inspect it, it’s recommended that you use a ladder, lean it against a sturdy wall and inspect your roof from the top rung. If you think one section of the roof seems to be okay and you are intent on stepping on the roof, wear rubber soled shoes for traction and step lightly.


Let’s take a look at the some of the common causes for roof sagging to help you identify the problem with your roof:

  1. 1.Ceiling Joist Connection

    Ceiling joists, or ceiling beams or ridge beams, are the horizontal, long blocks of wood (beams) that run parallel to each other up on the ceiling. They are used to the join the walls of a building together and to support the weight of the ceiling. Some ceiling joists on the second floor also support the roof as well as the ceiling- and these are joists we are concerned about.


    In homes with sloping roofs, a joist support is pre-attached to a rafter (support beams). Together, the rafters and the joist support keep the walls of the joined and the roof pushing the walls outwards. The ceiling joist may be made of wood and, in some cases, metal (which is sturdier).


    Ceiling joists and rafters are vulnerable to aging, wear and tear, like everything. In old homes, or in homes in areas with extreme weather, the ceiling joists and rafters begin to lose their strength and sometimes rot through, which will cause them to dip from the strain and cause your roof to sag. Sometimes the screws joining the ceiling joist to the roof may begin to loosen, which will again cause your roof to sag. Loose ceiling joists can be repaired, but ceiling joists that are rotted through will have to be replaced.

  2. 2.A Parallel Problem

    Typically, joists and rafters are constructed parallel to each other. But, in some cases, they may not be placed parallel. Lack of parallel placement will provide inadequate support to the ceiling and the walls. The roof may push the walls outwards slightly and sag in such cases.


    If your home has a flat ceiling, then the ceiling joists may be perpendicular to the rafters. This is an acceptable building practice, but not always necessary.


    Sometimes there are not enough rafter ties, which will cause the roof to sag is well. If you figure your roof is sagging because of problems with rafter and ceiling joist connection not being parallel to each other, you can blame shoddy craftsmanship and cost cutting. Rafters and joists are not always parallel, however, as the design of the building and the aesthetic value can dictate their shape, design, and placement.

  3. 3.Weight

    A common reason why roofs sag is because they can no longer support the weight of the roof. If you have a roof with heavy shingles, such as tile shingles, your rafters and ceiling joists may be sagging because of the heavy load. Your rafters and ceiling joists will lose their structural strength over time. If they were able to support the weight of the roof at one time, they may not be able to do so now.


    Snow, water ponding, and debris can also add to the weight of the roof. Not all roofs are built with consideration to the additional load the snow and water entail. Snow will collect on roofs, even sloping roofs, in winter and cause additional stress on the rafters. Water ponding refers to the collection of water in the form of small puddles on the surface of the roof. Water ponding can occur if there is inadequate sloping and/or if your roof is full of debris which allows the water to collect in one place or more than one place.


    If you think your roof is sagging because of the weight being placed on it, do not step on the roof. You don’t want to be deposited into your attic, along with most of your roof.

  4. 4.Weather

    The weather may also be responsible for the sagging of your roof. Apart from the snow being deposited on your roof, the hot sun, high humidity, cold and rain can all damage your roof in various ways. The UV rays are known to weaken and wear away the surface of your roof over time. Your shingles may also crack and develop splits under intense sunlight and extreme weather. The rain and snow also do their bit to tear away the protective mineral granule layer that is a part of the asphalt shingle roofs. Water can seep in through the cracks and find its way to your rafters. Over time, these rafters will rot and weaken, which can cause your roof to sag and eventually cave in.


    The weather also brings with it hails and heavy winds. Hails can tear up your shingles and expose the underlayment. The same goes for heavy winds.

  5. 5.Roof Inspections Made Easy & Fun

    Modern technology has enabled life to become much easier for many people. There is a simple way now to inspect your roof without even needing a latter or actually getting on your roof. You can use a remote controlled helicopter with a camera on it. The camera coordinates with a software program or a website so you can watch it via any device. This could be your home computer, laptop, smartphone, and so on. These helicopters come in every shape and size but a good one could be about 2.5 feet in length and have a propeller diameter of about 1.5 ft. You control the helicopter with a remote and a helicopter with a camera could cost about $200. The range is about 30 meters from the helicopter to the hand held remote.

A sagging roof, apart from being a safety hazard, is also an eyesore that can greatly reduce the curb-appeal of your home.


Find Roof Repair Pros

Get your home project started today with help from Pro Referral’s qualified network of pre-screened and background-checked professionals available in your neighborhood.

Get Expert Advice

Submit your toughest home improvement questions to our knowledgeable experts and receive free personalized solutions, product recommendations, how-to advice, and more–all within 24 hours or less.