Detecting Sagging Roofs Early


Have you ever noticed a house whose roof looks curved and drooping instead of straight and wondered what is happening? This is a sagging roof. It can range from a simple problem to a more complicated one where you need a professional. This can be worrying. A little sag does not mean there is an imminent danger of its collapse. It is however a sign telling you to take some necessary actions.

How Do You Know You Have a Sagging Roof?

You will need to inspect it to know. You can check out a few ways to find out here. You can inspect it both from outside and inside. To inspect from inside the house, you need to get into the attic. Be sure you have a source of light bright enough to see every part. The roof should have a shape of a triangle combining the rafters and the beam that holds them. If you notice an unevenness when it is not designed that way, then you have a sagging roof.

To inspect from outside, check from the side of the house and not from the end. See where the ridge of the roof is and measure with a straight plank or maybe a ruler. If it varies in contour from the straightedge, you most likely have a problem. If it is sagging, it can be repaired and reinforced. So, the earlier you detect it and take steps to correct it before it deteriorates into a bigger one, the better for you.

Causes of Sagging

Several individual factors may be responsible for sagging. It could also be a collection of these different individual factors. This website aims to explain these factors in detail. They include:


Although Roofs are designed for optimal drainage, if the gutter system is flawed or a damaged shingle or any other thing impedes the flow of water from it, rainwater and snow can gather on it. Over time, due to poor ventilation in the attic, trapped moisture creates an environment for mold and mildew to grow which weakens it and causes it to deteriorate and sag. If this is the case, the first step will be to address the problem that eventually led to the sagging.

Too Much Weight

A roof is designed to handle a specific weight. Excess weight from ice and snow can cause it to sag. If you suspect this, call a professional to clear the ice. Also, structural problems and design issues like insufficient sheaths, undersized or inadequate number of rafters may not provide the needed support for the weight it is carrying. Excess layers of shingles and materials might also lead to too much weight.

Inadequate Rafters and Joints

Improperly constructed rafters or joints can lead to this. The weight of the roof pushes down on the ridge line then it is distributed to the rafters, joints and walls.  A poorly constructed one will over time become structurally inadequate.


An average roof lasts between 15 to about 30 years when properly maintained and based on the climate and weather of where you live. They start to deteriorate when they reach the end of their lifespan.

Other Causes

These may include poor quality of materials and faulty installation. This is a good reason to get good contractors to handle the installation process. Also, a sinking foundation can cause a house to sag and ultimately affect the roof.

What to do

  1. Find out if your roof is sagging by carrying out a personal assessment of it.
  2. Contact a professional to assess it if it’s beyond you.
  3. Check your home insurance coverage to see if a roof repair or replacement is covered.
  4. If it is covered, get all the documents needed to file a claim for a repair or replacement.
  5. File a claim with the insurance company.
  6. Have a professional fix it as it as soon as possible.


If you notice or suspect any issue, it is wise to take steps to fix it immediately. This is so as not to make it worse and by implication, more expensive to fix. If left unrepaired, it could eventually cave in and can cause more damage to your house. It could also cause injury or death to someone.

Don’t forget that there could be one or more combined reasons why it is sagging. Let the professional assess and check all possible scenarios so you are sure that the root cause is discovered and fixed.


Latest Issue

BDC 317 : Jun 2024