My Roof Sags

Step 1 the first step is to the basement first.

My roof sags.

Check the ceiling for sagging by attaching a string on one end of the beam and run it along the bottom edge of the beam. A sagging roof can come in one of a few classic forms each with its own cause. The expert should be able to inspect your roof and explain to you what the problem is. From there you ll be able to decide the best next step.

Grab a flashlight and head up to your attic to inspect your roof rafters and decking specifically those where your roof is sagging. The fix here is to replace the thin sheathing with thicker sturdier sheathing. A sagging roof is one of the most serious signs of roof failure. A ridge that droops in the middle forming that unintentional western design feature likely is due to undersized rafters and or missing or inadequate internal bracing rafter or collar ties.

Also inspect the metal or plywood gusset plates used where your wood meets on a truss. Determine where the sag is in your roof in relation to your attic. Since roofs are designed to be straight a curved or sagging roof means that its structural integrity is insufficient and it may be a warning sign that your roof is headed for collapse. If the roof sags between the rafters or trusses the most likely cause is sheathing that s too thin for the area it covers.