Flat Roof Sagging

A wavy or sagging roof can be the result of one of several issues.

Flat roof sagging.

Foundation problems with the house. The other thing that causes this type of sag is an excessively long roof rafter without proper bracing and in old house that s not so unusual. The roofing structure should be in good condition to allow adequate water runoff from the shingles. Grab a flashlight and head up to your attic to inspect your roof rafters and decking specifically those where your roof is sagging.

Excess weight along the roof can occur from snowfalls. When the roof framing is assembled two ceiling rafters are often joined together to create a longer span. So what happens with those elements is that you get more sagging and delamination of the roof sheathing. Sagging or low spots in a flat roof may be due to undersized or weakened roof joists or problems with the buildup layers beneath the exposed roofing.

Also inspect the metal or plywood gusset plates used where your wood meets on a truss look for damage that includes cracks rot breaks and any other impairment. Being nervous about a sagging roof is understandable. Most people without any construction experience know that a roof should be flat and not wavy or sagging. Weakened sheathing rotting joists and sagging insulation are some possible causes.

Less common causes of a sagging roof poor quality roofing material and faulty installation can cause a roof to slump. Fixing a truss or rafter. So just you know doing some surgical cutting of the drywall may not get you to a solution here. Damage to the roof s surface permits an entryway for water and the subsequent weakening and sagging of the rooftop.

Why roofs sag as mentioned roofs sag because there s too much weight or load for the existing structure. Even the highest quality materials don t last forever though. Sagging roof lines can originate with the horizontal ceiling rafters. Low quality materials are more prone to water and weather damage and generally deteriorate faster.