Flat Roof Sagging

Why roofs sag as mentioned roofs sag because there s too much weight or load for the existing structure.

Flat roof sagging.

Weakened sheathing rotting joists and sagging insulation are some possible causes. Water damage from rain and snow can lead to a sagging roof. So what happens with those elements is that you get more sagging and delamination of the roof sheathing. If structural damage or decomposition is to blame it may be best to tear out the section of roofing and repair the problem before filling the hole.

Grab a flashlight and head up to your attic to inspect your roof rafters and decking specifically those where your roof is sagging. Being nervous about a sagging roof is understandable. Sagging roof lines can originate with the horizontal ceiling rafters. Even the highest quality materials don t last forever though.

So just you know doing some surgical cutting of the drywall may not get you to a solution here. Fixing a truss or rafter. When the roof framing is assembled two ceiling rafters are often joined together to create a longer span. Less common causes of a sagging roof poor quality roofing material and faulty installation can cause a roof to slump.

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. The roofing structure should be in good condition to allow adequate water runoff from the shingles. Most people without any construction experience know that a roof should be flat and not wavy or sagging. Low quality materials are more prone to water and weather damage and generally deteriorate faster.

Damage to the roof s surface permits an entryway for water and the subsequent weakening and sagging of the rooftop. 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. 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.