How To Repair A Sagging Flat Roof

Now add collar ties from one side of the rafter to the other.

How to repair a sagging flat roof.

Liquid fillers a variety of liquid patching materials are appropriate for fixing low spots on flat roofs. For most small punctures you can repair your roof simply by forcing sealant into them. If these already exist nail a 2x4 to them directly under the 2x4 plate you nailed down before. The first step in fixing a sagging roof is to identify the cause of the sag.

Cut around the damaged area until the membrane rests flat. The ideal fix is to remove all the excessive shingles and replace them. Cut a 45 degree angle so the edges will be properly mitered for a clean look. Nail a fill strip at the top and bottom of the beam which will bring the trim board to the desired width image 2.

Using a utility knife make a shallow cut until you can remove material around the spot without damaging the layers underneath it. Sometimes doing that is difficult. Drill holes in angle iron to keep the rafter from buckling again you will need to secure it with a piece of 1 2 inch angle iron. Once you have established how much the roof sag needs to be jacked up lay a 2x4 plate across the ceiling joists and nail directly under the ridge of the roof.

You will need to get up into your attic and examine the roof carefully in order to discover the underlying cause. On the other hand a property owner might replace the shingles with materials that are inappropriate for the roof s acceptable weight limit such as installing clay tiles in lieu of wooden shingles. Installing new heavier roofing materials or multiple layers of shingles can cause rooftop sagging even on well built roofs. Also inspect the metal or plywood gusset plates used where your wood meets on a truss.

You can also use a general epoxy concrete filler and apply mastic on top using a trowel. Roof patch putty can be applied using a trowel to fill low areas. Determining the problem determine where the sag is in your roof in relation to your attic. In most cases a sagging roof is caused either by a broken rafter or roof decking but in some more severe instances a damaged or sinking foundation can be the underlying cause of the problem.

Attach the trim piece to wrap the beam image 3.