What to Do When Your Tin Roof Is Too Short for Gutters

Roof Edges

• No matter what the type of roofing on your home, the edge of the roofing should extend at least 3/4 inches beyond the fascia to prevent water from curling back and running down the walls of the house, according to This Old House website. Metal roofing cut flush with the wooden roof sheathing soaks the edge of the sheathing with water and causes rot. Runoff curling under the lip of the roof damages paint and can rot the fascia and soffit as well. Metal roof-edge flashing formed to fit the contours of eaves shields the wood from water and extends the lip of the roof.

Edging Types

• Standard metal trim corrects many common construction errors. Roof-edge trims or drip caps come in an assortment of shapes and sizes to match common construction shapes. Some styles of drip edging only protect the roof sheathing and fascia without extending the lip of the roof. To direct runoff into gutters, an L-shaped drip cap works best. The L-shaped cap fits underneath the edge of the existing roofing, between the roofing and the roof sheathing. The top of the "L" extends the roof and the bottom of the "L" directs water into the gutter. Drip caps can fit eaves with gutters already installed.

Installation

• L-shaped roof edging adjusts to match gutters by sliding in or out beneath the roofing. A bead of roofing cement holds the flashing in place satisfactorily, according to This Old House website. Nailing the new trim increases the repair's strength, but might not be possible with metal roofing. If driven through metal roofing, even roofing nails with rubber washers can gradually work loose and cause leaks. Removing the gutters allows placement of the drip cap's back edge against the fascia, held by trim nails. Installing trim over gutters with an adhesive joint places the back edge of the drip cap in the gutter, instead.

Options

• Roof edging works best if installed before both roofing and gutters. For full strength, the upper section of edging should overlap the roof sheathing for at least 6 inches. Roofing nails set every 12 inches hold the flashing in place, and metal roofing or asphalt shingles overlap the nailed section. Correcting an existing problem with roof-edge extenders might require custom-built edging with less flashing under the roofing. L-shaped gutter aprons offer a flexible alternative, fitting underneath existing roofing and overlapping the back edge of gutters without extending the roof. Gutter hangers can mount to fascia directly through the overlapping apron.