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Replace roof mount skylight with curb mounted skylight

Replacing a leaky skylight

Replacing a roof mounted skylight with a curb mounted skylight.

This roof mounted skylight has leaked and been repaired many times. We decided to replace it with a curb mounted skylight and stop the problem once and for all.

Problem Skylight
Problem skylight

New Skylight

 

First we cut thru the 2 layers of existing shingles at least a foot wider than the skylight. We use an electric circular saw with an old saw blade turned backwards to cut the shingles. We remove the shingles exposing dry rotted sheathing caused by many years of leakage. We Find we need to to remove more shingles to get to rafters past the dry-rot.

 

Roofing removed
Roofing removed

We replace the dry rotted sheathing. We leave the old skylight in place to prevent dust and debris from entering the house. We use a blower to blow off the dust.

Sheathing Replaced
New osb sheathing installed

We create new sheet metal top and bottom flashings. Unfinished bottom flashing is shown here. A sheet metal shop can make these for you. The bottom needs at least 6′” of metal on the roof lip side. The top requires at least 12″ on the roof side. The more the better. Sheet metal step flashings are woven between the shingles on the sides.

 

Bottom flashing (unfinished)

We decided to use a skylight 2 feet bigger than our opening to reduce inside finish work. We create a 2″ x 6″ frame and fasten it to the roof. We installed some shingles between frame and roof to reduce a sag in the roof. We install new underlayment and shingles using new sheet metal top and bottom flashings and step flashings woven between roof shingles.

 

Frame secured to roof

Inside view of new skylight.
Skylight inside view