Skylights on flat roofs. Explaining why skylights leak. Pittsburgh Stamford

Why are skylights leaking?

It’s common to find skylights on a roof. They are more likely to be the cause of leaks on a flat roof.  They provide needed light in a house, but with this benefit also comes problems. We repair skylights from  Stamford to Westport to Greenwich and Darien to Pittsburgh and Westmoreland County.

Skylights are known to cause roof leaks. There are two parts to a skylight that needs to be discussed. The skylight itself or the glass and frame part and the the base part called the “curb”.

Skylight frame and glass.

Skylight on a flat roof
Glass glazed skylights are pretty and are more durable than plexi glass.

Not all brands of skylights are equally build. There are those that comes with tempered glass and those that are made of acrylic or plastic. Read this article on skylights.

Here are a few tips what to look for when the glaze part of the skylight is leaking:

  • Check for cracks in the plastic glaze part.
  • Check the metal frame that holds the glass or plastic in position for defects.
  • Make sure the sealant that secure the glass and frame is still good.

It is not easy to find a leak on a skylight. It takes experience and the knowledge of all skylights to detect problems.

Skylights - The corner that causes the most problems
This is a common area for a skylight to leak. Specially skylights that can open up.

 Corner causing leaks

When the skylight is installed on a flat roof,the picture on the right shows where it will leak. These type of skylights need special curbs to be able to be installed on a flat roof.

These type of skylights are less likely to leak and have less maintenance over time than other skylights. Because of the dome shape, no debris will collect on top and they will always be clean

Plastic Dome Skylights

These skylights are relatively easy to install. They are less likely to leak. If a leak does occur, check for a crack in the plastic.

Skylight-in-water - On a flat roof
The Curb flashing of a Skylight is what could leak. When flat roof doesn’t have good drainage, then water could pool around a skylight causing a leak in the weakest part of the roof

Curb Flashing

When a skylight is installed on a flat roof, there will come a time when water is pooling around the curb flashing of the skylight. It is critical to ensure that the roof membrane is properly attached to the flashing of the skylight.

Curb flashing on a skylight- Before the rubber roof is connected to the flashing
Curb flashing of a skylight before the membrane is attached. The most common problem is when the rubber roof is not properly attached to the flashing.

This is what the curb flashing looks like before the membrane is attached. If the membrane is not properly attached to the copper flashing, the roof will leak.

When an old roof is removed and prepared for a new rubber roof, care must be taken to clean the existing flashing.

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