How To Repair A Leaking Skylight

How to Diagnose & Repair Skylight Leaks

• Post a QUESTION or COMMENT well-nigh leaky skylights & how they are repaired or avoided

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Skylight leaks:

This commodity explains how to find the cause of skylight leaks and other sloped glazing leaks. The article continues with simple suggestions for skylight leak repair and leak prevention. Our photograph of a leaky roof skylight that has suffered repeated and non-durable repair attempts using roofing cement tin can exist seen at left.

We also provide an Commodity Alphabetize for this topic, or yous tin try the page peak or bottom SEARCH BOX equally a quick fashion to observe information y'all demand.

How to Diagnose & Repair Skylight Leaks

[Click to overstate whatever image]

Our photograph (left) shows an interesting sloped window installation on the roof of a barn silo that had been converted to living space. Conventional forest-frame double-hung windows were set up into the sloped silo roof - this was non a successful installation and the windows rapidly rotted, leaked, and disintegrated.

Article Contents

• SKYLIGHT LEAK DIAGNOSIS & REPAIR
  • HOW TO DIAGNOSE & REPAIR SKYLIGHT LEAKS
  • ROOFTOP SKYLIGHT LEAKS
  • HOW TO WATER Test SKYLIGHTS
  • HOW TO REPAIR SKYLIGHT LEAKS
  • HOW TO AVOID OR PREVENT SKYLIGHT LEAKS

As Mr. Bliss points out in SLOPED GLAZING DETAILS, a glazing system must perform many functions. Information technology has to shed and bleed water, back up and cushion the glass to avoid mechanical pressure points, and seal against air and water leakage. Information technology should be attractive and economical.

Yet many subtle and pervasive forces are working against you: thermal and structural movement, high UV radiation, current of air and weather. A pretty redwood cross batten is no match for sliding sheets of ice.

The bug inherent in vertical glazing are multiplied in sloped glazing: college levels of UV, water damming at the lower edges of sloped window frames or between the roof and the upper section of window and skylight frames, and structural loading.

See VERTICAL GLAZING DETAILS

Professionals in the large scale pall wall industries, as well as residential contractors, accept encountered bug with skylights and other forms of sloped window glazing. Fortunately, many new products and systems have been developed to beat the elements also as to reduce the chances of installation errors leading to leaky skylights and related structural damage or fifty-fifty leak-related mold contamination in buildings.

Sloped glazing such every bit roof skylights probably has historically had more leaks into the roof structure due to improper roof flashing than other window failure causes.

Leaks at skylights, left unattended, tin can lead to costly structural damage, rotted roof sheathing, rotted roof framing, and wet, moldy insulation too. These skylight leaks should non be blamed on faulty product design, although at some leaky skylights we observe a combination of multiple failures.

Our photograph at page top of a leaky roof skylight that has suffered repeated and non-durable repair attempts using roofing cement can be seen at left. From the blueprint of sealant application we suspect that the leaks at this skylight were around the window frame due to improper roof flashing at the time of installation. The photo merely above illustrates a site-built skylight using a corrugated fiberglass panel in a palapa-style roof in Mexico.

Building owners, having problem determining exactly where the skylight leak is occurring, sometimes merely slather caulk or roof cement all over everything in sight (an approach that is ugly but might work. But a roof-cement slathered skylight that is nevertheless leaking may be fifty-fifty more difficult to diagnose. Here are some tips that might aid diagnose the actual leak point at a skylight:

Indoor Clues Assistance Diagnose Skylight Leaks

• Indoors, look very closely at where water stains originate within the building - trace stains to their highest point. The leak will be at or up-roof from that spot.

  Our indoor photo of a skylight leak (left) shows a stain that is on top of the ceiling drywall; because this leak does not announced to be coming from inside the ceiling cavity, we suspect that this stain is either acquired past a leak at the skylight upper drinking glass frame itself or the leak is from indoor condensation. A closer look (from a ladder) was needed.

• Indoors, distinguish between a true skylight leak and indoor condensate stains

  that originate from indoor wet condensing on the cool skylight surface, running down into, and inundation a small condensate drip tray that some skylights include.

• Cut a small ceiling inspection opening:

  indoors, if the ceiling drywall is only modestly leak stained, there is a chance that ceiling insulation has become wet and may fifty-fifty contain hidden mold. In this case, unless the stain is really picayune in size, it may exist justified to cut a small-scale opening most the leak to investigate the roof crenel for rot, visible mold, or wet insulation.

• Remove ceiling drywall:

  indoors, if the ceiling drywall is badly leak stained it is appropriate to remove the damaged drywall material completely, remove whatever wet or stained fiberglass insulation, and clean the ceiling cavity. Leave the ceiling open around the offending skylight first to permit things to dry out thoroughly, and 2d to let our side by side diagnostic steps merely below.

Roof Flashing Cement & Other Rooftop Skylight Leaks

• Exterior, on the roof, ( Lookout out: don't try this if yous are not able to access your roof safely, and don't piece of work alone - falling off of a roof tin can be fatal), inspect the skylight for visibly obvious damage such as open seams, roof damage, or roof debris; likewise await for evidence of previous repair attempts such equally in the photo above.

  Four Types of Roof Cement Failures: Our photo of a roof cement "patch" on an asphalt shingle roof shows iv types of roof cement patch failures that hateful this patch is not really keeping water out of the edifice.

  • Flashing cement gaps:

    first, at upper centre yous see that the flashing cement did non bridge the gap between two shingles where the applicator was trying to brand a seal.

  • Flashing cement bonding failures:

    second, the roof cement did not bail to the shingle material below - probably it was applied over dirt or over a wet shingle - notice the raised cement surface around the hole in the cement in the center of the photo.

    Also see AVOID AHESION WINDOW SEALANT FAILURES for details.

  • Thermal Expansion/Contraction sealant failures:

    third, the roof cement has not survived thermal expansion and contraction as temperatures changed on the roof and in the roof materials. The result was a stretching movement that pulled the roof cement autonomously in a diagonal design of holes running from upper left to lower right in the photo.

    Come across TEMPERATURE EFFECTS on WINDOWS and likewise for technical data

    See THERMAL EXPANSION of MATERIALS for the effects of temperature changes on materials.

  • Flashing cement pinholes:

    the fourth roof cement patch is harder to see unless yous (click to) enlarge the photograph. Pocket-sized openings in the roof cement at the lower center of the photo show that this patch material has not but stale and lost its elasticity, but information technology is developing pinhole perforations.

• If the skylight is relying on roof cement to foreclose roof leaks, await very carefully at the flashing cement for cracks, openings, or for failure to bail to the skylight or to the roof. Oft something that looks "sealed" is actually an open leak.

  Our photo (above left) shows an older bubble-type skylight that was heavily patched around its perimeter using roof flashing cement.

  This unit of measurement has a ii-inch raised perimeter to get the plastic chimera above the roof deck. Below nosotros run across the sort of leak stains one may find around a problem-skylight.

Still older bubble type skylights that were mounted affluent with the roof surface (shown beneath) are notorious leakers because they relied entirely on sealants betwixt shingles and the skylight. Newer curbed skylights (having a raised perimeter to become the sloped glazing above the roof surface) are much more reliable.

Water Testing for Finding Skylight Leaks

• Garden Hose Skylight Test 1:

  Exterior, and from on the roof surface : in dry out weather, try pulling a garden hose to the rooftop to let alive h2o testing of the skylight for leaks.

  Beginning permit h2o to run down-roof onto the up-roof end of the skylight and around the unit. Look inside the edifice at the skylight for signs of new water penetration.

• Garden Hose Skylight Test two:

  Next allow hose-water to run onto the skylight surface itself. If the leak appears around the glass frame, visible from inside, and so the problem includes at to the lowest degree a drinking glass sealing problem.

  If leaks around the skylight appear only when h2o is flowing down the roof surface and non onto the upper surface of the skylight, there is a skylight roof flashing problem.
  Don't soak the edifice interior - only use plenty water to see it appearing indoors.

Simple Repairs for Skylight Leaks

If the insulating glass unit of the skylight has failed, yous can seal the unit confronting further water leakage, simply only replacing the unit will remove condensation, opaque skylight glass, and a failed window unit of measurement.

Our closeup photo of the down-roof corner of a leaky skylight (left) shows what is probably a double failure.

Leaks at the insulated-glass frame permitted water to enter the window structure where the freeze-thaw climate at this New York home connected to damage the window by forcing apart and losing the seal of the insulated glass itself.

See SEALED WINDOW Articulation FAILURES for more than on this skylight failure.

If the skylight leak is at the roof flashing, it may be possible to make temporary repairs using roof flashing cement around the perimeter of the unit, but a proper repair volition require removing shingles almost the skylight, installing proper head, side, and foot flashing around the unit, every bit you reinstall new shingles in the area.

Avoiding or Preventing Skylight Leaks

In add-on to installing skylights properly, using the methods discussed in this commodity and following the manufacturer'due south instructions, a menstruation inspection for testify of leaks into or around the glazing unit of measurement tin can avoid plush edifice impairment by early detection and repair of any problems.

If droppings collects on or around a skylight (see our photo above) the water held in that location combined with the working activity of extra winter ice (if the edifice is in a freezing climate) volition reduce the roof life effectually the glass unit, leading to early leaks in this expanse. Try gently brushing debris away from and off of your skylights when performing a roof inspection. Don't walk carelessly on a debris-covered roof - information technology's like walking on ball bearings.

Modern factory-built skylight units such equally the skylight shown beneath on a home in Port Angeles, Washington in the U.S. accept been designed by their manufacturers to make the window as idiot-proof as possible, including factory-made skylight flashing kits and simple, clear instructions.

Our skylight photo below illustrates a curbed skylight in a brand new installation in on a nearly-flat EPDM roof in Poughkeepsie, New York ca. 1999.

Below is this same skylight, now more than 15 years old. It has non leaked, only as it is installed over a bath, condensation on the interior of the skylght glass can nonetheless be an annoyance.

Still if the contractor is inexperienced with skylight installation, if the skylight was installed later in the life of the building equally a retrofit, and peculiarly if the installer did not read the instructions provided past the manufacturer, leaks at the skylight are probable.

Seal Skylight Flashing at Time of Skylight Installation to Forestall Future Leaks

Equally discussed in All-time Practices Guide to Residential Construction, affiliate

on BEST Roofing PRACTICES:

Every bit a backup to prevent leaks at skylights, during skylight installation and even though modern skylights are usually provided with a factory-built flashing and counterflashing, information technology is always a good idea to seal the skylight curb and surrounding roof area with a bituminous membrane (see Figure 2-v at left).

For proper skylight and other sloped glazing installation details,

see SLOPED GLAZING DETAILS.

Additional examples of skylights are institute

at WINDOWS & DOORS.

Also encounter SKYLIGHT VENTILATION DETAILS

and

see SKYLIGHT GLASS BREAKAGE.

- - Adjusted with permission from Best Practices Guide to Residential Construction.

Skylight Manufacturers & Product Sources

• Andersen Windows and Doors www.andersenwindows.com Skylights and roof windows with exterior sash clad with drinking glass-fiber-reinforced material
• Milgard Windows and Doors www.milgard.com Skylights with aluminum frames (thermal break optional) with vinyl subframes on operable models; optional motorized controls with rain sensor
• Pella Windows and Doors www.pella.com Wood interior, aluminum outside, optional motorized controls, and transmission or motorized fabric-pleated shades
• Roto Frank of America www.roofwindows.com Wood interior, aluminum exterior, optional motorized controls, and manual or motorized fabric-pleated shades; Sweet16 model fits sixteen in. o.c. framing
• Velux America Inc. www.velux.com Skylights and roof windows with wood interior and aluminum-clad exterior. Options include insect screens, blinds, motorized controls and shades with rain sensor, electrochromatic glass, and flashing kits for metal and tile roofs and mulled units
• Skylight Light Tube Manufacturers & Sources
• SolaTube www.solatube.com Lite tubes from 10 to 21 in. in bore; options include electric lighting, daylight dimmer, and integral bathroom fan
• Dominicus-Tek Skylights www.sun-tek.com Light tubes from 10 to 21 in. in bore; options include electric lighting and multitube Spyder skylight
• Velux America Inc. www.velux.com Sun Tunnel light tubes from 14 to 22 in. in diameter with flexible or rigid tubes

Reader Comments & Q&A

Ellen,

That leak stain could exist at the flashing or it could exist an overflow from a condensate tray found at the lower end of some skylights. Your cover prevents us from seeing enough of the window to be confident that we know what'southward going on. Perhaps you can post another image with that spring-rod and cover put bated.

Just noticed this stain today, definitely on top of the drywall and not coming from inside. Is this likely to be a leak from the glass? It looks similar to one of the example photos on this page. I'm not sure if the trickle stain is coming from under to wood trim or over it.

Y'all may be able to brand a temporary repair working from the roof surface using flashing cement or even clear silicone caulk. But what would exist most productive would exist a very conscientious inspection to find the exact reason for the leak such as damaged loose missing or incomplete flashing. If you lot tin safely admission your ruview best hire a roofing repair contractor.

I accept a leaky rectangular bubble skylight that has developed leaks in the 2nd floor bathroom. seems to be coming from the high point corners. should i use roof repair caulk or what do u recommend? thanks

No, Lisa. The curb allows installation of flashing effectually the perimeter of the skylight at the intersection of skylight edges and roof surface. Without that flashing the skylight would leak like mad into the roof structure and into the building below; flashing around whatsoever roof penetration (skylight, chimney, plumbing vent) is of disquisitional importance. For a time in the 1970'due south a virtually-flat skylight was popular, was nearly impossible to seal satisfactorily, and was a notorious leak source.

What is the purpose of a adjourn when a skylight is installed on a low pitched roof? Is the curb just to raise the skylight to allow for rain possibly not draining off the roof quickly? Or is the curb supposed to add pitch so that the skylight itself is pitched more than than the roof, assuasive water to run off the skylight quicker? Very dislocated since I run into examples of both pitched curbs and curbs that are equal height all effectually.

Anne:

Probably not. Sealing the inside of any leaking roof component is likely to drive the leaking water horizontally into other roof components. Nigh always, a roof leak needs to be repaired from outside, on the roof surface.

My skylight is a smaller version of the first one on your mail. There'south a wood beam in the middle on the within of my apartment that gets wet from outside when it rains. I tin can feel an obvious cakewalk from it and I can hear everything exterior, even cars and sirens passing by. I have no access to the roof.. Is there any way I tin repair information technology from inside? The manager of my apartment refuses to get it fixed professionally.

Annotate:

(June 23, 2011) Debbie G. said: Very helpful info. Thanks!

Question: is information technology condensation or a leaky skylight

(June 23, 2011) catherine said:

my skylight drips when information technology rains , I am not sure if information technology is condensation or a leak , the skylight is on my sun roof , it is a slightly raised slanted hardtop roof

Answer:

If the skylight drips ONLY when information technology rains I suspect in that location is a leak in the roof flashing around the unit, or in the skylight itself. Try spraying water up on your sunroof in warm dry weather and come across if you lot can reproduce the status. Exist careful nigh on-roof inspections on sunroofs as you don't want to damage other sunroof panels (nor slide off and fall).

Question: protective picture show to terminate skylight leaks?

July 18, 2011) Jean said:

HIOw's about if the skylight itself has a leak? does a protective film would be useful to stop such a leak?

Answer:

I don't call back a protective film on skylights is going to practise much to terminate well-nigh skylight leaks, Jean. Most skylights leak at their surrounding flashing. Skylight films are plastic coatings practical to the glass.

Question: why is skylight leaking subsequently new roof?

(Sept 1, 2012) Anonymous said:

skylight leaks and I wonder why? New roof put over the sometime roof and the the gap betwixt the new roof and the skylight is now much less, would that cause a leak, the 3 leaking skylights are operable and the one not leaking skylight is in operable. When I leave the skylights open up a cleft they practice non leak

Reply:

I tin can't diagnose this or even speculate from just the data in your notation. Check for improper flashing around the skylights or declining to even install flashing when the new roof was installed.

Question: leaks at skylight during hurricane

(Oct thirty, 2012) Todd said:

skylight only started to leak from lower corner, huricane sandy striking western Pa as of now. could this be from rain blowing, condensation from colder air, or acuall leak

Reply:

Probably a leak

Question: lite penetration effectually skylight - is this a leak?

(May 27, 2014) Debbie said:

What does light penetration into the attic mean in regards to a skylight?

Respond:

Debbie I think what we're talking about is inspecting in an attic for points that may be leaking. Sometimes (non always) if you lot wait up at a roof from within an cranium and see daylight, that'due south a hole or a leak point.

The reason I say not always is because light may exist reflected indirectly up-roof through flashed openings or betwixt wood shingles or slates nailed over spaced sheathing boards.

When you come across a point of light or "a thou points of light" in your roof, look at that place for water leak stains every bit well every bit checking the floor surface below that area for leak marks.

Question: risks associated with skylights

(June two, 2014) Jen W-C said:

Hi and thank you so much for all this info!
My question relates to the risks associated with skylights. I am in the U.S. at the moment but lived in Denmark the final viii years and at that place, you lot encounter skylights on well-nigh every house. I am helping a friend get a new roof on her log cabin, and desire to strongly recommend skylights. I know Velux has had excellent flashing that go with their windows and he slope is good. She has spoken with others (men, actually, whereas I am female simply have a lot of experience with construction) and iii have told her not to install skylights.

Her house is and then dark that even in summer if you lot desire to encounter annihilation in detail, y'all take to turn lights on during the 24-hour interval ($$). Bold that i buys proper windows and uses highly capable contractors to install them when a new roof is being put on, do you think in that location is a substantial adventure of failure down the line or think peradventure the people she spoke with were referring to window failures from the days when they were installed improperly, at a bad time (i.e. over the roof versus with the roof) or were less effectively designed products? Thank you for your response!

Answer:

Thanks for the question, Jen.

I don't know who the men are with whom your friend has spoken simply it sounds similar a lot of backbiting and arm-waving to me.

Modern skylight products take evolved significantly from early (leaky) products. The manufacturers have a neat interest in the success of their product, and to that finish have designed raised curbs that bring the skylight higher up the roof surface, and pre-packaged roof flashing components that are very reliable and leak-proof if the installer follows the manufacturer's installation instructions.

The people with whom she was speaking could be

ane. remembering the older products from xxx+ years ago that were not so well designed

two. confusing indoor condensation with roof leaks

3. people who installed skylights willy-nilly without using the proper components nor reading the installation instructions. I was talking with such a builder most a leak on a habitation he had simply finished constructing. "They all leak like that" he said, as if that meant it was OK. Well he was correct, all of his houses leaked at that point because he built them all the aforementioned fashion - with the flashing installed backwards. Some builders know construction. Others are ameliorate at arranging financing.

Jen

Delight also see

inspectapedia.com/BestPractices/Skylight_Installation_Procedures.php

on skylight flashing.

The skylights shown there were installed in a truss-roofed motel in Northern Minnesota, in a climate exposed to severe weather condition at the edge of Lake Superior. They don't leak.

Shown also on that page are the older "low profile" "bubble" blazon skylights that didn't have such a great success record.

Question: skylight leak sealant

(June 13, 2014) Gail said:

my skylight is leaking around the wood part of the skylight. what tin i utilise on this to seal information technology

Respond:

Clean the surfaces and try a silicone sealant

Question: many big skylights leak: nosotros want to install a roof over the whole shebang

Larry and Kathy Boso said:

I have a question. We have a roof that has 16 double 5x8 windows. The leak during rain and they leaks are in different places. We have tried fixing all of them, just decided to just put a roof over them all. Our delema is, how to put a roof over them. We are thinking about a gratis staind roof. Cant put whatever weight on the windowed roof. Each window weighs 200lbs? It would cost an arm and a leg to get a crane operater to lift out the windows. Afraid of the whole roof colapsing. Whatever ideas? Help?

Reply:

L&K

Wow what a dramatic set up for leaky roof windows. I sympathize the frustration. But before y'all decide on the roof-over option in that location are some considerations that pb to a bottom line: you need help from a blueprint professional and from your local building department. Concerns include:

1. Even with a roof over, unless the edges are enclosed on all sides, blowing pelting may still cause leaks at the skylights.

2. Special construction, perhaps trusses, would be needed to impact the ridge and eaves walls to span over the existing roof.

3. With a "double roof" construction in that location may be fire safety and fire code issues. Firefighters don't want to have to chop through multiple roofs if fighting a fire.

4. Ultimately the cost of the roof over project, done properly, may pb to a different approach: eliminating nigh of the 16 double roof windows in the existing roof, replacing whatever roof windows to be kept with curbed units with proper flashing, and then re-roofing that surface.

Employ our email institute at our CONTACT link to send me some photos and I may be able to commnent further.

...

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