How to Repair a Leaking Skylight? A Complete Guide

The moment that infamous drip starts showing up during torrential rains, it means that your skylight requires immediate fixing!

Skylights are a source of natural light in our household which improves the aesthetic, however at times they can lead to bringing in moisture when the seals break or during installation problems.

If you have observed water marks on your ceiling or you can literally see water dripping from the skylight, there is no need to panic as most skylight leak repairs are quite simple as long as it’s the right method.

Understanding Why Your Skylight Is Leaking

Your skylight leaking problem will require figuring out what the exact problem is before initiating any repairs. The most common causes are usually the following:

Deteriorated Sealant and Flashing Issues

The sealant applied to your skylight is almost always subject to cracking and sharp deterioration as a result of extreme weather. Loosening or weakening of the metal flashing also causes seepage during rains. The metal flashing is instrumental in driving water away from the skylight.

Condensation vs Genuine Leaks

What seems to be a leak could possibly be condensation forming on the internal surface of the glass. This phenomenon often occurs when warm, moist air comes into contact with the glass skylight. If you observe dripping during cold temperatures, but not necessarily during rainfall, condensation is far more likely than a leak.

Installation Issues

Skylights are especially susceptible to leaking if they are not installed properly. If a skylight was recently installed and has started leaking, then the installation could be the reason. Deficient placement of the flashing and voids on the underfelt collar (secondary water barrier) can both lead to water ingress.

Broken Windows or Frame Damage

Leaking can occur due to curls in the frame or cracks in the skylight glass. While not as likely as problems with flashing or sealant, these issues, if unattended, can escalate and require immediate repair.

Critical Equipment and Substances Needed for Leaking Skylight Repair

Prior to going onto your roof, ensure that you have the following items:

● A sturdy ladder with stabilisers

● Safety harness and non-slip footwear

● Silicone caulking with roofing sealant or roofing silicone

● Putty knife or equivalent tool

● Rags and soap that is not aggressive

● Flashings for replacement if required

● Eye safety equipment/ goggles and hand protection

While performing roof work remember your safety should always be your priority, If you feel uncomfortable, it is always wise to hire a professional.

Step-by-Step Guide to Fix Your Leaking Skylight

1. Identify the Exact Area of Leakage

For any steps in the repair process, partition your activity by defining a boundary. For water entry, start from the perimeter and work your way towards the center where you suspect the leak is occurring. With the below suggestion, try identifying water entry:

● Brown markings on the surface away from the installed structure.

● Seals and flashing noted gaps or fissures.

● Framing or glass parts with broken lines or damaged portions.

If diagnosis is cumbersome, ask a volunteer to spray water using a hose around the skylight as you sit indoors to see from where water ingress first occurs.

2. Conduct a Comprehensive Clean-Up of the Work Area

Prior to sealant application, or carrying out any repairs:

Clear away all dirt, leaves, and moss around the skylight. Such materials can retain water, obstructing the necessary drainage through the weep holes; these are the small orifices designed to allow moisture to escape.

Wash the frame with warm water and a mild detergent (scrub only lightly to avoid damaging the surface) to remove any soiling or old sealant residue. Ensure every component is fully dry before continuing with the repair work.

3. Address Sealant Issues

If deteriorated sealant is the culprit:

Carefully remove old, cracked sealant using a putty knife. Apply a fresh bead of external-grade silicone caulk or roofing sealant around the edges where the skylight meets the roof. Smooth the sealant with a wet finger or tool to ensure complete coverage and a neat finish.

Choose a clear, dry day with moderate temperatures for this task, as extreme weather can affect how well the sealant cures.

4. Repairing or Replacing Flashing

Repairing damaged flashing typically requires more attention than just a simple touch-up:

Lift the adjacent roof tiles or shingles to access the flashing. Look for holes, gaps or rust in the metal. Replace any removed sections with new flashing and ensure the overlaps are sufficient to divert water away from the skylight. Apply the edges with appropriate roofing sealant.

As with previous types of repair, this one too may mean having to remove several rows of roofing. Be careful while doing this, as doing so carelessly will result in more harm than good.

5. Fix Closing Mechanism Problems

For opening skylights, check whether the window closes properly:

Confirm that there are no obstructions that can be blocking the process of closing to completion. Inspect the rubber sealing strip associated with the frame for wear or mould. A worn out gasket could necessitate replacement to retain the watertight seal.

Check the opening and closing mechanism for any functionality issues which could prevent proper sealing when closed.

6. Address Concerns Related to Condensation

If condensation rather than leaking is your problem:

Improve ventilation in the room below the skylight. Consider using a dehumidifier if moisture levels are consistently high. For double-glazed skylights, condensation between panes unfortunately indicates seal failure, which typically requires professional replacement.

Proper ventilation is particularly important in bathrooms and kitchens with skylights, where moisture levels tend to be higher.

When to Call a Professional?

Some skylight leak repairs can be done by a confident DIYer, but the following cases suggest professional help:

Significant damage to the skylight and the adjacent roof.
Persistent leaks after multiple attempts to repair.
Under warranty skylights (repairs may be covered).
Work affecting installation of the skylight structure.
Discomfort working at height or uncertainty around leak source.

Qualified installers have industry knowledge and appropriate tools for working at height and resolving complex skylight problems. For a repair that generally takes under half a day, the average day rate of a skylight installer in the UK is £150 to £200, which is quite reasonable.

The best approach to leaking skylights is prevention. To avoid future issues:

Schedule yearly checks for your skylights and roof.
Remove debris build-up regularly from the skylight’s perimeter and inspect weep holes for blockage.
Seal maintenance every few years requires applying fresh sealant as part of routine maintenance works.
Cut overgrown branches which may damage skylights during severe weather.
Consider upgrading from older skylights to newer, more weather-resistant models if leaks become recurring problems

While installing new skylights, remember that on both pitched and flat roofs a minimum pitch of 5-degrees is mandatory. For frameless skylights installed on flat roofs, the recommended pitch is 2-4 degrees. This is necessary to drain water efficiently, preventing damage from stagnation and pooling that could harm your roof membrane or the skylight.

Sometimes what appears to be a leaking skylight may suggest some malfunction of the roof that is much more serious. Water has a tendency to follow the slope of beams and timbers before it drips so the leak that is visible may be located miles away from the actual problem.

In case all possible issues with the skylight have been checked and the leak persists, it is best to consult a professional contractor who should check the whole roof for broken soft tiles or slates and other roofing elements that might be hiding the problem.

To avoid skyrocketing costs, taking immediate action when a leak appears will eliminate the need for repairs to the ceiling, insulation, and interior. At the very least, taking prompt action to repairs around the skylight will serve to protect the home against sustaining major damages while reaping the rewards around the features

If you are looking to replace a quickly persisting leaking unit, here at Rooflights and Skylights UK we can assist you in picking out the best design which goes harmoniously with your house. Knowing that our products are award winning and the warranty is a decade long, you can trust that you are dealing with a supplier who is the best in the industry.