How to Stop a Roof Leak

The roofs of our homes have one main purpose, to keep the rain out. While they also help keep the heat and cold in our homes, as well as helping us to avoid a sunburn, their main purpose is to keep the rain on the outside, so that we can stay nice and warm on the inside.

But while roofs do an admirable job in that basic task, there are always the exceptions; times when the roof doesn’t manage to keep us dry. Unfortunately, we usually don’t know about those leaks until right in the middle of a rainstorm. That puts us in a reactionary mode, rather than a proactive one. But we still have to do something and we often have to do it fast.

But Can’t We Prevent It?

Obviously it would be better to stop the leak before it even starts, if that’s possible. Fortunately, it is for most leaks. All that’s required is a little preventative maintenance, something that can be done in an hour or two, once a year.

Assuming that the roof shingles and sheathing are in good shape, most leaks occur around vents which pierce the roof. While these are supposed to be installed in such a way as to prevent leaks, mistakes happen. Leaks are also possible in cases where vents were properly installed, as weathering of the seals and sealant can cause them to crack. This problem is especially prevalent in two major areas: the south, because of heat and the far north, because of cold.

There are two basic types of vents that pierce our roofs and both need to be checked. The first is the vents for the attic space. These come in a variety of shapes and sizes, from turbines to roof peak vents, but are unlikely to have any sort of rubber gasket involved. The only thing which can crack on these, causing a leak, is the tar or sealant around them. Such leaks will be visible as cracks in the sealant.

The other kind of vents that pierce home roofs are plumbing vents. These are sections of PVC pipe, which stick up through the roof. They are surrounded by a cone, usually made of a combination of galvanized steel and rubber, with the rubber forming the seal against the sides of the pipe. All together, the vent and seal look something like an upside-down funnel. Leaks can form in sealant around the base, as well as by the rubber seal cracking.

Either of these types of vents must be installed so that the shingles upslope of them and on the same level as them overlap the vent’s flange. The vents’ flanges should overlap the row of shingles downslope of them. edges where the shingles overlap the flange should be sealed with tar or sealant.

Patching These Leaks

It’s not hard to patch these sorts of leaks in a roof, if they are found in time, when the roof is dry. All that’s needed is a gallon can or caulking tube of roof sealant. No other tools are required, as the sealant can be smoothed into place with a gloved hand.

What if That’s Not It?

Dealing with other roof leaks is a much bigger challenge, usually requiring the replacement of shingles or re-roofing the entire home. While the work is not all that challenging to do, the sheer volume of it makes it very hard for the average homeowner to reroof their home. For this reason, most homeowners hire a roofing company to replace their roof, if it is needed.

If roofing shingles are replaced, due to a roof leak, the underlying roof sheathing should be checked for water damage. Discoloration due to water stains is acceptable, but when the damage causes rotting in the wood or delamination of the plywood or OSB, then the damaged sheathing needs to be replaced.

How to Stop a Roof Leak in the Rain

Most roof leaks are discovered because there is water leaking into the home while it is raining. If there is water leaking inside your home when it is not raining, it’s probably not a roof leak, but rather a plumbing leak or air conditioner catch tube leak. Such leaks can be taken care of inside the home, without having to do anything to the roof. Even so, they should be repaired as quickly as possible, to avoid causing any further damage to the home.

Catch the Leak

If a leak is discovered during a rainstorm, the first step in dealing with it is to catch the water, so as to keep it from causing any further damage. Buckets or plastic bins can be used to catch dripping water. But if it is available, the trash can from outside is even better, especially if it has wheels. Spreading a plastic tarp on the floor, underneath the container catching the dripping water, can help to protect the carpeting. Furniture and other items should be moved out of the way.

Sometimes, water will drip through the ceiling in multiple locations. This indicates that the water has formed a puddle in the attic, either in the insulation itself or under it. If that happens, it will seek out the seams between the drywall sheets to leak through. It is possible to reduce the number of places it is leaking by putting a hole through the ceiling, wherever the biggest leak is. Just push a screwdriver through the drywall there. The water will drain out through that hole and the other locations will stop leaking.

Find the Leak

Once damage control has been accomplished and the water is being captured, it’s time to find the cause of the leak. This usually requires a trip up into the attic with a flashlight. While it may not seem like it, the best time to do this is while it is still raining, because that’s when the leak will be visible. Waiting until better weather probably will end up meaning waiting until the next rain storm.

The actual leak in the roof may not be right above the leak coming through the ceiling into the living areas of the home; in fact, it probably isn’t. It is not uncommon for leaks to travel several feet, as they go through the layers of shingles, tar paper and plywood sheathing that make up a roof. About the only thing that is sure, is that if the water doesn’t enter the outer layer of the roof at the point where it exists into the attic, it will be uphill from that point.

If possible, it’s a good idea to put a bucket under the leak in the attic, catching the water there, rather than allowing it to soak through the ceiling, causing more damage. If that is to be done, it is important to place boards under the bucket catching the water, spanning the ceiling joists and allowing the weight of the bucket to be supported by them.

Stop the Leak

The easiest way to stop a roof leak is to cover it with a tarp or plastic film. This is what a roofing company would do as a temporary fix, if they were called out to deal with the leaking roof. They’ll charge between $200 and $500 to do it though.

Before the tarp can be installed, the location of the leak must be located. At a minimum, the tarp should cover the roof at least four feet on either side of that point. It also has to go over the roof peak. If it doesn’t go over the roof peak, then water is able to flow under the tarp and continue leaking into the home.

It is inadvisable to nail the tarp to the roof, as that requires nailing through the shingles, which can cause additional leak points. Rather, attach the tarp to 2”x 4”s with either roofing nails or staples, on the underside of the 2”x 4”s. Then spread the tarp out, allowing the 2”x4”s to act as weights, holding it down. If it is necessary to nail directly into the roof, be sure to use some sort of caulking or roof sealant around the fasteners, so as to prevent another leak.

The blue tarps typically used for covering a damaged roof will generally last for about six months. It will be necessary to check the tarp regularly, to ensure that it is still taut. If the 2”x 4”s move and there is slack in the tarp, it will allow the wind to beat the tarp against the roof, destroying the tarp.

Use extreme caution when going on a wet roof. Any roof is dangerous territory to start with. When roofs are wet, they can become slippery. The best footwear to use is something with a soft rubber sole, which will allow the grit of the roof shingles to push its way into the rubber, helping to create a lot of hold points. Make sure that the ladder is tied firmly to something or attached to the fascia board, so that the wind cannot blow it down.

Patching a Leak From Inside

It is extremely difficult to patch a roof leak from inside and any such patch will only be temporary. As long as the rain can get through the shingles and into the roof sheathing below, it will continue to cause decay of the wood. So while a patch may stop the rain from damaging the ceiling and insulation, it won’t stop the rain from damaging the roof sheathing.

To make a patch, start by defining the area the patch needs to be installed in. With a stout pair of wire cutters or a grinder, cut off all the nails sticking down through the roof sheathing in this area. Then cut a piece of plywood just big enough to fit between the rafters and long enough to ensure covering the entire area of the leak. Check the fit and verify that it will fit up snug against the underside of the roof sheathing, indicating that all the nails have been cut off.

Coat both the underside of the roof sheathing and the top side of the patch with a heavy coat of either roof sealant or tar. Then push the patch up onto the underside of the roof with enough pressure to cause the sealant to start coming out around the edges. Nail the patch in place by nailing into the rafters in such a way that the nails capture the edges of the patch board, rather than nailing into the roof sheathing. That will help prevent any new leaks from forming.

Repairing Interior Damage

Leaky roofs can cause a considerable amount of damage to the inside of your home, starting with water stains and getting worse from there. Even water stains can be difficult to deal with.

Any water damage should be allowed to dry fully, before determining the extent of any necessary repairs. Drywall and some other building materials will appear weak while wet, but may still harden up and be usable, once dried. Insulation may collapse from the weight of the water inside, but once it dries, it can fluff up again, although it won’t always do that.

Always replace any wood or insulation which has become rotted due to moisture. Insulation which has compressed from getting wet, that doesn’t regain its original form once dry, should also be replaced. Due to the long time it takes for it to dry, it might be better to just replace it, rather than waiting for it to dry.

Moisture in the wood and drywall can lead to mold. If mold exists, it should be killed before doing any other restoration work. Bleach or ammonia can be used to kill mold on non-porous surfaces, but they will not work on porous ones. However, vinegar will.

If wood and drywall have no more damage than water stains, they can be left in place and repainted. To hide the stain, use a white, shellac-based primer, before painting. Shellac primers are ideal for this, as they dry extremely fast, preventing the stain from leeching through. Normal primers will often end up stained, making it necessary to use several coats of primer, before painting.