Find and Fix A Leaking Roof
How to stop water getting into your home
By Donald Lowe
A roof that lets in water can cause a wide range of issues, with this guide, you'll be armed with the knowledge to effectively find and fix your leak
Something that every competent roofing company knows is that finding the source of a leaking roof is often made more difficult due to the typically recognised symptoms of a leaking roof appearing well away from the actual source of water ingress. More often than not, water makes its way into the internal area of a roof through a damaged section, runs down a truss or membrane, then drips onto the insulation and through to the plasterboard below, causing water marks to appear on the ceiling well away from the actual point of entry through the roof.
Common places for water to find its way through your roof is where there are worn, broken or damaged tiles, nails that have worked loose, or through poorly sealed or weathered flashing around the intersection of roof planes, skylights, vents or chimneys.
Identifying the signs of a roof leak
The most obvious indication of a leaking roof is the presence of dripping water. However, there are other tell-tale signs you’re likely to notice that can point to water making it’s way into places it shouldn’t be. These include:
- Missing or damaged roof tiles.
- Damaged or deteriorated flashing.
- Staining on the ceiling.
- Spots on exterior walls.
- Interior wall swelling or bulging.
- Musty or damp smelling rooms.
Any one of these signs could relate to a leak somewhere in your roof and should be inspected thoroughly to ensure no nasty surprises.
Finding the leak
During daylight, enter your loft with a torch, ensuring you only stand on the secure framing members and not on the insulation as this will not support your body weight and will result in damage to the plasterboard. Begin in the area directly above where the water is making its way into the room, inspecting the trusses and membranes for any sign of wetness, mould or black marks. If it has rained recently, the torch light should reflect in the water trail, making it fairly easy to find. If it has been dry, there may be tell-tale signs of water ingress, such as staining and discolouration on the wood, left by the dried moisture.
Once you’ve found and followed the water trail back up to where it meets the underside of the roof, switch off the torch and look for any daylight coming through the membrane, indicating the point of entry and the area needing repaired, keeping in mind though that several roof tiles may need to be removed to locate the damaged portion if it’s not easily identified. The membrane helps to prevent wind load and condensation build up inside the property, it’s primary function isn’t to keep out the rain, so the presence of damage or holes in the membrane, doesn’t necessarily indicate the initial location of water ingress.
- Start in the loft and look where the water is making its way through the ceiling
- Inspect the area for signs of a water trail or wood discolouration
- Follow it back along the membrane or framework to the point of entry through the roof
- Mark the area of the roof with chalk or crayon to be repaired once located
What to do if you can’t find the leak
If the source of the leak cannot be determined from a visual inspection of the internal roof surface, wait for a dry day and employ a helper to assist with a water test.
Ensure all adequate steps have been taken to ensure safety, one person is positioned on the roof with a water hose and the other person is inside the loft space with a torch and a bucket to catch any water what comes through. Starting at the eaves, the person with the hose slowly works their way up the roof, soaking one section at a time until the leak starts to present itself inside the loft. Once identified, take a nail and push it through the hole to help with identifying it at a later stage when coming to carry out the roof repair. Chalk or a wax crayon can also be used to mark the exterior of the roof to make the problem area easier to find.
- This method requires two people
- One on top of the roof with a hose pipe and one inside the loft space with a torch
- With the hose, start at the eaves or bottom of the roof
- Work your way up the roof, systematically dampening down sections
- Use torch light inside the roof to highlight the fresh water trail
- When water starts coming through the roof, mark the spot to make finding it again easier.
Repairing the roof
Slate roof repair
Once the problem area has been found and the damaged slate identified, you can start with the repair. Normally, the reason for water making it’s way into the a slate roof is caused by a slipped or cracked slate, this can be easily remedied by simply replacing the slate.
To do so, a tool called a slate rip is used to remove the fastening nails, which pass through the slate and into the wooden baton, securing the slate in place. If you’re not keen on buying the specific tool for this job, a large hacksaw blade between 12-14 inches would suffice to cut the nails in half, then lift the stubs once the slate is out of the way. Once both nails are removed, the slate can be wiggled out of position. Starting above the damaged area, remove as many of the roof slates as required to free the damaged slate for replacement. If the roof slate is simply missing, these steps will still need to be followed to allow access for installing the missing roof slate in the correct place.
To refit, slide the slates back into place and secure it with a nail, normally one nail will suffice to secure the slate, with the original slates overlapping and holding the new slates in position. In situations where the nail hole in the slate is too large or damaged, a new hole can be drilled in a suitable location to allow the slate to be secured, this method can also be used to stop slate swivel in areas where the new slates can’t be held in place by other slates, such as at roof edges. Before the final slate is refitted, hammer a strip of lead called a tingle into the wooden baton and once the new slate is in place, bend the lead up under the slate to hold it in place. Alternatively, a premade slate hook can be used instead of the lead tingle to secure the bottom of the final slate in place, leaving it tight and secure.
Use reclaimed slate to keep the overall appearance of the roof consistent and save a few pennies at the same time.
Tiled roof repair
In the UK, it is common for every third row of roof tiles to be secured by nails, with the remaining rows secured by the interlocking profile of the tile. For replacement, all that is necessary is to slide a flat pry bar underneath the tile to lift it up from the baton and wiggle it out of position. To refit, repeat the removal procedure, sliding the new tile into place with the aid of the flat pry bar, locating the top of the roof tile onto the baton.
If the tile to be replaced is one of those secured by nails, the flat pry bar can be gently wiggled under the tile and up to the nails position, then using a gentle rocking motion, the nail can be levered against and should pop out without any damage to the tile, allowing the roof tile to be wiggled free. To refit the new roof tile, use the flat pry bar to lift the existing tiles and slide the new tile in, locking it in place. There’s no need for nails if it’s only one or two roof tiles being replaced as the surrounding tiles will keep them in place.
To avoid the patchwork look that can be caused by having newer tiles in amongst an aged roof, using a roofing supplier that has a tile reclamation service to source the tiles not only allows the repair to go virtually unnoticed, but is also more cost effective.
Flat roof repair
Before carrying out any repairs to a flat roof, it must first be established that a spot repair will be adequate so fix the leak. Trying to patch up a flat roof that is in need of a full roof replacement may stop the leak in the short term, but will only work temporarily and will make it harder for a professional roofing team to replace the roof, making the time on job longer and increasing costs.
The first stage of repairing any flat roof is to ensure it is dry and free from any loose debris or moss. Going over it with a stiff brush will suffice and ensure a clean surface to work on, it’s important to remember that any loose dirt will hinder the bonding process when applying the repair materials to the existing roof and could end up causing another leak through the flat roof.
Taking a bitumen primer, like this product from Black Jack, apply it to the entire surface of the flat roof and spread it with a standard wall paper roller. Using a broom handle inserted into the bottom of the roller and secured with a nail saves you from having to bend over the whole time and makes it much easier on your back. Less it more when it comes to applying the primer, ensuring you have enough to cover the entire roof, but no excess left over as this leads to prolonged drying times and is generally just a waste of product. You must allow enough time for the primer to flash off, depending on conditions, this could take 30 mins in the summer or a few hours in the winter. Once it’s tacky, the flat roof is ready for the next stage.
Using a soft bristled sweeping brush, apply a solvent based bitumen roof sealer, to the top of the roof surface, making sure you achieve an even coating without leaving any gaps or pin holes. Make sure to give the contents of the sealer drum a good stir as the product settles at the bottom. Start at the furthest away point from your access to the flat roof and in sections, work your way back until a complete coat has been achieved. There should be a 2mm layer of roof sealer to ensure a waterproof and sturdy repair that will last, a second layer of sealer can be applied if required, allowing approximately 5-12 hours drying time between coats, depending on weather conditions.
For increased durability and coverage, fibreglass matting can be applied to the entire flat roof surface to increase the repair strength and cover any particularly bad sections. Add a layer of matting after the roof has been primered, applying the roof sealant over the top of the matting, ensuring all of the matting is covered. The fibreglass tends to make pinholes more likely, so make sure to fully check the roof for adequate sealant coverage before finishing off the coat, ensuring the repair is 2mm thick across the entire span still.
Additionally, as an optional final step to improve the appearance and reduce UV degradation of the roof repair, apply a coat of solar reflective coating to the entire surface, cutting in at the edges with a paint brush and applying the solar reflective coating with a 9 inch roller, using the same method as with the bitumen primer.
If you want to leave your roof repairs to the professionals, give the team at Dundee Roofer a call. We are specialists in carrying out all forms of roof repair, including tiled roof repairs, slate roof repairs and flat roof repairs as well as complete roof replacements for all types of roof.
Use the contact form below or give us a call on 01382 671026 to speak to the team.