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A guide for construction professionals to conduct pre-winter checks for residential roof leaks and damage.
Roof repairs: timing is everything.
When we talk about "timing," we're referring to the importance of identifying issues early. The ideal time for this? While the sun still shines, well before the winter rain and snow arrive. This period offers the best opportunity to uncover existing leaks and potential issues within a roof.
Consider the alternative scenario. Picture waking up on a stormy night to discover water dripping through your ceiling. It's a situation no homeowner wants to face.
This is precisely why prudent homeowners will turn to professionals like you during the summer months to inspect their roofs for leaks.
This article sets out how to carry out a pre-winter check of a house for roof leaks and offers BOSTIK solutions for the repairing of cracks or other damage you might find in bitumen membranes, bitumen liquid coatings, joints, or damaged top flashing.
The Bostik products that will be covered in this article:
Waterproofing Range
BLOCK B732 TOP BOND
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BLOCK B733 TOP FILL
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BLOCK B734 TOP COAT
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BLOCK B705 TOP ELASTIC
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BLOCK B747 TOP TAPE
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BLOCK H777 AQUA BLOCKER
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BLOCK H778 AQUA BLOCKER LIQUID
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BLOCK N531 MULTI FIBER
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Your seasonal roof inspection checklist.
When conducting a roof inspection for a house, the first thing is to ask the residents if they know of any problems.
In many cases, you will be called out because the residents have noticed a problem – most likely evidence of water damage to the ceiling, water dripping from the ceiling, or flowing down a wall when it’s raining outside.
That’s the easy part. When the damage has been noticed, you should be able to trace the exact point of failure in the roof above.
But you may have been called out for a preventative maintenance check, which will require your inspecting the whole of the roof area.
Our checklist has two main points: (1) Inspect the inside for water damage, and (2) Inspect the roof for leaks. It’s as simple, and effective, as that.
Inspect inside for water damage
After consulting with the resident, it's crucial to assess all areas of the ceiling directly beneath the roof. Look out for the following signs, which may indicate the presence of leaks:
- Discoloration/staining of the ceiling
- Softened and damp ceiling or wall plaster
- Flaking or bubbling paint
- Damaged wall coverings
If you do find areas of concern, map their locations within the house. This will allow you to inspect more carefully in the areas of the roof above those points. Bear in mind that water does not necessarily travel only vertically – it can collect and then flow horizontally until it finds an escape point. So you may need to inspect a wider area of the roof to find the damage to the roof that is causing internal damage at a particular location.
Once you’ve completed your inspection inside, it’s time to get on the roof.
Inspect the roof for leaks
Take your map of potential areas of interest with you up to the roof. (Make sure you get up on the roof safely, of course. You are a professional.)
If you know there are leaks, you will need to conduct a careful visual inspection of the entire roof, especially the key areas. Again, there should be visual clues. Look for:
- If it has rained recently, areas of ponding
- If the roof is dry, discoloration or silt indicating areas where water collects when it rains
- Discontinuities in the roofing, for example, joints that no longer appear to be waterproof.
- Cracks in the roofing material.
- Penetrations through the roofing membrane that appear to have deteriorated.
- Cracks and/or open joints in flashings and other linings.
Mark the areas where it is clear that the waterproofing on the roof has been compromised and also the locations where there may be the potential for damage to the waterproofing integrity to occur over the next couple of seasons if it hasn’t already occurred. (An ounce of prevention is better than having litres of water dripping through your ceiling!)
If the roofing system is old and you’ve found a large number of leaks, you might have to recommend full replacement. In the long run, full replacement will be more convenient for the homeowners than having you carry out leak repairs every few years.
For this article, however, we will consider only the scenario that simple roof leak repairs are all that is required.
How to use these products to repair roof leaks.
Bitumen membrane roofs.
The following Roofing Renovation System products should be applied during a period of dry weather.
Step 1: Preparation
- At the location of the damage, make cuts along the three sides of a rectangle surrounding the damaged area and roll up the bitumen sheet.
- Use a brush or cloth to clean the substrate and the underside of the bitumen sheet to remove all dust, oil, grease, and loose particles from the surfaces.
- Application temperature +10 to +30 degrees Celsius.
- Spread the BLOCK B732 TOP BOND all over the prepared substrate.
- Roll back the bitumen sheet into the adhesive and press down firmly to expel the air and prevent the formation of bubbles.
- Drying time 24–48 hours.
BLOCK B732 TOP BOND
BLOCK B732 TOP BOND is a solvent-free bitumen adhesive designed for cold application, for bonding bitumen roofing felts and bands. It is perfect for patch repairs on bitumen membrane roofs that are no steeper than 5 degrees.
Step 3: Filler
- Using a small roller, apply GRIP B501 BITUMEN primer to the top surface of the replaced bitumen sheet and 300mm into the surrounding area past the cuts that you made.
- After the primer has cured, use the BLOCK B733 TOP FILL to repair the cracked/damaged area and the cuts in the bitumen sheet. Using a trowel, apply it directly from the bucket to create a layer with a maximum thickness of 4 millimetres.
- Drying time 24 hours per 1mm thickness.
BLOCK B733 TOP FILL
BLOCK B733 TOP FILL is a high-quality bitumen-based filler and repair sealant that is suitable for repairing blisters, holes, cracks, and breaks in bitumen sheets.
Step 4: Top coat
- After the filler has dried, apply 2 to 3 coats of BLOCK B734 TOP COAT using a roller, brush, or suitable spray gun.
- Allow each layer to dry completely before the next application.
- In areas where there is a risk of cracking, place BLOCK T506 TERRA FABRIC in the second layer.
- Protect the top coat from direct exposure to the sun during application.
- Drying time 24–48 hours.
BLOCK B734 TOP COAT
BLOCK B734 TOP COAT is a water-repellent insulation coating based on bitumen and latex for the protection and maintenance of descaled, embrittled, and slightly friable bitumen roof membranes.
Bituminous liquid coatings.
Step 1: Preparation
- The substrate should be clean, free of grease, and completely dry.
- Cut out those areas if existing asphalt sheets or other roofing types exhibit bubbling or hollows.
BLOCK B705 TOP ELASTIC
BLOCK B705 TOP ELASTIC forms a stretchy, highly elastic, crack-filling coating that dries to become a seamless waterproof barrier.
Step 2: Application
- Application temperature range: +5 to +35 degrees Celsius.
- Apply 2 layers of BLOCK B705 TOP ELASTIC directly from the plastic bucket..
- Apply each coat with a thickness of 1.5 to 2 millimetres.
- Depending on temperature and humidity, drying will take 4–12 hours. The second coating can be applied when the first coating is no longer tacky.
- Protect the coating from rain until the second coating is absolutely dry.
Repair leaking joints or damaged top flashings.
Step 1: Preparation
- The substrate must be smooth, strong, dry, and in good condition.
- Make sure the substrate is free of dust, tar, pitch, formwork oil, contamination, or old coatings or layers that can affect adhesion.
- Degrease metal surfaces if necessary.
- For better adhesion, apply GRIP B501 BITUMEN before using BLOCK B738 TOP TAPE - LEAD.
BLOCK B747 TOP TAPE - LEAD
A sealing tape lined with lead and is perfect for difficult substrates and situations. Use it to repair leaking joints and roof penetrations and damaged gutters and top flashings.
Step 2: Application
- To prevent wrinkles from forming, remove the protective film and place the tape simultaneously as you unroll it.
- Press down with a cloth or roller to push any air bubbles out to the edges. In connecting areas, overlap the tape by approximately 2.5 centimetres.
- For small defects, cut out the desired length of tape, completely remove the protective film, and then press the piece into place.
- BLOCK B738 TOP TAPE - LEAD sticks immediately, so be very careful when applying it to get your positioning perfect.
General repairs and emergency situations.
When you need to repair a roof leak quickly to provide temporary protection, select from BLOCK H777 AQUA BLOCKER, BLOCK H778 AQUA BLOCKER LIQUID and BLOCK N531 FIBER.
Step 1: Preparation
- The surfaces to be coated must be free from any residues of oil, formwork oil, grease, dust, sintered layers, or other separation layers.
- The substrate must be rigid, capable of bearing loads, and free from other separating layers.
- Remove old loosely laid sheets completely.
BLOCK H777 AQUA BLOCKER is a thick waterproofing membrane ideal for brush-applied repairs. BLOCK H778 AQUA BLOCKER LIQUID has a more liquid rheology and is ideal for roller application over larger areas
Step 2: Application
- The ambient temperature and the temperature of the substrate should be between +5 and +30 degrees Celsius.
- Apply the product in two even, continuous coats using a short-fibre velour roller (or brush for H777 AQUA BLOCKER) to achieve a minimum thickness of 2 millimetres.
- Typically, 1.15 kg of product per m² will be required for each layer.
- Allow the first layer to dry adequately (approximately 4 hours at 20 degrees Celsius) before the next layer is applied.
BLOCK N531 MULTI FIBER is a flexible, cartridge-based, fibre-reinforced sealing paste designed for joints, small areas of leakage, and critical assembly areas. This product adheres to most common substrates but not to polystyrene or polyethylene.
Step 1: Preparation
- Remove dirt, moss, grease and oil from the surface.
- Scrape metal surfaces and/or clean with cellulose lacquer thinner.
- Fill deep cracks with foam or BLOCK T506 TERRA FABRIC.
Step 2: Application
- Avoid applying BLOCK N531 MULTI FIBER in thicknesses greater than 8 millimetres thick. (Use filler material if necessary.)
- Press and smooth the product in place to ensure optimal adhesion on damp surfaces.
- Depending on weather conditions, you can paint over the surface with acrylic- or solvent-based paint after 8 to 12 hours.
Regular maintenance equals peace of mind.
Most people don’t stay awake at night thinking about the possibility of their roofs leaking. A roof leak is never a problem until it becomes one. At night. During a storm.
A well-maintained roof is one whose problems are identified and addressed early.
BOSTIK’S range of roof repair systems will give you and your customers peace of mind.
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