Mastic Asphalt Roof Repairs

Asphalt roofing has always been a popular choice as a flat roofing system in the UK due to its incredible waterproofing ability as well as its durability.

Of course, like any flat roof system, there are some common roofing issues that can arise. However, the positive news is that asphalt roofing systems are normally able to be repaired by mastic asphalt specialists.

Let’s explore the common causes of problems with asphalt roofs, how to spot them and how these can be avoided or addressed.

Trapped Moisture

Unfortunately, there are occasions where moisture can become trapped on a mastic asphalt roof. Listed below are three common causes of why and when moisture can become trapped.

1) The first common cause occurs as the roof is being laid. When transferring the molten liquid asphalt to the roof for laying workers carry it in metal buckets coated in cement. Very rarely as the workers empty their buckets a small pocket of dust can become mixed in with the poured asphalt. Over time this dust pocket can contaminate the asphalt and cause it to spoil or ‘blow’.  

2) The second common issue occurs when workers fail to properly vent the asphalt overly - as if even a tiny amount of moisture becomes trapped amongst the layers of asphalt it will draw the bitumen1 to the surface. This occurrence means that,with time, visible bumps will begin to appear across the asphalt flat roof.

3) Lastly, should anything heavy by dropped upon the asphalt roof it can become damaged, particularly if the weather is cold as the mastic asphalt will be tight and contracted. Whilst the damage may only be small hairline fractures, unfortunately they will allow moisture to penetrate through, gradually expand and then cause the asphalt to blow.

Common Problems With Asphalt Roofing

1) Bumps: The good news is that they are normally fairly easy to spot! When standing on your roof you should be able to analyse whether there are any raised bumps running across it as they should stand out next to the level areas of your flat roof. These bumps would have been caused by moisture becoming trapped underneath the surface of the mastic asphalt.

2) Blisters: On first inspection blisters can be confused for bumps. But as you look at them closer up you will be able to spot that at the peak of the bump there is a split running through it. Asphalt blisters can be more problematic as they are the step-on from a bump and this means the mastic asphalt has been further damaged. The crack at the top of the blister allows small amounts of water to collect and makes leaks more likely to occur. The cracks can also mean that the roofing system itself has been compromised.

3) Splits and Cracks: If you notice any splits or cracks along your roofing system it is advisable to contact a roofing specialist and ensure that the problem area is inspected and dealt with as soon as possible. This is because a crack or split running along your roof is ultimately going to mean that water will start to pool and water ingresses occur and start to breakdown the surface of the mastic asphalt, which will affect the roof’s lifespan and potentially lead to leaks.

Changes in Weather Conditions

One of key problems an asphalt roof faces is the varying weather conditions experienced in the UK, where the temperature can change drastically from sunrise to sunset and we can experience sun, rain and snow within the same week.

When the asphalt roof is heated by the sun’s rays it causes the roof’s surface area to expand, then when the sun sets and the temperature drops, the surface area cools and contracts back to its original size. This cycle of expanding and contracting over time causes cracks to begin to appear on mastic asphalt roofs.

The sun’s rays can also cause further damage to the roofing system over time as the suns heat brings bitumen from with the asphalt to the surface of the roof and this process causes discolouration over time. Roof owners will be able to identify when this has happened as the roof will change from looking a polished black to a worn grey.

How Can I Prevent The Sun Damaging My Asphalt Roof?

By applying a generous coat of solar reflective paint to your mastic asphalt roof you are offering it the best protection you can from the damage of the sun. Also know as a roof’s ‘sun cream’ this paint acts as a barrier between the mastic asphalt and the sun’s heat – it provides immediate protection. The solar reflective paint2 has a life span if 3-5 years and is light grey in colour. 

Top Tips When Apply Solar Reflective Paint To Your Roof

• Ensure you are covering all parts of the roof including sections that have lead flashing (lead is a conductive material and so maintains the sun’s heat which can lead to slumping occurring on the roof).

• Apply the paint liberally across your roof’s surface

• For ultimate protection it is advisable that you also cover the lead flashing itself in UV protective paint.

It is worth noting that the solar reflective paint cannot provide 100% protection from the sun’s rays,but it does considerably protect the roof from becoming weathered and cracked.

What to do next?

If you are experiencing any problems with your asphalt roof please do not hesitate to get in touch with us today via our contact page or by calling 0207 781 8150. One of our friendly team will always be happy to offer advise on how to extend and maximise the lifespan of your roof.