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Asphalt Steps

Asphalt Steps Installation and Repairs | London Asphalt

London Asphalt offer a complete asphalt steps installation and repair service. No matter how big or small your problem our professional team will be happy to help you. With a wealth of experience and insurance backed guarantees you can be sure any work carried out on your mastic asphalt steps will be to a high standard, completed as agreed and problem free for years to come.

For a free quotation or any advice regarding asphalt steps please email us at or call us on 07739207726.

Why Choose Mastic Asphalt to Waterproof your Steps

• Mastic Asphalt is Carbon Zero Rated.

• Asphalt Steps are Environmentally Friendly.

• Mastic Asphalt is 100% Waterproof and is often referred to as ‘The King of Waterproofing’.

• Asphalters undertake a rigorous apprenticeship ensuring a high standard of work.

• Asphalt Steps can last for more than 30 years.

• Mastic Asphalt is a Time Tested Waterproofing System.

• Asphalt Steps are low maintenance and are easy to repair if there is ever a problem.

• Asphalt Steps are 100% recyclable.

• Mastic Asphalt Steps can be installed quickly with minimal disruption to your property.

• Asphalt Installation causes minimal disruption.

Using Asphalt Steps for Waterproofing

Using a set of mastic asphalt steps is a great way to protect your staircase from water ingress. Not only does asphalt have excellent waterproofing properties it is also extremely durable, carbon zero rated1 and easy to repair if something goes wrong down the line. Asphalt exterior steps are also aesthetically pleasing and can enhance the beauty of your home (in the image above you can see this finish of some Asphalt Steps, London).

The first step to take when applying asphalt to a staircase is to prepare the substrate. Without a suitably prepared substrate, a set of asphalt steps cannot be installed. The substrate must be level, have a suitable key for the asphalt to bond to and be free of any damp.

What To Do If The Staircase Already Has A Waterproof Coating?

If your staircase already has a waterproof coating the first step is to identify the material used for the waterproof coating. In most cases the waterproof coating will be asphalt or a liquid system.

If there is an old set of mastic asphalt steps present, these will need to be removed. This is specialised work as the improper removal can lead to the damage of the substrate below. The way in which the old asphalt coating should be removed is with a hammer and bolster.  Once most of the coating on the old asphalt steps is removed. The next step is to remove any remaining asphalt with an abrasive. Then the substrate is scrubbed down and sandblasted to complete the process. Once this is done the removed asphalt is taken away from the site and often recycled in to an asphalt screed.

If there is a liquid coating on the steps the process is slightly different. You can immediate rub the coating down with an abrasive to remove the liquid waterproofing from the steps. Next, you must scrub down the steps and finish the process by sandblasting the steps.

Once any existing waterproofing is removed you can move on to prepare the substrate for the installation of the asphalt steps.

Substrate Preparation for the Installation of Asphalt Steps

Once the existing staircase is stripped back to the substrate, the substrate must be inspected and prepared for the application of the mastic asphalt. Here it is important to ensure the surface is level, free of any damp and has a key which the asphalt can adhere to.

• If the substrate is not level it will need to be levelled. To do this any of the following can be used; concrete, render, or Unibond2.

• If there is not an appropriate key for the asphalt to adhere to one must be created.

• If there is any damp this must be dried out.

Once the substrate is damp free, dust free, level and has a suitable key, the staircase it is ready for priming and the cutting of the chase lines.

Cutting Chase Lines and Priming Asphalt Steps

Chase Lines

The asphalt steps will require a chase line which is 25mm by 25mm. A chase line runs up the side of the steps. You can see the chase line in the picture at the top of this page running along the bottom of the white walls and running into the top of the asphalt treads. A chase line is cut with an angle grinder and the purpose of one is to allow the asphalt to sit inside the chase line giving a complete watertight finish to protect your steps. Later, once the asphalt is sitting in the chase line it is finished with sand and cement mortar. You can see this sand and cement mortar finish in the image at the top of this page.

The required chase size for asphalt steps is 25mm x 25mm. This allows the asphalt to sit into the chase line and be ready for finishing with sand and cement mortar. The chase line is cut with an angle grinder.


Once the substrate is suitably prepared a primer must be applied. It is important to use a high-bond primer when priming the substrate for a set of asphalt steps. The reason for this is if you use a primer with a bitumen content, during the summer the bitumen will be pulled from the primer to the surface of the asphalt. This will create bumps in the surface and will eventually crack leading to the asphalt steps not being waterproof.

After applying a high-bond primer it will take 1-2 hours to dry out, if necessary a skilled asphalt worker can speed up the process by applying the heat of a gas torch on the primer.

Using Sheathing Felt to Allow Movement Between the Asphalt Steps and The Substrate

Next movement must be allowed between the asphalt and the substrate. The way in which this is achieved is with sheathing felt. The sheathing felt acts as a separating membrane allowing the asphalt to move independently of the substrate. The sheathing felt is loose laid and has a bitumen content which allows it to bond with mastic asphalt.

What Type Of Mastic Asphalt Is Used In The Installation of Asphalt Steps?

For asphalt steps, roofing grade mastic asphalt is used (mastic asphalt 988T).

Mastic Asphalt Type R988 (Roofing Grade Mastic Asphalt)

Type R988 roofing grade mastic asphalt can come in different compositions. Below we look at the two which can be used for asphalt steps R988 T25 and R988 T50:

1) Type R988 T25. This asphalt is composed of 75% bitumen and 25% lake asphalt.

2) Type R988 T50. This asphalt is composed of 50% bitumen and 50% lake asphalt.

Although the name roofing grade mastic aspahlt suggests this mastic asphalt is specifically for asphalt roofing applications it can be used in the waterproofing of all types of applications excluding ones where tanking is needed.

As you can see in the compositions of the R988 Roofing grade asphalt above some have an increased amount of Lake Asphalt. This Lake Asphalt comes from the famous ‘Asphalt Lake’ in Trinidad discovered by Sir Walter Raleigh discovered in 17923.

By increasing the amount of lake asphalt in the R988 the asphalt becomes both easier to handle and performs better. The reason for this is Lake Asphalt has a silky texture. This is because of the extremely fine particles of clay present in the Lake Asphalt. The result is a thixotropic characteristic which makes the mastic asphalt smoother and easier for the asphalter to apply to the roof.

The presence of 'Lake Asphalt' in a mastic asphalt mix brings a much faster weathering time than asphalt mixes which do not contain lake asphalt. Like all asphalt the finished surface will have a bitumen rich skin which will need to be rubbed with coarse sand to weather it. But mastic asphalt comprising of 'Lake Asphalt' will weather much faster.

The mastic asphalt is applied in two coats when waterproofing a staircase. Normally the first coat is formed in roofing grade mastic asphalt followed by a second coat of recreational duty mastic asphalt. The asphalt to the horizontal of the steps is applied in two coats to a thickness of 20 to 25mm. And the asphalt on the vertical is applied in two coats to a thickness of 13-15mm.

The First Coat of Asphalt

The first coat of mastic asphalt applied to the steps is applied to the stringers. This is the part of the asphalt staircase where a chase line has been cut earlier. The asphalt which is applied to the stringers is to a thickness of 7-8mm. This is the first of two coats to a thickness of 13-15mm The asphalter will apply the mastic asphalt using a wooden float making sure the stringers are tucked into the chase for a complete water tight finish.

The next part of the 1st coat application for the asphalt steps is to apply the mastic asphalt to the steps risers. The asphalt is applied to the risers of the steps and finished going on to the tread above.

Applying Asphalt To The Treads of the Steps

The next step is to apply asphalt to the treads. The height of asphalt applied to the asphalt steps will be two coats to a thickness of 25mm. The first coat will be 10mm in roofing grade asphalt and the top coat will be 15mm in recreational duty asphalt.

Both coats of asphalt applied to the steps are applied using a wooden float. Approximately 10-15% of the top coats mix contains additional 3mm coarse aggregate to provide extra durability to cope with the foot traffic the steps will have to withstand. Once the top coat is finished it is sand rubbed to extract the bitumen content of the asphalt.

Finishing the Upstands on The Asphalt Steps

On asphalt steps the upstands (also referred to as stringers) must go into the chase and be a minimum of 150mm high. The upstands are finished with sand and cement pointing. The top coat of mastic asphalt applied to these upstands is between 7-8mm thick. This will bring the two coats to a thickness of between 13-15mm. Just like before coarse sand will be rubbed into the asphalt.

Finishing The Risers on Asphalt Steps

The risers on asphalt steps are finished with an additional coat of asphalt to a thickness of 7-8mm. When the asphalt is applied, it is made to slump over the tread above. This technique is called the poultice method. The reason for doing this is to make a clean joint. The tread and the riser are blended together and it is finished with a double filler seal. This double filler seal creates a seamless finish for the asphalt steps. Once the second coat is applied to the riser it is sand rubbed.

Finishing the Asphalt Steps with Angle Fillets

To finish asphalt steps angle fillets are used. Angle fillets join the horizontal treads with the vertical risers and the steps with the upstands running along the sides of the steps. Once angle fillets are in place the asphalt steps are completely waterproofing. Aside from the effectiveness of creating a waterproof finish, angle fillets provide an aesthetically pleasing decorative finish for the asphalt steps.

Protecting your Asphalt Steps With Solar Reflective Paint

It is advised to finish your asphalt steps with solar reflective paint. This is imperative if your steps are southward facing. The reason for this is the exposure to sun can cause the steps to heat up and suffer from a problem called slumping. Also in winter months, the heat of the sun and drastic temperature drops at night can lead to the asphalt developing cracks. By applying solar reflective paint to the asphalt steps, you protect the asphalt from the sun and prevent it reaching such high temperature. This vastly reduces the risk of problems and extends the lifetime of your asphalt steps. The solar reflective paint comes in an attractive light grey colour.

The effectiveness of solar reflective paint normally lasts for between 5 to 7 years. This means to give your asphalt steps the longest possible lifespan, you should re-apply solar reflective paint every 5 to 7 years.

Can Asphalt Steps Be Repaired?

Yes asphalt steps can be repaired. If you do notice any problems with your steps it is good to repair them as soon as possible. Not only to protect your property from water ingress but to maintain the beauty of your property. This is especially true with asphalt front steps, as unattended probelms can significantly reduce your property's curb appeal. Below we will detail some common signs your asphalt steps require repair work.

Common Signs Your Asphalt Steps Need Repair Work

Cracks and Splits in the Asphalt Steps

It is common to see cracks and splits in failing asphalt steps. These cracks and splits allow water ingress meaning your asphalt steps are no longer providing waterproofing for your property. These cracks and splits are normally caused by bumps or blows in the asphalt splitting. These blows are caused by moisture trapped under the substrate attempting to escape. And as the moisture continues to escape the asphalt gives way and the result is a split or crack. If you notice any cracks or splits in your asphalt steps you will need to contact an asphalt specialist to carry out the necessary repair work.

Blows in the Asphalt Steps

Blows or bumps are like small mounds in your asphalt. As mentioned above these typically form before cracks and splits occur and are called by trapped moisture trying to escape from underneath the asphalt. If you see any bumps in your asphalt you should immediately get this looked at. A lot of the time it is a straightforward repair where the affected area will be cut out of the asphalt steps. The substrate dried and prime then new asphalt applied.

Upstands Not High Enough 

An upstand of at least 150mm is required to sit into a chase on the wall on a set of asphalt steps. If this is not the case there is a high probability of water ingress. If there is not an upstand or an upstand of sufficient height present on your asphalt steps, a chase will need to be cut into the wall and an upstand built to 150mm in height. 

No Chase Line Cut For The Asphalt Staircase

Another problem with the upstands on asphalt steps can occur if the upstand is not cur into the wall. When this happens, you will typically see a set of asphalt steps with an upstand finished with a bead of silicon. The problem with this is it does not protect from water ingress. The solution here is to remove the existing asphalt upstands. Then cut chases into the walls, then apply mastic asphalt in two coats to a thickness of 13-15mm to form the new upstand. This new upstand must be at least 150mm high and finished with a sand and cement mortar pointing. Once this new upstand is applied your asphalt steps will be protected from water ingress through the upstands.

Asphalt Steps Having No Solar Reflective Paint or Aged Solar Reflective Paint

As mentioned earlier it is strongly advised to finish asphalt steps with solar reflective paint. Asphalt steps without solar reflective paint ages faster and are more prone to cracks, splits and blows developing due to thermal movement. This also applied to solar reflective paint which has aged and needs to be re-applied. By using solar reflective paint and renewing it every 5-7 years you will prolong the lifetime of your asphalt steps.

Brickwork Pulling Away From The Asphalt Steps

The brickwork around the asphalt steps can pull away from the asphalt making a gap. The cause of this is thermal movement. The way to prevent is to cut a chase into the brickwork and insert a mastic asphalt upstand.

Impact Damage To The Asphalt Steps

When a heavy object is dropped on asphalt steps cracks or indentations can occur. This type of crack is referred to as impact damage. This is a particularly common thing to happen in the winter months when the asphalt surface temperature is colder and has less movement. If this does happen, it can be repaired by cutting out the damaged area and re-applying new mastic asphalt.

Need a Quotation or Some Advice About Asphalt Steps?

To get a quotation or any advice regarding asphalt steps please feel free to contact the team at London Asphalt us on 07739207726 or email us at One of our asphalt steps specialists will get back to you as soon a possible.