Wintery weather conditions are the main catalyst for potholes. So is it possible to fix these dangerous crevasses as soon as they appear? Discover the minimum temperature for repairing holes in tarmac roads and see whether you can fix potholes in winter. Includes all the essential tips for permanent road repairs.
What causes potholes?
Potholes are caused by a combination of weather and the gradual impact of vehicles.
Cracks can easily form through wear and tear of our roads. Water seeps into these cracks and repeatedly goes through a freeze-thaw process whenever the temperature drops below freezing and warms up.
This freeze-thaw process is when water freezes within the cracks, and expands once it thaws. Just like what can happen with geological weathering of mountain rocks, a previously flat road surface starts to increasingly crack and break apart.
Add to the mix the weight of vehicles running over these cracks, and especially heavy goods vehicles (HGVs), it’s clear to see how these cracks can snowball, eventually creating larger and more treacherous potholes.
This simple process is a recipe for disaster on our roads.
In 2023 alone, the AA said it dealt with just shy of 632,000 pothole-related incidents in the UK. The insurance giant estimates these claims cost its customers around £160 million, but believe the total cost for the entire country could be as high as £500 million.
But potholes affect all road users.
Motorcyclists and cyclists are especially vulnerable to pothole-related accidents, either through dodging potholes or failing to see these hazards before it’s too late.
Can you fix potholes in winter?
Potholes can be fixed during winter, but there is a big proviso: the ground must be completely free of ice or frost.
If you fill a pothole on top of frost, water particles will be contained within the cracks of the reinstatement. Then, just as described above, this water is repeatedly subjected to the freeze-thaw process.
During winter, freeze-thaw can happen on a daily basis when the temperature drops below freezing overnight and increases with the sun the following day.
Over time, the tarmac filler is likely to break-away from the original hole. The cured filler can then, literally, ‘pop out’ of the ground.
Yes, you got it: the whole reason why the pothole was caused in the first place can also be the reason for a failed filler job!
So if you ever fix potholes during freezing or close-to-freezing temperatures, it’s likely the repair job will fail and need to be redone.
While most quality pothole repair mixes – such as those from the Ultracrete range – do not contain any materials that freeze, they should still never be installed when the temperature is close to freezing.
What's the absolute minimum temperature for fixing potholes?
As explained above, you must be certain there is no ground frost before fixing a pothole. Therefore, the temperature must be above freezing – and getting warmer – before you even consider getting your patching tools out.
But the best-practice advice is to only ever repair potholes when the outdoor temperature is at least 3ºC and rising.
And there’s a good reason for it being at least 3ºC: ground temperature is a few degrees cooler than the outdoor ambient temperature.
Following the rule of a minimum of 3ºC will allow you to fix a pothole permanently and without risking it popping out at a later stage.
There are other vital tips for permanent pothole fixes, which we’ll cover next.
Industry best practice for permanent repairs
Regardless of the weather conditions, there are essential steps you must take to make a pothole repair job a permanent one.
Choosing a quality tarmac-repair mix is crucial: the formula must be right for the road conditions and the size of the repair job (we’ll go into the best pothole fillers for winter installation in a moment).
Here are the industry’s best-practice tips for fixing potholes:
#1 Cut vertical lines around the pothole
Using a circular saw, cut neat, vertical lines around the pothole and remove any rubble or debris. Having clean, vertical surfaces will improve the bond between the hole and the pothole repair mix.
#2 Apply a specialised sealant
Next, apply SCJ Cold Joint Spray to the pothole’s base and new vertical edges. A high-strength sealant specially formulated for potholes, SCJ can be applied in all weathers.
Install and compact the filler in stages (as directed in the instructions), applying the cold joint spray at every stage to the new base and sides of the hole.
SCJ spray deal
#3 Final step to prevent water ingress
Finally, professional contractors finish the job by applying an extra barrier to the edges of the repair job to prevent water ingress.
Secure the edges using Instaband Eco overbanding tape. This thermoplastic tape is then sealed with a blowtorch and left for 10 minutes before the area is opened to traffic.
Instaband Eco deal
Best pothole formulas for winter weather
When fixing a pothole during winter, use one of these three formulas for a permanent solution.
Tough Patch – improved workability
While most quality tarmac repair formulas can be used during colder temperatures (3ºC and rising), choosing a formula with improved workability on those winter days will make installation that bit easier.
Tough Patch Rapid is a hybrid pothole repair formula that offers increased workability during cold temperatures and is certified for use on roads and highways.
Whereas other bagged formulas of cold-lay tarmac cure when compacted, the innovative reactive binder within Tough Patch goes through a rapid curing process that is activated with water. Simply fill the pothole and sprinkle with water before compacting.
Importantly, it’s this rapid water activation that makes compacting the formula that much easier during colder weather. And, as water-activated, Tough Patch can even be installed during a light shower.
Tough Patch is approved by the Product Assessment Scheme (PAS) and made in accordance with the Specification for the Reinstatement of Openings in Highways (SROH).
With exceptional skid and rut resistance, using this superior cold-lay mix means the area can be instantly opened to traffic after installation (cored for assessment after 24 hours).
It can be used for permanent pothole repairs on driveways, car parks, high-speed roads and even areas with tight turning circles such as junctions and roundabouts.
Tough Patch 6mm can be used to fix potholes of up to 60mm in depth, and is available in either a 25kg tub or 25kg bag (discounts and free delivery available when buying in bulk).
For potholes of up to 100mm in depth, use Tough Patch 10mm (available by calling 0330 122 1025).
Tough Patch bulk deals
Ideal for wet weather: PPR Wet
Some cold-lay formulas can still be installed when it’s raining.
Permanent Pothole Repair Wet (PPR Wet) contains an anti-wash agent that stops the binder from washing out during wet weather, making it THE choice for installation in the rain.
PPR Wet can be used for potholes of between 10mm and 100mm in depth in trafficked areas on private roads, driveways and carparks.
Just like Tough Patch, after installing PPR Wet, the area can be open to traffic immediately.
Although this formula doesn’t come with all the necessary PAS or HAPAS approval for main roads and public highways, it is armed with a highly impressive skid resistance value of 88 PSV (polished stone value).
PPR Wet bulk deal
Hot-mastic formula: Enviro Mastic
For slightly larger potholes of up to 150mm in depth, there is a premade hot-mastic formula that comes with SROH compliance for roads and carriageways.
Enviro Mastic is a ready-made hot-lay, rubber-modified mastic asphalt. After heating the formula in a mastic mixer, this is another easy-to-apply pothole repair mix.
In fact, Enviro Mastic is ideal for fixing surfaces at remote sites as it requires no mechanical compaction. It is best suited for road ironwork, gullies and other street furniture, plus footpaths, cycle paths, utility reinstatements, airfield repairs and narrow trench reinstatements.
One thing to be aware of with this hot-lay formula is that, unlike the cold-lay options, you will need to wait for curing before opening the area to traffic. Typically, on colder days, Enviro Mastic takes roughly 1 hour to cure.
Enviro Mastic bulk deal
Final recap of essential winter tips
Check the outdoor temperature is at least 3ºC
Most important of all, during winter you must check that the outdoor temperature is at least 3ºC and rising before fixing a pothole. Doing so will ensure there is no frost within the pothole itself, something which would cause the pothole repair job to fail.
Check the ground for signs of frost or ice. Ground temperature is cooler than the outdoor temperature, which is why it should be at least 3ºC outside.
Fix potholes later in the day
One easy way to avoid low temperatures when fixing a pothole is to postpone your repair job until later in the day. The outdoor temperature is more than likely to be warm enough around lunchtime or by mid afternoon.
Allow more time for curing
Pothole repair formulas such as the hot-applied Enviro Mastic require more time to cure during cold weather. This particular mix takes roughly 45 minutes to cure on a hot day, and around 1 hour when the weather is cold.
If you don’t want to wait longer, choose a pothole repair mix that cures instantly. For example, after fixing a pothole with either Tough Patch or PPR Wet, the area can be immediately opened to traffic. That means no extra curing time during winter.
Store materials away from frost
Even though pothole repair mixes don’t contain any materials that freeze, they can still be affected by cold temperatures while in storage.
Always follow the manufacturer’s storage instructions. Often this is to store premade materials in a well ventilated area away from drafts. Ideally, elevate the bags or tubs off the ground, on a pallet or shelf.
Also, keep an eye on the use-by dates of the formulas. Most quality premade pothole mixes are made fresh and are to be used within six months.
What to do if the formula has hardened in the bag
Cold temperatures can sometimes cause a bag or tub of pothole repair formula to go hard. Don’t despair – this is very easy to remedy when the formula is still within its use-by-date.
See our guide on how to soften bagged asphalt so it’s ready to use.
Get in touch for extra help
If you have any questions around surfacing materials, such as cold-lay tarmacs, hot-lay tarmacs and all the ancillary items for permanent repairs, we’re here to help.
Call us on 0330 122 1025 for advice on the best formulas and protocols for your tarmac repair job, or post your question in the comments below.
