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When installing floor screeds in poor weather, damp conditions and/or during periods of low temperatures, it is important that adequate precautions and protection measures are taken to ensure a successful installation of a new screed.
First and foremost, we advise that you read and fully understand the manufacturers data sheet that should clearly show the recommended application temperatures.
Cold Weather / Low Temperatures
As a general rule, the colder the temperature, the longer the curing time will be. However, if the temperature drops too low, then this will affect the curing time so much that it could lead to a poor or even non-cure situation. Indeed, if the uncured material is affected by frost / freezing conditions, the screed will not cure and will have to be removed and new material re-laid.
If the area to be laid is in an unheated warehouse, or maybe in what is an unused/empty building, the area should be heated up with space heaters or similar to a suitable temperature, somewhere between 10°C and 20°C. Remember, if you are using space heaters, hot air rises and whilst it may indeed seem warn, the floor itself can take a lot longer for its temperature to rise, so it is well worth turning the heat on in the area well in advance of the day of installation, in order for the fabric (and specifically the floor) to ‘warm up’. Don’t forget, the temperature of a concrete floor is hugely influenced by the ground temperature externally.
Once the floor is laid, ensure the building stays at the minimum temperature for the duration of the curing process.
Other specific areas of concern are where the external perimeter of the floor meets with an external wall. Again, such areas can remain at a lower temperature due to cold penetration from outside.
Finally, doorways are another area that need to be considered, particularly industrial doors. Cold draughts able to penetrate under such doors can also seriously affect the curing process. Some people choose to sandbag or simply tape up along the bottom of the doors to help prevent such draughts. Other considerations are if the doors cannot be fully closed due to the screed passing directly below. In such circumstances, some people will lay cloths or some form of insulation material along the outside of the doors to help fill the gap and thus prevent unwanted draughts.
Wet Weather
It is vitally important that the newly laid uncured screed is not allowed to get wet before it has fully cured. Equally, the underlying substrate must not be too wet in order to be able to lay a screed on top. Such areas are best allowed to dry prior to the application of a screed. Again, refer to manufacturers data sheets and guidelines on such matters and if still in doubt, ring the manufacturer and speak to a qualified person.
Similarly, to what has already be touched on in the Cold Weather Low Temperature section above, take note of the seal under doorways and ensure they are watertight. Again, sandbag, tape or cover any such gaps with some form of waterproof material as damp/water penetrating onto an uncured screed with cause a poor or non-cure situation.
Roof leaks should obviously be repaired and sealed prior to the laying of any new screed in case of unwanted rain, as should any machinery or pipework leaks.
What can affect curing times?
The curing period of a new screed is hugely dependent upon the atmospheric temperature together with the existing floor substrate temperature. The colder the temperature, the longer the material will take to cure.
Equally, the humidity levels can hugely affect the ultimate curing and hardness of the new screed. Remember, water is added to the screed and this needs to be able to evaporate during the curing process. If the weather is inclement and/or the air is saturated with water due (mainly) to recent rainfall and low temperatures, the water within the new screed will be unable to dissipate into the already ‘waterlogged’ atmosphere and thus, this can greatly extend the curing process.
Good airflow through a building is always a good way of helping to dissipate evaporating water as a very hot, airtight area can have an equal effect of the room sweating and thus preventing the water from escaping from the screed.
Transportation and Storage
Water will affect the properties of both cement and aggregates. Therefore, it is vitally important that all materials are stored in dry locations and protected from moisture and rainwater.
It is worth noting that screeds, particularly self-levelling floor screeds have been formulated to have a specific amount of water to be added to allow both the product to be able to be laid, to be able to initially cure and to be able to harden to the strengths as proven in prior testing. If materials are allowed to take in water or dampness prior to the mixing process, this will affect all of the above-mentioned points, where it be the pourability of the and curing of the material. Finally, and as a result of too much water within the mix, this then impacts the ultimate strength/hardness of the cured material which will reduce the usability / longevity of the finished floor surface. All for the sake of not taking a bit of care!
But we’d like to finish on a good note so our final advice is; look after the materials and they will look after you!
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Polycote UK would like to take the opportunity to thank you for taking an interest in these product and application articles and hope they have been some help to you.
We would of course be pleased to answer any specific questions should you wish to contact us directly on 01234 846400 or email: help@polycote.com