To Screed Or Not To Screed: Do I Need to Screed My Concrete Floor?
You may have noticed that bare concrete floors aren’t very welcoming or appealing: they’re cold, hard and are intended more as a baselayer as opposed to a finished article, particularly as they rarely settle level. If your concrete floor has a levelling issue, you may ask: do I need to screed my concrete floor?
Though some are content with having concrete as a final finish – particularly commercial environments seeking an industrial aesthetic – the majority of homeowners and businesses prefer a more refined finish.
Even when complete and levelled, concrete can often remain uneven; therefore, applying a screed to your concrete floor can give the floor a finishing touch and amend any remaining unevenness.
Understandably, most have never heard of screed: it’s easy to assume that fully cured screed is just a part of the concrete floor to anybody outside of the trade.
First, what, exactly, is screed? Find our beginner’s guide to floor screeding here.
What is Screed? A Definition
Though similar in appearance to concrete, even made from the same constituent materials (aggregates, cement and water), screed itself is not a structural concrete product.
Screed and concrete differ in their appearance and application due to the manufacturing process of both products: screed uses much smaller graded aggregates than concrete, leading to a smoother texture and thinner consistency.
Screed is most commonly used as a finalising layer applied on top of prepared concrete floors to provide a smoother finish which improves the appearance of the floor and gives it added durability. A smoother, more level finish is often required as concrete rarely settles smoothly; to achieve that, it’s always advised to employ the services of a professional floor screeding contractor.
As concrete uses bigger, more coarse aggregates than screed, as well as nearly double the amount, concrete has a much longer lifespan owing to its durability.
As screed applications are much thinner than concrete, it is useful to use if underfloor heating is planned.
Types of Screed
Consider, there are multiple types of screed you can use depending on the intended location and application.
Bonded Screed
The screed is affixed directly to the structural concrete using a slurry of strong bonding agents or primers.
Typically used in environments requiring a thinner layer of screed, the thickness is typically anywhere between 15mm and 50mm.
Unbonded Screed
This type of screed is not directly bonded to the structural concrete. Instead, the screed is applied onto Damp Proof Membrane (DPM)/polythene which has been laid upon the concrete sub-base.
This method is typically applied to older structural concrete bases.
Underfloor Heating Screed
One of the most common applications of screed, this variety is used when there is an installation of underfloor heating.
Usually laid on top of thermal floor systems – instead of other, passive insulation methods – the fact that screed is thinner and less dense than concrete means that it insulates the heat adequately.
Floating Screed
Similar to unbonded screed, the floating variety has become more common in new-build dwellings as well as those homes that are being refitted to be more efficient and environmentally conscious.
This type of screed is used to cover a slip membrane that has been laid on top of thermal and/or acoustic insulation that has been separated from the concrete sub-base below by DPM or polythene.
So, Do I Need to Screed My Concrete Floor?
In short – no. There is no unwritten rule or law which stipulates that you must apply screed to a concrete base before finalising your floor.
However, as concrete is coarse, rough and often uneven, it is highly recommended to apply screed as a finishing layer to level off any discrepancies and inconsistencies.
If I Decide to Screen My Floor Anyway?
Though screeding a floor is not 100% mandatory, you may still wish to apply it. Read on to find out the answers to some questions you may have.
How Long Does Screed Take to Dry/Cure?
Though the drying time of screed varies based on the type used, its thickness and the general ambition conditions; however, the general advice is to leave at least 24-48 hours before applying any weight or allowing foot traffic. It is of the utmost importance to allow the screed to dry totally and undisturbed.
If the area that has had screed applied will experience considerable foot traffic, the screed should be given as much time as possible to cure completely to facilitate maximum structural integrity and durability: ideally, over one week at the bare minimum, with a month being the best and most advisable timeframe.
Can I Speed Up the Curing Process?
Yes, though this is dependent on the type of screed used: which is best discussed with your floor screeding experts on ways they can advise to speed up the process. Our friendly, specialist team at AB Drylining will be happy to advise in this area.
Generally speaking, for screed to be dried quicker, there should be optimum drying conditions such as adequate airflow, perfectly balanced humility and other ambient factors.
Are There Any Benefits to Accelerating the Drying Process?
The benefits are limited mainly to the logistics of the project. The quicker the drying process can be completed, the more quickly the finalised floor can be laid and the project can be completed; allowing workers to complete other tasks/jobs and the floor can be utilised for its intended purpose.
Alternatively, speak to the team at AB Drylining to discuss the best curing accelerant additives.
How Long is the Drying/Curing Time Before Foot Traffic is Allowed?
The screed application is thin and the ambient conditions are adequate, the drying process can be complete within as little as 16 – 48 hours.
Ideally, you want to wait at least 7 full days before allowing considerable foot traffic or heavy items onto the screed.
When Can I Apply the Final Floor to Screed?
As screed progresses through its curing process, the mass and size shrink: this is why you should never rush into applying your final floor before the maturing process is complete.
Ideally, you should wait at least one month before beginning the process of installing your final floor.
Which Type of Screed is Better For Underfloor Heating?
As screed is an excellent and robust insulation solution for underfloor heating, there are several screeding types suitable for such floors.
The best type of screed to use for underfloor heating is the specially formulated underfloor heating screed. Alternatively, liquid screed and self-levelling screed are excellent options, also.
Can I Use Screed As a Final Floor Finishing?
Yes, screed is a commonly used final floor finish, particularly as it is polishable. Commercial environments – such as leisure centres or universities – often have screed as their final floor as they are cheaper to install and maintain than other, more artistic, finishes.
FAQ
Can I use screed on any floor type or property?
Yes! Screed is used in domestic, commercial and industrial environments alike. The thickness of the application will depend on the intended property and use of the environment.
Can I apply screed to concrete?
Yes – the intended purpose of screed is to be applied to a concrete base.
How do I maintain my screed?
If applied correctly, levelled and given ample time to dry and set, screed should not require ongoing maintenance.
Does screed have soundproofing benefits?
Screed can have soundproofing benefits: please talk to our team for more information on how this can be accommodated.
Do all concrete floors need screed?
In short – no. However, it is advisable to apply screed to concrete floors to level them as well as mitigate any imperfections or blemishes in the concrete sub-base.
I want underfloor heating – should I use a screed solution?
Yes, this is advisable. As screed transfers but retains heat at an optimal rate, it makes this a more economical option.
How soon can I lay carpet on screed?
Screed should be given as long a time as possible before applying carpet as a final finish, to avoid the possibility of mould and spores from forming as a result of trapped moisture.
In this case, 28 days is advisable.
Can I tile a screeded floor and, if so, how long should I wait?
The screed should have enough structural integrity to be able to be walked upon before you can begin tiling.
This could be a minimum of 3 days – depending on the thickness of the applied screed – and the concrete sub-base should be at least 7 days old.
Can I laminate a screeded floor?
Yes, but give the screed ample time to dry before commencing: at least a week per centimetre of thickness up to 4cm.
Ensure that, if your laminate panels do not come with plastic foil pre-applied, you apply said plastic foil on top of the screed before beginning to lay down your laminate flooring.
Contact the Floor Screeding Experts at AB Drylining
Do you need to screed your concrete floor? Maybe AB Drylining can help!
Based in Wiltshire, South West England, AB Drylining provides market-leading floor screeding services applied and finished by expert layers.
AB Drylining provides the highest standard of work across a wide range of building processes, including dry lining, plastering and suspended ceiling work.
