With the implementation of the BS EN 13813 standard, there has been a buzz that ready-mix screed can be the new answer for failing screeds, and site-mixed screeds will no longer conform. Is there any truth to the story?
Ready-mix screeds are screeds mixed in the factory and delivered to site. These screeds are covered by the new European Standard BS EN 13813, which ensures the quality of the ‘screed mix’ by assessing various performance properties, before it is leaves the ‘factory gate’. This is a positive sign, and can help in ensuring the screed-mix meets the expected quality standards before it is installed. But, what once it leaves the factory gate?
Screeding is a skilled job, and requires attention to all the little nuances of design and site conditions, which often fall outside the remit of screed manufacturers and suppliers. The skill and expertise of the screeding contractor; a good understanding of the screed design, screed characteristics and its intended use are key to achieving a good quality screed, that is fit for purpose.
But when it comes to ready-mix screeds, the major downside is it is not always laid by specialist screeders. There is a general preference among specialist screed contractors to go for site-mixed screeds as it gives them more control over the quality, quantity, mix and water content and helps them avoid the logistical issues normally associated with ready-mix screeds. Plant breakdowns and late deliveries can cost heavily as there is usually no guarantee that the ready mix screed will have the right retarders to prevent the screed mix from hardening.
Screed definitely doesn’t come cheap at £15-20/sq. Add to it the huge carbon footprints that the industry is forced to leave behind, wasting screed is not an easy option. Ready-mixed screeds don’t provide much room for unprecedented delays or plan changes, and contractors are often forced to discard entire batches of premium screed-mixes, when faced with unforeseen plan changes.
Coming to site-mixed screeds – they also come with a host of positives and negatives. But when comparing the two, the positives of site-mixing far outweigh the negatives in terms of quality control, efficiency, cost, flexibility and waste management.
It is true that site-mixing does not always guarantee uniform quality and can be labour-intensive and inconsistent when the mixing is done manually. But, our past projects are testimonials to the fact that site-mixing can guarantee a high quality screed, when the mixing is carried out on site using the right products and equipment.
The major advantage of site-mixed screed is, when mixed using force-action mixers (similar to factory mixers), site-mixing allows a better control over the quality of the screed while providing flexibility that ready-mix doesn’t allow. Unexpected plan changes can be easily accommodated, and screed additives can be easily incorporated to accelerate drying times, as the screeds are mixed as and when required. This not only helps to keep the costs down, but also reduces wastage significantly.
Now, can site-mixed screeds guarantee the quality of the screed mix? Definitely.
The European Standards specifically states that –“the BS EN 13813 can be used in conjunction with codes of application and national specifications for site made material produced and laid by the same contractor, provided they can demonstrate a quality control system comparable to which would apply in a factory”.
At CSC, our high quality products and our meticulous quality control system, ensures that our site-mixed screeds meets all the relevant prescribed British and European standards. And, with the added advantage of employing the skill and experience of our specialist screeding team, we can proudly guarantee that the site-mixed screeds we install at CSC are the best in terms of quality, cost and efficiency.
Check out our FAQ on site-mixed and ready-mix screeds to know more.