Frequently asked

Welcome to the Frequently Asked Questions page. Below, we have tried to answer the most common questions visitors to this our Web site may have. If you find that your question is not answered on this page, please email contact@adhf.co.uk or telephone on mobile 07894742435. Q1. What is the minimum depth for an unbonded screed? A. Unbonded screed should not be less than 50mm deep for traditional screed, but flowing screed such as ‘Supaflo, Gyvlon & Truflow can go to as little as 30mm. Q2. What is the minimum depth for bonded screed? A. Bonded screed can go to a 10mm in thickness screed, as long as it is bonded chemically (epoxy) or laid with SBR/PVA bond and SBR/PVA modified screed mix. If the screed is to be cement bonded then 30mm should be the minimum depth. Q3. What are granolithic screeds? A. Granolithic screeds are very hard wearing, granite based aggregate, finished floors. They are used in industrial units, beer cellars & weight lifting areas etc. Q4. What type of floor screeding should I have in my new house/extension? A. Sand & cement screeds are the recommended floor screeds for domestic use, as cost implications can be quite high for small areas done by flowing screed Q5. What are the advantages of flowing screeds over traditional forms of floor screeding? A. Flowing screeds are good for laying a large area over a short amount of time, and sometimes it can be more economical over traditional screeding. But traditional screed, using sand/cement, is most often the cheapest system, and traditional screeding is the natural choice for floors that are to be ceramic tiled, as there tends to be a much greater bond.....Don’t be fooled by the mis-leading technical data supplied by LaFarge......LaFarge don’t do a traditional alternative product! (Apart from ‘certain areas of the country’). Q6. What reinforcing is the best option for an unbonded floor screed? A. Quite simply, polypropylene fibres in the mix with D49 wire mesh at any day joints. Some architects will specify that they want hex (chicken) wire, but this is the least effective system and has barely been used in the last 20 years. Q7. What is the tolerance for level on floor screeds? A. The industry standard is 10mm across a 3m straight-edge. At ADH flooring Limited we look for a tolerence of 3mm, or better, across the whole floor screeded area for, floor screeds. Q8. Why should I use ADH flooring Limited for my floor screeding works? A. Because you will receive a first class job for the most reasonable price. Q9. My underfloor heating system installer has told me that self-levelling ‘flowing’ screed is the best for UFHS, why is this? A. Many UFHS installers’ don’t know a great deal about floor screed.....Most tend to give info. parrot- fashion, just saying that is what you should use ‘cos liquid screeds wrap around the underneath of the heating pipe, giving better heat transfer’. But lets face it where is the heat going to go anyway, with a good amount of insulation that should be under the heating pipes it wont be going through the insulation....It is mis-leading sales pitch used by a company that isn’t a major supplier of traditional screed to floor screeding contractors.....Take into account that thinner screeds, such as flowing screeds, can have the undisired effect of hot/cool spots between heating pipes, so a lower thermal transfer would be an advantage in this instance.  We at ADH Flooring Ltd supply and install UFH. We install a traditional fibre screed over it, as this can be modified for faster drying if needed. It also leaves a very good surface for tiling applications without the need for preparation works that flowing screeds require Q10. What is the drying / setting time for floor screeds? A. Please see our drying time table in our ‘Technical’ tab. Q11. I’ve heard about shrinkage cracking & curling in floor screeds, what are these and how do they occur? A. Any material that has absorbed water, will shrink as it dries out. Sometimes, due to excessive drying, screeds will crack. If you try to artificially accelerate the drying times, of the table above, then there is more risk of cracking. Curling is caused by the same conditions but normally manifest along dayjoints and internal angles. The thinner the screeding material, to be used, the more likely that curling can occur, due to time taken to dry will be quicker on a thinner bed, than a thicker bed. Another way to reduce shrinkage & cracking is to use water-reducing agents (super-plasticisers), these are used in Truscreed and K-screed and greatly reduce drying times. Q12. What type of floor screed have you got in your house? A. I personally have a 1960’s house which has been converted to UFH by digging out the concrete slab & hardcore and replacing it with a 100mm concrete slab, DPM membrane, 100mm PIR insulation & 75mm floor screed incorporating a 16mm x 2mm Pex al Pex underfloor heating system. Q13. I have a floor that I need screeding, in London, can ADH Flooring Ltd do it? A. It depends on what quantities you have to be screeded. If you have a floor where you want us to install underfloor heating and install a fibre-screed it may well be viable for us to do your installation. If you require 50m2 of screed on its own, then I wouldn’t be viable, due to travelling time & fuel etc. If you had a 500m2 house, then the costs would be of a smaller importance. Q14. Flowing screeds will fully incase under-floor heating pipes, can traditional floor screeds do the same task? A. Yes, there is a simple technique that will ensure traditional screeds do that too, but is it really necessary? Iit actually wont achieve anything. It is something that the marketing people for flowing screeds came up with as sales pitch. Q15. We have a screed that is weak, cracking, or badly dusting. Is it necessary to replace the screed? A. No, but sometimes it may be the most commercially viable option. There are products that can be applied that will remove these problems, though they are not cheap, but it may be the most viable option when you consider the cost of removal of the old screed and the cost of replacement. For example PHS could be applied, and the following day it would be possible to apply floor finishes, including vinyl, as there would be no drying times to consider. Q16. There is another site that has the some of the same photographs and nearly identical text as this site, are you in partnership or co -operation of them? A. No, all the photographs on our site have been taken by us and are taken of work that we have done. Though it does make you wonder why someone would steal photographs of someone elses work to put on their site. Q17. Is your talk about ‘quality floor screeds’ just sale pitch? A. Sadly not. You have to be careful with any building related trade. There are a lot of good floor screeders, but it does seem there are as many, if not more , ‘screeders’ that are not quite so good. How do you know who is good or bad until you have the evidence? Just like used cars. Q18. I wanted a 65mm screed and I have measured it to be less, why is this? A. If you instruct your floor screeder to put on 65mm, unless your sub-base has been installed to a high degree, he will have to take some spot measurements to try to ascertain the average depth to be 65mm. Some parts of your sub-base may quite easily be plus or minus 15mm. It is good practice to make sure your sub-base is laid as accurate as possible to minimize this problem. Q19. Isn’t a floor just a floor? A. Yes. As is a road is just a road. Just as some may have humps, dips and pot holes, others don’t. We regularly hear of tilers having to spend a lot of time and money ‘building up’ badly laid screed floors to make the tiles work correctly. A problem that our floors don’t have. On the contrary we regularly get tilers praising our screed floors as the best they have seen. Q20. I have had a flowing screed laid on underfloor heating, with tiles on the surface. A lot of the tiles are becoming hollow and loose, is this common? A. Yes, most likely always due to the preparation not being done prior to tiling. UFH will push tile adhesives to the extreme. Flowing screeds need to be machine sanded, epoxy sealed and blinded with dry sand before tiling takes place. Without this being done, expect tiles to start falling off after a few weeks . This is because cement based tile adhesive does not take to anhydrite binder. Flexible adhesive will also be needed - but is in no way good enough without the preparation works on flowing screeds. Traditional screed does not need this process as the tile adhesive will take well to sand / cement surface. 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