Welcome to the Frequently Asked Questions (FAQ 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 adhflooring@btinternet.com or telephone on mobile 07894742435.

Q1. What is the minimum depth for unbonded screed?
A.  Unbonded screed should not be less than 65mm deep for traditional screed, but flowing screed such as ‘Supaflo, Gyvlon & Truflow can go to as little as 40mm.

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 50mm 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 tradional 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 technical data supplied by LaFarge......LaFarge don’t do a traditional alternative product!)

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 everyone in the floor screeding industry knows that it is the least effective system.

Q7. What is the tolerence 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 screed is the best for UFHS, why is this?
A.  UFHS installers’ are basically plumbers, they 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 a sales gimmick started by LaFarge....again a company that doesn’t supply traditional screed to floor screeding comapnies.....If after this you still want to go for flowing screed on a small UFHS floor, then there is an abundance of companies that will be willing to take your money.

Q10. What is the drying / setting time for floor screeds?
A.   Below is a list of approx. drying / setting times of common floor screed products:-

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Product

Setting time

Drying time

Strength

Traditional screed (Premixed 1:4)

24 - 48 hours

1mm per day

27 - 30N

   Mapei Topcem    (site batch 1:7)

6 - 12 hours

5 Days

30N+

Fast - set screed (1:5)

1 -2 hours

10 - 15mm per day

22 - 27N

K-screed (1:4)

6 - 12 hours

25mm per week

30N+

Tarmac Truscreed (1:4)

24 - 48 hours

25mm per week

30N+

Gyvlon / Supaflo etc (flowing screeds)

6 - 48 hours

1mm per day

25 - 27N

Granolithic screeds

12 - 28 hours

2mm per day

40N+

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 1950’s house, that was originally done in rock-asphalt. I built an extension a few years ago and laid a 85mm traditional floor screed (with PP fibres) over underfloor heating, with tiles on the surface. The tiles have firmly taken to the floor screed, with SBR mixed with fast-set tile adhesive.

Q13. I have a floor that I need screeding, in London, can you do it?
A.   It depends on what quantities you have to be screeded. If you had a 50m2 house, then I wouldn’t be able to do the work on a good price, due to travelling time & fuel etc. If you had a 500m2 house, then the costs would be of a smaller importance.

Q.14 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, it actually wont achieve anything. It is something that the marketing people for flowing screeds came up with as sales pitch

Q.15 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, these 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.

Q.16 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, one company in particular has stolen our photographs directly from our site and pasted them into their site. All the photographs on our site have been taken by us and are taken of work that we have done. It does make you wonder why someone would steal photographs of someone elses work to put on their site. We are pursuing for the removal of our images and text from this site.

 

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Site Last Updated 11 September, 2010

 

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Floor Screeding Frequently Asked Questions