epsilonGreedy Posted June 5, 2019 Share Posted June 5, 2019 I am coming under some pressure to screed my downstairs floor with flowscreed, as there would be an economy of scale thing (one pump for two houses). Reading up on Flowscreed I note a recommended max depth of 60mm. Why is this? Something to do with a mild exothermic cure perhaps? Background: This will be for a block and beam ground floor with UFH over 150mm of insulation. Link to comment Share on other sites More sharing options...
Temp Posted June 5, 2019 Share Posted June 5, 2019 (edited) In a rush but... Some liquid screeds can be hard to tile. The screed forms a weak powdery layer that has to be mechanically removed. Latiance I think it's called. Edited June 5, 2019 by Temp 1 Link to comment Share on other sites More sharing options...
epsilonGreedy Posted June 5, 2019 Author Share Posted June 5, 2019 5 minutes ago, Temp said: Some liquid screeds can be hard to tile. The screed forms a weak powdery layer that has to be mechanically removed. Latiance I think it's called. Eeek. Ceramic flooring will be the main floor cover downstairs. Link to comment Share on other sites More sharing options...
bassanclan Posted June 5, 2019 Share Posted June 5, 2019 Laitance needs to be removed shortly after pouring if you are tiling. If you wait weeks (like I accodentally did) it's a real pain to get off. 1 Link to comment Share on other sites More sharing options...
joe90 Posted June 5, 2019 Share Posted June 5, 2019 My flowscreed (if that’s the same tech name) was supposed to have no or little laitance. I scraped the floor to remove any “scum” and ripples, soaked the floor in sealer, tiled it and the tiles have come loose, not sure why, can’t bring myself to lift the tiles (fitted kitchen and skirting on top of tiles) but it’s on my “to do list in the future “. 1 Link to comment Share on other sites More sharing options...
Mr Punter Posted June 6, 2019 Share Posted June 6, 2019 I would price up a normal screed. It does not take long to do (for the screeder), it is normally cheaper and you can tile straight onto it. 75mm thick fibre reinforced seems to be a favourite. 2 Link to comment Share on other sites More sharing options...
Pocster Posted June 6, 2019 Share Posted June 6, 2019 2 hours ago, Mr Punter said: I would price up a normal screed. It does not take long to do (for the screeder), it is normally cheaper and you can tile straight onto it. 75mm thick fibre reinforced seems to be a favourite. My screeder also recommends sand / cement screed over other choices . Cheaper , and no issues when you tile to it . Also he was confident it would be more level ..... Link to comment Share on other sites More sharing options...
Ferdinand Posted June 6, 2019 Share Posted June 6, 2019 (edited) In my experience .. ie both bathroom floors have cracked .. trad sand and cement screed is vulnerable to the expansion and contraction due to ufh heating cycles. I know that one crack is in the screen because I have had the bathroom redone this week. I believe that the ufh pipes are in the screed itself but have not dug that up to investigate, as it is not a disastrous crack. Presumably fibres will mitigate (?) Ferdinand Edited June 6, 2019 by Ferdinand Link to comment Share on other sites More sharing options...
Pocster Posted June 6, 2019 Share Posted June 6, 2019 1 hour ago, pocster said: My screeder also recommends sand / cement screed over other choices . Cheaper , and no issues when you tile to it . Also he was confident it would be more level ..... Sorry sand , cement WITH fibre Link to comment Share on other sites More sharing options...
Temp Posted June 6, 2019 Share Posted June 6, 2019 (edited) Traditional screed with fibres is normally fine with ufh and tiles or stone. However some care is required where two areas of screed meet at a doorway. You should form an expansion gap at this point and not tile over it. Edited June 6, 2019 by Temp 1 Link to comment Share on other sites More sharing options...
Temp Posted June 6, 2019 Share Posted June 6, 2019 1 hour ago, Ferdinand said: In my experience .. ie both bathroom floors have cracked .. trad sand and cement screed is vulnerable to the expansion and contraction due to ufh heating cycles. I know that one crack is in the screen because I have had the bathroom redone this week. I believe that the ufh pipes are in the screed itself but have not dug that up to investigate, as it is not a disastrous crack. Presumably fibres will mitigate (?) Ferdinand Not sure what caused that. Looks like quite a wide crack. What's the floor make up? Link to comment Share on other sites More sharing options...
Ferdinand Posted June 7, 2019 Share Posted June 7, 2019 On 06/06/2019 at 14:21, Temp said: Not sure what caused that. Looks like quite a wide crack. What's the floor make up? It has some combination of ufh and sand/cement screed, on top of some combination of concrete / insulation. We took the view that the crack is stable and related to the strains imposed by ugh, so did not dig down to find out. It now looks like this 2 Link to comment Share on other sites More sharing options...
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