curlewhouse Posted September 20, 2017 Share Posted September 20, 2017 So I'm about to start to make the floors and lay the UFH pipes in the ground floor bathroom and utility (for various reasons I need these rooms useable albeit unheated ASAP). I have up to100mm to play with on top of the 200mm celotex now in place. I'm torn about whether I need to put steel mesh in or can do it with fibres alone. I laid part of a private road for a neighbour where I used to live using delivered ready mix with fibres a few years ago and it is uncracked to this day despite bin wagons etc etc. The two small rooms are 2700 x 2500 and 2700 x 3000 - and I've got a choice open to me of 75mm or 100mm with UFH in, which will then have stone/tiles on top. I've looked online to see what is suggested for various depths (i.e when/if mesh is preferred over fibre for certaibn depths of concrete) and TBH its not clear. I'll be self mixing for these two small rooms, so fibre would seem an easy option. I notice the CEMEX web site actually suggests fibre reinforced over rebar for domestic and light commercial use - but the old fashioned part of me cant quite accept that it will be strong enough if only say 100mm on top of the insulation (as presumably with the best will in the world there will be movement). I plan to do the biggest rooms with mesh (don't know why, just seems to me that the bigger span needs it?). Any experiences/thoughts? I know some on here really prefer mesh, but I'm interested to know what peoples experiences are between the 2 (not mutually exclusive) options. Link to comment Share on other sites More sharing options...
Simplysimon Posted September 20, 2017 Share Posted September 20, 2017 what's the concrete being laid on below the celotex? fibre is really only to help prevent cracking and is not structural reinforcement. Link to comment Share on other sites More sharing options...
Onoff Posted September 20, 2017 Share Posted September 20, 2017 That's about my bathroom size. TF I laid A142 mesh as I FORGOT to add the fibres! 1 Link to comment Share on other sites More sharing options...
curlewhouse Posted September 21, 2017 Author Share Posted September 21, 2017 Build up is beam and block, sand blinding, DPM, 200mm celotex Link to comment Share on other sites More sharing options...
Simplysimon Posted September 21, 2017 Share Posted September 21, 2017 i wouldn't bother with mesh, it's not a structural slab as on b&b, fibres should stop it cracking Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted September 22, 2017 Share Posted September 22, 2017 (edited) We had just fibres in our utility floor (Sand, radon barrier/dpm, 100mm PIR, 100mm concrete slab), and thats been spot on, not a crack in sight! utility is 5.4m x 2.5m. I'm sure you will have done this, but ensure that there is an insulant upstand all the way round the room, so the slab never touches the wall, this will also help with any expanding and contracting, and also with thermal bridging, we used 25mm polystyrene for this job Edited September 22, 2017 by MikeGrahamT21 Link to comment Share on other sites More sharing options...
Onoff Posted September 22, 2017 Share Posted September 22, 2017 If anyone knows where my bag of fibres is let me know please! Link to comment Share on other sites More sharing options...
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