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UFH screed question

  • 14-05-2008 8:31pm
    #1
    jagrace
    Registered Users, Registered Users 2 Posts: 20 ✭


    Hi,
    I am almost finished laying my UFH pipework and need advise on what to pour on top of them. I will have 65mm to my finished floor.The floor will be poured before the walls are in. Should i use a sand and cement mix or say a 25n concrete with a 10mm pebble and mix some fibre through it for strenght? I have ruled out the easy screeds as they are to expensive. I think the second option would be easier to work with but will it effect how the heat radiates through the floor? i have taped all joints in the insulation below the pipes. One last question there is rain water under my insulation will this do any harm when the floor is poured in on top? i have no way of getting it out!!!!!!!!!!!!!


Comments

  • #2
    sinnerboy
    Closed Accounts Posts: 5,433 ✭✭✭sinnerboy


    jagrace wrote: »
    Hi,
    I am almost finished laying my UFH pipework and need advise on what to pour on top of them. I will have 65mm to my finished floor.The floor will be poured before the walls are in. Should i use a sand and cement mix or say a 25n concrete with a 10mm pebble and mix some fibre through it for strenght? I have ruled out the easy screeds as they are to expensive. I think the second option would be easier to work with but will it effect how the heat radiates through the floor? i have taped all joints in the insulation below the pipes. One last question there is rain water under my insulation will this do any harm when the floor is poured in on top? i have no way of getting it out!!!!!!!!!!!!!

    few points of concern

    - min u value of floors with UFH is 0.15 - do you have enough insulation ?
    it depends on area / perimeter ratio but a safe rule of thumb is 120 total polyurethene ( 2 x 60 layers )

    - if using polyurethene - have you installed a polythene layer to protect the insulation from the screed over ?

    - have you pressure tested the pipes yet - best to do this before pour of screed

    - what is spec of "walls to go in" - not blockwork i hope - must not be built off screed/ufh/insulation

    - sand and cement won't do - you need agregates for strength

    - how much rain water and when did it get there ? you do have windows in ? dont screed untill water tight - roof felted + windows in

    you do have an architect or engineer for inspections ?

    Sorry for asking as many questions as i answer , but i am concerned ... not trying to "smart ass" you


  • #3
    AckwelFoley
    Registered Users, Registered Users 2 Posts: 12,555 ✭✭✭✭AckwelFoley


    Good advice sinnerboy..

    Hod did you clip the ufh to the mesh?

    As a matter of interest did u run the pipe at 4 or 6" centers?




    I hope you used Aluminium barrier pipe.. "Alupex" .

    Its imprtant that the screed is not much thicker that what you stated. Its not as ideal as the easy screed because its less dense than the easy screed, and you cant go below 50mm wuth concrete. The screed acts as a rad itself, absorbing and releasing the heat evenly, if its too thich it takes to much energy and time to heat it.


  • #4
    jagrace
    Registered Users, Registered Users 2 Posts: 20 ✭jagrace


    lads thanks for the replies and good advice yet again. although in this case i have now got the floor in before i had seen your replies. Had a few days off and some great weather. To answer afew question i have 100mm quinn insulation in the floor. the new floor is not carrying the block work i have it coming up from the the bottom slab. no polthene sheet down but scree was poured fairly dry and all insulation joints were taped. I did pressure test the pipes before pouring the floor. I have no walls up yet. There was no mesh used . I used tracking and clips straight onto the insulation with 200mm spacing.


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