Home  5  Books  5  GBEzine  5  News  5  HelpDesk  5  Register  5  GreenBuilding.co.uk
Not signed in (Sign In)


Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

Buy individually or both books together. Delivery is free!

powered by Surfing Waves

Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.

    • CommentAuthorYalch
    • CommentTimeMay 13th 2019
    I am currently planning to pull up my stone flag floor in a 1890s build house and to keep the floor breathable I am planning on putting down Geocel with a Limecrete screed on top.

    because we are then going to use a Junkers reclaimed gym flooring, I am going to put battens ontop of the screed and then the wood flooring; as this should help vent the screed and keep "breathabiliity".

    There is a joining extension with a suspended timber floor that has now had the wall between the 2 rooms removed and I plan on putting spreader plates in there for the UFH with supasoft insulation beneath.

    My question is, I have 2 options for the limecrete side and am wondering which would be the better option?:

    UFH in the limcrete screed,
    Pros: 1. potentially significantly more effecient?
    Cons: 1. any problems the screed has to be dug up, 2. needs to be run at a different temp to the suspended floor side.

    UFH on spreader plates on the battens ubove the screed
    Pros: 1. Accesible if any issues, 2. Can be run at the same temp as the suspended timber floor side
    Cons: 1. potentially less effecient?

    Thanks for any advice on this.
    I have a similar project coming up with solid and suspended floors, so interested in this. I don't plan to lift the existing subfloors so need a retro fit.

    I was looking at laying these boards over both the solid and suspended floors or something similar https://www.theunderfloorheatingstore.com/prowarm-25mm-floating-floor-panel

    But all new for me so interested to hear what others have done.

    Option 2, could the screed end up colder than the room and so attract condensation, esp when the ufh isn't running?
    Is there anything wrong with the (I assume original) flagstones? The most obviously compatible covering with both the limecrete and underfloor heating.

    Wood over any kind of underfloor heating has always seemed counter productive to me, as has an air gap.
    • CommentAuthorYalch
    • CommentTimeMay 19th 2019
    There's nothing wrong with the original flagstones but, one side will already have the timber so we would like To have a continuous flooring, but also for practicality as stone floor is a much harder fall for kids as opposed to wood floor.

    Would the spreader style heating be a better option as the heat would be that much closer to the wood or like Will said would it cause the limescreed to condensate?

    • CommentAuthorCWatters
    • CommentTimeMay 22nd 2019
    How thick is this reclaimed floor and how well insulated the house? We have 21mm engineered oak over our UFH and it has to be run quite hot to push enough heat through the oak.
    • CommentAuthorYalch
    • CommentTimeMay 22nd 2019
    20mm solid maple.
    The house is well insulated in general and the screed will be on top of a 150mm layer of geocel.

    • CommentAuthorRex
    • CommentTimeJun 1st 2019
    I have UFH covered with18mm engineered bamboo floor on g/f anhydride screen and on the ali covered poly spreaders on the first floor. The flow temp is generally around 38C.

    The floor never feels significantly 'warm' but it is generally around 21C. However, if one walks over a section where there is no UFH piping, the floor is noticeably cooler.

    Generally, the g/f (screed) retains the heat much, much better and even when the heating is off, it still feels warm.

    On the f/f, the engineered boards are laid directly onto the spreader plates. The rooms are never 'cold' but the floor never feels as warm as the g/f (screed.) There are some other issues that annoy me when the heating comes on.

    Obviously, the UFH pipe transfers its heat to the ali; the ali expands a micron, and as it all comes up to temp, there is clicking and popping all over the f/f for 10-15 minutes. I was told it was the bamboo expanding, but I have my doubts so have to live with it.

    In the f/f bathroom, I have vinyl on the floor, so covered the spreader plates with 18mm CaberBoard onto which, is the vinyl. The CaberBoard is of course, a different dimension than the bamboo floor, but one can still hear clicking and popping. However, even with 18mm CaberBaord, the floor is noticeably warmer than the bamboo.

    Bottom line is, I would not recommend the poly / ali sheets. Another time, I would use Fermacell flooring sheets or any other similar pre-grooved product. Alternatively, use the poly / ali combo and put Fermacell flooring on top to get thermal mass and a solid floor.
    • CommentAuthorYalch
    • CommentTimeJun 5th 2019
    Awesome thanks very much for this Rex.

    This is super useful.
    • CommentAuthorYalch
    • CommentTimeJun 11th 2019
    @Rex or anyone else,

    I am needing to raise the suspended timber side of the flooring by around 20mm. So the fermacel option sounds doable.

    Would I be right in thinking you would put the Fermacel panels directly onto the spreader plates/joists and then put the timber floor on top? Also would the Fermacel hold the heat similar to the screed?

    I was looking at fermacell boards that come with channels cut in them for ufh pipe, then sealed in with levelling compound, timber floor on top, like


    Other similar products available

    Not sure how breathable
    • CommentAuthorYalch
    • CommentTimeJun 14th 2019

    Thanks will,
    • CommentAuthorYalch
    • CommentTimeJun 18th 2019
    Hi Will,

    After looking into the fermacel option it looks like it needs to go ontop of an existing timber floor. If I was to do this it would raise the floor hieght too much unfortunately as it would end up being a make up of:

    timber (20mm)
    femacel/ufh (18mm)
    timber (20mm)

    Total being 58mm above the joist

    I need to somehow do the following as I have also already got the ali spreaders:

    Raising panel of some sort (maybe fermacel) (18mm)
    Ali spreader / ufh

    Total being 38mm above the joist

    I've also spoken to a fermacel provider to see if this was possible with their panel system and their response was the board my sag/ break under the foot trafic as it wouldn't be on a solid floor and the panels arn't structural.

    If anyone has any other Ideas let me know? :D

    Cheers all.
    That's a pity.

    You can also get grooved chipboard sheets which the pipes sit in with Ali spreader plates, like this, other brands available https://www.theunderfloorheatingstore.com/water-underfloor-heating/insulation-boards/profloor-boards
    • CommentAuthorYalch
    • CommentTimeJun 19th 2019
    Thanks will,

    That's actually a great solution! I don't know how I missed them. Hopefully should all work well :)

    Thanks again.
Add your comments

    Username Password
  • Format comments as
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   

© Green Building Press