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

Categories



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.




Heating and cooling: UFH on existing concrete floor?

Bottom of Page

1 to 12 of 12

  1.  
    • CommentAuthorzak99
    • CommentTimeDec 28th 2016
     
    Hi all,

    We live in a dated and rather tired detached brick and block cavity wall bungalow on a concrete raft, I guess late 70's early 80' build. Its semi rural so pretty exposed to wind. Heating is an old Worcester Danesmoor oil fired boiler, it works well but is rather noisy. Gas supply is not in the village apart from bottles or tanks. Also we use a wood burner.

    We are hoping to do quite a lot of work here, (roof repitch to gain loft rooms, possibly external cladding, new windows)

    My question - is UFH feasible given the concrete floor, or should I stick with radiators. I think the screed is around 50 to 70mm thick (from when I did some plumbing repair years ago). I dont know if there is any insulation in the floor but i doubt it as its a pretty cold place.

    I heard that electric UFH is thin but expensive to run.
    How thin could water UFH be so that i could possibly get some insulation below as well.

    Would i need to break out the screed, or go on top, ceilings are reasonable heights.

    Thanks for any help

    Rgds
    • CommentAuthortony
    • CommentTimeDec 29th 2016
     
    Ideally you want 200mm of insulation in the floor with UFH and I would say the same without it at least round the edge, from 2.4 in 100mm might suffice.

    If you are recladding and new roof best plan is to add a load more insulation tan is required by the regs and then you will be warm with low bills. Concentrate on air tightness, detail. Cavity insulation will help but nothing like enough, take external wall insulation down to foundations (see other thread).

    Nice project for the coming year, think it through first aim for right first time.
    • CommentAuthorowlman
    • CommentTimeDec 29th 2016
     
    Any underfloor heating system will require some form of insulation beneath. There are many systems available but if you want a wet system you can go for a low profile one where the small dia pipes are laid into pre routed, I believe gypsum boards,(usually 15mm), and screeded over, or alternatively something similar but a floating system. You'd still need insulation below, suppliers will advise.
    It all depends on how much you're prepared to build up the floor level, and hence loose room height, with the added knock on effect on doors etc.
    Electric is relatively cheap to install but again you'd need insulation boards below to realistically get any real benefit.
    • CommentAuthorgravelld
    • CommentTimeDec 29th 2016
     
    Just to throw my oar in, for what it's worth.

    You mention "We are hoping to do quite a lot of work here, (roof repitch to gain loft rooms, possibly external cladding, new windows)".

    My approach, and what I'm trying to do, would be to try to work out a vision for what you want the house to be, in terms of performance, and build a whole house plan to achieve that.

    Your heating demand will be related to that, and that might feed into whether UFH is a good idea.

    Why do you want UFH?

    UFH without some form of insulation is a bad idea I think.
  5.  
    I have/had similar scenario to you Zak. Old (1950s) bungalow in country, oil burner. At least mine is cavity filled (but poor state now). When we decided to extend, I stated to look into improving things. This has snow-balled on a bit and 3 years on, we are still in static caravan. I decided that there really was no point in having UFH without a decent amount of insulation in the floor. There are many 'refrofit' systems out there on the market and I was almost talked into it by their propaganda. They are probably fine for houses that have floor insulation already, but it's like pi55ing into the wind otherwise. They cover themselves by having a short phrase in the small print "good enough for properties that comply with current BR". In any case, I bit the bullet and have dug out the old slab and am down to 500m below skirting board. A lot of work, but worth doing properly. Combined with 3g windows, EWI, MHVR and more loft insulation, things should be a bit toastier.

    Of course digging up your floor whilst you are living in the house is a bit intrusive, but it could be done a room at a time. Or plan what you want, move out and get it all done in 6-9months....like we thought we would do....:cry:
    • CommentAuthorzak99
    • CommentTimeDec 30th 2016
     
    Thanks all for the helpful replies. I thought UFH might be the 'right' thing to do while we are refurbing the place.

    Sounds like I'd struggle to get a decent amount of insulation below the UFH without a mass of work, 100mm max maybe by removing screed and cutting doors, lifting skirting etc.. I guess its possible there is some insulation in the slab, I suppose drilling would tell me. But the floor is usually cold, no carpet, just tiles. Maybe for now, I'm better off sticking with radiators, and as Tony says insulating the slab foundations outside, when we do our external cladding with insulation behind and insulate the new roof well and maybe 3g windows as KG is having to look out of one day soon !!!

    Is breathable membrane on brick, Celotex/Kingspan between timber batons, then membrane again below timber cladding OK as an approach, its Essex here (' init )so we aim to get the essex coastal house look like many other old places around. Maybe I should start a thread on that. I'll have a search first.

    Our cavity was filled with rockwool but we had some damp problems and had a long battle with the awful woman at CIGA and Carrilion Some of it has been sucked out on one wall, they made an awful mess of the brickwork so are not welcome back to fill it. I never did find a decent firm to suck it all out. If external cladding, is it really worth the bother of sorting the cavity fill.

    Tks again.
    •  
      CommentAuthordjh
    • CommentTimeDec 30th 2016
     
    Posted By: kentishgreenI bit the bullet and have dug out the old slab and am down to 500m below skirting board. A lot of work, but worth doing properly.

    500 m? That sounds like 'a lot of work' is a substantial understatement! :bigsmile:
    • CommentAuthorgravelld
    • CommentTimeDec 30th 2016
     
    General consensus is, I think, if you are EWIing over cavity wall you need to fill the cavity and seal it to stop convection and the cavity acting like a chimney. See the Four Walls blog.
    • CommentAuthorgyrogear
    • CommentTimeDec 30th 2016
     
    Posted By: zak99I dont know if there is any insulation in the floor but i doubt it as its a pretty cold place.


    You could perhaps consider building a floating floor over the existing, using say 60mm XPS clad with boards.
    (even 30 mm XPS might be a big improvement).

    I laid such a floor over granite pavers when we converted our "car port" into a "pub": 60 mm xps; one-inch ledgers glued onto the XPS at 12-inch centers; then nailed distressed timber (= 15mm old roof boards...) onto the ledgers. Sanded, stained and varnished, it looks OK and is easy to maintain...

    gg
      in distress.jpg
    • CommentAuthorowlman
    • CommentTimeDec 31st 2016
     
    You've got your own pub gg,-- respect.
    :whorship:
    • CommentAuthorgyrogear
    • CommentTimeDec 31st 2016
     
    Yep - that's why the rest of my renovation is not coming along too quick :shamed:

    gg
    • CommentAuthorowlman
    • CommentTimeDec 31st 2016
     
    Do you brew your own? I'm looking forward to home brewing again, once I've got the outhouse sorted later in the year.

1 to 12 of 12

  1.  
Add your comments

    Username Password
  • Format comments as
 
Back to Discussions Top of Page
   
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   
Logout    

© Green Building Press