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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.

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    • CommentAuthornoob
    • CommentTimeJan 25th 2013
    Hello Everybody :bigsmile:

    I'm just at the start of my project to renovate my detached 2 bed 50s house, looking for useful advice and I came across this place.

    Ive £25k in the kitty right now, the house has loft and cavity wall insulation and faces due south, but the concrete floor is uninsulated, the crittall windows are single glazed, the fire burns coal, it needs a re-wire.
    Hi , Sounds good . Any extensions planned
    You should be able to do a lot with £25k , especailly if you can do some yourself.
    I dont see the floor as such a big problem .
    Good underlay for either carpet or floated wooden floor would help
    Rewires easy on a small place . steer away from down lights
    Top the loft up to 400mm if it's not
    If you're on mains gas stick a gas boiler in with rads . £2-3k
    If not , perhap look at Air to air ASHP with MHRV
    if you're not adverse to upvc then 3G windows might be around £300m2 supply and fit.
    4kw Pv nows around £6,000 with 8%ish return
    • CommentAuthornoob
    • CommentTimeJan 25th 2013
    Hi James,

    I'm hoping to do a conservatory on the south side and some kind of unheated porch on the north side but neither of them just yet, I'm planning on knocking the kitchen through to the dining room but really at the moment I just want to get the place as energy efficient as poss.

    I was considering the floating floor option, I've done them before but when I started to look at insulating underneath it looks as though I need about 3 inches of celotex or similar which means a 4" raise so then have to raise all the lintels and the interface with the stairs will be bad unless I make it a 7" raise so its flush with the first stair then the doorsteps from outside will be gigantic, I thought it might be better to break the floor out dig down then pay a proper builder to lay a new slab but I have no idea how much that'll cost.

    Rewires really down to finding a friendly spark, I could probably do it all but particularly the chasing as currently the wires are run through the wall cavity, still need it signed off though. I hate downlights btw .

    lofts topped up as much as I can, had to re-do all the work (or not work) of the (unnamed) insulation cowboys, which didn't fill me with confidence about the quality of their cavity wall work.

    No gas here, the plan is to swap the old fire for a new one which burns wood, some of which I should be able to harvest from the garden but also the plan is to try to insulate well enough to not have to burn much.

    Ill look into ASHP, I thought I would have trouble sealing it well enough for proper MHRV, I was planning MHRV for the extraction in the kitchen and bathroom.

    I am adverse to upvc, I think its crappy, I was considering windows made by a local joinery firm but they're not so cheap.

    I think Pv panels would be great but when I looked into it it became clear that I wouldn't get the best tariff unless the house was up to spec first which means insulating the floor properly which makes some sense as there's no point obtaining energy from the roof and then throwing loads away through the floor.

    Ow my head hurts
    Re floating floor, calculate the improvement with even 25mm of Pu, and argue the case with BCO.
    • CommentAuthornoob
    • CommentTimeJan 26th 2013
    It looks like I would achieve ~0.40 with 25mm, ~0.27 with 50mm, ~0.24 with 60mm then there's the ~25mm of floating floor on top
    • CommentAuthorjamesingram
    • CommentTimeJan 26th 2013 edited
    noob re. floor insulation , take a look at http://www.greenspec.co.uk/ground-floor-insulation.php
    The main thrust being
    "Solid ground floor insulation in context
    The temperature difference between an internal space to ground is significantly smaller than the temperature difference between the internal space to outside air. In general, recent research (George, Geens & Graham, BFF, Spring 2006) has shown that solid ground floor insulation as an addition to well-insulated walls and roof, contributes very little to the building’s overall thermal performance. The designer should balance the extra benefit(s) attached to installing a new slab with the cost, marginal carbon gains and pragmatics involved"

    You've only really two choices. Rip it out and start again or settle with it as it is and use the best underlay/thin insulation available. eg. reflective carpet underlay or 10mm+ woodfibre or maybe up to 20mm celotex then floated engineered flooring. Steer clear of tiles , unless you dont mind cold feet.

    Ripping it out isn't as hard as it may seem , there was a discussion here on similar a couple of weeks ago. question is , is it really worth it. I've done it for several clients , but only when wet UFH,in conjunction with a lower temperature heat source ( GSHP) was required, so it seemed to make more sense in the long term balance

    Possibly you'll have a 100mmish slab with 25-50mm sand/cement screed on top. You could potentialy just lift the screed ( which will break easily ) and then use the exisiting slab as your start point to build up from for a floating floor. ( stick a new dpm down if you did) If it's all over the place, level wise, self levelling compound or a SBR slurry mix would be the best way to sort it with the thinest build up.
    • CommentAuthornoob
    • CommentTimeJan 26th 2013
    Thank you James that's all really useful, it's all quarry tiles at the moment so I do have pretty cold feet.

    It sounds like Ill have to have a chat with the BCO again, see if he's got anything to say about how much it's acceptable to raise the floor in relation to the door heights and stairs etc then either go for that or start investigating taking up the screed, if there is any.
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