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  1.  
    Does anyone have experience of pumping insulation into underfloor voids. My in laws house has an expensive finish on suspended timber floors which they don't want to damage. The crawl space is about 400mm vented, but with no access. Could pump something in though. i noticed Viking House mentioned this on previous discussions, but not much detail given.
    • CommentAuthorpmagowan
    • CommentTimeFeb 7th 2012
     
    I think Tony mentioned pumped in EPS beads at one point when I was looking at my floor insulation.
    • CommentAuthorPeter Clark
    • CommentTimeFeb 7th 2012 edited
     
    Hi piersadler,

    there is a thread about this here:

    http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=6150

    Peter
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 7th 2012 edited
     
    I can't think how I missed diving into that http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=6150 ! I shall have to read right thro it.

    It's a question in my mind right now. Let me add - LECA (lightweight expanded clay aggregate) http://www.netweber.co.uk/uploads/tx_weberproductpage/06_500_Leca_insulation_fill.pdf .

    Hoping to convince Bldg Regs in 2 projects: one newbuild, timber joisted ground floor filled solid with Leca; one uprate of extg cav wall house with timber grd floor and variable (but not crawlable) underfloor void space - again pump/blow Leca in (from tanker) solid. Leca has insulation about one third as good as EPS, so make it 3x thicker - it's cheap.

    The latter particularly would be a great solution for extg buildings, subject to certainty that all extg joists etc are dry and sound, dpcs functional, no water ingress into the void. Damp subfloor wd be OK, as Leca is immune to water, happy to sit on wet, non-wicking.
    • CommentAuthorJoiner
    • CommentTimeFeb 7th 2012
     
    Tom, any idea of a m3 cost for that?
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 7th 2012
     
    Don't know but I think a 50 litre (think peat/compost from gdn centre) bag is about £5.
    • CommentAuthorPeter Clark
    • CommentTimeFeb 7th 2012 edited
     
    Bagged leca prices:
    http://www.mikewye.co.uk/naturalproducts.htm#leca


    Blown LECA - no prices.
    http://www.leca.co.uk/33736

    Look at the menu on the left for within ’ Flooring Insulation’.
    ‘For deeper foundations, the Leca® LWA can be blown directly from a vehicle into the void from a distance of up to 50 metres. Once the old floor has been excavated, the blowing vehicle pulls up outside the building and discharges the material at around 50m3 per hour’
    • CommentAuthorborpin
    • CommentTimeFeb 7th 2012
     
    Leca price depends on how close you are to a stockist. I looked into it and was quoted £75 for 1.2M3 Bulk Bag but about the same again for transport!
    • CommentAuthorJoiner
    • CommentTimeFeb 7th 2012
     
    Jeez, rules it out for this place then. :sad:
    • CommentAuthorborpin
    • CommentTimeFeb 7th 2012
     
    My thoughts exactly. It seems they do not have a great link with the big suppliers.
  2.  
    Posted By: piersadlerDoes anyone have experience of pumping insulation into underfloor voids. My in laws house has an expensive finish on suspended timber floors which they don't want to damage. The crawl space is about 400mm vented, but with no access. Could pump something in though. i noticed Viking House mentioned this on previous discussions, but not much detail given.
    I've pumped EPS bead under the floors of over 20 houses with good sucess. I imported a few loads of Leca back in the day but found it as expensive as EPS. Remove or re-route electric cables if you can.
      EPS Beads.jpg
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 8th 2012
     
    Viking gets there first - again! actually done it. How did you get it past Building Control - or you say they're toothless in Eire?
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 8th 2012 edited
     
    The choice (if acceptable to Bldg Control) is between Leca, and EPS bead. Can we list the pros and cons?
    Cost, delivered
    Insulation value (tho not as impoertant as it seems, because large thicknesses involved, which makes Leca's insulation plenty gd enough)
    Behaviour with water - absorbtion, effect of absorbtion on insulation value, wicking

    Also something trying to take form in my mind - EPS wd be a total insulation, isolating the interior from the subsoil. Leca, being much denser (tho still v lightweight as an aggregate) and having less fierce insulation value, could be seen as a thermal continuity with the subsoil, if doing the other things necessary to do the thermal storage tricks that subsoil can provide.

    On my forthcoming newbuild project, Leca is blown in (or placed in bags + loose) to enclose the floor joists soild and to come tight (in thermal contact) up to the 25mm CPB (cement particle board) deck and tile flooring thereon. Below, the Leca is on DPM direct on the subsoil (and the CPB is an inboard VCL). Towards the centre of the floorplan, the Leca is as thin as can be, just under the joist soffit. Going outboard, it thickens, just enough so the DPM will drain outward any water or condensation that might get into the void. Further outboard, the joists bear on railway sleepers (up to 6m long 'crossing (points) sleepers') on edge as ground beams and the dpm dips to go under them. So outboard of the ground beams, the Leca is in considerable thickness, around the floorplan perimeter. Then at the perimeter the wall EWI is continued down about 1m in narrow-bucket trench (i.e. 'free-floating', not attached to any wall) and the Leca comes out to the inner face of that.

    So the block of subsoil under the floorplan is enclosed in 200 EPS downstanding 1m, and that subsoil block is in thermal contact with the interior, via Leca of varying thickness under the CPB and tiled finish. This is an attempt to make an effectively heavy solar-absorbing floor (because tall wide glass area to SE) in contact with its subsoil (protected from edge-loss) but with a modicum of insulation to ensure that floor surface keeps cosy.

    This is the sort of thinking that makes me favour Leca over EPS.
    • CommentAuthorpmagowan
    • CommentTimeFeb 8th 2012
     
    I like the look of that EPS bead VH. What kind of coat are we looking at, installed? I have suspended floors on most of the ground floor apart from the kitchen and so this would seem to be a good idea. I am also going to do the Leca wing insulation french drain solution as per Fostertom. I have no DPC so I figure this will keep the base of all walls dry and thus avoid any 'rising damp' if it exists. It should also boost my insulation.
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 8th 2012
     
    I can't wait to get to grips with Therm. Did AECB/Peter Warm course on it but my borrowed laptop played up and I hardly got beyond sq 1, not even concentrating on the info given. Am promised a re-run at reduced cost.
    • CommentAuthorJoiner
    • CommentTimeFeb 8th 2012
     
    That all our services run under the building in the void is another problem. We bought this place when the upstairs wasn't owned by us so all the wiring and central heating pipework runs under and around the floor joists, and with boards over floorboards under fitted carpets throughout it just isn't on to relocate the utilities, not that there would be anywhere to put them anyway.

    Blowing the stuff in through the air-bricks would have been a simple application and, with a hallway running the length of the building down its centre, parts of that could have been lifted to ensure it was all coming through.

    Wish I'd been on here when we moved in eleven years ago! :cry:
    • CommentAuthorpiersadler
    • CommentTimeFeb 8th 2012 edited
     
    Thanks everyone. So much input in the short time since I started this.

    Having heard about the Viking solution and read all the above am thinking about pumped insulation under the suspended timber floor in my own house as well as in laws.

    My back wall is fairly damp due to having leaky cement render on the outside, so i am taking off the render and using a wood fibre board and lime render external wall insulation system (Diffutherm? not sure yet). As far as I know there is no effective dpc and the ground level outside is similar to that in. It is a little damp under the floor already. I think if I extend the EWI below ground level with EPS plinth board and use EPS/Leca under the floor, I have a reasonable chance of keeping joist ends warm.

    I thought of thinning the insulation, say 0.5m in from the joist ends to allow a gap between joists and top of EPS (as per Peter Clark suggestion on previous thread) to allow any moisture to evaporate.

    I favour EPS for the better insulation properties, although price will be a factor. Not really interested in thermal mass in my house as have plenty in walls. I have also done the THERM course and am reasonably competent with it-my advice Fostertom is have a go with THERM it's pretty straight forward. Perhaps I will model a simplified version and put on my website.

    Any comments welcome.
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 8th 2012
     
    Yr damp situation sounds dodgy, to be filling the cavity - shd sort it out fundamentally first. An external french drain might do it. What is EPS plinth board?

    I don't understand the next para?

    Looked at your website - interesting.
    • CommentAuthorpiersadler
    • CommentTimeFeb 8th 2012 edited
     
    Posted By: fostertomYr damp situation sounds dodgy, to be filling the cavity - shd sort it out fundamentally first. An external french drain might do it. What is EPS plinth board?


    Thanks fostertom

    I think the damp is related to the leaky render and poor back to front ventilation. The leaky render will be addressed with EWI. The back to front ventilation will no longer be required as condensation will occur only below the insulation (as per Viking comments). The External french drain is included in the design. Plinth board is board designed to be used at and below dpc ground level - this is the term used in the Diffutherm brochure and by other insulation manufacturers for similar applications.

    Posted By: fostertomI don't understand the next para?


    Next para - the idea is that in the middle of the room, away fro joist ends the insulation can come up to the underside of the floor boards, whilst at the edges, close to joist ends, the insulation is filled to a level just below the joists to allow them to dry if needed.
    • CommentAuthorRobL
    • CommentTimeFeb 8th 2012
     
    You should move electric cables when using either insulation type, but is it even more important with EPS beads - will these will make the PVC cables brittle ?
    Also, is there a flammibility issue with using EPS under floorboards ? Leca being expanded clay cannot burn exothermically I think.
    I have a friend who would love to use such a simple fix to his victorian terrace house. It seems so easy - why isn't it a standard approach here - a bit like cavity wall insulation ?
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 8th 2012 edited
     
    Indeed, if such a dodgy bodgy idea as CWI is found to work, why not this kind of under-suspended-timber-floor fill?

    What acronym shall we give to this procedure? - making history here! (like AFAIK I was first to use 2G/3G for double and triple glazing!)

    Posted By: piersadlerPlinth board
    I'm just using standard EPS board.
    • CommentAuthorpmagowan
    • CommentTimeFeb 8th 2012
     
    UFI?
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 8th 2012
     
    That cd describe many extg. practices - something more distinctive?
    • CommentAuthorpmagowan
    • CommentTimeFeb 8th 2012 edited
     
    Yes but so can EWI. You would normally give it a context such as 'blown eps UFI'. BUFI
    • CommentAuthorMike George
    • CommentTimeFeb 8th 2012 edited
     
    Regarding pumping polystyrene beads under a floor please read http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=7526&page=1 so that you are aware of the potential risks.

    There are quite a few other threads on the forum where people have proposed this but so far I haven't read of anyone getting it by Building Control.

    I don't beleive they will either as it contravenes several other requirements in Approved Document C - namely prevention of moisture ingress and ensuring adequate sub-floor ventilation.

    Don't do it
    • CommentAuthorpmagowan
    • CommentTimeFeb 8th 2012
     
    Why would you want to ventilate under your floor? Surely this is a case of designing a solution to building badly. i.e. Building so that damp gets at your timbers and thus ventilating them with cold outside air. Surely the solution is to keep them warm and dry i.e. EWI and blown bead UFI. In this case the entire inner fabric of the house is in the 'warm zone' and thus not at risk of rot.
    • CommentAuthorMike George
    • CommentTimeFeb 8th 2012 edited
     
    Hi Pmagowan. You would want to ventilate the floor to avoid condensation building up within the void and subsequently causing rot. I disagree with your interpretation of 'warm zone' (see the thread I linked to above)

    It is required by Building regulations Part C for this reason and makes no difference whether the floor is timber or any other construction.

    It is required in suspended concrete floos because of the risk of steel corrosion within concrete beams which can cause subsequent spalling and failure
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 8th 2012
     
    Agree exactly with pnagowan. In many climatic conditions/times of year ventilation actually imports a continuous moisture supply to a condensing surface.

    In newbuild, the whole fill can be protected from moisture - by DPM under and VCL above. Agree under an extg suspended floor no such DPM protection is possible, so non-wicking is vital; you'd have to convince yourself that no vapour will be entering from above; and otherwise rely on the floor timber being held at near room temp compared to other poss condensation surfaces within the void e.g. subsoil surface. And make sure that any accumulating moisture can drain away from there.
    • CommentAuthorpmagowan
    • CommentTimeFeb 8th 2012
     
    I read the whole thread and all I see is that the traditional method is rubbish. Lots of pictures of ventilated floors rotting even one where the timber is right next to the vent. It seems this old fashioned way of doing things is not very good. I appreciate that inappropriate use of UFI would be worse than sticking with the old method much the same as insulating your loft badly would but that is no reason for not doing it properly.

    If you EWI the house, have a french drain of Leca around the founds and use blown bead UFI I can not see how this would do anything other than protect the entire structure of the building. Under the house will be dry, the founds will be drained and thus dry, no rising damp (if such a thing exists), the walls will be warm, the floor will be warm. How, in this situation, will the wood get damp enough to cause rot. I am not really interested in the regs because I think they are likely to be designed for old fashioned, inefficient and poor building methods. I am more interested in what would work best.
    • CommentAuthorpmagowan
    • CommentTimeFeb 8th 2012
     
    Why should you treat the under floor timbers any different from any other wood in your house. The only reason would be because you have put them in a position they should not be in, i.e. coldish and wet. Warm them up and take action to avoid water under your house (why is it there?)and, hey presto, no probs.
   
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