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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthorOllyT83
    • CommentTimeMay 16th 2019
    I need to level up and raise the floor in my conservatory to tile it level with the house floor.
    The floor currently is the patio base that was built over when the conservatory was built. This is between 140mm and 210mm below the desired floor level. 4.2m long 2.4m wide.

    I want to do this as cheaply and simply as possible - I'm putting down quarry tiles and the room will have quite a rustic feel so the odd crack over time won't be the end of the world. I definitely don't want to start breaking up the existing floor (I think it is probably supporting the whole structure).

    My initial thoughts were to level the ground with rubble, then a sand binding covered with DPM and then lay 60mm insulated tile backer boards on top. This would be easy to level well and would get me tiling immediately. My biggest concern is that the backer boards are normally fixed down but I cant do that.They would be constrained on all sides but would they bow or lift? Being glass roofed there will be extremes of temperature.

    Alternatively I could fill it with concrete, perhaps with a few old bricks and slabs chucked in the deep side and smooth it over with self leveling compound before tiling.

    I'd really appreciate any ideas on ways to get this done with the minimum of hassle!
    • CommentAuthorowlman
    • CommentTimeMay 16th 2019
    Does raising the floor affect any DPM that may be in the conservatory perimeter wall, assuming one exists?
    • CommentTimeMay 16th 2019
    I'd consider using a more graded sub-base material (i.e. good mix of small and larger pieces in it) than is typically found in rubble (which has too many big pieces and not enough small bits).
    • CommentAuthorowlman
    • CommentTimeMay 16th 2019
    Hi Olly, why do you want to insulate the floor? If the conservatory is heated, you' ll need much thicker insulation to conserve energy and comply with building standards. If the conservatory is only heated by the sun, some insulation directly under the tiles will help them warm up faster in the morning, but they may get uncomfortably hot.

    A typical build up would be to level the patio base with compacted gravel with a layer of sand to smooth it,
    a damp proof membrane, then the best insulation you can fit in, then a screed layer, tiles on top. PIR Insulation boards have better insulation value than those polystyrene tile backer boards. You can also use insulating screed.
    • CommentAuthorOllyT83
    • CommentTimeMay 17th 2019
    Thanks for the responses,

    The room will only be heated by the sun and I was only really thinking about insulated boards for their ease of use to get me a nice level tiling surface quickly.

    I like the thought of using leca, and have used it in a limecrete floor before, but don't think I have enough depth to put a thick enough slab on top here.

    There is no existing DPM to worry about, if i didn't happen have half a roll left over I might even omit it from this job. The picture attached gives an idea of what I am working with.

    I think I will do what Will has suggested and screed over PIR boards - this would at least save me one morning with the mixer and I only have to wait for the screed to dry.
    • CommentAuthorOllyT83
    • CommentTimeMay 17th 2019
    Image of what I am working with
      IMG_0494 small.JPG
    • CommentAuthorowlman
    • CommentTimeMay 17th 2019
    You could incorporate LECA into a insulating screed possibly on top of some sheet insulation to take up some of the difference. Or just use a LECA aggregate mix altogether.
    I had a similar problem in my sun-room, I left the final finish to levelling compound.
    • CommentAuthorrevor
    • CommentTimeMay 17th 2019
    Have you considered doing a joisted timber floor. Packed under at intervals at say 400 mm centres will give you a very solid floor topped off with ply or P5 flooring grade chipboard then tiled. Would be easier to get level than screeding. I like the arch.
    • CommentAuthorOllyT83
    • CommentTimeMay 21st 2019 edited
    I'd be far more comfortable working with timber but worry that the lack of DPM and/or ground level ventilation could rather too quickly lead to rotten materials.

    Arched timber doors should be filling the arch tomorrow which will be somewhat nicer the aluminium sliding door set that was bolted over the front of the arch and flintwork by the previous owners!

    I now realise that quarry tiles are typically laid on a thick bed of mortar (15-25mm) so I needn't be too fussed about my screed finish. If I can find a good value LECA supplier I might just level out and smooth enough with MOT1/sand to lay the DPM then pour in a LECA slab and tile straight on top.
    Can anyone suggest a good LECA concrete mix?
    • CommentAuthorCWatters
    • CommentTimeMay 30th 2019 edited
    Probably too expensive but one possibility might be...

    Quarry Tiles 12mm
    Tile Adhesive 6mm
    Wedi board (which has Insulating properties) and PIR Insulation board totalling 110mm
    Sand blind 10mm?
    Total 138mm

    Wedi say you can tile over it directly in residential areas but they add... "Rolling loads with high point loading are not permissible". Not sure if that rules out a sofa with legs? Perhaps something else other than Wedi board would be better?

    Quarry Tiles 12mm
    Tile Adhesive 6mm
    Two layers of 12mm WBP = 24mm
    PIR Insulation board 85mm
    Sand blind 10mm?
    Total 137mm approx.

    Never done this so best get it checked out but I think it should work.
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