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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthorSimon Still
    • CommentTimeMay 17th 2016 edited
     
    This thread mentions them
    http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14258&page=1#Item_0

    and a few people say "wouldn't touch them" but no-one says why - what were the experiences of building/renovating a building built with them?
  1.  
    They are the standard building block over here, the older type had mortar top and ends, the new type just use mortar on top with T&Gs taking care of the ends. I think that they also use a thin type mortar now, although I am not sure about this. Any way they have been used here for ages with the thickness increasing with the insulation demands. The alternative is ytong type block (aerated concrete / aerated silicate blocks) but the vast majority house of building is Protherm. No one seems to have problems with them !
    • CommentAuthorringi
    • CommentTimeMay 17th 2016
     
    One issue maybe that drilling into a Protherm block or fixing into them needs a trade person that are used to them. I think Protherm blocks don't like it where a SDS drill goes anywhere near them....

    Likewise with cutouts for cables, pipes, etc.
  2.  
    Fixing into protherm blocks here is done by drilling a hole, inserting in a mesh tube then squirting in 2 part epoxy then either push in a plastic plug or a bolt (both before the epoxy sets !!): And yes you have to be a bit gentle with the drill.
    • CommentAuthorringi
    • CommentTimeMay 17th 2016
     
    How to you fix on the external wall insulation? (I don't trust systems that just use glue, and there are a lot of fixing to put in.)

    The concept of having to get ALL trades people that works on a building over my life time to drill in a different way to what they are used to, so that the "odd" bricks don't break, is just not nice.....
    •  
      CommentAuthordjh
    • CommentTimeMay 17th 2016
     
    Posted By: ringiThe concept of having to get ALL trades people that works on a building over my life time to drill in a different way to what they are used to, so that the "odd" bricks don't break, is just not nice.....

    It depends what the trade off is, I think. Brick is different to plasterboard, is different to fermacell, is different to wattle and daub, is different to cedar boarding etc etc
    • CommentAuthormarktime
    • CommentTimeMay 17th 2016
     
    We have a similar system in Spain called Termoarcilla,in fact I'm an accredited Termoarcilla Technical Construction Supervisor. Before using these construction systems it's useful to take a familiarisation course as they employ a slightly different laying method. And Peter is right in that they use a thin joint mortar.

    You don't need EWI if you are using these blocks so there is obviously no requirement for multple fastenings.
    • CommentAuthorringi
    • CommentTimeMay 17th 2016
     
    Posted By: djhIt depends what the trade off is, I think. Brick is different to plasterboard, is different to fermacell, is different to wattle and daub, is different to cedar boarding etc etc


    (fermacell is a none issue, as you can do anything to it you can to plasterboard.)

    One issue with Protherm is that it looks and feels like block/brick once it has been plastered.
    • CommentAuthorringi
    • CommentTimeMay 17th 2016
     
    Posted By: marktimeYou don't need EWI if you are using these blocks so there is obviously no requirement for multple fastenings.


    Will have give a U value of the level needed for a passive home without adding any other insulation?
  3.  
    Posted By: ringi
    Posted By: marktimeYou don't need EWI if you are using these blocks so there is obviously no requirement for multple fastenings.


    Will have give a U value of the level needed for a passive home without adding any other insulation?


    No way. I live in a house built using these blocks and it initially had no extra insulation. The walls are very very cold in winter with lots of thermal bridging.

    As a building material they are poor compromise between thermal mass and insulation with the added effect of thermal bridging.

    It seems to me that the manufacturers have cleverly persuaded people to buy a product that is more expensive but uses less materials than other blocks!

    They fracture very very easily which is made even more problematic by the fact that the joints are stronger than the blocks which is the exact opposite of what you want from block or brick work where any movement should be distributed through the joints, not the the
    other way round!

    If you want to work on a structure made with these blocks you need to be very careful how you go about it for the above reasons. Drilling a hole bigger than 12mm has the risk of fracturing the blocks. If you need to knock away some block work with a hammer drill or hammer you run a very good risk of propagating cracks and fissures to the surrounding blocks.

    Tradesmen like them because they are light to work with. Manufacturers like them because they use less material to fabricate despite selling them for more.

    Would be interested to hear from anyone who has worked on renovating a
    building made from these blocks...
  4.  
    Posted By: marktimeYou don't need EWI if you are using these blocks so there is obviously no requirement for multple fastenings.

    Quoted over here the 44mm blocks have a 'u' value of 0.22 whilst the 44mm with foam infill have a 'u' value of 0.17 so it depends on your target u value, you might not need EWI.
    • CommentAuthorEd Davies
    • CommentTimeMay 17th 2016 edited
     
    PiH, are you sure that's the U-value (conductance), not λ (or κ) (conductivity)?

    http://porothermuk.co.uk/products/porotherm-blocks/

    gives, for the 365 mm blocks, “TYPICAL BLOCK DRY CONDUCTIVITY (lambda) W/mK: 0.26”. That'd give a U-value of 0.712 - definitely needing additional insulation.

    To get a U values of 0.22 out of something 44 mm thick you'd need to have something a tad better than aerogel (λ = 0.00968).
  5.  
    Posted By: Ed DaviesPiH, are you sure that's the U-value (conductance), not λ (or κ) (conductivity)?

    44mm thick quoted as 0,22 W/m2K
    the 44mm with foam fill quoted as
    Anyagszükséglet 16 db/m2
    Nyomószilárdság 10 N/mm2
    Hőátbocsátási tényező 0,17 W/m2K
    Habarcsigény 3,96 liter/m2

    which translates as Anyagszükséglet = Number / m2 of wall, Nyomószilárdság = Compressive strength, Hőátbocsátási tényező = Heat transfer coefficient and Habarcsigény = Mortar consumption.

    Actually the error is in the 44mm. The blocks are known as 44 K actually they are 440mm or 44cm thick NOT 44mm :shamed::shamed:
    A structural wall 44mm thick would be some wall:shocked:
    • CommentAuthorEd Davies
    • CommentTimeMay 17th 2016
     
    Yep, for 440 mm a U value of 0.17 W/m²K is a bit more plausible. Still, it is λ = 0.0748 so something like twice mineral wool but still over 3 times better than the 2.6 W/mK quoted on the porothermuk.co.uk site. This isn't a conversation about two different materials, is it?
    • CommentAuthorSilky
    • CommentTimeMay 18th 2016 edited
     
    I had a quick peek on my fave u-value calculator and some of the porotherm blocks calculate to U=0.2 for a thickness of 440 mm, but there seems to be a huge variation in porotherm type blocks with a wide range of products and lambda values, obviously the calculator lets you put in any theoretical thickness even though the blocks may not be available in that format. I can't post direct links to this because you have to register before you can access the materials with the blocks ( so I'd have to give you my password ), but I'd highly recommend it if you want to research what is possible. try u-wert.net, the start page asks if you want to register or use demo mode, but in demo mode you can't get to the blocks... it's worth registering, then click on the flag to change language to English. Go to "Select material->masonry, new->then you have porotherm etc.. with specific products. Enter your thickness and you're away. I have no association with the website, but I am pushing it because I find it v. useful
  6.  
    Posted By: bot de pailleWould be interested to hear from anyone who has worked on renovating a building made from these blocks...
    That'll be me then. Well all my internal walls are made of the stuff anyway and I worked on a really big 'extension' where the massive reinforced concrete frame had infills of the stuff. There are at least 2 other types of effective fittings besides the mesh tube and resin approach - Fiescher make a rawlplug that works on most everything because in a hollow it curls up and crushes against the internal wall of the block (expensive though) and there are also the metal collapsible fittings that come with their own machine screw; the internal wings collapse flat to form a cross on the internal face (often used with a pull gun tool). Both have limitations. The std building process here uses concrete lintels over them too - is there a better cold bridge? Well yes actually there is, because underneath the lintel is a nice piece of marble or preformed stone cill that extends all the way across the wall - upon which the window sits. The only advantage to them is that you can reasilly knock a channel in the stuff with a hammer and chisel leaving a conduit sized square tube - then rendering covers up all the damage and splits etc.

    They are really bad news because they are often considered adequate insulation without careful checks of the actual U values (see Silky's comment) and by the time you have a few channels knocked in them on both sides of the wall, plus the odd vertical one, and the wall has lost a huge amount of its integrity.
  7.  
    Posted By: Ed DaviesYep, for 440 mm a U value of 0.17 W/m²K is a bit more plausible. Still, it is λ = 0.0748 so something like twice mineral wool but still over 3 times better than the 2.6 W/mK quoted on the porothermuk.co.uk site. This isn't a conversation about two different materials, is it?

    There are 2 types of 440mm protherm blocks marketed here, the ''old fashioned' type of honeycombed clay quoted as 0.22 W/m2K and the foam filled type that have less clay honeycomb and are filled with foam quoted as 0,17 W/m2K

    The 380mm are quoted as 0.25 W/m2K OR 0.41 W/m2K depending upon which type of 380mm block it is.
    • CommentAuthorringi
    • CommentTimeMay 18th 2016
     
    I seen them used in Grease/Turkey with massive reinforced concrete frames. Not too bad provided that AC is never used.

    I just question there usage anywhere where good insulation is required and/or the walls are expected to hold up the building. The thickness to get a good U value is so great that I see little point in their insulation value in the UK.
  8.  
    Posted By: ringiI just question there usage anywhere where good insulation is required and/or the walls are expected to hold up the building. The thickness to get a good U value is so great that I see little point in their insulation value in the UK.

    The use of blocks replaces cavity walls. The thickness of the block used would be a balance between thinner blocks e.g.30cm plus EWI to get the U value required vs. say 44cm blocks foam filled and no EWI needed. Do the costings and see which one you prefer

    The walls seem to hold up the buildings here and the floors are either concrete beam and block with 5cm concrete over or cast in situ concrete and rebar, quite a heavy construction method, plus roofs are all placed on concrete ring beams - nothing seems to fall down.
    • CommentAuthorringi
    • CommentTimeMay 18th 2016
     
    What about the cold bridges with the floor and roof? (From the concrete ring beams etc.)
  9.  
    Posted By: ringiWhat about the cold bridges with the floor and roof? (From the concrete ring beams etc.)

    The ring beams are built inboard and 5cm or 8cm EPS is put on to be flush with the external surface of the blocks.
    In practice this means that the shuttering is put up, the EPS is placed inside the external shuttering and the concrete is poured.
    • CommentAuthorringi
    • CommentTimeMay 18th 2016
     
    Are the blocks strong enough to fix the shutting to the blocks, if so it make a nice simple system.

    (A think a few ring beams, at window top height for example, would make be a lot happier about trusting the blocks.)
  10.  
    What about all the thermal bridging through the blocks themselves and the joints?
    • CommentAuthorSilky
    • CommentTimeMay 18th 2016 edited
     
    re- thermal bridging between blocks, I guess you use a special mortar, I just checked the one I'm using ( lightweight mortar for highly insulating blockwork ) and it has a thermal conductivity similar to the blocks ( 0.16 ), the beds are also thin, I just checked having 10 mm breaks every 40 cm and the difference to the u is negligible, using something like lime ( 0.9 ) with the same 10mm joints at 40 cm it will drop from 0.215 to 2.5. This is just to get an idea, the software I'm using is inserting these joints as continuous strips ( not horizontal and vertical ).
    • CommentAuthorPaulJ
    • CommentTimeMay 18th 2016
     
    When you look at the Porotherm website, they make no claims as to the U values (which, I suspect, are rubbish as they are just clay blocks).

    I think the "therm" bit of Porotherm is just greenwash.
  11.  
    The better hollow clay blocks are filled with insulation between the clay cell walls ... eg foam as in Hungary, perlite or rockwool in Germany. In France, the DTU (a non obligatory building construction standard but most builders use it to avoid insurance difficulties) demands a concrete column is cast within the brick and then linked to the slab and /or lintel ring beam so the building effectively has an concrete skeleton adding to the thermal bridges. This structurally is not required for 2 to 3 stories but the French DTU is mostly a belt and braces overkill. This is one solution that may be required in seismic areas but there are other alternatives such as a stressed skin reinforcement eg a reinforced render.

    They construct passivhaus buildings in Germany without this structure... thus less thermal bridging.

    The blocks are glued with a mortar glue 1mm thick, the vertical joints interlock without mortar

    see the Unipor passivhaus brochure 49cm Unipor W07 Coriso λR = 0,07 W/(mK) insulated hollow block. In Britain you could probably get away with the 42cm Unipor W07 insulated block ... check with PHPP.
    http://www.unipor.de/sites/default/files/waermebrueckenkat_download_0.pdf
  12.  
    idem
    • CommentAuthordelprado
    • CommentTimeJan 9th 2018
     
    Im struggling to see what the point is when you can just use concrete blocks and cover with wood fibre board?
    • CommentAuthormaxelaine
    • CommentTimeJan 10th 2018 edited
     
    We're nearing completion of a 95sqm floor area 2 storey house, built using 190mm Porotherm with 150mm EWI (graphited EPS slabs)

    The EWI/ render system is JUB's. The EWI is fixed at roughly 500mm centres in both directions with plastic Ejot mushroom shaped fixings, and adhesive - dot and dab that just about meets up.

    We fixed timber support blocks direct to the porotherm to take the big loads - Juliet balcony, mains supply at the eaves, TV aerial, outside lights. This is 140mm thick by 250 wide, used in lengths of 500mm or more, so it's surface is about 20mm beneath the render surface. We fixed them with Fischer resin anchor sleeves, 20mm hole, 120mm deep, m12 studs.

    You can also set a batten in the render, but under the mesh and topcoat.

    We've fixed downspouts and lighter loads (rated at a few 10's of Kg per fixing) straight onto the finished render surface with self-drilling plastic "pig tails" which take m8 screws (100mm depth).
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