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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthorCranbrook
    • CommentTimeFeb 22nd 2021
     
    Ive come across the attached image for an insulated raft but I cant tell if it is meant to be showing a masonry wall or not?

    I'd be interested to know if it is in fact possible to build a single skin masonry structure on this foundation, with EWI adhered to the masonry. The blocks would be 7N thermolites at 140mm most likely
      51a7b663130fdd870d08fc717cea3cb5.jpg
    •  
      CommentAuthordjh
    • CommentTimeFeb 22nd 2021 edited
     
    Yes, it is showing masonry. Your foundation engineer will design the slab and insulation to account for the imposed loads when s/he is given your design.

    edit: your structural engineer will design the wall to meet regs, given your location and what's hanging off it etc. The structural engineer may be the same as the foundation engineer or might not be. All depends on what they're comfortable with designing.
    • CommentAuthorCranbrook
    • CommentTimeFeb 22nd 2021
     
    Thanks, hopefully my SE will be able to do this!
    • CommentAuthortony
    • CommentTimeFeb 22nd 2021
     
    Yes but why use aerated blocks, they crack dreadfully, May as well use medium density concrete blocks -

    But I like it! Raft will need double layer of grids and possibly thickening at the edges. My engineer did that to me, and under internal load bearing walls. I requested a redesign and instead of 200 slab with thickened edges now have a 225thick reinforced monolithic slab with no thickening, no cracks or problems
    • CommentAuthorCranbrook
    • CommentTimeFeb 22nd 2021 edited
     
    Posted By: tonyYes but why use aerated blocks, they crack dreadfully, May as well use medium density concrete blocks -

    But I like it! Raft will need double layer of grids and possibly thickening at the edges. My engineer did that to me, and under internal load bearing walls. I requested a redesign and instead of 200 slab with thickened edges now have a 225thick reinforced monolithic slab with no thickening, no cracks or problems


    The thermos were really just to keep weight down on the foundation and for ease of use tbh, and as they are 7N and I thought that they had better resistance to cracking than the standard thermos...

    I'm hoping that theres no need to thicken the edges and I have no internal walls (this will be for an extension on my own house - if it goes well I'll potentially use it for customers going forward).. I'll be running UFH in the slab so i'll have some mesh in the slab to help this
    • CommentAuthorjamesingram
    • CommentTimeFeb 28th 2021 edited
     
    Have a look at 'passive slab' foundations
    Somewhere online there the SE details laid out.
    Try 'vikinghouse' not sure if it still up though. I may take a look now.
    Or the old AECB gold EWI solution , that'll give you more details
    +1 don't use thermo lite or any acc arrested block. Use fenlite, fibolite or similar. There a good mid weight block made out of recycled aggregate that's good can't remember it's name currently
  1.  
    •  
      CommentAuthordjh
    • CommentTimeFeb 28th 2021
     
    FWIW, I employed Hilliard Tanner, the SE in those links, to do our foundation design. Very pleased all round.

    Our situation was a little bit strange, in that our main SE - Paul Rose - was happy with certifying/designing straw bale walls but despite being happy with raft foundations (over subsidence-likely pit/mine areas) he wasn't comfortable with passive slab design :smile: But he did a good job on the bales, Hilliard did a good job on the passive slab, and two others did good jobs on the arched timber roof and the engineered floor joists!
    • CommentAuthorMike1
    • CommentTime7 days ago
     
    Posted By: CranbrookThe thermos were really just to keep weight down on the foundation and for ease of use tbh, and as they are 7N and I thought that they had better resistance to cracking than the standard thermos...

    Take a look at 3.6N lightweight expanded clay aggregate block (e.g. Plasmor Fibolite, Lignacite Fibo 850).
    • CommentAuthorCranbrook
    • CommentTime6 days ago
     
    Posted By: jamesingramHave a look at 'passive slab' foundations
    Somewhere online there the SE details laid out.
    Try 'vikinghouse' not sure if it still up though. I may take a look now.
    Or the old AECB gold EWI solution , that'll give you more details
    +1 don't use thermo lite or any acc arrested block. Use fenlite, fibolite or similar. There a good mid weight block made out of recycled aggregate that's good can't remember it's name currently


    Do you know of any suppliers that would deliver the aforementioned blocks to South Wales? Material sourcing is the biggest issue I seem to be facing when attempting newer build methods!
    • CommentAuthorCranbrook
    • CommentTime6 days ago
     
    Posted By: Mike1
    Posted By: CranbrookThe thermos were really just to keep weight down on the foundation and for ease of use tbh, and as they are 7N and I thought that they had better resistance to cracking than the standard thermos...

    Take a look at 3.6N lightweight expanded clay aggregate block (e.g. Plasmor Fibolite, Lignacite Fibo 850).


    My concern would be that 3.6n blocks might not suffice for steels?
    • CommentAuthorCranbrook
    • CommentTime6 days ago
     
    Are the interlocking eps300 blocks imperative in these foundations (as opposed to sheets of eps300)?
  2.  
    Sorry Cranbrook , I've not done one myself so never looked into supply.
    Perhaps djh might be able to help.
    I know you can order EPS to spec.from manufacturers as I've done it for ewi board in the past before it was popular.
    Minimum order is the block size m3 that they process at out their kit.
    I spoke to the tech guy at Kay metzler to figure out what I could order and how, then got my wholersaler to order it by phoning up the tech guy for details.
  3.  
    Re 3.6 Blocks for steels, they're usually fine with a single block padstone directly under load. Your SE will spec. it with steel calcs
    •  
      CommentAuthordjh
    • CommentTime5 days ago
     
    Posted By: CranbrookAre the interlocking eps300 blocks imperative in these foundations (as opposed to sheets of eps300)?

    You need strength in the edges of the EPS 'bucket' to contain the concrete.

    I bought my EPS direct from Kore in Ireland.
  4.  
    Posted By: djh
    Are the interlocking eps300 blocks imperative in these foundations (as opposed to sheets of eps300)?

    You need strength in the edges of the EPS 'bucket' to contain the concrete.

    I bought my EPS direct from Kore in Ireland.

    If you shutter around the EPS to contain both EPS and concrete then interlocking EPS shouldn't be needed. This might help if there is a supply/cost issue with interlocking EPS

    (Is the interlocking EPS strong enough to contain the weight of the concrete whilst being vibrated with a poker?? Just asking)
    •  
      CommentAuthordjh
    • CommentTime5 days ago
     
    Posted By: Peter_in_HungaryIf you shutter around the EPS to contain both EPS and concrete then interlocking EPS shouldn't be needed.

    You may be right, but I haven't tried it and wouldn't want to. Have you?
    •  
      CommentAuthorfostertom
    • CommentTime5 days ago edited
     
    Posted By: jamesingramusually fine with a single block padstone
    Wonderful thing, padstones, but much misunderstood. Often a thick wodge of so-so plain concrete is cast onto dodgy masonry, as a sort of ritual, without any understanding that the idea is to bind together, stabilise and share load across several bricks/stones or lower-strength blockwork, which individually aren't up to it. A cut length of presetressed conc lintol only 65mm high, well bedded in strong mortar onto well chosen bricks/stones, is going to be much better than a 8" high blob of rough in situ conc.
    • CommentAuthorjamesingram
    • CommentTime5 days ago edited
     
    Tom , I dont think people have cast padstones since the 70s ,You're showing your age , or is it better phrase 'experience' :devil:

    Yes, your right though , as ever ,
    I generally use engineering bricks rather than these premade block size dense conc padstones , easier to lift for my poor old shoulders :bigsmile:
  5.  
    Posted By: djh
    Posted By: Peter_in_HungaryIf you shutter around the EPS to contain both EPS and concrete then interlocking EPS shouldn't be needed.

    You may be right, but I haven't tried it and wouldn't want to. Have you?

    Yes - but for a different purpose. Over here concrete ring beams are routinely cast in situ with EPS outboard of the concrete to give a similar(ish) thermal performance to the blocks they are sitting on. The ring beam ends up thinner than the block wall by the thickness of the EPS.
    Method - the shuttering is put up level with the wall edges, the EPS is put inside the outer shuttering, the iron work put in and the concrete poured.
    To create the EPS 'bucket' I would lay the base EPS then use this to butt the shuttering to, then place the side EPS inside the shuttering. This way the shuttering is dimensioned by the base EPS and the pressure of the concrete keeps the side EPS in place. By way of a bit of extra security a batten can be fixed to the shuttering on top of the side EPS to make sure it doesn't get dislodged, although with ring beams here that is not done.
    • CommentAuthorCranbrook
    • CommentTime5 days ago
     
    Posted By: fostertom
    Posted By: jamesingramusually fine with a single block padstone
    Wonderful thing, padstones, but much misunderstood. Often a thick wodge of so-so plain concrete is cast onto dodgy masonry, as a sort of ritual, without any understanding that the idea is to bind together, stabilise and share load across several bricks/stones or lower-strength blockwork, which individually aren't up to it. A cut length of presetressed conc lintol only 65mm high, well bedded in strong mortar onto well chosen bricks/stones, is going to be much better than a 8" high blob of rough in situ conc.


    This is interesting as my SE was only the other day telling me it's always best to cast in situ! :shocked:
    • CommentAuthorCranbrook
    • CommentTime5 days ago
     
    Posted By: Peter_in_Hungary
    Posted By: djh
    Posted By: Peter_in_HungaryIf you shutter around the EPS to contain both EPS and concrete then interlocking EPS shouldn't be needed.

    You may be right, but I haven't tried it and wouldn't want to. Have you?

    Yes - but for a different purpose. Over here concrete ring beams are routinely cast in situ with EPS outboard of the concrete to give a similar(ish) thermal performance to the blocks they are sitting on. The ring beam ends up thinner than the block wall by the thickness of the EPS.
    Method - the shuttering is put up level with the wall edges, the EPS is put inside the outer shuttering, the iron work put in and the concrete poured.
    To create the EPS 'bucket' I would lay the base EPS then use this to butt the shuttering to, then place the side EPS inside the shuttering. This way the shuttering is dimensioned by the base EPS and the pressure of the concrete keeps the side EPS in place. By way of a bit of extra security a batten can be fixed to the shuttering on top of the side EPS to make sure it doesn't get dislodged, although with ring beams here that is not done.


    I think this is similar to the route I'm contemplating, but I'm also toying with utilising one of @jamesingram methods in putting slabs up against the side EPS and then actually backfilling before concreting the slab
    • CommentAuthorCranbrook
    • CommentTime5 days ago
     
    Posted By: djh
    Posted By: CranbrookAre the interlocking eps300 blocks imperative in these foundations (as opposed to sheets of eps300)?

    You need strength in the edges of the EPS 'bucket' to contain the concrete.

    I bought my EPS direct from Kore in Ireland.


    I wonder what effect Brexit may have on current shipping :cry:
  6.  
    Hi Cranbrook, it's not necessary to shutter the EPS L sections or interconnect them, the L's are made from EPS300 that's nearly as strong as wood, gravity and friction holds them in place on the compacted hardcore even when you use a poker. A 200mm thickened edge slab with 100mm inner slab means you have to heat less concrete with the underfloor heating . Swedish are better with foundations while the German's are better with structure.
    • CommentAuthorCranbrook
    • CommentTime4 days ago
     
    Posted By: Viking HouseHi Cranbrook, it's not necessary to shutter the EPS L sections or interconnect them, the L's are made from EPS300 that's nearly as strong as wood, gravity and friction holds them in place on the compacted hardcore even when you use a poker. A 200mm thickened edge slab with 100mm inner slab means you have to heat less concrete with the underfloor heating . Swedish are better with foundations while the German's are better with structure.


    Can I achieve this is one pour.. i.e. get to finished floor level with one pour?
    •  
      CommentAuthordjh
    • CommentTime4 days ago
     
    Posted By: CranbrookCan I achieve this is one pour.. i.e. get to finished floor level with one pour?

    You have to make the slab in one pour, otherwise you will lose strength. It's doubtful that the top of the slab will be your FFL unless you're committed to a polished concrete floor? In which case think very carefully in advance about how you will achieve level access.
    • CommentAuthorCranbrook
    • CommentTime4 days ago edited
     
    Posted By: djh
    Posted By: CranbrookCan I achieve this is one pour.. i.e. get to finished floor level with one pour?

    You have to make the slab in one pour, otherwise you will lose strength. It's doubtful that the top of the slab will be your FFL unless you're committed to a polished concrete floor? In which case think very carefully in advance about how you will achieve level access.


    Apologies, I meant FF level (well just below) I will be tiling the finished concrete
  7.  
    Posted By: CranbrookCan I achieve this is one pour.. i.e. get to finished floor level with one pour?
    I understood what you meant, the answer is yes.
    • CommentAuthorCranbrook
    • CommentTime2 days ago
     
    Posted By: Viking House
    Posted By: CranbrookCan I achieve this is one pour.. i.e. get to finished floor level with one pour?
    I understood what you meant, the answer is yes.


    Thanks, do you have any images that would help?
    • CommentAuthormikael
    • CommentTime1 day ago
     
    Posted By: Cranbrook
    Posted By: jamesingramHave a look at 'passive slab' foundations
    Somewhere online there the SE details laid out.
    Try 'vikinghouse' not sure if it still up though. I may take a look now.
    Or the old AECB gold EWI solution , that'll give you more details
    +1 don't use thermo lite or any acc arrested block. Use fenlite, fibolite or similar. There a good mid weight block made out of recycled aggregate that's good can't remember it's name currently


    Do you know of any suppliers that would deliver the aforementioned blocks to South Wales? Material sourcing is the biggest issue I seem to be facing when attempting newer build methods!


    I have used pumice concrete blocks supplied by Besblock in Telford. http://www.besblock.com/pumice.php

    These feel much more solid like regular concrete blocks, are 7n, but have the thermal performance and similar weight to Thermalite. They were also of similar price. Given they are in Telford, delivery to South Wales should be feasible. I also have a few spare pallets of 100mm blocks which I might consider selling.
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