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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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    • CommentAuthordelprado
    • CommentTimeMar 7th 2018
    Just can't see a solution to the problem
    • CommentTimeMar 7th 2018
    Posted By: delpradoJust can't see a solution to the problem

    Correct. You insulate around the end, or the entire length, because the whole beam is either cold or warm. Or you break the beam in two and put a thermally broken connector in the middle (as used to cantilever balconies from flats). Since neither of those are usually terribly practical, the best solution is to design the building so steel doesn't cross thermal boundaries.
    • CommentAuthordelprado
    • CommentTimeMar 7th 2018
    This looks like an interesting padstone replacement:


    I guess if (in my case) the beam is not as deep as your joists, then you can insulate all the way around it, but not ideal if it can only be 25mm of insulation before it touches ceiling (again in my case)
    • CommentAuthorgravelld
    • CommentTimeMar 7th 2018
    Do you even EWI bro? :wink:
    • CommentTimeMar 7th 2018
    Posted By: delpradonot ideal if it can only be 25mm of insulation

    aerogel :cool:
    • CommentAuthorSigaldry
    • CommentTimeMar 8th 2018
    Insulate externally (definitely best choice), or failing that, try and introduce a degree of appropriate thermal separation/sheathing?

    Boxing's all well and good, but if you can prevent the end getting as cold in the first place, that's a much better approach.
    • CommentAuthorrevor
    • CommentTimeMar 10th 2018
    I agree with DJH. My architect when he designed my balcony had steels cantilevered out from well within the floor space of the floor space. I told him to come up with another solution which in the end was supporting pillars. I did not do that in the end we built a steel framed Atrium bolted to the outside wall so ending up with an enclosed balcony.

    What are you trying to achieve?
    • CommentAuthordelprado
    • CommentTimeMar 11th 2018
    I need to put a steel in as shown here to reduce the span of the really under sized historic joists above

    • CommentAuthorrevor
    • CommentTimeMar 11th 2018
    What is supporting wall made of and how thick. What is the current insulation of the wall. Is it possible to make an enlarged hole and insulate around that. If the beam is supporting an upstairs joist presumably it will be exposed in the kitchen so would need boxing in.
    So does it in fact need to be an UB could you have a timber beam supported by an upright beam and make a feature of it could look good in an older property.
    • CommentAuthorgoodevans
    • CommentTimeMar 11th 2018 edited
    If you can create a ledge/corbel/bracket/pier on the inside edge of the external wall and place the beam on that you would be able to mitigate the effects of warm steel penetrating the wall - in this case don't forget that stone is an insulator (compared to steel). You won't win any awards for insulation - but it will be better than nothing.

    The downside is that unless that support is carried down the wall there will be an overturning moment on the wall. with a 'timber column' fixed to the wall (and also creating a beam ledge) under you've created a kind of wind post. Your engineer may be able to sign off on that. That column may not have to reach the floor to distribute the moment into the wall.
    • CommentAuthordelprado
    • CommentTimeMar 11th 2018
    The supporting wall is 1920s clay brick, imperial, so 110mm thick. Cavity built - 70mm eps filled.

    The diagram is actually misleading because its going to be hidden within the joists, and the joists hung off it.

    goodevens I cant do that as eventually the north elevation wall will be knocked down in order to create an extension
    • CommentAuthorTimSmall
    • CommentTimeMar 11th 2018
    Err, so isn't the proposed steel all on the warm side anyway, since it'll stop short of the 70mm EPS insulated cavity?
    • CommentAuthorwookey
    • CommentTimeMar 17th 2018
    I've seen people (a greentomato project IIRC) put the beams on foamglass (with a foamglass surround too). Probably easier to get past the BC is putting them on fibreglass pads (bottom and sides). Any sort of thermal break makes a big difference when there is a big steel involved, so even a relatively thin fibreglass pad greatly reduces the bridge. But as Tim says, isn't it all on the warm side anyway?
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