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    • CommentAuthorbogal2
    • CommentTimeMar 15th 2017
    Planning a new passive house commercial building. About 10 m X 15m on a brownfield site. Present building being demolished now. Has anyone done their own passive slab? If so how, and where did you get the materials. Can you get a way with just a 100mm slab with a deeper ring beam? The building is going to be timber framed. Not sure whether I beam or twin walled. any suggestions there also appreciated. Thanks.
    • CommentAuthorDarylP
    • CommentTimeMar 16th 2017
    @bogal2, why do you want/need a deeper ring beam?
    100mm XPS sheets, 600mm x 2400mm IIRC, laid on a bed of compacted gravel, upturned at edges, giving 300mm underneath and 200mm at sides/edges.
    Support the edges, lay in the dpm, chairs, steel reinforcement, pour and polish..:cool:
    • CommentAuthorPeterStarck
    • CommentTimeMar 16th 2017 edited
    Posted By: bogal2Can you get a way with just a 100mm slab with a deeper ring beam?

    We have an Isoquick PH slab. I wanted 100mm concrete slab with deeper ring beam but the structural engineer vetoed that idea and said we had to have a 200mm slab because of ground conditions. We have 250mm compacted type1 then 50mm granite fines then 300mm EPS(Peripor) with a 200mm thick upstand.
    • CommentAuthorbogal2
    • CommentTimeMar 16th 2017
    Thanks. XPS rather than EPS, Daryl?

    Did you install it yourself Peter?
    • CommentAuthorDarylP
    • CommentTimeMar 16th 2017
    I went for XPS as it was :
    easier to cut

    Others here will advise EPS. S'up to you...:bigsmile:
    With TF do you need a deeper 'ring beam'?
    V easy to lay down, and keep on top of details!:wink:
    • CommentTimeMar 16th 2017
    I bought the EPS from Kore in Ireland. 100 mm graphite EPS 100 sheets for the bulk of it with specially formed EPS 250 parts to form the edges and a separate ring beam (because of our weird wall structure). The basic slab is 150 mm deep with a 350 mm section where we take the roof loads and 250 mm ribs to stiffen the whole slab. As I understand it, our whole slab is a raft because of the clay and depth of EPS we have underneath. I think the normal slab is 100 mm with 200 mm at loadbearing places. Tanner Structural Design did the engineering design and signed it off and Kore supplied all the EPS to suit. My groundworkers hadn't ever done such a thing before, but found it pretty straightforward to follow Hilliard's drawings. There are example details on Kore's site.

    As Peter pointed out, the engineer will need to provide a specific design to suit your particular ground conditions. I expect they'll want a survey to base their design on. There are various passive slab suppliers. I'd suggest getting quotes and then commissioning the design and materials from one of them rather than trying to find an engineer and materials separately. I had a different engineer for the house itself, again because of our weird walls, and because that engineer wasn't familiar with passive slabs.

    Posted By: bogal2Did you install it yourself Peter?

    No, it was the first Isoquick installation in the UK and a German technician came over to oversee the work. Unfortunately the UK groundworkers weren't up to the job the first time! In fact installing the sub-base and EPS is DIY because it fits together like a jigsaw puzzle. It was the UK concrete workers who were hopeless. There's a bit in my blog about it.

    • CommentTimeMar 16th 2017
    Agree with Peter. You need an engineer for the design. After that putting down the sub-base is standard and can be DIY. Putting down the EPS is not standard but is easy and is a matter of following the drawings and can be DIY. Putting in the steel reinforcement is standard and can be DIY if you know what you're doing. Putting in the concrete is standard but is only DIY if you know exactly what you're doing and have enough bodies (i.e. have done it before). Your groundworkers do need to know how to pour a reinforced slab.
    Posted By: djhI bought the EPS from Kore in Ireland and Tanner Structural Design did the engineering design.
    This brings back memories, In 2001 I had a few Estonian workers who mentioned houses they'd built on EPS in Scandinavia, I was curious so went to Sweden for 6 weeks working for an Insulated Foundation company. In 2002 I brought over renowned Swedish EPS Engineer Eric Thalberg to meet a few young Irish Engineers who had just started out on their own, Hilliard Tanner was one of those but there was also a few others, we also visited a few EPS companies, Kore was one. We educated them on EPS grades, the risks, the loading's, the long term creep and so on. The first few Passive Slabs we installed were jointly signed off by the Irish and Swedish Engineers until the Irish Engineers got comfortable with the system. We had many early problems with ring-beams becoming exposed at door thresholds and radon barriers but no structural issues in close to 1,000 foundations.
    The double L was one of my early innovations that solved the Radon Barrier issues, but the ring beams were still an issue. I solved this by combining the Passive Slab with the Twin-Stud, it took a few months to convince the Engineers to only use the inner stud as the load bearing element and let the outer stud hang over the EPS and just hold the insulation. We tried I-beam and regular Timber Frame on the Passive Slab but these had to be built on a ring-beam as wide as the wall so the ring-beam was often exposed, the best method is to bring the load bearing element to the inside.
    • CommentTimeMar 17th 2017
    Yes our ring beam was very unusual because the bales and render need full support. So the ring beam is separate from the slab, although tied to it for stability and the bales are cantilevered over the EPS uprights by a timber upstand.
    Posted By: djhYes our ring beam was very unusual because the bales and render need full support. So the ring beam is separate from the slab, although tied to it for stability and the bales are cantilevered over the EPS uprights by a timber upstand.
    I wouldn't have used a ringbeam in your case!
    • CommentTimeMar 17th 2017
    Then you would have had a thermal bridge
    • CommentAuthorringi
    • CommentTimeMar 17th 2017
    You can still "cantilevered over the EPS uprights" without a ring bream.
    • CommentTimeMar 17th 2017
    Posted By: ringiYou can still "cantilevered over the EPS uprights" without a ring bream.

    I have no idea what you're trying to say.
    You could have built a Thickened Edge Passive Slab, stood the structural Timber Frame on the edge of the slab and installed the bales afterwards, no need for a ring-beam and less risk of cold bridging.
    • CommentTimeMar 18th 2017
    There is no structural timber frame.
    Ok, is the ringbeam exposed at the door threshold then?
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