bigreadie Posted August 7, 2019 Share Posted August 7, 2019 Just had a Structural Engineer out for a ground test and he pretty much skipped away as the ground conditions in his opinion was as good as it gets! We have an old pool that we are building over and he has said that a raft would be the best choice to achieve this...our groundworker said this initially without the SE so it's good they are on the same song sheet. We are not going for a passive raft and my thinking is that the raft is laid, ICF walls built up, a barrier laid underneath the insulation, UFH, screed, job done...Am I missing anything? A lot of the passive raft (isoquick) use the the insulation as a container for the concrete whereas I think we will use the ICF walls? Can this be problematic? Link to comment Share on other sites More sharing options...
Russell griffiths Posted August 7, 2019 Share Posted August 7, 2019 How can you use the icf walls to retain the slab ?? what are the icf blocks sitting on?? Link to comment Share on other sites More sharing options...
K78 Posted August 7, 2019 Share Posted August 7, 2019 1 hour ago, Russell griffiths said: How can you use the icf walls to retain the slab ?? what are the icf blocks sitting on?? Strip foundations? Link to comment Share on other sites More sharing options...
ToughButterCup Posted August 8, 2019 Share Posted August 8, 2019 8 hours ago, bigreadie said: [...] A lot of the passive raft (isoquick) use the the insulation as a container for the concrete whereas I think we will use the ICF walls? Can this be problematic? Show us how the ICF wall can contain the concrete as efficiently (financially and thermally) as insulation on it's own. Link to comment Share on other sites More sharing options...
Russell griffiths Posted August 8, 2019 Share Posted August 8, 2019 6 hours ago, K78 said: Strip foundations? If he has strip foundations, he won’t need a raft. There could be some confusion here with terminology. Link to comment Share on other sites More sharing options...
Gone West Posted August 8, 2019 Share Posted August 8, 2019 10 hours ago, bigreadie said: A lot of the passive raft (isoquick) use the the insulation as a container for the concrete whereas I think we will use the ICF walls? I would have thought that is exactly what is needed. The outer layer of insulation of the ICF wall would line up with the insulation upstand of the Isoquick creating a thermal bridge free construction. Link to comment Share on other sites More sharing options...
nod Posted August 8, 2019 Share Posted August 8, 2019 I can understand the benefits of using a passive raft But can’t understand why your engineer has decided to use a conventional raft if the ground is good Link to comment Share on other sites More sharing options...
scottishjohn Posted August 8, 2019 Share Posted August 8, 2019 there is a house on the river Nith at glen caple that is built on theesturay banking which is mainly mud =sand etc they dug down and made a raft from 1metre cubes of eps and linked them alltogether then poured a concrete slab on top --that was built 25 years ago --still there so good eps slab works on anything really 1 Link to comment Share on other sites More sharing options...
bigreadie Posted August 8, 2019 Author Share Posted August 8, 2019 No strips foundation. The SE said that he will specify a step on the edge of the raft and the ICF will sit on that. Link to comment Share on other sites More sharing options...
Temp Posted August 8, 2019 Share Posted August 8, 2019 4 hours ago, nod said: I can understand the benefits of using a passive raft But can’t understand why your engineer has decided to use a conventional raft if the ground is good That will be because of the pool. He means good ground everywhere except where filling in the pool. Link to comment Share on other sites More sharing options...
Temp Posted August 8, 2019 Share Posted August 8, 2019 The idea with a raft is that everything sits on it and its strong enough that it can bridge poor/made up ground, bit like a raft on water bridges between wave crests. Hence the walls must sit on the raft as well. Link to comment Share on other sites More sharing options...
bigreadie Posted August 8, 2019 Author Share Posted August 8, 2019 (edited) 6 minutes ago, Temp said: That will be because of the pool. He means good ground everywhere except where filling in the pool. Spot on Temp he pool is approx 5mx8m and 1.5m deep. This will be drilled to allow water to drain and then filled with compacted hardcore. Raft on top. Edited August 8, 2019 by bigreadie Link to comment Share on other sites More sharing options...
Temp Posted August 8, 2019 Share Posted August 8, 2019 Just a heads up... We only have 80mm of PIR insulation under our UFH. I now consider that a bare minimum and would put in more if building again. Perhaps 160mm PIR or 200mm EPS? See what others suggest. Link to comment Share on other sites More sharing options...
nod Posted August 8, 2019 Share Posted August 8, 2019 1 hour ago, Temp said: That will be because of the pool. He means good ground everywhere except where filling in the pool. Ah the pools pretty big then We had two 7 mtr by 2 mtr tanks and decided to fill and use strip foundations Link to comment Share on other sites More sharing options...
Jeremy Harris Posted August 8, 2019 Share Posted August 8, 2019 160mm of PIR roughly equates to about 250mm of EPS. I'd be inclined to consider that a sensible minimum if fitting UFH, and there's some merit in going up to 300mm of EPS. We have 300mm of EPS and our UFH still loses about 8% or so of the heat input to the underlying ground. Link to comment Share on other sites More sharing options...
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