A Raft it is then...

[bigreadie]

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?

[Russell griffiths]

How can you use the icf walls to retain the slab ??

what are the icf blocks sitting on??

[K78]

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?

[ToughButterCup]

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.

[Russell griffiths]

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. 

[Gone West]

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.

[nod]

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

 

[scottishjohn]

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 

[bigreadie]

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. 

[Temp]

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.

[Temp]

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. 

 

[bigreadie]

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

[Temp]

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.

[nod]

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 

[Jeremy Harris]

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.