Strip foundation vs insulated slab

[Conor]

14 hours ago, K78 said:

 

 

The house will be 6.5m x 12.5m. 

 

Almost exactly the same size as my floor area. Got a quote for £4k for insulated forms delivered, and engineering fees Inc 

[Jeremy Harris]

3 minutes ago, Conor said:

 

Almost exactly the same size as my floor area. Got a quote for £4k for insulated forms delivered, and engineering fees Inc 

 

 

Interestingly that's slightly cheaper than I was quoted back in 2012 for roughly the same size slab.  IIRC, the SE costs plus insulation came to about half the £10,500 total.  The rest was the steel reinforcement, concrete and labour.

[Conor]

2 hours ago, JSHarris said:

 

 

Interestingly that's slightly cheaper than I was quoted back in 2012 for roughly the same size slab.  IIRC, the SE costs plus insulation came to about half the £10,500 total.  The rest was the steel reinforcement, concrete and labour.

I've calculated the other costs - hardcore, binding layer, tanking membrane, rebar, labourer for 1 day, and concrete and it comes out at £9405. Not accounted for soil pipes, power floating or UFH yet. That'll add another £1000 I'd guess. So give or take, a passive insulated raft comes out at about £100/m² installed.

 

Savings over traditional strip foundations come from the reduced excavation and disposal, no secondary screed, and labour costs for not having to build up footings. Not done a comparison yet.

[Jeremy Harris]

2 minutes ago, Conor said:

I've calculated the other costs - hardcore, binding layer, tanking membrane, rebar, labourer for 1 day, and concrete and it comes out at £9405. Not accounted for soil pipes, power floating or UFH yet. That'll add another £1000 I'd guess. So give or take, a passive insulated raft comes out at about £100/m² installed.

 

Savings over traditional strip foundations come from the reduced excavation and disposal, no secondary screed, and labour costs for not having to build up footings. Not done a comparison yet.

 

 

That's a bit cheaper than the quotes I had back in 2012 for a similar sized passive slab.  I had prices from Kore, Supergrund and Isoquick, and all came out over £10k.  Looks like prices may well have reduced a bit, perhaps because there's a bit more competition in this market sector than there used to be.

[Conor]

1 minute ago, JSHarris said:

 

 

That's a bit cheaper than the quotes I had back in 2012 for a similar sized passive slab.  I had prices from Kore, Supergrund and Isoquick, and all came out over £10k.  Looks like prices may well have reduced a bit, perhaps because there's a bit more competition in this market sector than there used to be.

Definitely, more and more people are using them. Think it also helps that Kore are little over an hour's drive from me so delivery is cheap. Also quarry materials in NI are a good bit cheaper than the UK average. Stone quarry 3 miles from my house and concrete yard about 10miles. 

[K78]

9 hours ago, Conor said:

 

Almost exactly the same size as my floor area. Got a quote for £4k for insulated forms delivered, and engineering fees Inc 

 

I could live with that. 

 

I’m not that surprised prices are coming down a bit.