How much should an insulated raft cost?

[AliG]

Hi,

 

I am just awaiting our ground survey and the plan is to go with an insulated raft assuming there isn't something stopping this.

 

I have a quote from MBC for a frame and a raft. The frame cost is a little high as I expected, but not crazy.

 

The raft price seems very high. I have not seen anyone actually quote how much an insulated raft foundation is costing them.

 

We like the idea of MBC doing the whole shell, but I am just curious as to what would be considered a reasonable price. The quote is almost £250 per square metre of footprint. We would still have to do the groundworks on top of that.

 

So people who have paid for or had quotes for an insulated raft, what kind of cost are you seeing?

 

 

[Dreadnaught]

Hi @AliG, I just checked my MBC quote and I was quoted £220 per sq.m of internal floor area back in November 2019 and £212 per sq.m before that in December 2018.

 

(I did not use MBC in the end, for a range of reasons.)

 

[AliG]

Thanks, that is about the same as mine as I calculated it on the external footprint.

 

Hopefully we can get an idea of what other people are quoting.

[nod]

45 minutes ago, AliG said:

Hi,

 

I am just awaiting our ground survey and the plan is to go with an insulated raft assuming there isn't something stopping this.

 

I have a quote from MBC for a frame and a raft. The frame cost is a little high as I expected, but not crazy.

 

The raft price seems very high. I have not seen anyone actually quote how much an insulated raft foundation is costing them.

 

We like the idea of MBC doing the whole shell, but I am just curious as to what would be considered a reasonable price. The quote is almost £250 per square metre of footprint. We would still have to do the groundworks on top of that.

 

So people who have paid for or had quotes for an insulated raft, what kind of cost are you seeing?

 

 

Slightly off topic A Could you give a similar price m2  example of your TF cost 

[AliG]

£410 per square metre for 0.14 U-Value.

 

Rises to around £515 for a twin wall frame, I have taken out the roof insulation cost to make them comparable.

 

Our frame does have quite a bit of steel in it which will be boosting the cost by quite a bit. Maybe as much as 20% would be my guess.

 

I had a quote from Scotframe that was around 15% cheaper once adjusted to be like for like, but I think it is worth it to have one company responsible for the whole shell build.

Edited August 9, 2020 by AliG

[LA3222]

My raft worked out about £170 per sqm of footprint.

 

I also had alot of muckaway and extra stone costs involved as I had to put 800mm of stone in. I believe MBC only include the top 200mm of stone? anything below that is your problem.

 

If you take out my additional groundworks it would be around £140 per sqm. 

 

I did most of the work myself - the only two jobs I didn't do were to operate the 20t excavator and to pour/powerfloat the slab.

 

I looked at MBC but found them to be too expensive. 

[SuperJohnG]

I got two quotes for insuakted raft. 

 

Simple t shape 185sqm footprint. 

 

MBC - 39K (210sqm

Econnekt - 36k. (195 sqm)

 

Both didn't include site leveling, they assumed coming in to a ready cleared and levelled site ready to out the hard-core down onto. 

 

Consequently I am semi diy similar to @LA3222. I think I can do it for somewhere between 20-25k. (108-135 sqm).

 

Ill try and remember to update with final prices. 

 

Kores system (what MBC use) is without a doubt the cheapest route. By miles in my experience so far when compared with econekt (izodom system) and isoquick. 

 

Food for thought - try scottish suppliers for your kit. I have found this much cheaper in general by comparison. I nearly died at MBC price when compared with my SIPS pricing. (Different systems yes but still able to reasonably compare). 

 

For comparison I've a 300sqm SIPS kit 1 3/4 story T shape. 73k supply and 18k erect from SIPS eco. SIPS@CLAYS were very similar and they are still in the running. 

 

 

[AliG]

Clearly an insulated raft is more expensive than I expected.

Edited August 9, 2020 by AliG

[willbish]

£145/m2 with as much DIY as possible

 

108m2 footprint of raft

 

That's for

300mm deep Isoquick (discounted when purchased with Logix) 

32m3 concrete 300mm deep

Pump hire

Tonnes of rebar, two layers of mesh and perimeter cages 

A bit of labour on pour day

50 tonnes type 1

Roller hire

Excavator hire

Diesel for the machines

DPM and tapes

10 tonnes 2-6mm clean limestone

Muck away 22x 10t farmers trailers

Few sundry items

 

Doesn't include any drainage, ducts, mdpe plumbing etc   

[ianfish]

We have been quoted 4k for Insulhub 

 For a 9x5m extension 

[SuperJohnG]

11 hours ago, AliG said:

Clearly an insulated raft is more expensive than I expected.

@AliG possibly. 

 

but don't forget whilst it seems expensive you have to think about how much more straightforward it is than strip founds after you do a ground bearing slab, add insulation inside, do UFH, then screed. Much more labour intensive and longer to do in my assessment (I've done neither before by myself) 

[AliG]

That I totally agree with. That is how my house is built and it seems ridiculous to build a massive concrete slab, then put down insulation, then cover it in concrete(screed) again, when you could do it all in one layer. Also you get much better insulation around the perimeter with the raft.

 

It sounds like the price is correct unless you are able to DIY a large amount of it.

Edited August 10, 2020 by AliG

[joth]

8 hours ago, ianfish said:

We have been quoted 4k for Insulhub 

 For a 9x5m extension 

Off topic here, but be careful about BC design sign off for this. We had a raft foundation approved for our extension, but after it was dug (but prior to pour, thankfully) the building inspector changed his mind and wanted strip foundations dug and tied to the existing, to stop the raft floating away from the old house. 

[ianfish]

2 hours ago, joth said:

Off topic here, but be careful about BC design sign off for this. We had a raft foundation approved for our extension, but after it was dug (but prior to pour, thankfully) the building inspector changed his mind and wanted strip foundations dug and tied to the existing, to stop the raft floating away from the old house. 

Was there anything untoward locally with the ground?

[joth]

1 hour ago, ianfish said:

Was there anything untoward locally with the ground?

 

Nope. When they dug it out and everyone agree the ground was as perfect as could be hoped for.

The issue was the building inspector renegade his previous (verbal) design approval for it, and the structural engineer that signed it off had since retired for poor health, and the new SE our architect took on to replace him sided with the BC which left us high and dry. (I guess we could have sued the first SE's professional insurance to recoup costs but seems crap to throw that onto someone with poor health, and after legal fees we'd barely recover costs. Still doesn't make it more pleasant to have to pay the cost of putting right other people's errors, PLUS VAT on it and the wasted work)

 

Edited August 10, 2020 by joth

[ianfish]

1 hour ago, joth said:

 

Nope. When they dug it out and everyone agree the ground was as perfect as could be hoped for.

The issue was the building inspector renegade his previous (verbal) design approval for it, and the structural engineer that signed it off had since retired for poor health, and the new SE our architect took on to replace him sided with the BC which left us high and dry. (I guess we could have sued the first SE's professional insurance to recoup costs but seems crap to throw that onto someone with poor health, and after legal fees we'd barely recover costs. Still doesn't make it more pleasant to have to pay the cost of putting right other people's errors, PLUS VAT on it and the wasted work)

 

Thanks for your input 

 

Sorry to hear of your experience