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DIY Insulated Foundations


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I got all the insulation, EPS300 and 100, from Varley Insulation, they came in cheapest.

 

Regarding the L shaped edge up stand, the design from Hilliard Tanner called for 200mm wide 200mm tall up stands on three sides and 100mm wide 200 tall up stand at the front. I cut these pieces, all 90 of them, using a table saw. I cut one side then turned the 100mm thick insulation slab over and did a second cut. The cuts were all ok, in a few cases a bit wavey, but remembe4 the cuts are facing the concrete and the outside, so are of little consequence in the grand scheme. I glued each peice using low expansion foam, staggering the joints of the second course. Once set they were solid. 

Edited by Triassic
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The costs so far...

 

Excavate the hole for the basement        £14,872

Mot type1 and bedding sand.                  £1,109

Radon Barrier.                                          £  218

Insulation EPC300 and 100.                     £5,581

Reinforcing mesh and bar.                       £4,297

Labour to fix reinforcing and insulation.   £6,548

Concrete for raft                                       £2,763

Sundry items say.                                    £. 500

 

Total spend on basement, excluding walls £35,888.

 

I've worked along side everyone working on site, so I moved excavation material, fitted radon barrier,  worked alongside steel fixers tying steel reinforcing, worked to place the concrete, tidied up etc etc. My time is free!

 

Edit

To put the above total length not context, I got three quotes for this work, the lowest was £50k and the heights the £150k. Having done my homework it was clear the lowest did not include everything and would have resulted in extras. The company who quoted the heights price, the M.D. drives a £100k Range Rover, I’m not inclined to support his lifestyle.

 

Edited by Triassic
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Total area is 130m2. Some parts are only 100mm thick.

 

That works out at £276/m2 including the excavations. Or £162/m2 excluding the excavations.

 

 

 

Edited by Triassic
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12 minutes ago, Triassic said:

Total area is 130m2. Some parts are only 100mm thick.

 

That works out at £276/m2 including the excavations. Or £162/m2 excluding the excavations.

 

 

 

Just want to add what a great job you have achieved doing the insulated foundations yourself with some ground workers. All for DIY.

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On 02/05/2018 at 08:56, Triassic said:

The costs so far...

Thanks for the cost breakdown. Did you have professional fees on top of that?

 

I'd be very interested in how the SE did the sliding calculation -- did they have a coefficient of friction between the concrete and insulation?

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On 03/05/2018 at 12:18, matt-shrops said:

Just about to start on my slab... any tips? I am planning to use Jackodur XPS for the insulation as it works cheaper than EPS.

 I am worried about getting the slab level and smooth!

In also used XPS as it was cheaper. 

 

To get the site level we started by wackering in the stone drainage layer, as we did the various layers we checked for level across the area using a laser. We then blinded the area using sharp sand, to get an even layer we used 25mm roof battens as screeding rails. Again this was wackered down, a final level check was carried out and any low spots filled and wackered. We then installed the insulation layers and the radon barrier. 

 

Our concreting guy checked levels around the edge of the raft and he commented that there was only one low point, about 5 mm low,

 

As the concrete was poured he checked levels and racked the concrete about as required. He then put a final finish on the concrete using a magic screeder , this is a vibrating aluminium float around 3m wide. Once the concrete went nearly set he power floated the slab.

 

Now the slab is set I checked levels and it’s within 5mm all over.

Edited by Triassic
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Concreting looks straightforward but is one of the most exacting things on site.  It is very easy to mess up and timing is crucial.  Check out @PeterStarck's blog https://forum.buildhub.org.uk/blogs/entry/73-now-for-the-foundations/

Most sites the contractor would get away with this and it is probably only becase Peter was meticulous that he didn't get flannelled into accepting a cock-up.

 

Good to see you checking levels at each stage - not just assuming that the next layer will compensate.  Give yourself a pat on the back.  A fantastic job.

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22 hours ago, matt-shrops said:

Was he on his own?

The concrete pump guy is a one man band, he set up and pumped the concrete on his own, My foundation was 25.5m2,  the previous day he’d pumped, placed and  finished an area of 58m2. He’d pump, levelled and finished my concrete wi5nin three hours, he then came back three hours later and power floated it all to a smooth finish.

 

He came highly recommend as a very hard worker, he was, If you look at the above photo of  the concrete pump  you’ll see how far away he had to park, we had around 20m of extension pipes on the end of the boom pump.

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  • 3 months later...

Someone @Alexphd1 asked for more photos of my DIY insulated foundations, so here you are.

 

This is the basement complete with ICF steel reinforced retaining walls.

 

D40611AC-1489-4C05-9CF5-776668CBA01F.thumb.jpeg.4e8eccde4350ce9533d6f7e75c2de187.jpeg

 

Here is a photo of the lounge. This sits at the elevated ground level at the far corner of the basement, just to the right of the pile of white insulation in the above phot.

 

BAFF2884-7DCC-4645-B365-B33B12067659.thumb.jpeg.5875f4d9d328805e0395264a33c2bf49.jpeg

Edited by Triassic
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Having never used ICF before I was unsure about the practicalities of filling them with concrete and how to compact then. My local concrete pump guy has some experience and it was he who suggested they needed limited compaction. Hence this was our approach. 

 

So so about a month after the pour I've stripped off some of the ipolystyrene insulation to allow an internal wall to the keyed onto the concrete wall. Here is a photo of the concrete fill that was exposed having removed the polystyrene.

 

81BB4BFA-B068-4F06-98D8-4D648D40BBD3.thumb.jpeg.45cbb4322f3920cd567933f0e65ac966.jpeg

 

Looks good to me!

 

 

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Hi Triassic

 

I am also in Cumbria, Ambleside. We are currently peckering out very, very hard rock to create a basement workshop, as part of an extension and renovation of an existing house. 

Can I ask who you used for the concrete pump and power floating?

For your retaining walls, did you compare a block built wall with ICF on costs? Our SE has specced a 140 block 175 conc filled cavity and a 100mm block, with steel reinforcing in the cavity linked to the slab. Our slab is specced at 200mm.

How are you waterproofing the basement? I have looked at Newton 400 if we fit to the exterior, and also the Sovereign Hey Di system that is applied on the inside, but have not yet chosen. We are up against the exposed foundations of the existing house on one side.

Your pics have inspired me to try and do our own slab and also place our own steelwork and UFH pipes

Is EPS or XPS best for under the slab, as get conflicting advice when speaking to suppliers, and need to make a decison soon.

Looking forward to the day the rock pecking stops!!

 

 

 

 

Digout9.JPG

Digout7.JPG

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@Chablais Sorry for the delay in getting back to you, I’ve been labouring for the concrete block layer. 5 tonnes of blocks shifted!

 

Your mate Ian Parker did the concrete pump and power floating.

 

The SE would  not hear of using concrete blocks, he insisted on a steel reinforced concrete retaining wall, so the options for me were traditional shuttering or ICF, after looking a price and practicality I went with ICF as it’s easy to install and Ian had experience of pumping into ICF. I installed all the ICF myself as it saved me money.

 

Our slab has a 200mm thick 500mm wide steel reinforced ring beam around the edge and is 100mm thick in the middle. I’ve also installed  under floor heating pipes within the slab.

 

The basement slab has a Radon barrier within the build up. This is then linked into a stick on waterproofing membrane stuck to the exterior of the ICF walls.

 

EPS or XPS are both acceptable, you just need to use the correct grade, mine has XPS300 around the edges and EPS100 in the rest.

 

It took 12 weeks of peckering to remove around 1200 tonnes of rock.

 

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I know you all like photos. So here you are......

 

We now have internal walls in our basement.

530DB436-D6CB-4E87-8C46-2E8EED0349C2.thumb.jpeg.10eb43b492684b33e4bbcbc8567c0d14.jpeg

 

its all getting very real, the timber frame comes in seven weeks and I’ve not even ordered the windows, or a scaffold, or roof tiles, or rendering, or ASHP, or ventilation kit, or first fix anything!

 

Time to get my finger out!

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