Time lapse of concete pour

Here is some time lapse footage taken from our webcam.

Timelapse Polarwall concrete pour

ICF walls concrete pour completed

Polarwall ICF walls concrete pour completed

Well, after about 6 weeks of working evenings and weekends, we were ready for the concrete pour to fill the walls.

The run up to the pour was pretty nerve wracking for us. As anyone who has watched the drama series 'Grand Designs' will know, every single house build by ICF has a 'burst', which is where the polystyrene blocks burst open and all the concrete pours out.  Even all the self build guides cannot mention ICF without referring to a burst. For us, this would be even more of a problem as we are building inside an exiting structure - any bursts on the outside would be impossible to contain. Alan fom Polarwall assured us that if we had built it properly, there would not be a burst.


Craig took a week off work and built most of the walls. There were a lot of intricate details, particularly around the parts were the floor levels are different and where we had to build 'up and over' the internal existing concrete walls. Prior to the pour, we had to get the concrete mix right. Most people have no ide who complex and interesting concrete is.  We ordered a C40 CEM1 with 120mm target slump oversanded pump mix. Easy, yes?!

To give you an idea :

'Slump' - this is how much the concrete will collapse under it's own weight (when fresh) - the lower the number, the less this happens. The higher, the more watery the concrete. The problem with a high number is that there is more water, and this increases the pressure when you pour it into the walls, increasing the chances of a burst. The lower, the less workable the concrete is, which means it will not find it's way into every corner and crevice, round all the ties and reinforcing bar. Polarwall wanted a 90m slump, but because we were pumping through a long hose, the pump company wanted a higher slump nearer 150mm. We settled for a target of 120mm.

Compressive strength - Concrete is measured in difference strengths - this means how much force can be applied to it before it breaks. We were going to go with a C35, but on speaking to the Labs at Breedon (the readymix company), I identified that a higher compressive strength would 'go off' quicker - i.e start to set. This is because of the higher cement content, creating a reaction that would generate more heat, thus start to set more quickly. We settled on C40.

Cement content - readymix companies nowadays will generally sell you a CEM2 mix - what this means is that whilst there is a lot of cement, they also use by-products of other industries that have cemetious propertie e.g fly ash. This is cheaper for them (And us) and more environmentally aware. However, Alan from Polarwall wanted a CEm1 mix, which has more cement, so we went with that.

Because we were pumping concrete through a 2inch hose, we needed to make sure that the mix was wet enough and fluid enough not to cause blockages. To facilitate this, we asked for a oversanded mix, which adds more and with lightly less stone. Because we're adding more sand, we need to add more cement too...you can see how complicated it all becomes! The chap at the ready mix company was great and helped me understand it all and work out the best mix. I remember  long time ago reading that in many cases, the concrete for a job is often wrong and I can see how. If i had not paid so much attention, we could have ended up with too wet a mix, and lots of bursts, too dry a mix, and lots of voids in the walls, too thick a mix and lots of blockages....

So, Tuesday arrived, the pump guys setup their line up to the water tank. If you are wondering - we couldn't use one of these big booms you see because our house is too far back from the road. The guys were quite muted, but as they were never normally the chattiest, I didn't bother. The first load of concrete arrive and we started the pour. When the second turned up, I started to work out where the next load should get to and realised we wouldn't have enough. I then identified that I had miscalculated the concrete volume - I had ordered 20m3, but needed 23m3. I had not taken into account the fact that the walls actually started 300mm under the floor level.  A frantic call to Breedon ensued and thankfully they managed to find a mixer that was free and could get back up.

Everything went well and there was no drama. The pump guys completed the pour up to wall height and we put in the wall plates. We finished up at 5pm before heading to the airport to drop Alan from Polarwall.

When the pour was complete, the pump crew told us they had been dreading the pour - the do a lot of ICF for one company and there are always bursts, so they assumed ours would be even worse. That pleased us!

And so some pictures...

The story of our red telephone box

Back in September, I happened across an advert for a red telephone box needing restored in Scotland - in near Crinan as it happened. It's the sort of thing I like and I decided to buy it - I'd not seen it, neither did I know how to transport it, or where it would even go! No matter...I needed to get it first!

It so happened a friend lives in Inveraray and is just the sort of person you need to help with a task like this, so I phoned him and he was up for it. I met him after work in Inveraray and we made our way to Inverary in his VW flatbed, with some steel and plastic skids and a pinch bar.

On arriving, we found the box stuck way up the back of the garden on a ledge amongst trees...not a good start! The box used to belong to the man who was on Restoration Man having converted the Ice Box. The owners left us to it, and a couple of hours later, somehow we'd managed to shimmy it about, get it out of the mud, chop down parts of the tree, turn it 90degrees and start winching it on the flat bed. It's at this point I should point out that phone boxes of this ilk are made of cast iron, and weigh a ton - 3/4ton to be precise! Well, eventually, the box was standing upright on the back of the truck and strapped on. We returned to Peters and I left the box on the flat bed, till without knowing when to put it, or how to get it there. I eventually told my parents about it and could hear their eyes rolling as I spoke, but oddly they didn't seem too critical of this random purchase - in fact, my mother told me she'd always fancied one. You could have knocked me over at that - eventually, my parents agreed to let us keep it at their house until we had a home for it.

Cue me rocking up at Peters  week or so later with a V8 Wrangler, huge trailer and not much else. We took the trailer round to a yard in Inveraray with a huge tracked digger - a sling was attached and without sweat, it picked the box off the truck and onto the trailer...off I went, Houston bound.

On arriving, I started unloading - I had read up on how the Egyptian did things like this in the past and had an idea. As the box was lying on it's back, all I had to do was roll it off onto the ground! I had bought some round fence posts for the occasion and started to roll it off. I can't remember if I asked, or it was just good luck, but next thing my friend Steven appeared and had some good ideas, and in no time, we were rolling the box off the trailer with the aid of a high lift jack and some rachet straps! Once it was on the ground, we somehow had to get it upright again - cue a call to Mr Mercer, so 20mins later appeared in a massive tractor with front lifter. 10 mins later, it was upright and sitting on some skates, and we moved it round the side to it's new, albeit temporary, home.

Winter passed and the box was unattended - pointless trying to paint in damp, wet weather. as spring approached, my father starting making noises about painting and what sort of paint we should use. We had a lot on with starting to build the house, so just didn't have time to paint the box, when one night on the phone, my other announced that my father was painting the phone box...over the next few weeks, he worked solidly on it - rubbing back the rust and paint, applying primer (many coats), applying the red, cleaning, painting the crown - it really looked stunning. and so with the box painted, we still didn't know how to get it own to the water tank, it's new
home.

In October, we had to hire a HIAB to pick up scaffolding for us, and it made sense to pick up the phone box at the same time.

And so, it is now in it's new home near Largs - not quite in it's final position, but nestled next to the shipping container, causing many a passing motorist and cyclist to have a double take!

Building the walls

I'm aware it's been  while since our last post, but we have been flat out building the walls. Sounds easy, yes? well, not quite.

first off - our 'flat out' is flat out at weekends and after work in the evenings, with tht time reducing every night as we go into autumn.

We are building our walls using something called 'Insulated Concrete Formwork', and in particular, a product called Polarwall. Our walls will be pure concrete, but to build a concrete wall, you need to have something to make the shape. If you look at bridges made of concrete - for the supports, they were not actually built like that. What they would have done is built a strong frame the shape of the support out of timber or metal (something called 'shuttering'. The frame would be very strong, and into that frme, they would pour concrete. Once the concrete is set, take away the frame and bingo - you have a concrete bridge support. You can use the sme framework for the next support and so on.

With ICF, we build the 'frame' using polystyrene blocks - except they stay in place when the concrete is poured and are actually the insulation for the house. It's n incredibly simple, but clever concept. Most ICf companies offer blocks that literally look like Lego - the problem with that is that virtually none of our dimensions were standard - the tanks are all slightly different sizes, the external walls and internall walls are differen thicknesses, plus a whol host o other factors that meant a standard ICf solution would not have workd for us. With Polarwall, we can make any size or shape wall we want.

Rather than rabbit on, I'll sumarize the tasks.

• Build frames for the windows and doors.
• Cut panels to fit down the sides and tops of the openings to make sure when the concrete is poured, there are no 'thermal bridges' - basically bits without insulation that let cold in. 
• BUild up the walls
• Build scaffolding
• Cut and place rebar for all the lintels
• Pour the concrete into the wall

This has taken us many weeks, but we are finally nearly complete. The two outstanding tasks are the last two on the list.