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About this blog

Getting started at last

 

Like a good few people on the build hub it's taken us a while to get to the point where we are finally breaking ground. We now have the diggers arriving the week 11/02, so time to get blogging.

I'll start by providing some background and project overview. We'll update the blog as we progress.

We started well over a year ago, kids grown up and house more than we needed, and both with no intention of ending up in sheltered accommodation. Fortunately for us our existing house is on a corner plot with a large detached garage providing an opportunity to build a small house without detracting from the original house. We want to future proof the house as far as we can.

Having played with the idea for a number years we started to actively look at what we could achieve. It was not long before we came across the concept of passive housing. We ended up speaking to PH15 and to Zero Bills (Zed Factory). PH15 do passive house timber frame solutions, had a really good feel about the organization but quickly realised they were talking much bigger budgets than we could manage. After a visit to the building research establishment (BRE) and a look at the Zed Factory house there we decided to take a look at that route. ZED provided either a shell or turnkey solutions, both of which were within our budget. The cost per square metre in the ZED literature at BRE indicated a very competitive turnkey price in the region of £1,350 a square meter. As with all things the low price came with compromises as it was a “cookie cutter” solution and finish was not all that we would have liked. We had a meeting with ZED, to talk about what we wanted. It quickly became apparent that the “small changes” we would have liked came at a very high price pushing the cost per square metre to £1,6434 which is in the region of 40% higher. Some of the additional cost were also high, for example £7000 for preparing tender documentation, £4500 for planning documentation and £5000 for building control drawings. All in all a deflating experience, got the impression that ZED are structured for big developments not the self builder.

We took a while to get over the disappointment of the ZED negotiation and ended up going to a self build show a couple of months later at Bicester. It was a good show and we came across MBC who had a small unassuming stand, one technical guy and a very satisfied customer. After a long chat we realised we could achieve our build for our budget and get a house designed for us rather than generic build.

Planning permission was the next big hurdle. We had spoken to our neighbours over the years about the opportunity to build on our plot to replace the garage with a small house, they had not raised any objections. At this stage we used Sketchup to model a couple of designs and engaged with the local planning department pre-planning process. This was very useful as it allowed us to establish what would and would not be considered, basically set the boundaries for us to push. We came away from the process with the knowledge we could probably build but not necessarily on the scale we wanted. At this point we found a local architect and started the design process and the subsequent planning approval process. The design process is a odd one, conflicting interest between the architects creativity and what you want to build and can afford. It's certainly a phase that having done once you are a lot wiser. Not a disastrous relationship but a very frustrating one. In any event after a couple of iterations with our planning officer we reached a point where we could submit a planning application. I'll not go into the problems we faced in planning other than to say it's arcane and the neighbours who were supportive at the start now raise issues with bat flight paths, ancient privet hedges and many more distractions. In any even after going to committee twice we finally got approval.

At this point it should have been simple order the MBC kit...enter the build hub. Having done a bit of reading on construction techniques and their problems we decided to take a look at ICF as it was comparable in price with timber frame without some of the long term problems that timber frame can face with external water ingress. More research looking at ICF block led us to JUB who had a “no cut on site solution” which appealed. The block are not flat pack and have substantial webbing which should reduce the risks of bulges and leaks when the concrete is cast. Having selected a brick the next problem was to find a builder. Not as simple as we would have thought as builders who use ICF are would appear in the main to be in exclusive partnership with the a block manufacturer. In the end we went with “Intelligent Building Solution” a firm with considerable ICF experience who are based in Glasgow.

JUB ICF:

The web site literature for JUB sells the blocks as a well established solution. JUB have integrated raft, wall roof and render systems which should minimise compatibility issues.

It was not long into the process before we discovered from sources other than JUB that they had not built any houses in the UK. The bricks are in use in Europe but mainly in off the peg solutions, in the UK it's being marketed as a solution that can build pretty much any house you like within a 75mm of your design. The marketing support for the blocks is best described as tentative, having nothing to base there quotes on. We had expected them to be keen on getting a build under way but getting a competitive price was not straight forward. At £79 per square meter for the 390mm blocks and £58 for the 300mm blocks put it toward the high end for ICF. What I will say in their favour is that the technical support has been excellent. We are now dealing direct with the JUB technical guys in Slovenia and they are being very practical and helpful.

Structural calculations:

One problem you face with the JUB solution is that the block plan can alter the build dimensions, not only by the 75mm figure but also to simplify wall interfaces. The result is that you have a bit of a “chicken and egg” dilemma with what order you get things done in. We opted to get a first pass on the ICF block layout and use this as input to the structural engineers. This has worked out well with only minor rework of the calculations and amendments to block layout.

As far as finding a firm to do the calculations, our builders warned us to go with a firm who were familiar with ICF to prevent over specification of the steel in the structure. We ended up getting in three quotes and decided on Tanner Structural Design a firm used by others on the buildhub. Not having any experience of the process it was most refreshing to deal with Tanners. I have no reservations recommending them, their communication was excellent and they were happy to take external input into account.

 

Insurance:

We wanted to get build insurance. JUB recommended BLP. We got quotes from Advantage, Aedis, BPL, and Global Home Warranties. We wanted to combine the warranty with building control as we figured this would get the best result for us on the basis “if your going to provide insurance it's in your interest to make sure it's built properly”. BPL provided a very expensive quote so have been ruled out. Aedis put additional liability on the builder which may discount this option. It will be interesting to see just how usable the service turns out to be.

 

Windows:

This proved to be a decision that consumed a lot more time than anticipated. Who would have thought there would be so many manufactures out there, spoilt for choice I think is the expression. The build hub proved a very useful source of information and advice. We very nearly went with Rhino who make a very competitively priced double glazed aluminium solution. In the end we went with triple glazed windows from Velfac which rather stretched the budget but we felt would pay back in quality of living/comfort.

 

Site soil survey:

This was a new area to us like so many when you come to self build. In order to do the raft foundations design the structural engineers needed us to get site soil test done. We duly got in three quotes, the cost was a complete surprise as it was not an item we had budgeted for. Professional fees of over £800 for an engineer on site for the day, sample holes, and reports drove the figures close to the £3000 mark. A bit of research opened a whole new world of soil plasticity. We contacted our structural engineers to establish what they required and they were happy with the soil plasticity figures. More digging and we found a firm Ashdown Site Investigation who provide site survey and laboratory services. They were happy to do sample analysis and only charged £35 for each sample. We dug a hole 1200 deep taking 1kg samples for each layer, in our case there were just four pretty well delineated layers. We bagged and labelled the samples with their depth from the surface and sent them of for analyses. A week later we had the information required to do the structural calculations.

 

 

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Entries in this blog

 

First concrete pour done and scaffolding up

Well, it’s been a month since my last blog update. We've witnessed out first concrete pour and now have floor joists so we are all set to build the next floor. The bracing plan we have from JUB looks like we have the potential to pour the second floor and gables in a single  pour. This is a decision I'm only too happy to leave to the builders who continue to impress us with their ability to get on with a job regardless.     In my last blog we had got on really quickly and had the ground floor pretty much ready for a concrete pour. We needed to wait as there was no rebar on site for the cantilever lintels for the first floor. Our structural engineers had provided a revised structural plan toward the end of February, but it did not have a bar schedule. One was requested and sent through quickly. So far so good, we had the second lot of blocks scheduled for delivery on the 24th March. The original schedule allowed the pour and joists to be in place prior to the block delivery. At the same time as this was progressing the pricing for the next phase was finalised and we gave agreement to proceed.     A hiccup with the joist delivery delayed work on site. On a small site the second block delivery pretty much took up all the available space. ICF blocks and a cramped working site are not good news. The ICF is pretty dense but it’s easily damaged when it gets in the way. We ended up playing shuffle the blocks to get the remaining work done and for the first pour.  Our builders did a splendid job and just took it all in their stride they were careful with the blocks and didn't complain about the site restrictions once.   We had been warned that pours are not for the feint hearted, thankfully in the end ours went pretty well. The only real surprise was the bottom courses of blocks on one side of the build started to move outward on the raft. Fortunately it was spotted and the pour was suspended while Mike and the other lads added some more shuttering. With the new shuttering in place the pour continued and was completed without incident. Apparently it's unusual for the bottom row of blocks to move, but given they are not keyed into the raft and are subject to the greatest concrete pressure it's not entirely surprising. The blocks on the second floor will be keyed into the existing blocks so they should not suffer.   With the pour done it was time to get the ledger beams in place to take the first floor joists. Our structural plans had the ledger beams fixed by bolts at 500 centres with the joists at 400 centres. Sounds OK but in practice it’s not ideal as it means you get clashes of beams and bolts, so the plan was revised and the bolts put in at 400 centres so they would not clash with the joist. Ledger beams in place the joist went in pretty quickly, transforming the house.   Once you get past the ground floor you need to get scaffold in place for an ICF, not to build from but to prevent possible accidents if someone were to fall through the blocks from the inside. Our builder wanted us to arrange the scaffold, not sure if this is the norm, I suspect it’s liability related. We have used a local firm ROM Scaffold. Their guys arrived on Wednesday and pretty much had completed their work on the Thursday. The scaffold will also allow for our window installation and rendering.   Looking forward to getting the next floor up and starting work on the roof.      

Simon R

Simon R

 

Blocks delivered and we're up to the first floor

It's been a week of mixed emotions, we've made good progress on site but hit our first major budget overrun. First the good stuff, blocks got delivered on Monday. JUB will only ship them on pallets which sounds OK but in practice, but causes several problems on site. For a start we didn't have a fork lift on site and fork lifts don't tend to do well on soft ground. In the end we got in a tele-handler for which a single days hire is a significant cost. It should have been a small unit, but in the end the hire company delivered an 8 ton  far too heavy and large for our site. It was so heavy it ended up damaging the new dropped kerb work done for the build. Besides unloading the blocks, other problems with having them on pallets soon became apparent. It's a small site with limited space for storing materials we needed to store the pallets on the raft leaving room for bracing to be put in place once the walls are built. Each pallet had a manifest of the blocks loaded onto it. No cutting is required so it should just be a case of selecting the blocks and putting them in place. JUB provide a nice block plan for the build giving a cross reference of block type and location. 646-2018 WALL - Assembly plan 1of2 A1.pdf It quickly became apparent that finding the right blocks would be a challenge. There are a fair number of types, some quite small, all carry an identifier in the form nnn-tt-nnn but it's not that easy to read, so we thought it would be a good idea to use a marker to add wall position. Not such a good idea as the same block has multiple wall position numbers which further complicates finding blocks as a no 5 is in fact just the same a no 11. I've now looked at the wall assembly plans a couple of times and the logic for the labelling escapes me. It would be a lot simpler on site if each unique block type was allocated a single number for a given kit and the number was used consistently throughout the kit assembly plans. This is a first for JUB in the UK so I expect the kit process will get refined. In any event the block assembly went very well and by Wednesday the blocks were up to the first floor and the bracing was in place. First impressions of the JUB systemare very favourable. One other item completed was the connection and testing of the sewer pump station. The pump has to be connected with “class C” 63mm MDPE pipe which is designed to withstand the pressures associated with a pump. The pipe is referred to as flexible but it's anything but especially over short distances. The result was that making a connection required the use of an angled connector, just a single 45 degree, but we would have preferred no connections. The 63mm run is very short less than 1M and has good access from the pump meaning it can be easily rodded. Now the less pleasant news, budget overrun. In hind site this is a self inflicted wound and I should be old enough and wise enough to have avoid it. Back when we started our project we had a budget offer from our shell builders Intelligent Building System. The budget included the raft and associated concrete and steel but not the ground works. From various items on the build hub and other web sources I had come up with a figure in region of £15K for the ground works. I didn't verify this with the builder or get a phase 1 statement of works prior to the work starting. Sounds a very basic error and I still wonder just how I ended up in this position, my only excuse is that I got carried away in the practical aspects of the build. The phase 1 works came in at 34K added to this was 4.4K for the insulated raft which I had to purchase directly from JUB, so 38.4K total. The original budget offer was 14.3K a figure which included an insulated Isodom raft, assuming this would be about the as the JUB raft brings the figure down to 10K. Some analysis of the costings showed the labour had changed from around 5K in the initial offering to 15K in the costings. There were also additional materials costs which are much easier to understand, we also added items like a very big hole for the rain water harvesting tank and soak away . I had discussions with our builder over this but they are adamant it's correct. My own fault for not getting the work properly defined  before starting. I'm still on talking terms with the builder, whom I'm generally very happy with and would recommend to other self builders. They have been very proactive and helped considerably with getting JUB to engage with the build and many other items.

Simon R

Simon R

 

Raft delivered, conrete poured and rocks in the road

Bang on schedule the raft components arrived on Monday morning. We knew it would be quite a big volume of material on a small site and getting it unloaded and put somewhere it would not get damaged or need moving was s little tricky. JUB insisted on sending the raft on pallets. Our builder was not that impressed with this as unloading the lory requires a folk lift which is something we don't have on site. So we had to hire a set of folks for the digger. With the raft safely stored at the back of the plot the work to prepare the site progressed. The drainage had been marked in the site setting out exercise along with electrical and water ducting. Trying to keep raft punctures to a minimum but also allow for future needs was a concern. In the end we kept it to a minimum with electrical conduit for the rain and foul water pumps and two for water.   Along with the raft we received a letter from our neighbours complaining that I had put our water meter box on their garden wall. In retrospect a valid complaint, it was one of those decisions made in expediency without enough thought. Our water supplier Portsmouth Water will now only make new connection when an above ground water meter box is installed. I duly bought the one box they permit (so much for choice), water pipe and water conduit.  Not having a house on which to mount the box, I made the required connections and left the box mobile so it could be put in place in due course. At which point I called in the Portsmouth Water, regrettably they said they could not make the connection until the box was in situ. Having explained our situation and the need to get water on the site it was suggested I could mount the box on the wall by our property. At this stage I should have thought about it rather than simply get on with it, my mistake entirely. The wall it outside my boundary, by millimetres true , but still NOT ours. Our neighbours were not impressed so Monday was spent  moving the box and apologising to my neighbours. I  shuttered and cast concrete into the wall footings and backfilled with type 1 MOT to repair the wall. Having done this I then putting in two concrete posts 200mm inside our boundary and mounting the water meter box on them. This is what I should have done in the first place.  Slightly different subject, the Groundbreaker Water box, this is the only box that Portsmouth Water will connect to. At around the £150 mark it's a pretty hideous piece of kit both aesthetically and in product design terms for installation. Given their current monopoly and the fact that all new connections will require one it made me consider looking into producing an alternative. A swift kicking from the boss and I was reminded to get on with the house...maybe later once the house is done. .     With the drainage in place the MOT type 1 sub base was spread over the raft area,  levelled and compacted. Our builders ICF-homes did this with considerable care and we ended up with a good surface to spread the sand layer which was again compacted before putting down the membrane. Our structural engineers had specified a Radon barrier, we ended up using a standard plastic DPM as Radon is not a problem in our area. The DPM gets glued to the side of the raft sealing it and providing some additional protection for the polystyrene. .   With the membrane down the work of setting out the raft. The perimeter is all keyed together   It took a while to get the corners located precisely but once this was done the raft slotted together very well with a really solid interlock.   The raft was then completed by adding the rebar, four layers around the perimeter. All in all a lot of steel, Pat and I spent most of Saturday morning helping get the rebar in place and wire tying it to make is solid before the concrete pour.    Our raft is now complete and this week the surface water drainage will go in.   Along with the problem with the water meter box our neighbours also bought up the "Party Wall act". Doing a self build is nothing if not educational. The act came into law following problems with basement excavations in London. It dictates that excavations in close proximity to your neighbours 0-6M have to be notified and agreed. In our case we were within notifiable distance, but fortunately were not excavating to a notifiable depth. Our builders were not familiar with the act and no mention had been made by building controls. The act did effect our other neighbours and I contacted them letting them know what work has been done.  Fortunately all the excavations were made and backfilled without incident.   Hoping for a less eventful week to allow us to regroup before our first block delivery next Monday. As this is the first build for JUB in the UK the factory are sending someone on site to assist with the build and wall bracing.   It's very positive to see the house taking shape, we have our EPC which suggests we should require in the region of 68wats/K to heat the house which is great, but we still only come out as a "B" energy rating! the rating system is bonkers.

Simon R

Simon R

And we're off

The firework instruction phrase "light the blue touch paper and retire to a safe distance" comes to mind.  It's been a real baptism of fire, however our builder says it's the worst time and it should settle down now.  All in all it's been a productive week and almost all work has moved us forward.   The digger arrived to dig out the raft area at 8am as requested and work got under way. We had muck lorries scheduled for Tuesday and it quickly became apparent that we did not have enough space on site to build a significant spoil heap. After a bit of phoning around found a local company who could supply vehicles. Our builder had asked us to take care of paying for the muck lorries which was fine by us, getting the lorry company to accept that it should be a zero rated VAT service was more difficult. Contacted HMRC and had a discussion and they were adamant that it should be zero rated and that if VAT was charged I could not reclaim it as it would have been at the wrong rate... Managed to resolve the problem in the end. Now we had lorries arriving and clearing the soil we were able to make real progress. Tuesday the rainwater harvesting tank arrived, we knew it was big and boy was it big! The tank needed to get dug in just 2.5M deep and 4M long, a very big hole. Fortunately the ground conditions were good and a nice clean hole was achieved without the need to grade the sides. By Wednesday we were ready for site setting out. An interesting  activity and an example of technology being used because it's there rather than essential. Making sure the house position is millimetre perfect seems a bit over the top when string and triangulation would get it positioned within 10mm. Where it really does help is  positioning services and getting drainage levels set. A second visit on Thursday had all the levels set and perimeters marked, by the time the guy left the site I had changed my opinion and consider it money well spent.   More and more lorries to take muck away, the tally now sits at twelve loads and we are mostly done thank goodness as at £240 a 12 ton load for the clay it was making a bit of a whole in the budget, a quick calculation of the volumes validated the figures, so it really should not have been a surprise. In hindsight I'm surprised our builder didn't ask me to organise in more lories in the first place. If I do this again I'll order the lorries in advance rather than madly phoning round for spare capacity so that work can continue.   The foul water pump arrived on Wednesday, having the levels all sorted from the site setting out I was able to cut the input to the tank, so it's all ready to get dropped into a hole once it's been dug and a concrete base is in place. The next task was to get all the drainage runs under the raft in place. With the raft due Monday and the builder having to go to another job on Friday to supervise another ICF concrete pour we were running out of time. Hopefully resolved the problem by getting a crew in on Saturday to get the drainage done.  Stone for the raft substrate should star arriving first thing Monday, so fingers crossed we should have the raft ready for concrete which is booked for Thursday...we shall see.

Simon R

Simon R

 

Almost ready to start

Well with just days before we start we have our house block plan. All the bricks have ID's so all we have to do its put them in the right places.   The blocks are coming loaded on pallets, each with it's own manifest. The scale of the kit is a bit daunting and having done my bit of Lego with the kids in the past I can't help remembering the fun of looking for that special brick that seems so illusive. Fingers crossed we don't end up with one left over after the last concrete poor.   With site works just about to commence some of the details we thought were sorted are coming unravelled. Our rain water harvesting tank (RWH) which was nicely located on the edge of the property has had to be moved as the builder is concerned over the size of the hole next to the public highway. At 2.5M deep and 3.2M long. I can only agree, just a pity it didn't get mentioned until the week before we start digging. The tank is being moved to the rear garden along with all the associated changes to surface water collection drainage. While sorting this out it was spotted that the  tank overflow was connected to the sewer, the sewer company takes a dim view of the idea of connecting surface water the sewer system. The fact that the tank capacity is very over specified and the overflow will probably never see any water is irrelevant.  One of the main reasons we are an RWH was to take care of surface water as our plot is small and we could not get the 5 metre separation required by the building regs.  There is a surface water drain in the road outside the plot but it's very deep which will make connecting to it prohibitively expensive. Just another detail to sort out that we would rather have handled before we started. Still no ones hurt so it's not serious...   An 8 ton digger is scheduled for delivery first thing Monday and site setting out scheduled for Tuesday faternoon. Lots of lorries for waste and MOT.  With the raft components being delivered the following Monday it's going to be a busy week. Hopefully we'll find no bodies on the site...      

Simon R

Simon R