This twenty sixth entry was published originally by JSHarris on the 10th January 2014 and received 1,386 views on the closed forum
The bad weather over the past few weeks has delayed getting the last of the solar panels up, which in turn delayed getting the scaffolding down, which then meant we couldn’t get the full skip off site (as the scaffold was in the way). One thing I’ve learned with this building lark is that there are dependencies all over the place, so one small problem can end up costing money in other areas and lead to delays in getting other work done.
Anyway, now that the scaffold is almost all down, it’s time for a photo.
The PV system in the roof looks pretty good, and is a good match to the colour of the IkoSlates. There’s a little bit of shading over the edges of a couple of panels with the low angle of the sun at this time of the year, but hopefully not enough to cause any appreciable loss in output.
Having worked through the final SAP calculations, I had a dig around to see if there was any way out of paying a consultant to do the as-built EPC. Regretfully there isn’t, the government have stitched things up so that, even if you’ve done all the work yourself, done your own SAP calculations etc, you STILL have to pay someone who’s never seen your house to repeat these calcs and lodge the certificate with the government body responsible. In the end, I found an assessor who took the SAP calculation file I’d created, checked them against the raw data I provided, printed off an EPC for us and lodged it with the government, for a fee of £100. The good news is that we significantly exceeded our design energy rating that I submitted as a PEA for building regs approval. We ended up with an energy rating of 107, off the top of Band A in effect (a zero energy house should score 100, I think), and a CO2 rating of -0.9 tonnes per year. So, we should be a net energy exporter over the year and hence a net CO2 absorber.
The one daft thing that the EPC has thrown up is that the SAP process is unfit for purpose when it comes to assessing the performance of low energy homes. For example our certificate suggests we could improve our energy rating from A107 to A109 by fitting a solar thermal system, at a cost of between £4,000 and £6,000 and save ourselves £195 over three years. The flawed logic that investing around £5,000 in order to save around £65 a year (which wouldn’t be a real saving anyway, as SAP takes no account of the PV system being used to heat the water) seems to have passed the BRE by when they came up with the assessment method. Even if we weren’t using the PV system to heat the DHW, then the payback time for investing in such a system would be around 77 years, even if it didn’t ever breakdown or need replacement. Barking mad……………..
We’ve had a few visitors to the site over the past few weeks, too, some from this forum, a couple of architects who’ve dropped in to see what we’re doing, as well as a few of the neighbours. The house seems to have caused a bit of a stir in some quarters, as word spreads that there’s something a bit unusual being built in this little corner of Wiltshire. Even the BCO has commented that the house energy performance is “impressive, to say the least”. I suspect we may well have the lowest energy house in the county; as far as I know there’s only one other passive house in the county.
We now have the plasterers in and they’ve just about finished putting the plasterboard up everywhere. This has, for the first time, given us a real idea of how the rooms look. Overall we’re pretty pleased with the room sizes, particularly the bedrooms, with their 4m high vaulted ceilings. The bathrooms are, as we expected, pretty dark, as we couldn’t fit any outside windows. However, I’m sure that, once we get the lighting in then they’ll be fine. The worst job I’ve done so far was just before the plasterers arrived, stuffing 200mm of insulation into the ceiling space to reduce noise transmission to the bedrooms above.
This was a truly evil task, as I ended up with my hair and beard full of rockwool fibres and dust.
I’ve also been following the plasterers around and stuffing 100mm rockwool in all the internal wall cavities, again to reduce noise transmission between rooms.
As the services room comes off the second bedroom, I’m going to line the walls of that with acoustic foam, I think, to absorb any hum from the MVHR unit.
I did make some last-minute changes to the house wiring before the plasterboard went on, by running Cat 5E cable around to all areas where it might be useful and bringing it all back to a panel in the room where the router will be. I was going to rely on wifi to get data around the house, but following a debate on the forum here I decided that adding some network cabling might be better. We have a big multi purpose wall plate that sits behind where the TV and audio system will go, and this had a spare module that I could fit an ethernet port in, so now we have a single wall plate that delivers 4 power outlets, 2 satellite outlets, a DAB aerial outlet, an FM aerial outlet, a TV aerial outlet, a telephone point, three speaker connections (that feed speaker sockets around the room) and an ethernet port. This makes for a neat solution on the wall, and gets rid of a lot of trailing cables, but it is a bit busy in the box behind it, with a mass of different cables.
One mistake made right at the start of the build came to light over the past week or so. I’d already had to correct the temporary access drive level by hiring a mini-digger and taking out about 1/2m of excess crushed concrete right at the entrance, as the initial groundworkers had left the gradient at far too steep a level. They were in a rush to get off the site and do another job and I made the mistake of not checking before they moved their plant off site. The gradient is still way out, but with all the heavy rain we’ve discovered that the “topsoil” left for our garden is really just clay subsoil and needs to be stripped back by a foot or so. I’m keen to get the finished drive in as soon as possible, as now the inside of the house is being fitted out a lot of muck is being tracked in. This has meant getting another ground works company in to strip back the site, put in the big soakaway crates under the drive, get the drive levels right and no doubt a fair bit more muckaway costs at £185 a load. With hindsight I should have included this work in the initial ground works contract, and should have kept a closer eye on the levels and soil that was being left on site. At a guess we’ll have wasted a couple of thousand pounds from this error, as the cost of this extra work would have been about that much lower if we’d had the work done whilst all the heavy kit was still on site. This might be a worthwhile lesson for those reading this and looking to do a self-build – make sure you get all of the heavy digging work needed done in one hit, as there is a fair bit of cost in mobilising kit and getting guys started on a job, making it expensive to get them back for more work.
Still, the good news is that I’ve found a chap who’s local and can get his digger in the Monday after the plasterers finish, so at least we won’t have to delay getting the other trades in. He’s not that cheap, but is VAT registered, so at least what we pay him will be zero rated, and around half his bill is materials (pipework, drainage crates, teram, drive sub-base etc). Most of the other tradesmen we’ve been using have not been VAT registered, which means I’ve had to buy all the materials needed, pay the VAT and claim it back at the end of the build. This does have an effect on cash flow, as we are lending the VAT man thousands of pounds as an interest-free loan that comes out of our build budget. In some cases (like this one) using a VAT registered firm that is slightly more costly gives the benefit of a lower overall immediate expenditure, as we’re finding as we get closer to the end of the build that cash flow is more important than absolute cost. This extra work won’t cause a significant problem (apart from the extra cost) as we have a week of plaster drying time anyway, plus the electrician can still do second fix whilst the extra groundworks are going on, as he and I only need pedestrian access to one or other of the doors.
I’ll take some more interior photos next week and edit this entry to include them. With all the work that’s been going on I’ve not had time to take as many photos as I would have wished.
ProDave 19 Jan 2014 01:58 PM :
Excellent progress. Looking very nice, I like the feature window above the front door.
Your site is a complete contrast to ours. you are having to remove excess soil with all the muck away charges, whereas all our ground will be made up to a higher level, so we shouldn’t have muck away to pay for.
And yes the groundwork can be a puzzle to get it all done in the right order. One I’m already thinking about on our site so things get done right first time and no re digging up the same spot again and again.
I’m just preparing a temporary site access to my plot, but to avoid removing and re doing things, even my temporary access will be formed with MOT type 1 so it does not have to be dug out and replaced later on.
oz07 19 Jan 2014 03:24 PM :
Looking good Jeremy.
Those epc calcs are nonesense. A lot of the time the payback periods are twenty years plus!
Dave, forget that, use the bigger stuff for your bottom layer if you have dodgy ground underneath or big levels to build up on the drive. And the proper fabric n all. I found out the hard way!
jsharris 19 Jan 2014 03:36 PM :
I’d second not going for MOT 1 on the access. We put down crushed concrete over heavy duty teram, and the big stuff has stayed put even with some pretty heavy trucks going over it. MOT 1 would have rutted up and sunk into the underlying ground. The other advantage of all the crushed concrete (which is way too deep in places) is that it drains well. I remember having a drive sub-base laid with compacted MOT 1 years ago, some weeks before the final surface was laid, and it didn’t drain very well.
So far I think we’ve taken away something like 480 tonnes from the site, and may need to take away something like another 50 tonnes to get the levels right.
ProDave 19 Jan 2014 03:56 PM :
I’ve started a thread to discuss my driveway base as this isn’t really the place.
coopers 19 Jan 2014 06:46 PM :
Looks good, Jeremy. I think I’m sold on the Ikoslates.
Sorry to hear about your groundworks issues. I dread to think how ours will go, with this clay and high water table.
What are you doing about drying out the plaster, with the airtightness?
Nickfromwales 19 Jan 2014 07:00 PM :
House looks great, and mikes looking proud up top. 🙂
jsharris 19 Jan 2014 07:39 PM :
Suzanne, the plan is to leave the first floor windows open and held on the safety catches to dry the plaster out. If that doesn’t do the job, then I have a portable air conditioning unit that has a dehumidify setting. If I end up using that, then I’ll raise it up to the first floor and connect a pipe to the water drain so that it can extract as much water as possible before shutting down when the tank fills up.
The ground works problem is solely down to my lack of experience. Had I realised that I needed to be more hands-on with checks on levels, and that it was vital that we put the soakaways in early, then this problem wouldn’t have arisen. All just part of the steep self-build learning curve……………..
Nick, everyone now seems to notice Mike the Guardian Dragon, as he really stands out now the scaffold is down. It’s been suggested by a couple of the neighbours that we incorporate him in the name of the house, but, as he’s not red and my connection to your part of the world only extends to having spent many years crawling around underneath it (and learning enough Welsh to know when we were being talked about by locals in the pub) , I suspect that, if we do choose a dragon related name it will be Gaelic rather than Celtic.
coopers 19 Jan 2014 07:52 PM :
also, what are the alternatives to rockwool for the internal walls? is rockwool the best value for money?
jsharris 19 Jan 2014 09:19 PM :
Rockwool is cheap, which is why I used it. It’s not as effective as the acoustic insulation products, but is 1/3rd the price so it’s easier to use more of it. As we’re putting a 2.5mm to 3mm plaster skin on top of 12.5mm plasterboard I felt that 100mm rockwool completely filling the walls (rather than use 50mm acoustic bats) would be fine. For the ceilings I opted to put double the thickness normally used in, in the hope that this will give adequate sound absorption.
There’s only the two of us, so noise insulation isn’t that critical.
coopers 19 Jan 2014 09:39 PM :
thanks Jeremy. All these decisions to make …. I just had a bit of a wobble looking at the 2nd draft of our current plans. That awful sinking feeling that everything is in the wrong place.. arggh. Then you have to go back to the beginning to remind yourself why things are as they are. Sigh.
rickwales 19 Jan 2014 09:45 PM :
Looking great, cant wait to see the finished pictures.
jsharris 19 Jan 2014 10:05 PM :
Make a model, Suzanne, at around 1:50 scale, using 5mm foamboard. It will help a lot in getting a feel for the spaces and how they will work. I made 5 or 6 models before finalising our house design, with the final one sitting on our dining table and being stared at every day over breakfast (I find I’m far more likely to be critical over breakfast than at any other time of the day!)
My models had lift off roof and first floor sections, so the internal spaces could be looked at closely. I also bought some cheap 1:50 scale plastic model people, to get a better idea of scale inside the rooms.
wmacleod 20 Jan 2014 10:47 AM :
The roof is a thing of beauty Jeremy, by far the neatest and best thought out solar installation I have seen, I can see planners pointing to that as an example of how it should be done and not just a set of panels plonked on afterwards. Well done!
joiner 20 Jan 2014 01:23 PM :
Now breathe out!
jsharris 20 Jan 2014 02:42 PM :
Thanks, we’re really pleased that the panels and roof came together as well as it has. It did take a bit of faffing about to get everything just as we wanted it in terms of design and colour matching, and for some reason panels with black anodised frames are slightly more expensive than silver ones, but overall it’s turned out well, I think.
Taking away the cost of the slates we’d have had underneath, the 6.25 kWp in roof installation will have cost around £8k, so probably around £1k or so more than an on-roof install of this size, I think. Worth paying the extra, though, just to get the neater look.
coopers 20 Jan 2014 04:54 PM :
Hi J thank you, re the model building, yes we probably will do that before submitting for planning, although we think we have the room proportions just about perfect. One of the struggles is with the orientation on the plot and position of garage etc. Then today my dad mentioned upside-down house, which got me thinking again (see new post!!)…head in hands !!!
ProDave 20 Jan 2014 09:51 PM :
Just a thought.
your solar PV roof looks fantastic.
What will you do though if in 5 years time, a panel gets damaged?
I would almost guarantee in 5 years, you will not be able to get an exact replacement. and a different panel would spoil it.
Personally I would look at buying two spare panels now, and storing them carefully. Just in case.
21 Jan 2014 09:32 AM
“Personally I would look at buying two spare panels now, and storing them carefully. Just in case.”
Good plan – get them vat free now too. I guess that goes for any other spares you think you might need ?
21 Jan 2014 09:44 AM
Thanks for the update and photos. The house is looking great. Love the timber cladding, we’re hoping to do something similar. Can’t wait for our visit in Feb!
coopers 21 Jan 2014 06:42 PM :
I’ve started drafting the Design and Access statement , and want to put in info re the building’s “Eco” credentials, but want to get all my facts and figures right. The MBC website a bit confusing.
I know you are really busy, but can you help at all with the wording? Maybe you already have something you’ve written that I could copy? I would be really grateful.