Sunday, 31 March 2013

A good roof overhead ~ part 9 ~ finishing touches

The tiles were on, the flashing was complete, but there was still more to do - a lot more!

The first job that had to be tackled was to get all the weatherboards back in place to make the house weather-tight so that work could begin on the top coat of house paint.  Some weatherboards had been removed so that flashing could be fitted underneath them, and as the level and contours of the roof are now slightly different they had to be custom-fitted to match.  It was yet one more aspect of the project that required skill and finesse, and when I saw John and builder Andrew McCurdy setting to work on it I plucked up my camera and hurried over to catch the action:


The image below shows the new flashing all ready for the replacement boards which would fit down over the vertical sections of stainless steel.  The rolled curve of the ridges presented the challenge of how to fit the boards over them without leaving a shiny portion exposed, which I could see looked wrong.  The image above shows John and Andrew experimenting with a short section of weatherboard which neither of them found satisfactory...


They decided to shape a board which fitted right across the back of that wall.  You can see it amongst the jumble of stuff in the photo below.  Where?  At the lower right hand corner of the image you can see the thick end of it.  It's up-side-down.


Below you may be able to see more clearly where that weatherboard has to go: behind the chimney and across the width of that wall, sitting across the top of two curved humps which are the ends of stainless steel ridging:


There it is: John admires the fit! 


Fitting weatherboards is a skill which requires careful consideration and good spatial judgement.  John and Andrew took their time getting those boards to sit just right:




Here is a closer look at part of the detail:


And here you can see it from the other end once the other boards were fixed in place above it.  The thinner bit in the middle of the one mentioned above is hardly visible but believe me, it is essential - it looked all wrong without it!  Why does it make such a difference?  It just does!


I was careful to keep out of the way!  However the two of them were happy in their work and Andrew took time to share a joke: he suggested I post a photo of the jigsaw - as shown below - inviting readers to see if they could spot what was wrong with it.  It seemed that my response was a little too hilarious as John told me with mock severity that "That's enough of all that!"


The blade is in upside down!  John had been puzzled that it had hardly seemed to cut at all.  Oh well, in amongst all the beautifully hand-crafted work even the experts have their moments!

When we went down for morning tea I commented on Andrew's ear plugs.  Up on the roof he had been wearing ear muffs, but he had been wearing these underneath:


These ear plugs were custom made by an audiologist: they are made of silicon and have tiny noise filters in them.  Andrew wears them all the time when on building jobs as they provide excellent hearing protection reducing sound by about 26 decibels while still allowing normal conversation.  I asked him if he could hear the birds, which he said he could.  I've written an article about them here:

The new tiles took all the foot traffic well: John, Andrew and Mike the painter, all did a great deal of (careful) walking around on them and only one of them cracked - and needed to be replaced.  Andrew remarked that if it has been corrugated iron it would have had dents all over it.

Andrew needed to get away to another project but stayed a little longer to help replace the one remaining section of roofing.  Old houses that have been added to and altered over the years can contain a multitude of different segments each of which may require individual treatment.  This has certainly been the case with this project, and this section of roof was just one more bit to be dealt with.  It had originally sheltered an entranceway.  It might be small but it was certainly awkward.

Andrew and John decided that the easiest way to tackle it would be to mount tiles directly onto a single sheet of ply - with butynol between the two surfaces.  Here you can see how it started out:


I didn't like to think too much about the weight of the finished slab as that quality of ply is heavy and it had to be hoisted into position.  Here it is snugly in place - looking as if it has always been there:


There was still plenty to do, but John could manage the remaining building work by himself.  We were all sorry to see Andrew go.  His building expertise had been first rate and he had been great to have around!  Andrew, take a bow! 

One of the remaining jobs was to re-fit the timber casings,  which cover the corners of the upper level of the house - these are called external box corners.  In the next image you can see in detail how exacting all this work has been!  Everything shown has been completed except the additional zigzag edging of the timber casing, called scribers, which makes the corner of the weatherboards weather-tight.  I have included an image which shows the finished result clearly further down the page:


Here John is getting these casings just the right length and fit:


Doing this sort of work on your own requires a high degree of manual dexterity!


My curiosity was caught by the unusual screws John was using on the weatherboards: each one functions as a screw complete with drill bit!  This greatly reduces the work required as these jobs would otherwise need to be completed separately.  Special serrations make this possible:


John showed me just how easily they worked: the impact driver (a sort of power screwdriver) fitted with a torx (star-headed) driver bit got them in in no time!  He says that these screws never ride out.  However, they can be removed  easily if need be, which gives them an advantage over nails. 


These screws are designed for securing decking timber, with the bare part of the shaft designed to draw the two surface of timber together snugly (and, I am told, also to prevent creaking - I'm not sure how!)  John's weatherboards are the same thickness as usual decking timber, so fit the purpose perfectly. 


Once all the timber-work was complete Mike could water-blast it and the roof prior to getting on with the paint job:


Fortunately the weather held!


He and John worked away busily.  John, who seemed indefatigable, remarked, "I am a painter now!"  Time for a new badge, John!


The shingles over the front door, yet another facet of this old house, were painted a perky red to match the garage door and detail in the window surrounds:


Finally the whole house begins to look as it should, with all the different components coming together harmoniously.  To the casual eye good design and careful craftsmanship simply looks pleasing, but to those who are observant and know more all the careful thought, talent, skill and plain hard work that has gone into making it a success rapidly becomes apparent.  Here all the different angles and materials fit together with a sense of ease:


How well those angles of flashing fit together!


In the image below you can see the carefully fitted corner casing: the angle for each weatherboard has been individually measured and cut to size.  And again, the neatness of the flashing underneath it is barely noticeable. 


Good workmanship is like that: things look and function just as they should and we don't question it; we just know that things are right in a way that makes us feel comfortable.  There is no hint at all of the massive expenditure of energy, and sometimes struggle, that has gone into reaching that point! 


The scaffolding was no longer needed so was cleared and swept prior to removal.  Here it is looking unnaturally tidy.  It had been invaluable.  Just look at that cable - it carries the mains electricity into the house: the number of times it had been carefully stepped over was beyond counting!



Close inspection of the upper level of the house revealed just a few small points that still needed attention:  John's wife removes a spatter of paint from the window...


... And John addressed some small patches of exposed undercoat with an artist's paintbrush:


Perfect!


Downstairs there is still some paintwork that needs to be completed, but the great majority of the work has been done.


That's one beautifully hand-crafted roof.


And the tiles look great!  What started out as the main reason for this big overhaul, the need to replace the basic roofing material, turned into a summer and autumn marathon, but what a success it has been: the new slate-style tiles made of synthetic resin have taken the place of the old and rusting corrugated iron without disturbing the dignity of this old house.  This is the best possible outcome for the refit of an old building: that the new components look as though they have always been there.  However, no one can mistake that the shiny stainless steel flashing is new: it brings it up to date - very handsomely!

Well done John, we are proud of you!


My grateful thanks go to John and his wife for permitting me to document their big project.  Congratulations to you both!

Readers can click through to other articles in this series via these links:

A good roof overhead ~ part 8 ~ site management: all those tools and all that stuff

In the course of any building project the range of tools and materials in use can be mind-boggling.  Here is the sight which greeted me one morning when I climbed up the ladder to an outside landing:


A closer look shows an assortment of tools used on any building job - with the exception of that nice clamping tool with the orange handles that John made especially for working with the steel flashing:


... A saw bench comes in handy!


... And of course there is the timber!  That landing was certainly being used to maximum capacity!


I turned to look down into the garden.  My word, there was stuff everywhere!


Outside the gate a peek into the back of Andrew's ute showed a similar profusion of all manner of things! 


It's all essential, even exciting, to have the right gear for everything, but how to keep track of it and keep it in some kind of order can present more of a conundrum than a question!  Someone has to keep a semblance of order, but with the amount of hard physical labour expended daily it's a big additional effort for a builder to do this at the end of a long day - and it's time-consuming.

During this project that special someone has been John's wife!  She has been the person who has kept track of things, kept John and Andrew fuelled with sustaining food and drink, and at the end of each day has been there to help clear up and take stock of things.  

In the photo below you can see her helping to clear up after John had put in a twelve hour day.  Andrew had bailed out at about 7.30, while John worked on for another hour.  Work that day had been back-breaking hard-out physical slog and an astonishing amount had been achieved - but there was still the clearing up to be done at the end of it:


She made sure that in the mornings all the gear was lined up ready for action.  Each one of the tools you can see below needed to be easily to hand with their battery packs charged up.  Both John and Andrew needed to have their own tools to work with so it was fortunate that they both used the same brand!  John aimed to have six spare battery packs to hand at any one time to rotate as needed. 


Then there were the thousands of screws of many different types all to be kept in order, as well as the protective gear, which is so easily put down and mislaid:


Waste materials needed to be sorted for disposal.


The stainless steel could be recycled by scrap metal dealers, or stored for some possible future use...


 ... The old sheets of corrugated iron needed to be stacked where it wouldn't be tripped over:


Fortunately even this was of value to someone:


Being the wife of the main man when he is working on your own home is demanding: there have been times when contractors haven't done things to satisfaction, as with the original roofers, which required decisive and not always pleasant communication; there have been mishaps, as when Someone put their foot through the kitchen ceiling dislodging a sheet of gib-board and sending a thick load of the most frightful detritus several decades in the making down onto the kitchen bench; and even the most popular of visitors have called at awkward moments.  Food needed to be organised constantly, and a steady hand kept on the pulse of things: expenses, the range of options at any given point - sometimes a source of disagreement, and the support of the man himself.  On top of this, workers of one kind and another have often been about, and action around the place has been constant making it difficult to settle to any other activity.  

It has been quite a time.  John, you are a fortunate man: she has backed you all the way, and my admiration and respect goes to you both! 


A good roof overhead ~ part 7 ~ solar panels are in!

ELECTRICAL PRINCIPLES CLARIFIED BY AN ELECTRICAL ENGINEER 
~ 10TH APRIL 2013 ~

As at the date of publication the solar panels are in place on the roof but have yet to be hooked up electrically.  They look great!  Most of them, 40 in total, are installed in the top roof.  The others have been fitted in a lower section of roof. 

These panels have been manufactured as integral tiling components - quite a step forward from fitting them on brackets as separate gear. 

It must be acknowledged however, that at this latitude the angle of the roof is not ideal for maximizing the suns energy as it is a long way south and the angle at which the sun strikes the panels is relatively oblique.  There is an advantage in being able to choose the angle at which the panels are set. 

Both solutions have advantages and disadvantages. 

In the photograph below John is fitting the final two lengths of ridge flashing:


The tiles and matching solar panels were manufactured by Fangxing Roofing.  You can find out more about them here:
Details of their photovoltaic solar units can be found here:
I propped one of the solar tiles against the balcony railing to photograph it. 


The following data is from their site as linked to above:
Overall size: 410mm x 940
Effective size: 350mm x 900
Thickness: 13mm
Weight: 6.0 kilos

Each Duer Solar Slate with standard power of 30 watts contains 12 pieces of monocrystalline silicon solar cells. 


I am interested in solar power for the independence it can give from services delivered by large networks, as well as the reduction of dependence on what I think of as dirty energy sources.  Although most electricity generated in New Zealand comes from hydroelectric power stations it still utilizes natural resources, rivers and lakes which may have sensitive ecologies, and would otherwise be quite different environments; and the power still has to be conveyed from one place to another requiring vast lengths of wiring, lamp posts and associated materials.  If sunshine can be put to work, for goodness sake, lets use it!

Solar generated electricity is clearly an excellent innovation but how does it work?  
I must say I found most descriptions rather over my head, and like anything else a few building blocks of basic information went a long way.  I share here what I've gleaned:

The best website I've found is this one:
To grasp of how solar panels work a simple ABC of electrical principles is not only helpful but essential, so if this is of interest you might like to start of here:
  • Electricity basics: on this page you will find explanations of what power is, definitions of volts, amps and watts, the difference between DC (Direct Current) and AC (Alternating current), and, importantly, how solar electric cells generate electricity - excellent!
My attempt at interpreting that content turned out to be somewhat flawed, and I was pleased to be set straight by my friend Simon Dalley, who is an electrical engineer.  My introduction here describing John's solar panels sets the scene:
The components within the solar panels where the energy is generated are referred to as photovoltaic or PV cells.  The manufacturer of John's panels refers to them with the more specific technical term: monocrystalline silicon solar cells.  If you look at the photograph above of one of John's panels you can see the 12 solar cells it contains.  These cells are energised by daylight, preferably sunlight, which sets off an electrical reaction within the units.  Okay so far.  Our electrical engineer takes up the explanation here:
This reaction converts light energy to electrical energy - electrons, instead of being stationary in the circuit to which the cell is connected, are driven round it and can perform useful work. Each PV cell produces about half a "volt" of electrical voltage (tension or pressure), and about three (guesstimate) amps of electric "current" (flow) when the sun is shining on it. The amount of "power" (rate at which it can do useful work, measured in watts) from each cell is its volts times its amps, in this case 0.5 x 3 = 1.5 watts.
Cells can be connected in "series", like a string of Christmas lights, ("+" of one cell to "-" of the next), in which case the voltages (tensions) add together. You can think of it like a whole team lined up on the rope in a tug-of-war; each individual player's tension adds to the total. In the case of the Solar Slate, its twelve cells are connected in series like this and give a total voltage of 12 x 0.5V = 6 volts. The current from this string, since there is only one path going via all the cells, is still 3 amps. The overall power is the overall voltage times the overall current: 6 x 3 = 18 watts; you will note that this is also the sum of the generated powers of each of the twelve cells: 12 cells x 1.5 watts = 18 watts total.
Cells, or series-connected strings of cells as in each tile, can also be connected in "parallel", all the "+" terminals connected together and all the "-" terminals connected together. Imagine 12 taps into a trough running at the same time. Each cell (or string) is like a water tap creating its own flow. In this case, the individual currents (flows) add together, but the voltage (pressure) is still that of each individual tap. Again, the total power is the sum of the individual powers, and also, the overall current times the overall voltage.

The inverter is rated for a certain input voltage, e.g. 48 V. The tiles are connected in whatever combination of series and parallel that will supply this voltage, e.g. several strings of 8 series 6V tiles are then connected in parallel.
A more detailed article giving an overview of solar power technology can be found via the link below.  When I looked at the content on this page I was heartily glad I had read about the theory of solar electricity as outlined in 'Electricity basics' linked to above, and didn't need to plough through this much more detailed content:

Of course there is more to it than that.  Their library page outlines coverage: 
These clips looked useful too:
There were a few points that I continued to find difficult however, one of which was the difference between wiring panels in series or in parallel: why would solar panels linked into groups (described as 'in series') provide more voltage than the same number of panels wired independently of each other (described as 'in parallel')?  The answer is that they all provide the same amount of power, but grouping them together ...  Here I hand over to our electrical engineer once more: 
A simile that could be used is this: imagine each cell as a machine that pumps golf balls (electrons) up to a height of 0.5 metres (volts) and then emits them from a spout. The golf balls run down a channel (circuit), achieving useful work on the way, maybe turning a paddle wheel or something, and back into a bin at the bottom of the machine, from where they get pumped up again. 3 golf balls are emitted per second, representing a flow of 3 amps.
Connecting in series is like having 12 machines stacked up to a height of 6 metres, receiving golf balls each from the one below or, for the bottom one, the return chute. Same current (number of balls per second) but height is multiplied by 12.
Connecting is parallel is like having 12 machines side by side, each adding their balls to a (larger) channel which is now taking a flow of 36 balls per second. But they're still only going up to a height of half a metre (0.5 volts).
When the sun is dimmed by clouds, the number of golf balls per second decreases.
Re-stating this in basic electrical terms, amps are a measure of the electrical current, and voltage is the force with which they move about, so, in relation to the wiring of solar panels...
  • In series, the voltage (force) is multiplied by the number of panels
  • In parallel, the amperage (current) is multiplied by the number of panels and the voltage remains the same.  
Applying the principle of 'in series' wiring to John's solar panels each of which has an output (force) of 6 volts, when these panels are wired up into groups of 8, the output from each group could be as much as 48 volts - when sunshine is producing a maximum effect. 
This video helped me gain this understanding:  (Do overlook the use of a weird synthetic voice at the beginning - it's very brief!)


Okay, so once the wiring of the panels is all hooked up in series, what are they hooked up to?  If general household usage is the goal the wires will plug into a device called an inverter, which converts the electricity generated from one form to another:  This is necessary because solar panels, like batteries, generate electricity in the form of what's called a Direct Current, usually referred to as DC.  Household electricity is provided from the 'mains' power supply in the form of an Alternating Current, usually referred to as AC, so the Direct Current from the solar panels needs to be converted to an Alternating Current.  The inverter converts DC to AC.   

I initially found the difference between AC and DC baffling as most explanations describe AC as going 'backwards and forwards'.  This diagram from Wikipedia article on Alternating Current was helpful.  The vertical axis shows current or voltage, and the horizontal axis time:

Diagram courtesy of Wikipedia, thank you.

Our electrical engineer explains about the backwards and forwards movement of AC:
AC really does move backwards and forwards, and not basically forward. This motion is represented by the sine wave in the diagram, whose negative (backward) half cycle is equal and opposite to its forward one.  Why?  Because that just turns out to be the easiest form of electricity to generate with a rotating machine, which is what all mechanical generators consist of.  You might recall from trig that a point on a rotating wheel describes a sine wave with its x or y displacement: x = r cos (t) and y = r sin (t) where t is time and r is the radius of the wheel. Mains electricity is AC of course, and pulses backward/forward at a rate (frequency) of 50 cycles per second (Hertz).
(I never did get competent at trigonometry!)

Why do we use AC rather than DC?  The best explanation I could find was in Wikipedia's article about the historic struggle that went on between inventors and those whose businesses depended on them:
As things stand in the modern world, both AC and DC have their advantages and disadvantages
Again our electrical engineer clarifies the overview:
The AC has the great advantage of being able to be "stepped up" or "stepped down" in voltage by a transformer. Converting this to DC is extra hassle and DC also doesn't work in a transformer.  But DC at a high voltage is unbeatable for sending large amounts of electricity efficiently over long distances, as in New Zealand's HVDC inter-island link.

Batteries and solar cells, on the other hand, intrinsically generate DC. An "inverter" is required to convert this to AC at a voltage and frequency suitable for normal home appliances.
Very many thanks to Simon, my obliging and patient advisor!

Back to the story of our neighbours' roof: 
The solar panels were installed as planned but an unexpected shortage of the larger tiles needed to fit alongside the solar panels led to a lengthy hiatus while more were ordered from China.  Even though airfreighted there was a further lengthy delay when the pack reached New Zealand Customs; they held onto the tiles for far longer than could be considered necessary or reasonable, but eventually they arrived.  The photograph below shows the top roof completed apart from the one edge and its ridging:


Before the last of the tiles were put in place John had the job of fishing out the cables belonging to the panels, which he did with a long pole with a hook on it.  There were some tense moments as it is a very confined space but all were located and brought to a point where they could be worked on inside the house!


Once the remaining large tiles and the last lengths of ridging were screwed into place the roof looked splendid.  Looking at the tiles on these neighbouring slopes side by side, you can see how much larger the solar panels and their adjacent tiles are from those on the other side of the ridging. 


That photograph was taken at sunrise which is why the background is in sunlight and the roof still in shade.

Before work could begin in the lower sections of roof the scaffolding which had been providing access to the top level had to be taken down.  John had one last job to do up top, which was to clean the roof.  He explained that the drilling of holes in the ridging for the necessary screws generated small fragments of steel and butynol underlay which needed to be carefully removed.  It was a delightful sight however, and I feel sure that this photograph is one of a kind: not many people vacuum their roofs so this one is doubly historic!


The remaining tiles were fitted into the lower roof, which you can see below:


Once the solar panels were installed in the roof the job of hooking them up and putting them to work was set to one side: one can only do so much at a time. 

However, interim testing was carried out.  An electrician paired up and tested all the leads.  Here they are hanging down through the hole made in the ceiling to gain access:


A selection of plugs designed for the hook-up had been tipped out on the nearby bed - not your average bed-time toys.  Note the beautiful old light bulb at the top, which John produced for testing:


Let there be light!  The light bulb sprang into action: 


That light bulb is an electrical curiosity: made by Philips in Holland, date unknown, it carries 82.4 volts / 6.6 amps, an oddball amount.  Other packaging information states 10,000 LUM. (presumably lumens), E40 Street Seriel.  Hmm.  The screw fitting is unusually large.  

I'm aware that there will be those who find my interest in this sort of thing baffling.  In response I must say, with feeling, that mostly we don't look at things properly.  Once you learn to do so life can never be dull - there is so much to notice; also, Dad was an electrician, so I have at least a cursory knowledge of these sorts of things.  It is beautiful.  If you doubt me, find another that has been as pleasingly crafted.

[Note: I've removed from this section the photograph of the kettle and the related paragraph as it proved to be inaccurate and unhelpful!]

Before the solar generated electricity can be put to use further gadgetry will have to be installed.  This has to wait as more work needs to be done to complete the exterior of the house before the winter weather closes in. 

The final chapter about the solar panels will have to come later: the story of how well they will function in relation to household usage and how much solar generated electricity will contribute to saving on the cost of power provided by the local supplier.  

In the meantime, those readers who are interested in learning more about both the theoretical and practical aspects of solar panels may find this video useful.  I learnt a lot from it.