Sunday, September 30, 2012

Aluminium raised seam roofing goes on

30 Sept 2012: [Extension] I'm lucky to have Henry on Sunday for another half a day, because we both had to go elsewhere at lunchtime, but that helped us to work faster as we had a deadline to work to. We've managed to run out of all materials, no more roofing felt left, and all aluminium used up! The roof is now watertight without needing a tarpaulin. 
At the start of the day, the extension is felted at the east and west walls and across the roof. The scaffolding above will be needed for the amendment to the Surya Sunbox.This is the view of the house for the walkers passing the house. It is a 'stealth extension' !
Time to get started with cutting. The first sheet takes the longest time - we are nervous about it, and you always have to think of the first one as the 'research' workpiece. We had our cardboard template that was near enough perfect - only the smallest mods were required. We have cut both sides of the sheet according to the template. The blue colour is the protective plastic covering the metal. The 0.7mm sheet is easy to cut with a power tool, and is also very easy to cut with a hand tool. 
Now getting ready to FOLD. We have bent test pieces, but this is the real thing. It's time to feel how stiff it will be, and whether we get a nice sharp corner. The sheet has to be clamped along its entire length.First fold 'Male' went well, so now the second and larger fold has also been done. This is the 'Female' side and the final welt will be done when the tray is set into its place between the angles. We are using a much stouter piece of plywood for the hard edge, and one can put one's knee on the ply, so that the grip is very firm - and use a rubber mallet to beat the metal into place.
Henry carries the first aluminium tray to the scaffolding to fit into its place. It was a windy day, so gloves are advisable in case the sheet is blown in a gust.It fits! the tray is a perfect fit, with enough space for thermal expansion from summer to winter thermal difference. It won't get massively hot in summer because it is reflective, and most of it will be covered with the solar panels. 
The remaining metal trays are produced with great speed now that we have established a good working method.The abutment fold is also done, and there is enough sheet left to make a small securing tab to maintain the tray shape. This might well be riveted when it is finalised.
Henry is considering the welting process. We found the 'male' part to be up too high above the angle top by about 5mm, so we had to decide whether to cut it back or beat it down…. beating won.The three main trays are in place, and it's now time to make the end panels for the verges. There is only enough aluminium to make one, so we make the east end, and I will order another sheet for the west end.
Henry works his way up the seam, beating the up-facing edge to the left and downwards so that the seam angle is well gripped.The rubber mallet is about 37 years old, still doing a good job. I've hand-built a house extension to every house I have lived in (in Nottingham), and this is the latest in the line.
We are using 1metre wide sheets, so the seam spacing is precisely 900mm. 100mm is the sum total of the male and female parts of the welting detail. The three middle trays are 895mm wide, so there is a comfortable fit. The extension is exactly 3600mm long, so the end trays are 450mm each.It's nearly lunchtime so it's time to go, but the extension is now well weatherproofed. the little white pipe in the distant panel is actually a conduit into the room below so that we can draw a cable through from the loft. We intend to have a 12v lighting system.
Another task is to build the vertical duct that comes from the loft down to the extension roof. Its a lot easier to build this with all the scaffolding up, instead of having to climb a ladder. The metal hook has been there for a while, it was put up to give me a safety point for when I go up the ladder. Two 22mm holes are now drilled. They are diagonally related, as a horizontal pipe run in the loft has to convert to a vertical pipe run in the duct. I started drilling a hole next to the first, then remembered the need to 'mitre' the joint.
At Sunday sunset, it's looking good. The scaffolding and garden can be tidied of scrap wood, tools, tarpaulins, bits of insulation etc.
Some people have asked for a drawing of the raised seam.... here it is!


  1. Hi David,

    Are you thinking along the lines of a DC microgrid (or in your case femtogrid!) running a 12V system. I have been looking into this as an alternative model for solar PV - i.e. forget the whole inverted AC and (soon to be irrelevant) FiT malarkey and run a system which powers suitable appliances/circuits with the native DC current from the array.

    As ever, it's the US that seems to be leading the way with a few products available:

    With PV module prices the way they are and being able to remove the cost of the inverter, it's becoming a viable, albeit DIY proposition, with the scouring of Maplin catalogues for now.

    1. Hi Matt (which country are you writing from?), the first electricity in buildings was DC, and Edison believed in it so much that he invented the Electric Chair as a means of demonstrating how dangerous AC was (and still is). The problem was power loss over distance. The first buildings with electricity (in Wall St) used DC and had to have either their own power plant, or be within a few metres of one that might serve a number of buildings. Westinghouse demonstrated that AC could work over long distances, so he won the battle, but is not as famous. I've left a conduit in the roof so that I can bring a DC line down from the future battery, giving me the option for DC lighting. I don't really intend to have power appliances with it, battery or boat style.

    2. I cant find DC lighting in Maplin's website, except things like disco or entertainment lighting. Clearly I need to do more research!

    3. Hi, Im doing some research into 12v lighting, there seem to be companies which supply for Motorhomes and Marine, and with a bit of luck I'll find out what is needed.

  2. Great tips. very well-written, keyword-oriented and incredibly useful. its really interesting to many readers. I really appreciate this, thanks

    1. Thanks for your kind comment. I have added a new drawing to the bottom of the posting, a detail of the aluminium folding welt and rivet over the alloy angle.

  3. I havent any word to appreciate this post.....Really i am impressed from this post....the person who create this post it was a great human..thanks for shared this with us. Click here for steel roofing sheets


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