Gus Potter

In the grand scheme of things a difference of 2.0k is neither here nor there when you consider maintenance, replacement cost with a system that might not be compatible with your roof makeup and the fundamental design choice of ground or roof mounted. The way we mount solar panles on roof has changes a lot just in the last few years so expect this to continue. There is discussion around net zero and we can see good farmland getting build over. Ask, why are we not covering industrial buildings in PV right next to the point of demand.. it's down to cost and ongoing maintenance. So for self builders if you have space then just follow the ground mounted route.

To add a bit. The framework for ground mounted solar panels is often galvanised steel cee sections, similar to what you seen on motorway barriers. These are designed to last about 25 years, if in the country you just need a local fencing contractor to knock these into the ground for you. They are used to getting fences straight so not a challenge in this respect.

Ok let's say you have a big plot and in that case I would say if you want to get there, don't start from here! Consider a ground mounted system even if to rule out. There are significant advantages of ground mounted. You can optimise the orientation of the panels. In the years to come as they start to fail you can replace easily in stages from ground level. If you need a soakaway for say your sewage plant then put that under the solar field if possible as the panels will restrict plant growth that could clog the soak away. Every time you add something to a roof it requires flashings and details.. all that is extra maintenence and cost. Think forever home and resale value if you need to move out. Well from my experience they used to be. When I worked as a designer for a cold formed steel shed business ( the biggest by far in the UK, we did at least 700 to 800 sheds a year) the feed in tarrif was exceptional. The company I worked for sold a deal to farmers whereby their shed came free but they had to agree to put a 40kW solar system on the roof. During that time they were responsible for maintenance and after 25 years they got to keep the lot. It was a great deal but the folk that were supplying the invertors were cowboys and two buildings went on fire and one from memory killed valuable animals inside.. the word got about on say the Farming Forum and the game was a bogey. So yes, there is still a fire risk but why take any risk if you don't need to? Best to keep the invertor and so on outwith the building envelope if you can. For all on BH if you have ground available then use it for a solar field. Think maintenance. Say you have a two story house and someone needs to go up and clear the drainage around the roof and panels and give the panels a wash. Two men half a day = £400 quid plus a cherry picker.. call it £ 800 -1000.00 a visit. But if ground mounted you can give you solar panels a quick wash when you are mowing the grass. Even if you do a quick sum you can see that long term the maintenence is a key issue. If you split the difference you can then maybe buy the best performing panels and best quality currently on the market and still be quids in on ground mounted once you consider the maintenance cost. Like this analogy. @saveasteading I've made some points. Good design is often about ruling things out rather than in as this allows you to focus on the things that you really are going to build. This is where Build Hub excels as it let's members float and discuss their ideas at a really basic concept design stage without any real pressure or getting slagged off and dismissed.

I was talking to a Client about this the other day about the difference between a geodetic survey and a plan survey that we might do on a small site. But @steamy love your post as for high accuracy we need to decide if this is material. Case in point could be if we want to monitor settlement in a sensitive location. For all if you get a professional surveyor in with modern equipment there is a button you press that does all this complicated maths in the software with a bit of manual input on the curent weather conditions.

So if you go over the score and blow the transformer up.. you'll get a bill for it but the chances are no one will get hurt, you won't cut off the old folks home down the road and so on. Incedentally animals are very aware of electircity, that's why cows lie down in a thunderstorm.

Something to look forward to. Just to be pedantic I'm assuming that your neighbour is one of the six houses served by the private treatment works. If that is the case then we can rephrase the question and direct this to the Thames Water. A public sewer is a Thames Water asset, so you need a buildover agreement to build over their infrastructure. If this is one of their assets then they have adopted that including the treatment plant and should be maintaining that at their expense. Ask them if this is a reasonable statement of fact and invite them to confirm. What may be the case is that you have a private agreement with the other home owners to share maintenence and upkeep of the shared private sewage system. You have a duty not to do something that will cost your neighbours extra money if there is a failure of the drainage system, say if your extension is badly built. If you want to build over then its your title deeds to look at and you may require your neighbours consent rather than Thames Water. Now it's a bit late in the day for this so if push comes to shove you may be able to take out for example an indemnity policy or just build it properly so you never have a problem. Now generally if the drain is outwith your founds then it's fairly simple, if within the foot print then you need to take extra care before you get the build underway.

Good approach, let pragmatism prevail and march on!

@Roger440 threads are overlapping you beat me too it!.

There are ten pages to this thread Roger. Can you describe what is upstream of your connection? Don't forget that nothing with the leccy board is transparent and often is driven by some accountant rather than engineering knowledge. In some ways it's worth trying to see it from the leccy boards point and how diversity works at their end. If you can put yourself in their shoes and "see it" the way they do then you'll be in a stronger postition as that will let you get past the admin / accountant and talk to one of their engineers who will probably sort this out in half an hour for you.

Check that you flashings are compatible with the cladding in terms of galvanic corrosion. Get a good innovative and skilled roofer and discuss / walk through how you make them weather tight, you may need a "bespoke solution depending on how " flush" you want things.

Lot's do but I bet your house is level... and you have had the last laugh! You can check a water level the same way as the two peg test. Set it up by pinning it to your datum where you want to start.. go round the corners (laser levels need a line of sight unless you are good at transferring the datum, encourages error) and mark the bottom of the miniscus always. Then un pin and start from where you ended. Mark your starting miniscus, could be 200mm below / above does not matter and go back the other way. If you have no air in the pipe you will get a 200 mm difference as you retrace your steps. The great thing about this is that you can plug the ends and use it as often as you like.

Hi Roger. I've not read the full thread here but can see your dilemma. Maybe if I make a miss step @ProDave will correct me but I'm thinking can we find a pragmatic solution. So say you have a nominal 80 amp DNO supply. To get the min kVa we look at the min voltage supplied by the leccy board. 216.2 volts x 80 amps / 1000 = 17.296 kVa. The maximum would be when the voltage is at it's highest 253 volts. So here we could draw 253.0 * 80 / 1000 = 20.24 kVa. Now as understand the main fuse is not there to protect you, rather it's there to protect the DNO infrastructure. A pal of mine (Electrical Engineer) told me that the incoming cable actually has a short term load capacity of a lot more. For the cable to fail it needs to heat up first.. but is often buiried in soil which keeps it cool. So bearing that in mind we need to look at the type of fuse that the leccy board provide. These tend to be sand fuses and there is a table in BS 7671 that tells us how long a sand fuse takes to fail depending on the load. This table is hard to find mind you. Now from time to time you may draw 80 amps or potentially a lot more if you have short surge.. that is how sand fuses work.. if they blow at the slightest whiff of an over current then the leccy board would be out to houses all the time. The simple way is to install a main breaker on your side that cuts off if you exceed that 80 amp load. Now if you go and research load diversity and apply a bit of common sense when using stuff then I think you'll find that you can work around this and still run all the things you want on an 80 amp supply.

Ah this is a variant of the traditional two peg test we use when we get the level out. Normally I set the level up in the middle of two pegs 25m apart and mark the level. Then move the level 25m outside off one of the pegs and remark. This makes the difference easy to see. But for a lazer level it's often not that bright so you need to do it late or early in the day and work over a shorter distance. Do this a few times each time setting the tripod up again to check if the self leveliing on your lazer level is working ok and not sticky. For abosulte confidence: The water level is fool proof provided you purge all air from the pipe. Sometimes in the past if I turned up and the found was flooded I marked the water levels! Every cloud has a silver lining.

Interesting SE work there. The position and diameter of the service holes are critical. Tidy looking job in the photos, well done!

It looks like what you are intending to do is to create a horizontally spanning wall, hence your placement of the rebar on the outside face as the load is from the inside outwards. I have my doubts as to whether your framework is strong enough for it to work this way. Your column to rafter connection looks iffy and the timber bolted joint between the bracing and rafter will likely not pass a design check. For economic wall design for grain or cattle we often run a cee channel along the top of the wall and this way we convert into a two way spanning wall. But for all that to work we need a decent steel frame and we need to be careful around openings as these interrupt the spanning assumptions. My feeling is that your steel frame is too slender and flexible thus you maybe just want to see if it can resist the wind load and snow load alone and then design the grain / cattle wall to be free standing. If you are willing to install a good thickness of floor slab then you can use that to restrain the vertical cantilever wall.. with a good amount of rebar.

Ok it's a shed, call it agricultural. I used to do the SE calcs that underpinned the software that was used to design these sorts of things. So technically I've had a hand in, as an SE, in thousands of these types of frame, all over the world and not just in the UK. So I know a bit more than many SE's about this. But let's be pragmatic and look at the risk if it falls down. First thing is we don't wan't anyone to get hurt. To reduce the risk we want make sure that folk are not near it or in it when it snows a lot or it is windy. In agricultural design codes we call this the duration an occupancy rating. If it was a chicken shed then you would only be in it say 2 hours a day and there maybe only two folk at the most at any time. Now the other thing we look at is how close to the boundary your shed is. If the roof flies of your shed and hits a house or a car driving along the road that is not good. In the agricutural design codes there is a bit that deals with how close to the road it is. So once we have dealt with the risk you may or may not want to get some insurance. Up to you but some places like yours are next to care homes and schools.. catch my drift. Now once we have satisfied ourselves that we have not done something that is downright dangerous we maybe want to look as how the building moves about. Is is going to move differentially at roof level so much that within a few years the roof cladding fixing start to oval and leak.. then we have wasted out money or if it is just for that we can we live with a bit of a leaky roof? Don't do this unless you design them to be free standing.. it's bloody dangerous other wise. Or you can get an SE to sort this out for you properly.

From my pheasant rearing days a Fenn trap is a satisfying solution. No nonsense, but you must protect it to stop other wildlife from detriment.

Ha ha..this is a hot topic on my books at the moment! story for another day. The secret is in the detailing. Let's go back to traditional leadwork. In any place where you get regular dripping of water then we would go for code 5 lead as a minimum . Your first port of call is to look at the exposure condition, is it sheltered or near the coast with salt in the air. Next is to refer to say Kingspan cladding techincal data for steel coated panels, similar to Greencoat... your cill is just the same. To give you a direct answer in ideal conditions say as a roofing panel away from the sea.. 50 years.. but as a cill maybe not unless it is under shetlered eaves. But will your window last that long?

This is a good conversation as it lets new folk on BH see what can crop up and how you might go about dealing with things. There is I think at least four or more BH members chipping in on this topic, including yourself who do this as a day job. OK. In the round let's take these welds as a case in point. I pointed out why I would not pass them and uploaded a guide to weld inspection so that folk on BH can get a feel for what might be a good or a bad weld. Temp pitches up, no mucking about and says they are crap. I responded by saying let's not panic .. can we be pragmatic and find enough good weld that will do the job. "So far I've not met an SE who didn't concur that my 'bespoke' solutions wouldn't pass with flying colours." And that is an interesting statement. I work from time to time as a checking SE. In a post earlier about William Le Messurier, the wind thingy on tall buildings off the back of what @SteamyTea was saying. One of Wiliams errors was that he was arrogant and self appointed not least, he would broke no dissent as a person and that primarily lead to his downfall. The point here is that SE's especially in this day and age make mistakes. I make mistakes occasionally when I do calcs. But I have a process that picks these artithmetecial errors up nearly all the time. Nine times out of ten these get spotted in house when doing or looking at the drawings as your eperience tells you.. that does not look right! Nine times out of ten when I check other SE's calcs I'll find mistakes. Some are benign, some are dangerous. I had one recently where the wrong axis of notation had been used by a well know UK SE company. The design was dangerous by a long way. But the main thing was that we caught it early, it was dealt with an no one fell out. On this project we are all experienced Engineers and designers and recognised that we caught it in time. And that is why you probably want Nick to do your job! It's rare these days to find a builder / commercial designer / project manager that has this commitment. "welcome being dumb and well rested, trust me!!" and then you would die of boardom Nick! Keep doing what you are doing.

No, but that is the great thing about the building trade.. oh I've admitted this on BH before. When I was a building Contractor in my last life I did a telephone exchange conversion for Mr Boom the Man on the Moon. He went off to AU and left some of his stuff under a hap, it was big pile and in there was his tractor, never lifted the hap as it was his stuff. He came back and said "where is my tractor?" I said what tractor! He said the one under the hap. So now the tractor is boxed inside the conversion and won't get through the narrowed door openings Luckily a couple of lads who worked for me were Farmers, they took it apart and reassembled outside.

My thoughts as a philistine are. By all means look to install an ASHP and let it tick over most of the day and night, It makes sense, less wear and tear on the switching and moving valves. Think maintainence and cost of that, this is key to long term performance., often overlooked on BH. You can have as many fancy controls as you like, but these will all break down at some point and you may want to sell on the house so you might want to make sure your ASHP is an asset rather than a liability. Let's say you can square that circle, size you tanks and so on. If I was you I would certainly look at ASHP as a solution. But here is what I would do first. "The loft has been insulated up to standard 10 years ago." This is your low hanging fruit in terms of improving the existing insulation. In Scotland we look for a U value of 0.12 W/m^2K. To give you a flavour for this 400mm of glass wool will get you over the line. But you must make sure the roof void is properly ventilated, loft haches are sealed and you are not pocketing up bathroom down lighters that let moisture into the attic. You can't go flooring the loft unless you ventilate that properly also. Look at the type of roof you have and see how you can ventilate it. "My property is early 1900's solid wall construction." There is a good chance you will have a timber suspended floor? Now you are going to spend a pile of cash so you want to make sure your floor does not rot. Make sure you get that ventilated properly. Now it may be that you are going to do some work that will let you get extra insulation into parts of the floor. So you trade that off, you have now plenty ventilation under the floor so you need to get the skirtings and so on air tight. Your solid walls are probably more insulating than you realise! But it's the apertures (windows and door) that will let you down. Spend time getting this detail right. In summary I think it's doable but unless you are going to live in the place for a very long time then it will take you a long time to get your investment money back. Some folk are happy with the techy stuff as it becomes a hobby and are happy to take the financial risk and potential right down when they sell they house. In terms of ASHP cost and sizing. There are a few on BH that say.. ok lets design for 11.5 months of the year and if it gets a bit chilly then we will plug in a couple of fan heaters. This make much sense!

I was trying to be diplomatic. That said as an SE I come across this quite often where folk have done remedial stick welding, not ground down the surfaces and so on. Yes, I could be anal about this but what I do on site is often to get everyone together and say what is the problem and how much load does the connection need to carry. Are we doing something that might chuck load in unwanted places? We then look for any part that might be a good weld and say ok.. can we count that and then check.

Well that is my good turn for the day, make folk laugh! Glad to see you used the backhoe as much safer than trying to yank it with a telehandler? To be serious, looks like you have done the job getting that to 5.0mm per m, well done! What's going on with the top of your column to rafters connections? I don't know where you shop for your clothes but these look a bit like a "summer blouse". Are you going to leave one side open. Any ideas on wind bracing as yet?

Yes I think I mentioned this a few years back. It was the quatering wind that blew the gaff. It was from memory a student at uni that was looking for a dissertation project and that is where the "discovery" started. There are a few on BH that are involved or have been in education. One great example here is Jeremy Harris. He wrote some design codes, has a huge wealth of knowledge. From time to time I discuss with other Engineers / designers what we call loss of grand father experience / loss of tacit knowledge. You get to call yourself a designer when you have enough experience to appreciate that what you do is an art underpinned by your theoretical knowledge. One theme that crops up a lot is that the latest generation, given the information over load that young folk experience means that they just don't have time to look back two generations and learn from some of the horrific mistakes. Tacoma narrows brige is a good video! The other big problem is that young Architect's, SE's and other construction professionals are under a lot of commercial pressure which leads them in to more specialist areas of design.. they just don't have time to learn more about the general design craft and that leads to mistakes. In summary you only need to be a self builder trying to get your TF manufacturer to talk to say your Achitect or SE to see the results of this.

Fair enough. Sometimes though we need to be careful when doing remedial work on site. As SE's we often deliberately design connections to be flexible. If we make them overly stiff they attract more load and that load can go somewhere we don't want it to. A good example is say you have a two storey house and converting the attic. Often you find that someone has knocked a hole in the central spine wall to create a more open plan space on the ground floor and chucked in a beam. You do all the right things, sistering the attic joists and so on. But when you first look at the attic floor joists you see they are lapped over the spine wall by max two feet (600mm), so the joists are simply supported and mainly act as ties to stop the roof spreading. But sistering often means you are making the attic floor joists into a continuous member and that stiffening attracts a lot more load onto the spine wall which can then end up on the ground floor beam.. and then trouble can arise as it was never designed for that. So before you go welding stuff to death stop and think.. are there going to be knock on consequences?