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This is a classic mathematics problem. One of the most practical uses of differentiation is finding the maximum or minimum value of a real-world function. In the following example, you calculate the maximum volume of a box that has no top and that is to be manufactured from a 30-inch-by-30-inch piece of cardboard by cutting and folding it as shown in the figure. What dimensions produce a box that has the maximum volume? Mathematics often seems abstract and impractical, but here’s an honest-to-goodness practical problem. If a manufacturer can sell bigger boxes for more money, and he or she is making a million boxes, you better believe he or she will want the exact answer to this question: Express the thing you want maximized, the volume, as a function of the unknown, the height of the box (which is the same as the length of the cut). Determine the domain of your function. The height can’t be negative or greater than 15 inches (the cardboard is only 30 inches wide, so half of that is the maximum height). Thus, sensible values for h are 0 ≤ h ≤ 15. Find the critical numbers of V(h) in the open interval (0, 15) by setting its derivative equal to zero and solving. And don’t forget to check for numbers where the derivative is undefined. Because 15 isn't in the open interval (0, 15), it doesn’t qualify as a critical number. And because this derivative is defined for all input values, there are no additional critical numbers. So, 5 is the only critical number. Evaluate the function at the critical number, 5, and at the endpoints of the interval, 0 and 15, to locate the function’s max. The extremum (dig that fancy word for maximum or minimum) you’re looking for doesn’t often occur at an endpoint, but it can — so don’t fail to evaluate the function at the interval’s two endpoints. You’ve got your answer: a height of 5 inches produces the box with maximum volume (2000 cubic inches). Because the length and width equal 30 – 2h, a height of 5 inches gives a length and width of 30 – 2 · 5, or 20 inches. Thus, the dimensions of the desired box are 5 inches by 20 inches by 20 inches.

Hi All I just thought I would share my VAT reclaim timeline to let other people know current timings etc.. I completed the VAT 431c form using the online method (excel spreadsheet) on 4th September 10th September I received an email asking to submit 21 invoices, i sent these back the same day using the online portal I received a letter on 27th September saying how much they will be paying and queries they had regarding 5 invoices(not enough detail) Money received 1st October Re-sent the queried invoices with additional details on 9th October The remainder of the money received today (4th Nov) In all honesty I found this process very good with no issues, I rang up once to ask a question and got through straight away It certainly helped keeping an up to date record/spreadsheet throughout the build otherwise this would of been a mammoth task at the end and no doubt things would of been missed

I don't own this particular saw but as it's the yellow and black dream machine it's bound to be top notch!

As usual with sound you have 4 issues. 1. Airpathways. The big issue here is the doors. They're very lightly to be the weak point. Really focus on getting an absolutely seal all around them. (This may require dedicated ventilation to the music room) Similarly seal the ceiling plasterboard and the stud partition plasterboard with acoustic sealant in a hermitic fashion. 2. Decoupling. Mainly an issue with the stud walls and ceiling. A dropped metal ceiling or resilient bars will do here. 3. Reverberation. "The drum effect". Anything that you hit a thump of your fist that noticeably acts in this manner needs a layer of fluffy stuff inside to prevent it. Similarly dissuading harmonic frequencies is important. Use differing thickness of plasterboard on both sides of a wall for example. Add some foam to the back of the fire doors to stop sound bouncing around in the void there. As it's a dedicated music room you could consider lining the walls and ceiling with acoustic foam too. 4. ADD MASS. Not required for the 225mm wall or the poured concete wall. There's literally tonnes there already. Remember all that you are doing is buying kilogrammes, not magic beans. Dense rockwool, MLV and other secret sauces are expensive ways to buy these kgs. Standard plasterboard, soundbloc and OSB and are all the cheapest at about 60p per kg from memory. More is better, including on the doors.

I think there is some program to interrogate the submitted list. They asked us for 26 invoices, some large item invoices kitchen, windows, treatment plant etc, but they also found a duplicate( this was an invoice and a proforma invoice submitted in error, for the same amount different reference. Also they found two invoices that were actually quotes / proforma's) we sent the wrong ones, and the reference were e.g. q123456 and pro9986. . Top tip :double check your list before typing in the the details.

I used 25 x 50, don’t think you can get 30 x 50 battens without having them specially made.

Just to double check as we are soon to start this, is it 6 months from building control sign off as a general rule to stick to? Great info though, thank you.

Ok thats easy. It is all tried and tested. Just remember that the contructions are tested in laboratories... a lump of wall inside a controlled testing box. You will have junctions and corners, and services and doors. I think i recall building a music room next to a maths classroom, and it worked out fine. I haven't got details any more but the requirements will be published. Once you find the construction, which will be as dcsibed by others above, you should choose the next level up, to overcome the difference between laboratories and real life. And avoid service holes and doors. Now it's coming back to me. Stud walls with flexible (acoustic) bars and many layers of board, plus dense mineral wool. I think we sliced the floor slab under the wall to break continuity. Floor above similar with plasterboard under a cushioned floor boards for density.

I think you'll need a sum put aside by the vendor (or knocked off the price) for the two issues. Or delay until the vendor has fixed both. >>> Does anybody know how much water there could be between zero bar and 1 bar in a 4 bedroom central heating system? Water isn't compressible much: ... 4×10−5 per unit atmospheric pressure i.e. bar. So if your heating system has say 8 off 10l radiators, then that's 80 x 4 x 10^-5 x 1 ~= 3ml i.e. a small teaspoon worth. i.e. quite a small leak, say one that you might see dripping v slowly or detect slight wetness on a pipe. I might go around checking all the valves, pipes, bleed nipples and see whether any are at all damp. Of course, if the water is hot, it'll evaporate reasonably fast. If you like, you could get a plumber to pressure test the system in sections until they find the culprit.

Pay particular attention to detailing on doors / windows, these will be your biggest problem. Is that a french door to the left of control room? It will probably be more leaky than others. Consider making stud walls double & decoupled Check your room ratios aren't going to cause acoustic issues I suspect you'll want the room pretty "dead" at that sort of size, so incorporate absorbers / bass traps in the design early on A great resource: https://johnlsayersarchive.com/ Keep us updated on your progress

An old mate of mine designed radio & TV studios most of his working life. He said - 'there's no substitute for mass'. I'm thinking sand... I might also check out the sound booths that wind instrument players can practice in.

Bedec black barn paint. Like painting with yogurt. On softwood if you like (can come ready with basic stain/paint from factory) or hardwood if you want longer life (the wood, not you unfortunately). Then there's a bunch of grilled wood options - search the forum.

Up in the attic I found the remains of a plastic tub of poison blocks. Mice (and/or rats) had chewed their way in, eaten the remaining poison, then eaten the lid of the tub, which was like lace. We don't appear to have mice or rats at present.

I hope so, as I'm gradually going over to Dewalt 18V XR tools.

Mice only need a tiny hole to get in, about the size of a hole in an air brick. If it is a normal cold loft it will be ventilated and the standard sized vents will allow a mouse in. Not much you can do but traps, poison and get a cat. This is not a problem unique to timber frame. If there are no obvious signs of water damage all you can do is keep topping up the heating pressure and see if anything develops. Is is solid floor or suspended timber floor downstairs? If suspended are there any access traps to the under floor space? If it only loses pressure when the heating comes on and then goes off, it is equally possible the expansion vessel has failed and water is getting expelled via the discharge pipe each time it heats up.

I used a mix of 25x50mm and 25x30mm coloured roof battens. I followed the TDCA guidelines, but I was fitting thermowood timber. I actually bought the full book in the end, but I think the free one covers nearly everything. https://www.tdca.org.uk/publications/the-timber-cladding-handbook/

Just thinking about it logically, I would turn both off and see what the effect is.

I definitely agree with remove corridors but we found a stairwell right in the middle of the house worked very well. Straight in from front door into a small hall area giving access to all downstairs rooms from the one small hall. Up the stairs, 180 degree turn at the half landing, and the upstairs landing is directly above the hall, and gives access to all upstairs rooms. Nice and compact and efficient. The only one we struggled with downstairs was how to get a utility room and downstairs WC without a corridor or having to pass through one to get to the other. Simple answer combined utility and WC all in one room. Not to everyone's taste I agree but it works well.

Long corridors waste a significant amount of space. As does a stairwell in the middle of a house unless you want to make a feature of the entrance and stairs. We mostly designed out the internal corridors as there were two, one upstairs and one downstairs stairs, both pokey and dark. The neat feature of our stair design is it hidden behind the kitchen wall so takes up very little floorspace and creates a big cupboard off our kitchen and a wardrobe under the stairs off the guest bedroom. The 45° roof pitch and ridge beam also gives you a lot of flexibility in how you finish the upstairs ceiling both in height and style. We also removed the coomb storage on one side of the upstairs and made the other side slightly wider. Consequently the two upstairs rooms feel big and airy. A room in roof design creates quite a neat compact looking house on the outside and plenty of extra space on the inside.

I think Any house with two or more floors will always be cheaper and have a lower risk of escalating costs. The biggest unknown on all buildings projects is what you find when you start digging. 200m² single storey has twice the risk of hitting something expensive at foundation level, than a 100m² foundation for a 2 storey house. Other factors - form factor for heat losses, nearer a cube the better. Space usage, stairs take up space, but so do long corridors to get to the large footprint of single storey. So you are trading one for the other. Future proofing - single storey will always have easy access to bedrooms if stairs cannot be used. At the end of the day it's about what is right for the site, ours was single storey, long frontage and not very deep. Rubbish form factor, more expensive to heat. Has a long corridor. But great views from all rooms.

Is the ASHP part of the MCS scheme? If so, then contact the governing body. But as @nod says, terminate with them.

Terminate any deal you have with them Hopefully you haven’t paid to much and get someone local to do the first fix and get a separate LOCAL company for the HP Same with the plumbing

Could be worth staying stum. Maybe the seller thinks the saw is no good and want rid at a bargain price.

+1. I splashed out on a Dewalt and the accompanying leg stand for it. Well worth the money. It’s done everything from skirting, flooring, stud work and lots more. just don’t tell @Pocster I bought yellow and black as he’ll never let me live it down.

'... How do people in their 60's even do this?!!...' By planning for it. I don't know of one builder over (say) 50 who isn't careful with their upper body. If it's not backs, then it's shoulders or necks. And I'm just about the same as you are: cursing quietly when [...] clicks in. That's what young folk are for - saving our backs. Learn the warning signs, sign off straight away, not '...Oh I'll just [...] ...' For me, it's the single hardest lesson of the build so far. And nobody can see anything except my refusal to get on with it. SWMBO notices the analgesic consumption, but that's about it. Now I look at jobs done in both haste and pain and repent at leisure.

I have an early, 255mm, Rage 3, sliding mitre saw. The nephews each have later model, 255mm ones that seem more accurate but I don't think it's a wear issue on mine. I think Evolution have improved the design. I don't have mine set up on a bench just grab it, manhandle to where I'm working, the car etc. I then need to set it up every time if I want an exactly square cut. I use one of these: OSALADI Carpentry Angle Ruler Industry Protractor Angle Miter Gauge Miter Angle Finder Metal Stencils Finder Measuring Ruler Goniometer Angle Finder Aluminum Alloy Work Carpenter Magnetic https://amzn.eu/d/fsI2C8O Useful as a periodic checker even if the saw is set up on a bench. It allows a fairly acceptable degree of repeatability for say mitre cuts. My mate has a big DeWalt sliding mitre saw, several hundred Pounds worth. The Evolution and DeWalt are streets apart. He'll do 6" skirting on his and it's perfect. By the same token his can't cut conduit, Unistrut or with a change to the Evo diamond blade, brick slips. Imo the Evo saw is nearer to a rough and ready shed/fence building saw than something a proper chippy would use for say cabinet making.

Take it steady. I slipped my disk in 1991, still gives me trouble.

Love this site! Thank you all again!

@Nevik This is an area of some disagreement, here is my take and experience, you will need to decide for yourself. "Proper heat loss surveys" can be utter garbage if the surveyor (for example) ignores fabric upgrades they cant see (which some do as a matter of principle) or puts in an unrealistic value for air changes, or miscellaneous other sources of error. The spreadsheet/software looks sophisticated, but as ever GIGO applies. Personally I wouldn't rely on a 'proper heat loss survey' alone unless you validate both the inputs and the calculation and also have some independent handle on air change rate. I had two done, one of which I paid for, and they were total nonsense because the surveyors ignored invisible fabric upgrades ('if we cant see them how do we know they are there' was their argument, an argument which I have heard from others since) and double counted room to room losses. To be tolerably certain I would have a survey done, then check (a) the u-values used (b) how they have treated room to room losses (they should be counted for for radiator sizing but not for whole house sizing, unless room to room gains are also counted) and (c) what value for air changes has been used if you can collect smart meter data from a season where you operate your boiler fairly constantly and are heating your house a good proportion of the time, then do various plots eg daily consumption vs degree days, average power over 3, 6, 12, 24 hrs and utilise what this tells you Do the rule of thumb calculation, although a divisor of 2200 or even 2000 is also suggested by some and there are arguments for various values in between, probably depending on the assumptions you make about boiler efficiency and location. For the second and third of these, if you can, make some intelligent assumptions about your boiler. If its very old then it probably has an efficiency ~75%. If its a condensing boiler but you have plumes of vapour coming out of the flue (ie the norm in the UK), then its not actually condensing, so efficiency might be ~90%. If its a modern condensing boiler, run at a FT of 55 or less, and there are no plumes of vapour, then it is condensing and might be running at an efficiency of 110%. All figures rough and ready. If you cant work out what assumptions to make, at least you can account for the uncertainty. Once you have all of that (if you can be bothered to go to this much trouble) then see what this tells you. If they are all tolerably consistent then you are good to go. If there are major discrepancies then I would suggest you might try to work out the explanation. In my case the discrepancy was a factor of two, the difference between 8kW (measured) and 16kW (calculated), a difference which has major knock-on consequences. If your house is low loss (eg ~3kW) it matters less because you are anyway going to be limited by available models and the need to have sufficient capacity to heat DHW, so you are probably going to end up with 5-6kW anyway. All that said a tolerably oversized heat pump is probably not a disaster unless it pushes you into consequential actions such as upgrading pipework, requiring planning permission or something else, all of which are more likely for a high loss house than a low loss house. An oversized pump will cycle more than a right-sized pump, possibly even at very low temperature. This does reduce efficiency, but nobody really seems to know by how much with modern inverter driven pumps (perhaps a topic for another thread sometime). Heat loss surveys will tend to overestimate because that's 'safe' for the installer. Whether its 'safe' for the customer depends on the circumstances as exemplified above. It sounds like your house fits into the high loss category in which case a sizing error might make a massive difference to the scale of works needed.

Not sure I would pin myself to passivhaus, but instead follow the principles. A2A you still need a heater for the DHW, so I would stick to a normal ASHP. MVHR several ways to do it, the normal way with a duct and terminal in every room, or cascade, generally duct to each wet room and a couple of supplies only that suit the layout. You will have a demand activated fan through a wall or two for awkward layout rooms that do not lend themselves to being cascaded. An example of said fan https://www.ventilationland.co.uk/en_GB/p/brink-indoor-mixfan-co2-gestuurd-tot-70-m3-h/17927/?gad_source=1&gclid=CjwKCAjwkuqvBhAQEiwA65XxQNHSp3Am0ssSPnBCSOd5avKVIvBbL4-5yDgamc6Up--18SUdWGZUpBoCV34QAvD_BwE Get yourself a thermal camera and see where all the cold bridges are, so you can focus on fixing.

@Pocster Sound proofing a basement? Btw, how do you overcome cold bridging where the manacle rings are?

Did anyone understand any of this 🤯