Ferdinand

The one I'm thinking of had a huge feature stone wall bisecting the house, and iirc it had a GSHP heating it up. But I am not at all sure without finding it.

There was a Grand Designs project that used a full height inside wall as a massive storage heater on the similar "chimney in the middle of the house to heat all directions idea". It may have been slate or stone. A quick search and I can't locate the exact project.

OK, breakfast having gone down and teeth polished, it is time to earn the full value of the money I am not being paid 🙂. This is a bit of a brain dump, so pull things out. Let me first be sure I understand the problem. The core problem here is 1 how inexpensively to insulate a 300-350 sqm roof on an ~4-4.5m sloping up to 5.5m 'tin' roof, with a subsidiary of 2 how the duck to attach insulation to steel joists, and 3 how to be sure of an ability to manage humidity. All for not very many £££. I think one thing not mentioned that needs a passing thought is potential fire hazard. Another is whether particular activities need particular temperatures or RHs (eg does doing X to a car require the temperature to be Y for the process to work? - you know about that), and do T and RH therefore need to be controllable? Also it is not clear where you are on aesthetics - can it be ugly? I think that Rockwool is the correct material if possible, or something similar but less prone to releasing fibres. I had not met the space blanket water bubble issue, though it does obvs prevent fibre shedding, but I have never used space blanket. I also note that unwrapped rockwool is ~1/2 (?) the cost of space blanket. Now - analogies. In the past the cheapest insulated roof I did was for a conservatory (with 7" deep wooden joists) repurposed as a lounge, where I put a tin roof on top of the joists (over the existing polycarb), and staple-gunned 100mm rockwool just above the bottom level of the joists to leave a ventilated 25-50mm gap, with routes for air circulation in and out. Then wiring was done along the joists, and it was clad with white shiplap (at about £5 per sqm). I would not use plastic shiplap now, as I am unhappy about gases it would potentially put out in a fire situation, but risk is managed. Nearly ten years later it is still solid. The other thing that strikes me as similar is putting insulation under a suspended floor. Again my standard inexpensive was is as much rockwool as possible stapled in place, which comes in at about £1 - £1.50 per sqm per 100mm of thickness. The other one I have been involved in has been renovation of a 6000 sqft mid-height (20m by 30m ish, prob. 5.5m high walls and a 8-9m ridge height) former warehouse into a gym. We did not try and insulate; we did repaint. Possibilities A How to support rockwool on the pitch? The one that jumps to mind is something like sheep netting (metal or plastic) or even wire mesh. Very inexpensive. Though roofing laths every 1m or so may be more practical. But that leaves... B How to attach to steel . Are those modest depth I-beams * or simple rectangular cross-section? If I-beams, can you just wedge roofing laths or something a bit stronger across each ~2m inter-rafter gap, and secure with spray foam? If rectangular section, can you just attach laths using spray foam to keep the rockwool up there? Will it support it? Perhaps a test? Is such a light structure an issue if bits fall down (I'm guessing potentially yes 🙂) ? Or is there a kind of punch nailer that will go into the steels, or bolt through every 2m or so across those 2 to 2.2m inter-joist gaps, or attach clamps and attach roofing laths across? Those feel more tricky except the last, but structural metal-work is not my thing. C How to be sure of an ability to manage humidity I'm with those who say ventilate above the insulation, and making sure there are inlets / outlets at top and bottom, or both ends. I'd say do it by putting rockwool depth in 75-100mm shallower than the depth of your beams, aligned to the bottom, and seal within reason around the edges. With dehumidification as an available Plan B when required. I wonder, is there something to be said for a workshop version of a lowish volume PIV fan as a humidity control, as these are heroically cheap to run. Triggered by humidistat? D Make it a cold loft. @Onoff touched on this. What about a mezzanine or similar structure, or putting sub-buildings inside it? My wild thought is that could you use a mezzanine partial mezzanine of 3m scaffolding? It's structural, gives you the chance to subdivide cells when you need it, on 2.5m or 3m cells or with larger bridged cells probably suitable for cars, and you can just roll out the insulation on top. I make it about 6 x 10 max cells, so is that doable? Plus you get a structure to subdivide if needed. With scaff you get to take it down and sell it in 20 years, plus the rockwool, and the building is unchanged. Needs a detailed think check, and probably a bankrupt sale. It feels like quite a big chunk to spend, perhaps. But can you build your scaff framework, roll out fencing mesh on top (attached with zip ties), then roll out rockwool on top of that? Needs thought about access - perhaps a run of scaff planks along an edge of each cell? E Make it beautiful I think this should be criteria 27 on the list, and that criteria 1 through 26 should be cost and practicality, but in at least one comment above you imply it matters at least slightly. I think that in that case you are looking more at a modest renovation, and may need to be looking at things like internal cladding beneath your insulation. On that I cannot do better than the plastic shiplap I mentioned, unless you put box section tin on the inside. That's my random thoughts - I hope there is a spark there somewhere. F (Update: I realised that I have missed the suggestion of using glue to secure the insulation supports to the roof joists, which is really in the same type of idea as supporting it using spray foam. Are there suitable glues around? Which may be expensive - when we glued down 4500 sqft of rubber matting to our gym floor we used £900 worth of the strongest glue from B&Q. But 4 years later the matting is still firmly attached, and the only thing that pulled it up was when the ^&*(())_ landlord insisted on bringing a mini digger or a forklift or something in to do maintenance. But if it does the job satisfactorily, it would be worth it.)

Might a dehumidifier be a suitable solution to any humidity problems - personally I would ventilate the roof / seal the insulation as well as practicable (rockwool is good for that), and then see. I've been putting my thinking cap on on this project, and will do a separate post. F

What are the dimensions of the roof? Is it a simple oblong building?

How are you going to warm it if you have a 1m diameter hole to the outside with a fan in it?

It's 3 feet. That's waist deep. IMO anyone would spot it. Is the bit by the house still at the same level? One concern I would check by email with the architect is whether there is any loss of lateral support to the structure of the house. Is there a change of level wrt to your neighbour. If you are lower on your side, are they sufficiently supporter? As an N, that would be a concern for me.

OT. I'm interested in that road, and the mandatory * cycle lane. That cycling lane looks dangerous, how wide is it? Given that the standard bus lane in ROI is 3m, I'd say it is perhaps 1m wide - not very adequate imo for a parent with their toddler in a trailer with 2.5-2.6m wide buses tearing past about 0.3m away. Is there a 30kph speed limit on that road? Cheers Ferdinand (* Mandatory cycle lane in ROI is one that motor traffic is not allowed to enter - basically the same as UK, but ROI is better where parked vehicles can't block cycle lanes freely. Up until 2012-2015 plus a bit - because the reform was botched - people on bikes were also required to use even dangerous cycling facilities in ROI.)

A clear explanation - great. My questions are: 1 - How did you affix the larch offcuts at the bottom, given no wallplate? 2 - How long do round wooden posts in concrete last in that situation? In my area, that would be a recipe for post rot I suspect. Does the wind blow all the rain away 🙂 ? F

I'd support the letter to the CEO. Octopus trade on good customer service and being nice - TBF they have achieved a Which top rated assessment 5 years in a row - so perhaps it may work. F

Welcome. He means pics of the building, just in case you are an exhibitionist 🙃 . I like your mix of projects, and willingness to take tactical advantage of one for the next one in the future. I'd quibble slightly on your definition of "superinsulated" - to me 80mm of wall insulation is normal, though pretty good for a reno. I'd start superinsulated in a wall at about 125mm of Kingspan these days. It's interesting that the new building regs have just somewhat caught up, and now require a wall u-value of 0.18, which is something like 90mm of Kingspan. On the export energy price, you might have a look at an agile tariff such as Octopus Outgoing Agile, which pays you the wholesale price per unit, at present averaging 20-25p per unit (their fixed outgoing alternative is paying 15p). I've just switched. There are various threads about this on the forum.

Technically I don't, but I have not had much success trying to preserve apples whole. We used to wrap individually ion newspaper and put in the cellar. I am more inclined to chunk, blanche and freeze. Or dehydrate. I'm also currently in the habit of buying soft fruit in decent volume (ie kgs of blueberries, blackberries etc) in season for smoothies, breakfasts and puddings until the next summer. Plus I'm buying fish, some meats, game etc direct from source in enough volume to avoid delivery charges. So a small chest 70-80 cm wide chest freezer or an upright seems a suitable idea. No current plans to get in half a wild boar, however. Though several portions of horse are arriving today. F

When you think about your power flush, check the cost of replacing your rads and possibly your pipes as well. The last time I looked at one, the power flush would have been 70% of the cost of the entire replacement, so I just changed the whole shebang.

(I'm assuming a fairly complex extension, since you mentioned the word "wraparound".) No. These are *exactly* the people you should be asking, since there's no existing relationship potentially to distort the perspective, or damage. And they have no bias in your favour, or bias against you, and they do not have a preconceived idea of you and so will not have a notion in their head about what they think you should probably want. And what a fantastic way to meet all your new neighbours on a subject that you will all be interested in. They all have local knowledge, and weather knowledge, and sun direction knowledge, and can tell you what did not work, and you can avoid repeating any mistakes. I'd suggest getting all their plans off the Council website, and studying them. Then coming up with your list of questions, based off your own definition of your own needs / requirements. Then do some chatting over the fence, or some door-knocking. People *love* talking about how clever they have been, and if they did not build it they love talking about how much better they *would* have done it.. Make sure to ask for what worked / what didn't / why they did what they did / is it warm / how are they planning to cope when kids have gone away / what was their best idea. Treat it as narrative market research. If you do that you need to be careful not to unacceptably criticise others' houses, or gossip to neighbour X about what neighbour Y's extension is like and what you think of it; be a sponge and keep shtum. You also need to be sure that you manage the relationship with your immediate neighbours carefully around if they object to what you want to build; that can work well or can be a shark-infested custard. There are people on BH who argue "don't engage at all", and others like me who argue in favour of engagement with neighbours. Then you need to end up in a position where you know enough to be an active client for your architect or architectural technician. Whether you need yourself, an A, or an AT, depends on how much you know your own mind, how complex the job is, and how much help you will need to avoid design or planning elephant traps - for example an A should protect you from being inefficient in use of space, and should guide you to make a space which is more inspirational to live in, whilst an AT will more need you to supply the vision. Your first job is to get to a place where you have the nouse and confidence to make that determination. We can help with a range of opinions, and there are a lot of projects described in the blogs that can broaden your views. One point: on "stone extension on a stone house", there has been a perspective for the last 25 years or so that argues the validity of deliberately making it different in order not to blur the form of the original building - especially in listed building circles. That depends on the circs - if it is a big plot, or if it is a bit extra on the existing. All the best, and remember to enjoy the process. Ferdinand

I find myself in need of a backup freezer - the immediate cause that has flagged it up is the apple (an dother) harvest and the need to preserve some of it for winter heating, but it was on the agenda anyway. Ironically, I chucked out an ancient one about 4 years ago, and now find myself wanting a replacement. Where are we with chest freezers vs upright freezers, now? Traditionally I have viewed chest freezers as more efficient due to less air leaking out when the door is opened, but now this seems to be a minor factor. As I have it: Chest freezer - More floorspace per storage volume, but need rootling around like a warthog to find things. Can go beneath shelves / cupboards. Price ranges £1.20-£3 per litre of storage. Less efficient energy-wise (?). Upright freezer - store more in 600x600mm. More expensive. Price ranges £2-£5 per litre of storage. I'm quite taken by the idea of an upright with a small wine cooler on top. Does anyone have any thoughts or views? Cheers. Ferdinand

Late to this one - what a wonderful introduction.

I think you now have lots of options - fairly low cost for a key feature, and no need to upset your brickie. Thank him profusely for being willing / talking the initiative / listening to your suggestion to do a to do a one-off prototype (whichever is least untrue) to let you get it right before they were all built different to your imagined expectations, then move on with your selected option. In BH, you usually get very good answers by the (notes that himself did post 13) the 12th reply, or whatever, then we sometimes devolve into spats about detail. ATB. F PS We demand a photo of the finished hoose in due course. If you don't you will be haunted by the Ghost of Pevsner, carrying a clipboard and a plumb bob.

Hmmm. Don't for get that vestigial autumn / winter solar can also effectively boost the CoP for a heat pump. My gas bill reduction solution for the winter is to try a free standing air con / heat pump, and use it the morning for a gentle heat boost. If I need to in due course I could go for a small house battery to help reduce the elec bill to nearly zero. It is on now - spec is delivery of 3.2kW of heat from 1.4kw of power input for a CoP of 2->2.5. My somewhat shaded not yet powerwashed for winter mainly E-facing solar array is delivering something approx. 1 kW at present (total house load including baseload at the heat pump is 450W on the Smart Meter), which means that the effectively CoP is somewhere well above 5. Being rigorous I would need to take lost solar export into account, but these SOTP figures make the point. F

Ah the vortex. Happy memories. With graphics done on a BBC Micro. And I think Bonnie Langford. The lid - yes, fix it. We had one in the middle of a field where some scrote had dropped the rectangular lid inside years previously. There should be a law for all sceptic tanks to have circular lids.

So I'm at the final step of moving to Octopus Agile - getting on for the actual payments. This has taken since August, and is clearly still a developing process. Received yesterday: Ferdinand

Octopus had a trial in the Sprring where they rewarded customers for timeshifting their demand away from the Peak Period when requested. Results were modest and the average loadshift was only 0.7kWh, but across 100k customers that was a larger number. This now seems to be going ahead in a more formal manner, as reported by the BBC here: https://www.bbc.co.uk/news/business-63175030 Perhaps potentially of interest to people who can timeshift their export energy? A small extra return on existing facilities. Suspect that on the whole many BHers can't shift very much energy as we use relatively little. Personally I am totalling about 28-30 kWh per week at present. As I only have solar not a battery yet, this is not me. Ferdinand

I have a couple of commercial dehumidifiers, potentially for drying out tenants' houses should a roof or pipe leak. Has never happened again after the first occurrence, perhaps as I educate and have SureStop fitted everywhere, with encouragement to use it. But i think DH's would not generate enough water. I also have a portable heat pump I am using for gas-bill-control during solar hours this winter, which generates a surprising amount of residue water, but nor enough for this. I think that will be the option (other than perhaps @PeterW's in line ion-exchange, as the plot is to have a IBC fed watering setup for container plants, which would be pump fed from the IBC. May be suitable for repurposing for windows / roof - and the pump feed in the tank would be wearing tights or similar. Various options to try. One thing I have not mentioned is that at some stage I plan to run CuSO4 solution (see previous threads about lichen and roofs) through the detergent feed once a year or so to keep the solar clear. It will need careful cleaning afterwards but the Nilfisk long lance has a feeding head with a mesh-filter that you just drop into the bucket of detergent. Will need thorough cleaning afterwards with clean water, which is not a problem. The solar hosting roof goes to a different gutter-downpipe than the rainwater collecting roof. F

Ok. First test done. Using hose water rather than rainwater, and no detergent. Very happy with the Nilfisk slightly expensive (£90) 4.2m extended lance and nozzle - clearly a bit of kit that will work well if not abused. Though even without the detergent feed being used (a separate tube) there is much rats' nest potential in the various feeds once the into and out of the pressure washer are in place. Careful tube managent required, and adequate space in front of the facade with the target windows helps considerably. However, washing of two bats and 3-4 upstairs windows took 5 minutes once the kit was assembled. I think I need a tighter set of hose-clock-joints though, as there was a bit of water leakage. So far so tolerable. Still waiting the Nilfisk roof-brush, and planning to have a go at the solar once that arrives.

Can we have a site and orientation plan, with indications of how your rear elevation and the area outside there is shaded? A Google Maps satellite photo would help, or perhaps Bing as they are usually clearer. My 'fat at the back' extension (there when I bought the house) faces North, and is therefore quite shaded. It is sometimes rather gloomy, but the extension I have is two storey (it's a bungalow extended up, back and sideways), so no roof windows. Instead I have a conservatory at the side. Peter is right about roof windows, but if you have shown us your full plot width interfaces with neighbours and access for roof etc maintenance become important. You may be better with a door at one side and a picture window from say knee height, perhaps with a window seat. As soon as you have a huge galumphing bifold wall you end up either keeping it clear and nowhere to put anything, or not keeping it clear and never using it. I'm wondering is where is that garage on your plot? If you have extra width more than the house width itself, then there may be something to be said for eg going a little sideways to get some sunlight into the kitchen diner where you spend your weekends. I think one big issue you have not addressed is storage and utilities - where are washing machine etc going? I'd suggest partitioning off your washer and dryer if needed, and also consider having a wall of storage somewhere. F

Thanks all. Most useful.