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On the other hand, Spacetherm with aerogel technology offers a number of options worth considering. For example, Spacetherm Wall Liner allegedly offers a 61% reduction in heat loss for solid walls from a thickness of only 13mm, which seems impressive, at least to this layman. One advantage, at least for me, is that the 1200mm x 600mm panels only weight about 3.5kg, which would be especially useful for lining the walls inside the built in wardrobes. There is also Spacetherm Multi for Walls, which offers good insulation options in sheets of various dimensions. However, having to mount them on 25mm battens rather negates their space saving advantage. Has anyone tried the Spacetherm products? https://www.proctorgroup.com/products/spacetherm

Thanks @A_L. I used this calculator https://www.resurgence.org/resources/heac.html and it came up with a cost saving of nearly £500 p. a., albeit based on a unit cost of 5p per kWh, which is higher than my current tariff of 3.4p. Nevertheless, as the years roll by I suspect the job will seem like money well spent by improving the overall efficiency of the house in terms of heat loss.

After a bit of digging it looks as though using a 60/12.5mm insulated plasterboard fixed with dot and dab could reduce the U-Value to around 0.30 W/m2K, which is a lot better than the existing figure. As part of the process I would block up both fireplaces in the lounge/study, which will no doubt help even further. Has anyone out there done this before? It's all very well me reading about it, but there is nothing like a first hand account to bring a sense of reality.

Thank you all for your responses. I will need to sit down with a cup of coffee and try to understand, although first impressions are that if I go with an insulated board of 72.5mm (60 + 12.5) then the U-value will be better still. Having had a quick look at Kingspan''s Kooltherm K118 on Insulation Express's website it looks as though the thicker the insulation the cheaper the board! Also, in the grand scheme of things, I suspect a board that is 20mm or so thicker isn't going to affect usability of the room to any noticeable degree. The bay windows, which I suspect might be single brick, will obviously need special consideration, and this article seems to cover it pretty well: https://www.wartonwoodworks.com/how-to-insulate-a-bay-window-warton-woodworks/

Thanks George, I had a look at that site, and others, but they don't seem to include solid walls, presumably because they are mainly intended for new builds and extensions. Perhaps the best option is to ask the manufacturer what U-value can be expected. I would still appreciate experiences from anyone who has been down this route though.

My modest 3 bedroom detached house, which is in a conservation area, was built in 1936 and three of the walls are solid, although strangely the south facing wall is of cavity construction, which is insulated. There is a modern composite front door, with a glazed porch, and all the double glazed window panels have been upgraded to the latest specification because the existing 20 year old units were deteriorating. In my view energy prices will ever only get more expensive so I am investigating improving the insulation of the house as whole and think that insulated plasterboard might be the best solution because it seems to give the best improvement without encroaching too much on the floor and being reasonably DIY friendly. Payback is not a factor because the aim is to make the house more efficient in terms of heat retention overall, hopefully with a small reduction in the monthly fuel bill. Apparently, according to Homebuilding.co.uk anyway, the current U-value of a solid brick wall is around 1.9W/m2. I have been looking at insulated plasterboard and 50mm Gyproc Thermaline Super allegedly has a U-value of 0.020W/mK - a significant improvement. However, I notice the two figures are expressed slightly differently, is this important? In other words, am I comparing like with like? Does the lower figure of the insulated board override the higher figure of the wall, or is there some formula to combine the two? I appreciate there are practical hurdles to overcome, such as fitted wardrobes, radiators, electrical sockets, window reveals and boards, bay windows, skirting boards, coving, carpets, plastering, decorating and no doubt others I haven't spotted yet. Obviously this will involve major disruption so I plan to do it on a room by room basis. Any advice, hints or tips would be appreciated.

Noted.

I can see that might be an issue, although that's exactly what has been happening for several decades. The gulley pot (nice to know the correct terminology) accepts waste water from the downstairs WC basin, kitchen sink, upstairs bath and washbasin, as well as rain water. For obvious reason I assume a soil stack/pipe would not have a trap, but could it accept all of the above, plus toilet waste? What are the implications? That sounds like a better figure. Are you saying the rainwater needs to be separate? I get the general consensus about macerator toilets, but I'm trying to establish the viability of modifying the current waste system to accept toilet waste.

At the moment both grey and rain water discharge into the sewage system through the same pipe. I believe the occupier was given an informal figure of around £6,000, possibly by a neighbour who is, or was, a building inspector. However, I think that was on the basis of connecting the existing ground floor WC outlet, which would involve a lot more work than utilising the other drain pipe below the bathroom. I have changed a couple doors in my own house to outward opening, so don't see much of a problem. The house needs decorating anyway! I was thinking that also, although design-wise the toilet shouldn't be opposite the door, but we're hardly in a position to observe such niceties. Excellent ideas. There is no central heating, so she relies on a wall mounted fan heater at the moment. Far Infrared panel heater perhaps? Nothing formal. Probably just an open window. I should add that at the same time we are planning to convert the downstairs toilet into a shower room, just in case she can no longer get upstairs. What we trying to do is make life more comfortable for my wife's sister-in-law (long story) who has health issues and very little money, even though the property actually belongs to our son (another long story!). Anyway, thank you for all your ideas and advice - food for thought indeed.

I am unable to provide pictures, but have attached a scale sketch of the current layout, which I hope helps. As you can see, the bathroom is very compact. The trap that the grey water and rainwater currently discharge into is below the bathroom window, which is convenient. Based on the assumption that the drain connects to sewer system then perhaps the trap can be replaced by the correct connection for a soil pipe, connected to the (presumably) underground clay pipe. Can the rainwater also discharge into the soil pipe? I should explain that the lady who lives there, on her own, is quite keen on the idea of a macerator toilet, having seen a neighbour's installation, although that's probably based on the belief that a sealed system is not required. We have selected the Sanicompact because of it's dimensions, which are 390mm wide and 435mm deep. Even short projection conventional toilets, with a cistern, start at 600mm deep. Part of the plan is to rehang the door to open outwards and perhaps move the washbasin a little nearer to the door. The toilet can be either on the same wall as the washbasin, or under the window, although in the former case there is limited room in front of it. I understand there should be at least 50cm clear space in front of it. Taking the long term view it would be best to keep the bath, because it's potentially a family home, although changing it for a shower would free up a lot more room and make it easier for the current occupier, who has some mobility issues. That's another question, but I think the focus here is to see if a toilet can be included without costing thousands to connect it to the sewer.

Noise issues apart, the unit would be mounted on an outside wall and the waste pipe could drop down at an angle in the direction of the existing WC underground soil pipe. I assume the expense comes with trying to connect the two. Mind you, in that scenario an ordinary toilet would be the way to go, provided there is enough room. Has anyone tried the compact toilets with a small washbasin on top of the cistern?

I'm involved in the renovation of a small Victorian terraced house which has a small bathroom upstairs containing only a bath and washbasin. There has never been a toilet in it, so there is no soil pipe. The bath and basin water discharge into an external hopper, together with rainwater from the roof, the downpipe then discharging into an open P trap with a metal grate. There is then an underground pipe (presumably) to the nearby chamber, which also receives foul waste from the downstairs WC. To install a soil pipe to the chamber is likely to cost several thousand, so using a small macerator toilet, such as the Sanicompact, seems like a workable solution. However, I understand the installation should meet Building Regulations, but I'm not quite clear what they might be. Also, most of the material I have read refers to connecting to a soil pipe, so I am concerned the current open system will not suffice.

Good point!

Thanks for your responses. To recap then: A) Focus on draught proofing. B) Use fan heater (s) for background heat whilst under the car. C) Install an IR heater above the workbench. After that I may reuse some of the double glazed units from the house, which are being replaced, since presumably the window glass is the least thermally efficient material in the structure.

I am in the throes of refurbishing my single attached garage to try and make it more user friendly in the colder months. It is single brick thickness with a timber door and a large window at the back. The roof is felted and tiled. It has no insulation so I am focusing on making it as draught free as possible, which shouldn't be too difficult. From experience fan heaters are not particularly effective, so I am wondering about an infrared heater of about 2Kw over the workbench instead. Does anyone have any experience of these, either good or bad?

Having done a little more research it looks as though an insulated slab might be the way to go, and based on a cursory calculations might not be much more expensive than conventional foundations/floor systems, bearing in mind the advantages of speed, reduced excavating and spoil removal, less concrete and better insulation.

@JSHarrisEven better! Less work and less muck away. How much above the landscaped ground level is the finished floor?

Passive slab foundation- that looks interesting. Another option for the list to be investigated. If I understand correctly, the site is usually excavated to a depth of 600mm, unless conditions dictate otherwise, and a highly insulated raft foundation built up, obviating the need for trenches. Being a self build virgin I find Mark Brinkley's book very useful, and interesting, but to be tempered with questions on this wonderful forum, where real world experiences can be applied.

@JSHarris, thanks for the information. You seem to have followed the method suggested by Mark Brinkley in his excellent Housebuilder's Bible 12, in that you dispensed with the screed and used a power floated finish instead. He also said that not many people plan ahead enough to incorporate the UFH pipes into the slab. Can I ask how much your slab cost please? Mark Brinkley suggests a figure of £83 per m2, albeit including screed, but not including fitting the UFH pipes. I notice you didn't mention hardcore and sand blinding though. As to the micropiling system, I will put that idea further down the list for the moment. Because I will be building a bungalow the foundations/floor represent a higher percentage of the overall cost per square metre than for a 2 storey house, so even a 10% difference between various systems could be £2 - 3,000.

The plot itself appears to be straightforward, having had a non-residential building on it for several decades, until a couple of years ago, when the vendor demolished it. Yes, I might be accused of over-thinking the matter, but what appeals to me is the technical nature of the system, as well as the other benefits, such as speed, reduced disruption and traffic, accuracy and predictability of costs. Of course, I might go right off the idea when I get a quotation, but in the meantime I am just exploring the alternatives. Perhaps my question should be wider, such as "What are the pros and cons of micropiling against concrete trench fill foundations?"

Whilst waiting for the plot purchase to move forward I am still undecided on the build method of a 130 sqare metre bungalow, although I am tending to favour either timber frame, or SIPs, or a hybrid of the two. Anyway, I saw an advert for this lightweight pile system on the back of a magazine which piqued my interest: https://www.shire-uk.com/product/shire-quickbase/ Although apparently more expensive than the traditional concrete it does seem to have a number of advantages, one of which is a degree of adjustability to meet the frame manufacturer's stringent criteria on levels. It seems to me that it should also provide a predictability of cost, provided the required topographical survey is done. Apparently the insulated floor slabs need covering with timber sheets if UFH is to be installed and they are even strong enough to be used for a garage, so no more lying on a cold floor! A brick outer skin can be accommodated, though this obviously has an effect on the structural calculations. The depth of excavation is only 600mm and is only required where the beams sit, so potentially much less muck to cart away, and therefore less disruption on the single track cul-de-sac where the plot is. It seems an attractive idea to me, but I welcome any comments .

Thank you all for your responses. The Planning Permission's 3 year period expires in February 2020 and development has not yet started. The reason for the delay is that although I agreed to buy the plot in September last year a very small part of it belongs to the Government, so the seller is trying to buy that piece, because it is key to the viability of the site. I did raise a topic last year about this scenario, but we are no further forward, due to problems at the Government Property Office. The seller's plan was to start the development by putting in a small stretch of footing, but the problem I see with that is he will still have to comply with the condition about a contamination assessment, as well as the one about getting the external materials approved. However, apparently he has now been told by his architect that the PP could be extended, although having had a quick look on the internet there seem to be a lot of "ifs" and "buts" attached to that approach. In any event, I do not wish to use the approved plans, so if the seller is compelled to reapply, we need to come to an arrangement, because I will have to engage a professional to draw up plans for submission, which will take several weeks/months and cost a pretty penny no doubt. Obviously I don't want to spend a lot of money unless the plot is "in the bag". Since writing the original post I have spoken to three different companies about a contamination assessment, all of whom were substantially more expensive that the one I mentioned. However, it did seem that a Phase 1 desk study would be sufficiently detailed enough to act as a pre-purchase report, although probably not enough to satisfy the local council.

I have found a local plot, with Planning Permission, and agreed a price with the seller. However, one of the conditions imposed by Milton Keynes Council (MKC) is: "Prior to any development taking place, the developer shall carry out an assessment of ground conditions to determine the liklihood of any ground, groundwater or gas contamination of the site." It then goes on to explain that any remedial work will have to be approved by MKC and carried out to their written satisfaction. I have received a quotation to carry out such an assessment, which would be in two parts. The first phase consists of a site walkover and desk study, and this costs £700 plus VAT. In the quotation, the following comment is made: "As the site was a residential garden, it may only require the Phase 1 report. However, there seems to be an electrical sub-station close by, so may need soil testing and risk assessment". I assume the inference is that there may be underground electricy cables, although I need to ask what triggers the requirement for the additional tests. This extra testing would cost another £1,000, plus VAT, so potentially £2,040 in total. The seller has not complied with this condition, as far as I am aware, so my question is: should this be done before I sign on the dotted line? Is the ground surveyor's report likely to be full of caveats, bearing in mind the acid test is when the groundwork contractors actually start work.

Valid points, but then height when raised might be an issue. Another visit to a showroom might be needed at some point.

Thank you everybody for your responses - there are some excellent ideas to consider. I like that idea, especially with pivot and slide doors. Already on my "wish list", but part of me wonders about the ramifications when/if it goes wrong. Perhaps with the Blum electric motor? Another excellent idea for the list.