Jeremy Harris

The temperature reading depends very strongly on the emissivity of the surfaces being measured. IIRC, all these IR imagers are calibrated at an emissivity of around 0.9, using a grey plate emitter with that surface emissivity. So, if you have something with a higher emissivity, say something that is darker and close to a perfect black body emitter, then the reading will be higher than the true value, and if you have something that has a lower emissivity, something like a shiny bit of chrome handle or hinge, the reading will be lower than the true value. This effect can be quite large. A perfect black body radiator (emissivity 1.0) will produce an over-reading of a bit over 10%, a chrome door handle, with an emissivity of around 0.1, will under-read by over 90%. There is a table of emissivity values for different materials here that may be useful: http://www-eng.lbl.gov/~dw/projects/DW4229_LHC_detector_analysis/calculations/emissivity2.pdf One cause of the Seek Thermal (and the FLIR) readings drifting off is if the calibration shutter sticks, or needs cleaning (not an easy job to do!). Every time the camera clicks, that is the noise of the calibration shutter moving across in front of the bolometer sensor to re-calibrate for changes in the sensor temperature. In essence, it's a constant emissivity plate that slides across the whole sensor and allows the sensor to self-calibrate for changes. This self-calibration is never perfect, as there will always be some difference between the sensor temperature and the shutter temperature, and this is especially true of the Seek Thermal, as if the plug-in camera module is held in the hand when in use then the sensor will tend to warm up faster than the calibration shutter. I should add that the hand held IR thermometers are subject to the same errors, but usually they are a bit greater, because they don't have a calibration shutter.

I had something similar with a neighbour. I wanted to keep him on side, so went to a great deal of trouble to minimise the damage to the edge of his garden and restore everything, including some carefully dug up and potted shrubs, afterwards. I'd budgeted for erecting a new timber fence along the boundary, to replace the 30+ year old broken down post and rail fence that had been there, so went around to see him and let him choose what type of fence he preferred. He said he'd rather have a stone wall along the boundary, so I bit my lip, had the retaining wall redesigned to accept a stone wall on top, and spent around £4K on having it built (I'd budgeted £1500 for the fence). We restored his garden, replanted the shrubs etc and when doing this he asked if he could have some of the left over coping stones, to make a set of steps in his garden. I got the guys to lift around 30 big coping stones up and over the wall, and stack them on his side for him. A few months later he asked when our landscaping guy was coming. I told him and he asked when his steps were going to be built. At this point I reminded him that I'd given him around £100 worth of stone for the steps, as a good will gesture, but hadn't agreed to have the steps built for him as well. At this point he got a bit shirty, saying that we'd caused him a lot of inconvenience, and it should be the least we could do to do some odd jobs for him. I lost it, pointed out he'd bought his house knowing there was a building plot at the bottom of the garden, knowing that the plans included building a big retaining wall and that I'd already spent a few thousand pounds more trying to keep him happy, but enough was enough. The funny thing was that he just waited until I'd stopped ranting, smiled and said, "well, you can't blame a chap for trying, can you?" and wandered off.

Some links that may help:

I ran the camera around our build in a few places. No thermal bridging except where expected, the window frames, but even then the temperature difference was small and barely showed up on the image (the frame was less than 1 deg C cooler than the walls, IIRC). I have a Seek Thermal camera, the Android version, that just plugs into my Sony tablet and seems as good as some of the more expensive kit, although I imported mine from Canada before they were on sale here and it was a lot less than the current price. To get any meaningful result you have to wait until the outside air temperature is low, the colder the batter. No real point in doing anything until it's at least 15 deg C colder outside than inside, preferably a fair bit more. Nice, cold, frosty nights are ideal. Thermal imaging during the day is not a good idea, as even on a cold day the sun will warm up the outside walls that it's shining on. I can try and take some more images later in winter, when the outside temperature has dropped to below 5 deg C or so, as a benchmark for what a pretty thermal bridge free build looks like. The most significant thermal bridges, the door handles, don't show up well though, as their surface emissivity is very low. This is something else that needs to be taken into account, a thermal imaging camera only measures the radiated heat from surfaces. If a surface has a low emissivity at the long wavelength IR that the camera bolometer is sensitive to, then you will get a false reading. This means that the camera will "see" something like a chrome finish door handle as being at a very different temperature to that which it's really sitting at, for example.

I think there is also the added issue that some of us self-building have significantly higher expectations than some contractors who build stuff every day. There are some really good tradespeople around, but my experience is that they are a bit thin on the ground. There are many tales on this forum, and it's predecessor, that bear this out. One consequence I found was that I ended up teaching myself to do things, rather than contracting it out. Even if it takes me four or five times longer to do, at least it will get done to the very best of my ability. Finally, a comment about the observations that it's the small stuff that gets to you, in terms of decision making stress. Many years ago I was subjected to a "management transformation programme", one week a month away on the course for 6 months, that was intended to produce the needed new generation of senior managers for the brave new world of running defence research as an internally-trading "business". Generally it was a load of BS, but there was one session that was brilliant, so much so that I can remember practically all of it. It was run by a psychologist, and as well as the usual stuff about personality types, building teams etc, there was an exercise to demonstrate how the importance of a decision was often inversely proportional to the amount of effort put in to the decision making process. This is the sort of thing we've probably all seen; spending more time researching what new widget to buy than you spend on choosing what house to buy. In this case we were divided into two sets, and sent off into separate rooms, where there was a sealed envelope with a question in it. These rooms had video cameras set up, so that we could watch how we behaved afterwards. In one room, the question in the envelope was "How many nuclear warheads should the UK have in order to form an effective deterrent?". In the other room, the question was "What is the ideal size for a garden shed?". There was a time limit, around 10 or 15 minutes I think, to come up with an answer. The interesting point was that the team asked to decide on the number of nuclear warheads came up with an answer very quickly, after less than 5 minutes of debate. The team asked to decide on the best size of garden shed didn't reach a conclusion; they were still arguing about it when their time ran out................

I think it took me around three weeks to do half the ground floor and almost all the first floor of our build. Knee pads were essential, as were copious supplies of Voltarol...............

I used the Sikaflex stuff to bond our bamboo flooring down. Easy to use, bonds very well indeed, with the only drawback being the high cost. Given the labour involved in laying the flooring, I didn't begrudge the high cost of the adhesive, as the last thing I wanted was to have to pull it all up and do it again, because a cheaper adhesive failed.

Ian, Our build stalled because, frankly, I lost it mentally a couple of years ago, around the time of the borehole saga. It took a long time to get back to doing constructive work; somehow I just felt very depressed about the mammoth amount of work left to do. Added to that, our old house started to develop problems, too, partly as a result of me having done little maintenance whilst I was focussed on plot hunting, planning and starting the new build. Running out of money didn't help, either, although thankfully I've managed to pull in some contracting work that has pretty much paid for all the remaining materials needed, and left a bit over for a holiday. The latter is key. I have my wife to thank for spotting the state I was getting into and booking a holiday, without telling me, so I had to take a break from the build. I came back from that with a changed approach. I don't set out to do ten hour days, either on the old house or the few small jobs on the new one. I set out to spend at least two hours a day only, actually working, and then use any time after my "allotted" two hours to work if I feel like it, or do something more relaxing, like planning things to do or change, or do a bit of research. Having the odd consulting job coming in helps a great deal, as it's totally different to working on the house, and often involves a fair bit or research, data gathering and analysis, activities that are far removed from putting insulation up in the workshop roof, or painting walls. My biggest hurdle now is clearing out and making saleable our old house. It's accumulated a massive amount of clutter, and I hate throwing stuff away, as I know that as soon as I do I will find a use for it...........

For once, the Wikipedia entry is reasonably spot on with regard to the physiology of "dry rot" and gives a pretty accurate account of the moisture levels needed for survival and growth. These match up reasonably well with those in the reference book I bought years ago, when we were doing up old cottages, that I quoted in the previous post : https://en.wikipedia.org/wiki/Dry_rot I agree that the key is getting the moisture content of the timber down below the ~15% needed for the fungus to lie dormant, but with no source of moisture available and good ventilation it's usually possible to get covered timber down below about 12% or so. At that moisture level it's unlikely the fungus could survive, even in a dormant state. Having said that, although "dry rot" spores are pretty much everywhere, from natural decay of timber in woodlands, hedges etc, there is likely to be a greater concentration of spores in areas where there has been an outbreak, so removing and burning all affected timber and treating the surrounding area with a fungicide before fitting replacements would seem a sensible precaution. The bottom line here is that as long as moisture is present then there is a risk of rot, so the key to resolving the problem is getting rid of the source of the moisture. If it's condensation, then ventilation needs to be improved, if it's seepage leaking in from a defect than the source needs to be found and eliminated.

We didn't use an architect, but I did spend a great deal of time trying to learn enough about architecture and building regs to design our house myself. I passed this outline design (once we'd got planning permission) to a company that supplied the insulated foundation and airtight, insulated, frame, as a package, and they did all the detail structural design. I looked at it in terms of my time being free, so the more I could do myself, the more I could save. Not the fastest option, but we did save a lot of money. In terms of building work, I just did the stuff I felt comfortable doing, and left the other stuff the sub-contractors that we hired in.

The bearing stress thing is very often forgotten about, but is 99% of the time more critical in shear than the fastener. An example: Take a 10mm plain shank bolt of ordinary mild steel (the cheapo stuff with a max allowable single shear stress of around 60 N/mm², something like AISI 1010). Let's say we're using this to bolt a bit of 50mm thick timber to a wall, and the timber is, say C16, with a max allowable bearing stress of around 1.8 N/mm². Ignoring the small contribution from the wall to timber friction, let's look at what the bolt will take versus what the timber will take, in terms of max allowable load (no safety factor here, so reduce these values by AT LEAST 1/3rd for a real design): The bolt bears on an area of the timber that is equivalent to the bolt diameter x the timber thickness, so in this case 10mm x 50mm = 500mm². The bolt max allowable load in single shear is the cross sectional area of the bolt x the max allowable shear stress, so 3.14159 x 5mm² x 60 N/mm² = 4712 N The timber max allowable load based on the bearing stress limit = 500mm² x 1.8 N/mm² = 900 N So, even the very crappiest bolts you can find will be at least 5 times stronger than the hole in the timber, so that is factor that is limiting the max load. This is almost always the case with construction, it is really rare to find that the fastener strength is the limiting factor, it's almost always the bearing stress in the hole that limits the max load.

Shear strength of the fasteners is almost certainly secondary; the critical factor is almost always the allowable bearing stress in the holes in the material through which the fastener passes. This is why much larger fasteners are often used than would seem necessary from just looking at the max allowable single shear stress limit for the fastener itself. What you need to know here is the max allowable bearing stress for the materials being joined. That then gives you the fastener diameter needed.

When I wanted to add some ballast in my old boat, a friend knew someone that worked at a perforated metal manufacturer. I went down there and they gave me some very heavy sacks of stainless steel punch outs that were waste. I cast them up in resin to make ballast weights, worked a treat, as I cast them in place in the bilges, with some polythene sheet to stop the resin sticking to the hull. The result was custom shaped ballast that fitted each space perfectly. I only wanted small ones, but IIRC they had a wide range of different sizes.

Another fire risk with fridge freezers is the defrosting element, like this potential fire hazard from a faulty defrost switch that kept the element on all the time, until it burnt out:

FWIW, we ended up getting an interest-only mortgage from the Leeds on our existing house, to overcome the problem caused by Santander, it wasn't good value, but we were in a corner. IIRC, their maximum loan to value for an interest-only mortgage was either 50% or 60%, I can't remember which. It wasn't a problem for us, as we didn't need that much. Our situation may have been similar to yours, I was retired, my wife was still working. I'm not sure what sort of income multiplier they use, all I know is that they didn't need to know my wife's income, they were happy to lend on the basis of my pension income only. This did speed things up, apparently, as they only needed to do one income check. The only significant restriction was that the mortgage had a time limit of 5 years, beyond that we either had to repay it or renegotiate.

I agree about cloud storage, and cannot for the life of me see why people seem to think that "free" cloud storage is provided to them by the benevolence of companies that make a great deal of money. Where do these people think the company revenue stream is, for goodness sake? It doesn't take a rocket scientist to work out that somehow the company giving you the "free" storage is extracting something from you of value, which it is then selling or using to generate revenue. The same model has been used for years by store "loyalty" cards, and more recently supermarket in-store self-scanners. When Waitrose introduced these they were giving them a hard sell on the door, so I asked if I could read the terms and conditions. Sure enough, by signing up for one you agree to the John Lewis Group being able to use all the data on your shopping habits, payment methods etc, both for their own use and for that of selected third parties. In other words, the scanners are paid for by the customers data being used or sold on for marketing purposes. When it comes to open source software security, I'm not so convinced that there aren't a lot of people around who genuinely spend masses of time looking for exploits and getting them corrected. There does seem to be a hard core of privacy and security aware people who are committed to trying to keep stuff as secure and private as they can, at least for as long as the software remains at the stage where it is developed by enthusiasts. Once you get to the stage where allegedly open source code ends up being controlled by large software companies (and Android and Google is a good example, as is Ubuntu and Canonical) then things get messy, quickly. Android is dire in terms of privacy, really, really dire. Put a packet sniffer on a connection from any Android device and the amount of hidden data being sent to mainly Google servers is staggering, much of it completely irrelevant to the applications being used. Once I'd seen just how much stuff was being transmitted back (why does Google need to know my GPS location if I want to use the email app, for example?) I rooted my Android tablet and am now running LineageOS, with no Google integration at all, not even the PlayStore. It's very fast, compared to the Sony version of Android that was loaded originally, and the only downside is having to side load apps from known to be good APK files, but one major benefit is that the tablet battery lasts around 30% longer than it used to. Another benefit is that my data usage has gone down a fair bit. I only use a handful of apps on it, anyway, and one neat feature is that the best open source mapping software doesn't need an internet connection to work - it allows you to download maps and run them locally when there's no data signal available.

Once all the obvious causes of moisture penetration in the house have been looked at and ruled out, I wonder if the problem could be coming from the empty place next door? Might be worth asking the current owner of the empty place if they will allow a surveyor in to see if there is a problem. If they won't, then I wonder if it's possible, legally, to gain access to an empty attached property in order to inspect for things like water leakage that could be causing problems to the adjacent property?

It seems that Google/Nest are launching an "Internet of Things" full home security system, with an alarm, internet connected video etc: http://www.bbc.co.uk/news/technology-41336093 Sounds an interesting idea, BUT, and it's a big BUT, would I want to trust Google with all that data about our house? Given their track record for what I believe is abuse of personal data, I'm not at all sure I'd want to trust a our home security to such a system. It's bound to become a prime target for hackers, and as a former IT security colleague was very fond of reminding us at any opportunity, you can never be 100% sure that any internet connected system is secure. The same individual was also fond of reminding us that we spent many times more on our network security, per user, than practically any other organisation, and he still couldn't be 100% sure our systems were secure.

If the timber is dry (specifically, a moisture content of under about 20%) then dry rot cannot grow. 20% is quite moist, the sort of moisture level that timbers in a poorly ventilated underfloor void might sit at, or above. However, keep the moisture level of the timber down below the sort of moisture content of typical, as-supplied, kiln-dried timber (around 8% to 10%) and dry rot can neither establish nor survive. When the timber dries out to about 15% moisture content dry rot can remain dormant, but not grow, so there is a marginal condition where timber can remain infected, but not grow or develop. Once the moisture level in the timber creeps up to about 19%, the dormant fungus starts to grow again, but doesn't really start to spread and produce fruiting bodies until the moisture content has crept up above 20%.

99% of the time damp in houses comes as a consequence of either penetration or condensation, in my view, so the fix is to find where the moisture is coming from. Given there is a rear extension, then, as above, the chances are that the underfloor ventilation in the older part of the house may have been degraded by the blocking of air bricks, leading to condensation in and around the floor timbers, which is then causing the dry rot. There's a high probability of the cause being penetrating moisture, though, from gutters, flashing or even leaks coming through from next door. My experience of living in and doing up old places years ago was that damp was always from penetration in every place we lived that had a problem. We had one place where the building society insisted on the house having a silicone injection "damp proof course" to fix damp in plaster at the lower edge of one wall. We had no choice but to do it, but it didn't fix the problem. Not surprising, as the walls were solid granite, a stone that's as near as dammit impermeable. The problem was that, like a lot of old cottages, the ceilings were too low, so instead of raising them the floor had been dug out and a concrete floor laid a fair bit lower. The result was that the ground level at the front of the house, where the damp problem was, was around 100mm above the floor level. The fix was easy; dig a narrow trench all along that wall on the outside, to a depth that was a few hundred mm below the internal floor level and fill it with gravel, to create a French drain. This worked a treat, and the problem went away, to the point that when we sold the house a couple of years later, the surveyor for the purchasers expressed surprise that the walls were all dry according to his meter (I'm convinced some surveyors get a back-hander from the damp course injection people.........). I've seen water coming in from bad flashing over poor render, running down inside the pitched roof of an extension and filling the extension cavity wall with over a foot of water inside. It was only when we took a window out and shone a torch down the cavity that we saw all the water and we ended up ripping all the ceilings down in order to find where it was tracking in, as there was nothing obvious outside. Once we found the source indoors, climbing up on the roof revealed flash band flashing stuck to render that was all loose. A leaking gutter on the house roof above was letting water in behind the render, where it was running down behind the dodgy flashing until it hit the wall plate for the new extension, where it then ran down the rafters and dripped into the cavity wall on the outer side of the extension. There were no weep vents, so the cavity just filled up with water.

I can't see why not, but you may need clarification, and perhaps a permit to discharge, from the Environment Agency. We cheated, because the stream is the other side of the lane, so did a percolation test in the band of porous soil where the surge tank was going to drain to. We knew this was hydraulically connected to the stream, via the hardcore under the lane, but as far as building control were concerned as long as that area passed the perc test we were OK. You may be able to make some sort of hidden porous "leak" to the stream, cover it up, then do a perc test in the area where you want to discharge your surge tank/pond. That might get around having to jump through hoops with the EA.

I think the first thing is to find out, for certain, where the damp is coming from. "Rising damp" isn't at all common, as very few building materials are porous enough to sustain capillary action for more than a few tens of mm at most, and as long as the vertical surfaces of the lower walls are ventilated any tiny amount of moisture that does wick up though something like soft Victorian bricks will usually evaporate away from the surface before reaching floor level. The two most common sources of damp are external penetration from the ground outside the building being higher than the floor level, allowing moisture to penetrate sideways, and leakage from defective gutters, downpipes or other drains that allows water to run down or into walls. Checking that the ground all around the house is at least 150mm below the internal floor level would be quick and easy, as should checking that all the gutters and rainwater goods are in good condition, and not leaking or overflowing. Making sure all underfloor vents (airbricks I suspect) are clear would also make sense. Rot only grows when the conditions are right, and that means damp, usually. "dry rot" is really a misnomer, as the fungus needs moisture to survive - dry the area out and it will die. There are other things to look at, but right now I'd hold off from suggesting any form of damp proof course injections or wall treatment, as the best fix will be to find a way to keep the lower walls dry (I'm assuming from the description that there is a suspended timber ground floor). One other thing to check might be the height of the local water table, as there is a suggestion it may be high. A test pit fairly near the house, covered with a board for safety, and to prevent rain and evaporation from affecting things, might indicate just how high the water table is. Knowing this will help in coming up with schemes to try to keep the lower walls of the house dry.

The standard'ish way to deal with this (we are on clay, too, with a stream close by) is to fit surge attenuation. Several ways of doing this, but the idea is to slow down the release of a surge of rain water and allow it to enter the stream at a much slower rate, so reducing the risk of a flood surge downstream, or any other area. In our case we didn't have room for the cheapest option, which would have been a pond with a slow leak to the stream, so had to install 20 off Aquacell crates underneath the drive. These have created a permeable "tank" that can store up to around 4000 litres of water, and which drains away slowly from permeable soil in one corner, under the lane to the stream. I managed to buy some crates that were surplus from a big civil engineering job (they are used a fair bit on some road drainage systems, apparently), which reduced the cost, but we still had to excavate a hole about 1.5m deep to put them in, covering them with teram membrane and connecting all the rain water drainage pipes to this. In practice it works very well, with no sign of any water run off from the drive or lower edge of the site. It wasn't cheap though, and would have cost a lot more if I'd paid full price for the crates.

Both our house slab and garage slab are on 150mm of blinded sub-base - as above it does seem to be standard for a soil with a reasonably good bearing load capacity.

The foil on that CF5000 looks very different, and much thicker, than the silver stuff on the sheets I have. If nothing else, this illustrates a wide variation in surface treatment between the different types, which is useful to know.