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May 29

Habitable black holes [i.e. spherical chunks of rock, water, etc. with a primordial black hole at the center]

A primordial black hole reputedly consumes very little material even when it passes through a planet, and thus potentially represents a habitable object. But there are some details I'm not entirely clear on...

• Atmosphere should be held when escape velocity is 10x the mean thermal velocity of the gas, and for a shorter term of millions of years even when it is only 6x. I would assume that if it is 1x gas should stream out in large amounts. The simple-minded calculation would be that escape velocity from a hole is the same as escape velocity from Earth when the radius / 6371 km is the mass / 6E24 kg. Primordial black holes range 1E14 to 1E23 kg, so the corresponding location for 1 atm is 100 km out for the largest ones. However, gas actually leaves Earth from the exobase, some 500 to 1000 km above the surface; for a black hole the scale height drops quickly as you go further out. So I'm thinking the real size of the atmosphere will turn out to be much less, starting with an exobase not much above 100 km, and requiring something like 110 scale heights stacked up on each other below it, which start at 8.5 km and decrease in a convergent series approaching the hole, i.e. a size for Earth-normal atmosphere only about (91.5/100)^110 km = 57 meters. <-- on second glance this calculation has to be radically wrong; the gravity there would be insanely high, and hence there would be many scale doublings beyond 100; it should be bigger than 60 meters (the issue here is that dP/dx = k P GM/x^2 dx, not GM/x or GM/x^2... will have to calculate that) Wnt (talk) 10:53, 30 May 2016 (UTC)
• As I understand it, the holes this size, even 1/6 of the Moon's mass!, only consume atoms "occasionally". But how occasionally? If one is in the middle of a 60-meter chunk of iron, or rock, or water, will that shield inhabitants from any radiation? Is the thermal energy output enough to roast the asteroid, or heat it, or have no effect? I don't even know where to even start calculating the eat rate, though the paper below suggests a 10E5 Gray rate for radiation.
• Suppose such a black hole roughly 1/10 the mass of the Moon passes through the Earth or some other body. The write-up in primordial black hole makes it sound like this is a big nothing, but I assume it would crack rock formations all the way through, pulling them inward, thereby modifying its own trajectory (more mass behind it than in front). This naturally depends on the speed, and is dealt with somewhat at [1]. Has anyone tried to figure out how much a body would retain an outgoing black hole, i.e. is it possible for one to have a fairly stable orbit that passes through a planet on rare occasions, or would it quickly become captured by the planet?
• How slowly would a black hole have to exit a planet to leave with its own little chunk of rock or soil and as much atmosphere as it can hold?

Wnt (talk) 11:05, 29 May 2016 (UTC)

It took me a while to figure out that "habitable black hole" meant a spherical hunk of rock with a small black hole in the center. I don't know the answer to most of your questions, but I don't think this would be stable, because by the shell theorem there is almost no gravitational coupling between the black hole and the rock. For similar reasons, a black hole couldn't pull a hunk of rock from a planet to form it in the first place. -- BenRG (talk) 19:23, 29 May 2016 (UTC)

@BenRG: The shell theorem only applies to the full spherical shells, so if the material is differentiated somewhat by density (if rocks and dirt fall into the pile, say) the filled shells shouldn't really cancel out. (also, in the meanwhile I realized that the 60 meter figure is very wrong, not quite sure why) Whether the shell cancels out or not, objects further away from the hole are still higher, so a glob of water that goes off center from a hole ought to flow downward to make itself centered again... I'm momentarily nonplussed to think that the hole is not attracted to the center of the water yet the water centers itself on the hole! [the black hole will be "outside" some sphere of water at the center, which therefore attracts it normally; the water might respond though by flowing downward at its surface] As for gathering material, my thinking is that a black hole emerging from a planet is going to have some a certain time where nearby objects fall into it, including rocks faulted by the compression of its gravity; they could fly away on the far side but I think turbulence would dampen their energy as they would swirl around the hole and hit each other. I'm imagining a huge swirl of rock and air and the occasional hapless Kansas girl that sorts itself out by density over time. Wnt (talk) 21:59, 29 May 2016 (UTC)

My answer wasn't very good. I was imagining a buffer region of vacuum around the black hole because that's the only way to avoid ridiculously large forces on the rock. That configuration isn't stable (by the shell theorem if there's spherical symmetry or by Earnshaw's theorem more generally). There's nothing to stop the hole from drifting to the edge of the buffer region and pulverizing the rock. But that argument doesn't apply if you embrace the huge forces and assume some kind of matter soup around the hole, as Dragons flight did. (And I'm not sure it applies if the black hole is rotating.)

A black hole passing through a planet wouldn't end up with a hunk of rock surrounding it, but that isn't "for similar reasons" (I should cross that out twice). It's because it would be a perfectly inelastic collision and there's no obvious way to dissipate all of that energy. You could end up with hunks of rock orbiting the hole, but I don't see how you could get from there to a hunk of rock with the hole at rest in the center. -- BenRG (talk) 21:40, 30 May 2016 (UTC)

A mini-planet of a black hole with a shell of rock, dirt and air would be seriously damaged by punching its way through the Earth or a planet. It would be worse than a meteor, and you could expect that the shell would be vapourised and stripped off. Anything left stuck on the black hole would be very hot and in a gas state as it has had a few thousand kilometer of friction at high speed. Graeme Bartlett (talk) 02:23, 30 May 2016 (UTC)

@Graeme Bartlett: This depends on how slowly the hole can go relative to a planet without being captured, but yes, one way or another if it is headed to the surface everything around it is going to stop. But, if it can go slowly enough, it might recover a new shell of material on the way back out. I'm not sure how high I can go on this flight of fancy or what destinations are within range - is it possible for a small slow moving (relative to Earth) black hole to suck up Dorothy and her house and some good Kansas dirt in a miles-wide bubble of air and later deposit them on some hapless Wiccan devotee? Can you have a classic space-western 'barren asteroid in the middle of space' surrounded by breathable atmosphere? It'll be up to the math. But as far as I can tell from primordial black hole, nothing at all is supposed to stick; it's supposed to move through the planet like a ghost. Wnt (talk) 10:45, 30 May 2016 (UTC)

It is a bizarre question, but let's wave some math at it, and see how much more bizarre it becomes. Primordial black holes are usually assumed to travel at astronomical speeds (km/s) if not relativistic speeds, but for the sake of argument, let's assume we have a primordial black hole that somehow came to rest at the center of a solid object. The surface gravity, ignoring the accreted mass, is of course:

${GM \over R^{2}}$

Let's say, for the sake of argument that we want a surface gravity tto be he same as Earth's, implying that:

$R={\sqrt {GM \over g}}$

For a 1×10²³ kg black hole, that would be an 800 km accreted mass but if you dial it back to 1×10¹⁴ kg, it would be a friendly 23 m. In normal considerations, a primordial black hole has only a limited impact on the matter it passes through because A) it is tiny, and B) it is moving very fast. Black hole world is not going to be normal. The force exert on matter in its immediate vicinity would be literally astronomical. To first order, the black hole would eat matter at a rate of:

${4\pi \rho _{0}G^{2}M^{2} \over c^{3}}$

For a 1×10²³ kg black hole, that would be ~1×10⁶ kg / s but if you dial it back to 1×10¹⁴ kg, it would be a positively dainty 0.1 g / yr. [I'm assuming a density of matter just outside the event horizon of roughly 500 g/cm³, comparable to the center of a large star. Frankly, I have no idea how to guess the equation of state of matter approaching a micro black hole, so this might be off by orders of magnitude.] Now, black holes are fantastic mass-energy conversion engines. Roughly half of the rest mass energy of matter falling into a black hole is radiated away before the matter crosses the event horizon. So, micro black hole will emit energy at a rate of roughly:

${2\pi \rho _{0}G^{2}M^{2} \over c}$

For a 1×10²³ kg black hole, that would be ~1×10²³ W but if you dial it back to 1×10¹⁴ kg, it would be a practically puny 500 kW. Going one step further, the surface temperature required to dissipate that much energy would be:

$\left({\rho _{0}G^{2}M^{2} \over 2\sigma R^{2}c}\right)^{1/4}=\left({\rho _{0}gGM \over 2\sigma c}\right)^{1/4}$

At 1×10²³ kg, one would have a temperature 30,000 K at the surface. In other words, the object would be doing a pretty good star impression. At 5×10¹⁴ kg, the dissipated power would be roughly the same as a warm summer's day, 360 K.

So, if you want an object that is livable for humans in terms of surface gravity and temperature one probably needs to go very small. More like the home world of the The Little Prince, I suppose. At that point though, you probably wouldn't have enough basic resources (e.g. air / water) to make it sustainable. Dragons flight (talk) 11:22, 30 May 2016 (UTC)

@Dragons flight: Great answer! I assume $\rho _{0}$ is the density of the rock, but I haven't figured out sigma yet. However, you do leave out the Hawking radiation ... I know from that article a black hole has temperature 1.227 x 10E23 kg K / M ... I'm not sure what power output that is for one so small, but we'd be around 10E8 kelvins at its puny event horizon.

The "star impression" is a very interesting result. It may be a very small star; nonetheless, astronomers have some phenomenally good telescopes. I'm wondering - if such a thing can exist, and is expected to radiate like a star, doesn't the absence of weird dim stars with spectra like iron disprove the existence of primordial black holes altogether? But perhaps too interesting ... someone should have thought of this already if it's true. Wnt (talk) 11:58, 30 May 2016 (UTC)

$\rho _{0}$ is the quasi-equilibrium density of matter in the immediate vicinity of the black hole. As I noted parenthetically, I assumed something like the density in the center of a star. Not at all sure how accurate that is, but within a few cm of a stationary black hole you are going to encounter extraordinary temperature and pressures. Even a very small black hole introduces forces of millions of times Earth gravity when you get close enough. $\sigma$ is the Stefan-Boltzmann constant. Dragons flight (talk) 14:01, 30 May 2016 (UTC)

It looks like I may have a major conceptual problem here after all. The problem is that for a black hole to hold air, the top of its atmosphere has to be around were GM/r is about the same as on Earth - maybe a little less for more temporary retention, but not much. However, the gravity at this point is GM/r^2, which is to say, when M and r are proportionally reduced, the gravity at the top of the atmosphere increases in direct proportion to the degree that the hole is smaller than Earth. This ruins the vast majority of entertaining applications! I didn't realize it until I started making an absurdly crude calculation at Module:User:Wnt/Sandbox... Of course, a hole near the size of Earth could be used, but as you have shown, this would generate extreme heat, well in excess of a star. This still leaves open the tiniest crack for hand-waving about how fast air disperses in space, but it's looking grim at this point. Oh, you could still wrap it in a membrane and hold the air in, but you might as well use a plain asteroid. Sigh... I thought I had one here. Wnt (talk) 15:05, 30 May 2016 (UTC)

On consideration, I suppose there's still one save possible - put it in an atmosphere that is externally supplied. (I was interested in crashing it into a planet anyway) A hole 1/10 the size of Earth, say, would have a gravity well 1/10 as deep above Earth-normal gravity, so if put in orbit at 1/10 Earth radius, 400 mi above the surface in the exosphere, it ought to have normal-ish atmosphere around it. (Not sure if it would get all the same elements over time, or be enriched for hydrogen and prone to occasional cosmetic explosions) The problem with consumption might be reduced by making the shell hollow, as we're already dealing with a more and more artificial or at least contrived situation by this point. The shell theorem would seem to attack with a vengeance however, as the hole would then literally be in a shell, though the external water still ought to flow in varying downhill directions as it bounces around inside, and the bounces would produce high amounts of energy on occasion. Hmmm, best carve a nozzle out of the hollow chamber and call it a maneuvering thruster. :) But it still seems like it might get too hot by the above arithmetic. Such a hole would experience some drag, but if the ISS can go a few years without fuel at 4E5 kg, I'd think a hole that weighs 6E23 kg shouldn't be slowed much even if it is 120 km in diameter, i.e. 10000 x the size of the ISS and 1E8 x the area. But smaller holes have to be closer; one 6E20 kg would have to orbit at just 4 miles I think for the same 1G environment to be at standard pressure. Unfortunately, "orbit" implies considerable speed through the atmosphere, which would tend to make things unpleasant at such altitudes. Wnt (talk) 10:47, 31 May 2016 (UTC)

Have branching spikes been invented yet?

I was recently admiring a garden and regretting some rhododendrons that had been severely chopped back to make them grow out bushier and less spindly. I was thinking there is or ought to be some kind of plastic spike that you can drive into the woody stem of such a plant to make it branch out at the chosen site. Some very shallow searching makes me think strigolactone and auxin hormones would be useful ingredients, [2] maybe other plant hormones like cytokinins and gibberellins. Does such a thing exist yet? Wnt (talk) 14:35, 29 May 2016 (UTC)

Mr Wnt: I'm not sure if this answers your question, but for the rhododendrons that you mention, it seems that the act of pruning itself (pinching at the bud), tends to form a new branch link. No hormones needed. Gabs Blue Labs (talk) 15:13, 29 May 2016 (UTC)

A reasonably thorough Google search suggests "no", although there's plenty of advice for doing it the old-fashioned way. I'm not sure that your proposed device would have the effect that you intend; I've seen plenty of nails hammered into trees, but have never seen new shoots as a result. Alansplodge (talk) 15:15, 29 May 2016 (UTC)

@Gabs Blue Labs: well, ideally, one would get the new branches without cutting major trunks that already exist. @Alansplodge: I realize a nail by itself doesn't have this effect; I was thinking that plastic impregnated with plant hormones might be able to. Wnt (talk) 17:06, 29 May 2016 (UTC)

Grafting works with Rhodeodrenimons (spellchecker's packed up). No hormones necessary and one gets a new twig any-where's u wants it. One can even choose to have different coloured flowers on the same shrub.--Aspro (talk) 17:14, 29 May 2016 (UTC)

No, I don't think anyone has developed and sold a commercial a device that can cause spontaneous budding/branching in plants. But I do think you're on the right track that it might be conceptually possible. We do know a lot about apical dominance, and how various plant hormones tend to act. It does get very complicated e.g. the same hormone can do very different things based on concentration of itself and others. I certainly wouldn't be too surprised if you found that you could induce branching at a point by injecting a paste of e.g. auxin and GBA. Some of the hormones are commercially available with a little searching, so it is definitely something you could experiment with yourself. You can also often fake out plant response by cutting out patches of cambium instead of cutting off the whole branch, this is how air layering works. So a nicked branch with some hormone paste may well work for some species. I don't see much of an advantage compared to pruning and grafting methods though. Did you have a use case in mind, other than "it would be interesting"? The other thing to keep in mind is that plants generally know what they're doing. If your rhodo is too spindly, it probably doesn't have enough light. If you try to induce branching down low while leaving bigger branches intact, I think they would probably not do that well even if you did get them started - if it was a good place to grow a branch, the tree would have already done so :) SemanticMantis (talk) 17:24, 29 May 2016 (UTC)

The use case is basically people who are not familiar with even basic horticultural techniques whose approach to dealing with a giant beautiful rhododendron that is too barren on the bottom is to clear-cut it and let it grow back from scratch [I mean, from the roots, which apparently can survive this mistreatment]. I was imagining something like a staple gun that you could just blast away wherever you want a branch to appear. Wnt (talk) 22:10, 29 May 2016 (UTC)

If that were possible... it would no longer be a rhododendron truly but an aberration of any twisted-mind who was armed with a staple gun. Prune often or be very patient after you finally get around to doing it.--Aspro (talk) 22:23, 29 May 2016 (UTC)

Fire's good too. Or a nice relaxing holiday on Lundy Island. "Hi, welcome to Lundy. Here's your machete, the rhododendrons are that way." Andy Dingley (talk) 22:32, 29 May 2016 (UTC)

See Rhododendron#Invasive species and Lundy#Flora in connection with Andy's post above. Alansplodge (talk) 20:16, 30 May 2016 (UTC)

Lundy has a favourable low pH for rhods'. Just use a fishermans baiting catapult to spread quick-lime. It acts like sea water acts to a triffid. With the effort thus saved, you are welcome to a relaxing holiday at my place - to hack down our giant hogweed. I'll even provide you with a bowl of porridge at breakfast time (served properly of course with salt and not sugar an' ye may get treated to a little wee dram of the good stuff cometh the evening). --Aspro (talk) 20:31, 30 May 2016 (UTC)

I suspect that your method may be detrimental to the existing flora, as the "slash, burn and poison" technique is widely used to remove rhododendron from sensitive environments: "... the most common [methods] are cutting and then burning or chipping the vegetation, stem injecting individual plants with glyphosate based chemicals or simply spraying the leaves of the plant using standard knapsack equipment" See Rhododendron in Snowdonia (p, 15 of 18). Alansplodge (talk) 17:32, 31 May 2016 (UTC)

Insulation causing damp in houses

I've noticed that modern, well insulated houses often seem stuffy, and have mould visible on walls despite only being a few years old. Is that simply caused by insulation, plus heating to a comfortable temperature, plus people living there - or is there something wrong with the way they are built? Is it possible to make a house warm, energy efficient, and not damp, or is there always going to be a trade off between those priorities? 129.67.118.9 (talk) 20:44, 29 May 2016 (UTC)

It's lack of insulation, or uneven insulation, that often causes condensation in winter. That is, the house is warm, but the walls and windows are cold, so water condenses on them when the temperature drops below the dew point, and runs down. Of course, there are other sources of dampness, like leaking pipes, a leaking roof, or a leaky basement. (In the case of a leaky basement, the cure isn't so much to seal the basement as to provide proper drainage outside, so that water isn't just standing along the walls of the house, looking for a way to get in.)

My Mom's house is a good example of poor exterior drainage. The downspouts from the roof gutters originally just dumped rainwater out at the ground, with no attempt to drain it anywhere. They then added short underground pipes to drain it to the sidewalk, but that wasn't far enough away and the pipes were too shallow, so froze solid in winter. The idea was that from the sidewalk the water would drain to the parking area then into the sewer, but they then repaved the parking area, making it higher than the sidewalk, so that stopped the drainage again. What they really needed was deep drains leading all the way to the storm sewer, or, better yet, a retention pond. StuRat (talk) 20:54, 29 May 2016 (UTC)

Yes, I suppose I don't know that the wall or loft insulation was any good. The places I'm thinking of did all have double glazing though. 129.67.118.9 (talk) 21:27, 29 May 2016 (UTC)

Swap insulated for draft proofed and then the OP's question makes sense. In my-day (many Moons ago) houses did not have double-glazing and walls were only one-brick-thick but they didn’t suffer from mould. Water has a very high vapour pressure. Old houses that where not draft proofed also had a chimney and had an unbelievable equivalent to over a 2 foot square hole allowing the water vapour to escape. All this remember... was before one lived on frozen vegetables that have been blanched before being frozen and thus now only require about 3 to four minutes in the microwave. Back in my-day, fresh veg had to be simmered for some 20 minutes and that added a lot of moister to the air. If they where simmered on a gas stove, then the burned gas products added more water to the atmosphere too (town gas = H plus CO plus oxygen = H2O & CO2. For methane CH4 just do the sums) . So the kitchen window was alwaysleft open in order to let that moister escape. So in answer: It is not the thermal insulation but the lack of adequate ventilation that causes mould. Today, one can buy heat economizers that returns some of the waste heat back into the home whilst providing the necessary air exchange to maintain a healthy environment. It just requires the appliance of science. --Aspro (talk) 21:53, 29 May 2016 (UTC)

Just get one of these things File:Wetdryhygrometer.JPG More accurate than any cheap electronic gizmo. My rule of thumb is 40% = good. 45% = bad. My interest in this, is the preservation of historic buildings- so I already know a little bit about this subject.--Aspro (talk) 22:10, 29 May 2016 (UTC)

Then you would know that 40% is too dry. Andy Dingley (talk) 22:33, 29 May 2016 (UTC)

Disagree. 35% may be too low (dries out nasal passages and makes one more prone to cold viruses etc.) but 40? --Aspro (talk) 20:40, 30 May 2016 (UTC)

40% is unpleasant. Certainly bad for books. If you have a general climate much above this, then the main problem will be movement in timber. It's not the absolute humidity that's the problem, it's the changes that timber is subject to.

40% could be acceptable in winter. There are relative humidity values and as a Western European I have a maritime climate, so I think of low RH as being due to low absolute humidity. In the continental USA, then it could also be due to the very low Winter temperatures and although it's still a low RH (and timber will move on that basis) but it's a higher absolute humidity. Andy Dingley (talk) 21:42, 30 May 2016 (UTC)

With respect: Can see where your coming from but I think you are too influenced by book learning than practical experience. Even articles.mercola.com/sites/articles/archive/2014/01/13/low-humidity-health-effects.aspx Mercola] has sussed it out.--Aspro (talk) 21:57, 30 May 2016 (UTC)

For modern houses, this is generally a lack of ventilation. A major source of damp, if unventilated, is the inhabitants just breathing. In a sealed house, this is enough to cause damp. Then there's laundry and showers.

So basically the OP is right, about modern houses? They are simply over-insulated, and need to be made less heat efficient by leaving windows open? 82.6.151.23 (talk) 11:47, 30 May 2016 (UTC)

Ventilation isn't the same thing as insulation. But yes, providing _enough_ ventilation becomes a problem in modern houses, especially when they're mis-operated. An obsession with "draughts" (even in an already warm house) can lead occupiers to close down everything controllable, or to tape over essential trickle vents, then cause damp problems for themselves. Some years back I worked in housing with a "difficult" client group. We'd see things like newly refurbished groups of flats in really good modern condition growing mould inside within months because people would cook without ventilation. "I don't like the noise of the extractor fan" was a common complaint. Or they'd install tumble driers without venting them outside.

To ventilate in a really heat efficient manner can involve things like heat exchangers and all ventilation being forced draught through them. Easier to achieve in an office (with locked windows!) than a domestic house. Andy Dingley (talk) 12:55, 30 May 2016 (UTC)

• Yes, this sums up the gist of the problem. When OPEC created the 1973 oil crisis, the government via press and TV, misguided people on how to economize on fuel... So the sheeple's mindlessly abandoned the wisdom of their old fashion parents . They alone now, suffer from mould. Try an enlighten them and they fall back on the fallacy of argument from authority (i.e., journalists that know dam all about anything) , because that is what they have been told to believe and choose to blame their landlord instead, for the problems they alone are creating for themselves.--Aspro (talk) 21:32, 30 May 2016 (UTC)

In an older house, the cause (due to insulation) can often be added cavity wall insulation. Uninsulated cavities have often been insulated since the 1970s with added insulation as blown polystyrene beads or blown fibres. These (unlike cavities built with insulation) no longer have the cavity gap which stops moisture crossing between the leaves of the wall. As a result they can have terrible problems with penetrating damp. There are many instances of lawsuits against installers and industry schemes to pay the costs of removing inappropriate added insulation. Andy Dingley (talk) 22:20, 29 May 2016 (UTC)

Would the solution be to put insulation panels on the outside wall of the house, perhaps covered up with a coat of render afterwards? Or are they not solid enough to last if you did that? 82.6.151.23 (talk) 11:47, 30 May 2016 (UTC)

Insulate within the wall, by replacing the wall, on the inside face of the wall or outside? All have drawbacks. Inside insulation reduces space and can cause overlaps around doors or windows. There's also the problem of cold bridges (gaps in the insulated shell). If there's space outside, and appearance isn't an issue, then external clad insulation, rendered over, is reckoned to be possibly the best way of doing this. The Yellow House project [3] is a good write-up of doing this to a UK terrace. Andy Dingley (talk) 13:03, 30 May 2016 (UTC)

Another problem is that blown-in insulation can cause fires in older homes, where wires in the walls rely on the air gap for cooling. These air gaps were there for a reason after all, not just because the original builder forgot to add insulation. StuRat (talk) 22:41, 29 May 2016 (UTC)

That's American practice, where fire is seen as an acceptable consequence of using electricity. In Europe we do it better. Andy Dingley (talk) 12:57, 30 May 2016 (UTC)

It's hard for rocks to catch fire. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:21, 30 May 2016 (UTC)

Is coal not a rock? When coal burns, is it not often difficult to extinguish? Coal seam fire. There are places on this planet where the ground just spontaneously catches fire.--Aspro (talk) 21:45, 30 May 2016 (UTC)

Is the the stone of stone houses commonly coal? Sagittarian Milky Way (talk) 01:04, 31 May 2016 (UTC)

Reading all of the above, I nominate this whole train-wreck of a section as THE worst bunch of "answers" (i use the term loosely) I've seen on the science reference desk for a long time. From Aspor's loony conspiracy theory rant, to Sturat's usual "useless facts pulled directly from his butt", and not a single relevant reference in sight, just up and down a complete shamozzle. Any budding prospect contributors would do well to study the above, as a fantastic lesson of how NOT to answer questions on the wiki ref desks. Vespine (talk) 00:25, 31 May 2016 (UTC)

And since you've provided no useful information to the OP, while attacking other editor, your own comments would need to be included in that "what not to do" study. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:52, 31 May 2016 (UTC)

I'd have added Marshall & Worthing's The Construction of Houses as a standard introduction (UK practice) or their Understanding Housing Defects in more detail (a whole chapter on damp and its issues). But "book learning" is seemingly unwelcome here. Andy Dingley (talk) 09:31, 31 May 2016 (UTC)

This publication & chapter you quoted appears to support what I have been saying: [4]. And yes, I grant you -it is a book. You say you have added this Marshall & Worthing ref but you failed to mention to which article(s).--Aspro (talk) 19:41, 31 May 2016 (UTC)