Wall insulating paint

Johnandabby

Electrical resistance as an analogy?? Don't think I've got the energy after reading such an awful argument to point out all the flaws in the argument..... Bottom line is that there will be no noticeable improvement by applying paint to walls. Don't waste your time with the cowboys, just insulate your property properly with PROVEN insulation.

If it was genuine then it would be certified by the BRE and other genuine institutions . . . but it's not!

zeupater

DaveAt168 wrote: »

Let us start by being fair. Applying a 2mm coat of this paint to a 100mm wall covering of expanded polystyrene will make absolutely no difference.
Applying it though to 9" of solid brickwork, or worse, 4.5", will make a HUGE difference.
We have the same problem with the supergreens.
Starting with bare bricks, the first 2mm of insulation makes an enormous difference.
Think of it as an electrical circuit, the temperature difference being the voltage, the heat leakage, the current, and the insulation, the resistance.
For argument, shall we say that the resistance of brick is 1 ohm/mm, while that of polytyrene foam is 1000 ohm/mm.
The solid brickwork, at 9", or 220 mm is then 220 ohms, while the resistance of the polystyrene foam, at 2 mm is 2000 ohms.
The insulated wall section now has a resistance of 2220 ohms, which, you can see is equivalent to increasing the wall thickness to 90",
That is, the insulation is increased by a factor of 10, so the heat loss is reduced by 90%.
Doubling the insulation to 4 mm will then reduce the loss from 10% to 5%, and so 40mm will reduce it to 1%.
So, you can see, the first 2mm of insulation achieves five times more than sticking 4" of insulation on the walls.
If you are in the situation, then of having solid brick or stone walls, and you do not want to lose valuable room space by dry-lining, then, if you can apply a coating, shall we say with a resistance of say 10 ohms/mm, then a 2mm coating of this paint will raise the resistance from the basic 220 ohms to 260 ohms. Not an incredible increase, but for the same voltage, the drain will be reduced by about 15%, or turning that on its head, for the same heat loss, the temperature drop through the wall will be increased by 18%.
Shall we say the outside temperature is freezing, or 0 ̊C, and the heat setting, before the insulation was applied, resulted in a room temperature of 20 ̊C, then the inside surface of that wall will increase by about 4 ̊C.
These figures seem to match the values claimed by most of these additive manufacturers.
Their claims, with in their context seems to be entirely plausible.

The more paint you can slap on, the better.
And yes, a top coat of untreated paint is a good idea.

As a cheaper alternative to the customary dry-lining, (do you remember those dreadful polystyrene ceiling tiles, so lethally applied to kitchen ceilings?) We covered the exterior wall, from the skirting to the ceiling with these tiles, including the window reveals, then, when the tile were secure, we slapped old emulsion paint on the new inner surface, then dabbed, and dotted 8 mm plasterboard straight on top of these tiles, the boards horizontal, standing on the old skirting boards. By good chance, these boards were flush with the old skirting boards, and we simply nailed new skirting boards on top of the old ones. Voila! Job done. Simple, took less than a weekend.
If you take drying time out, less than half a day. If you go bak to paragraph 1, and consider that these ceiling tiles were 6 mm thick, this reduced the heat loss by over 90%. The devil can argue over how to subdivide that remaining 10%. The house need ventilation anyhow, and even heat recovery ventilators are only about 60% efficient. That 10% is down in the noise. You can fight over it, it is the 90% which concerns me.

Hi All

There's a simple sanity check on this one .... The thermal performance of a brick 220mm single skin wall (R-Value is) ~0.44W/sqm/C & polystyrene 6mm would be ~0.08W/sqm/C .... the calculation for electronics would be the same as adding resistors in series, therefore the addition of the polystyrene would reduce heatloss by 18%(8/44), not 90% .... a coat of paint is also ~0.1mm, not 2mm, so the insulative property of the paint would be a factor of 20x lower/coat, or the total cost of the paint would be 20x higher with 20 coats ...

Let's now look at the electrical terms analogy above .... If brick is taken as 1 Ohm/mm then 220mm of brick=220 Ohm, so in agreement so far. However, there is a complete issue with the relative resistance for polystyrene being 1000 Ohm/mm ... it would be much more realistic to say that it would be 7 ((0.08*(220/6))/0.44), therefore adding 2mm of polystyrene would have the effect of increasing the resistance of the wall from 220 Ohm to 234Ohm (220+(7x2)), the equivalent of increasing the wall thickness by 6.4%(234/220), not by 900% (90"/9") ...

Okay, so let's now look at the paint. I've no idea what the thermal resistance of the (so called & claimed) 'heat-saving' paint is, so let's be generous and say it's as good as polystyrene (:rotfl:), so it has a resistance of 7Ohm/mm and is two coats thick (0.2mm), then the resistance of the wall is increased from 220 to 221.4 (220+(7*0.2)), that's much lower than the 260 Ohms calculated, and of course, the paint is very unlikely to have anywhere near the thermal resistance of polystyrene ....

So overall nothing for anyone to fight over ..... it's just that the figures used in the analogy to support the hugely overstated effectiveness of the paint were themselves hugely overstated ....

.... This Mythbusted ?? ....

HTH
Z

DaveAt168

Ok, the figures were purely imaginary, and I thought them, from experience to be reasonable.
From some American figures, the actual values are unimportant, as this is a relative comparison...
Brick = 0.1 ohms/mm
PolyFoam = 5.0 ohms/mm
Air = 0.9 ohms/mm
DryWall = 0.4 ohms/mm
Assuming a fixed area.
Then, what is the improvement by adding 6mm of PolyFoam + 10mm of Dry wall + 2mm of uncontrolled air, ignoring the dots.

Well, the wall is 220 mm thick, so, that is 0.1 x 220 = 22 ohms.

That then is the reference.

Let us now add 6 mm of PolyFoam, that is 6 x 5 = 30 ohms.
Then 2 mm of still air, that is 2 x 0.9 = 1.8 ohms.
Then 10 mm of DryWall, that is 10 x 0.4 = 4 ohms.

What we now have is 22 + 30 + 1.8 + 4 = 57.8 ohms.

I can't help feeling that the R values for air and foam are pessimistic, but I accept I could be wrong.
Nevertheless, this simple procedure improves the situation, reducing heat loss by nearly 2/3. It certainly feels better than that, but I will not argue with the numbers.

To achieve the 90% improvement, which I would still call the best criterion, unless you are going in for heat-pump thermal recovery ventilation, you would then need, for the 9" bare bricks standard,
8 x 22 = 176 ohms of PolyFoam, which at 5 ohms/mm, would require 176 / 5 = 35.5 mm.

So 100 mm is GROSS overkill unless you are going to use heat pumps. Remember, they also consume power.

So back to the microbeads.
Yes, if the paint layer is 0.2mm, then the gain will be microscopic, but the beads are quite large, and I would expect the layer, after 2 or 3 coats to be more than 1 mm, getting on for 2 mm.

From the above, I would estimate then the relative resistance of the bead filled paint to be about 2 ohms/mm, so the 2mm coating would give about 4 ohms.

If, as devil's advocate, we say 3 ohms, because the layer may not achieve 2 mm, then the improvement is from 22 ohms to 25 ohms.
25 / 22 = 1.136 or about 13% improvement. This is the ballpark claim made by the manufacturers, and so is NOT unreasonable.

An improvement as small as this could be the difference between condensation forming on an outside wall, and it not forming.

zeupater

DaveAt168 wrote: »

Ok, the figures were purely imaginary, and I thought them, from experience to be reasonable.
From some American figures, the actual values are unimportant, as this is a relative comparison...
Brick = 0.1 ohms/mm
PolyFoam = 5.0 ohms/mm
Air = 0.9 ohms/mm
DryWall = 0.4 ohms/mm
Assuming a fixed area.
Then, what is the improvement by adding 6mm of PolyFoam + 10mm of Dry wall + 2mm of uncontrolled air, ignoring the dots.

Well, the wall is 220 mm thick, so, that is 0.1 x 220 = 22 ohms.

That then is the reference.

Let us now add 6 mm of PolyFoam, that is 6 x 5 = 30 ohms.
Then 2 mm of still air, that is 2 x 0.9 = 1.8 ohms.
Then 10 mm of DryWall, that is 10 x 0.4 = 4 ohms.

What we now have is 22 + 30 + 1.8 + 4 = 57.8 ohms.

I can't help feeling that the R values for air and foam are pessimistic, but I accept I could be wrong.
Nevertheless, this simple procedure improves the situation, reducing heat loss by nearly 2/3. It certainly feels better than that, but I will not argue with the numbers.

To achieve the 90% improvement, which I would still call the best criterion, unless you are going in for heat-pump thermal recovery ventilation, you would then need, for the 9" bare bricks standard,
8 x 22 = 176 ohms of PolyFoam, which at 5 ohms/mm, would require 176 / 5 = 35.5 mm.

So 100 mm is GROSS overkill unless you are going to use heat pumps. Remember, they also consume power.

So back to the microbeads.
Yes, if the paint layer is 0.2mm, then the gain will be microscopic, but the beads are quite large, and I would expect the layer, after 2 or 3 coats to be more than 1 mm, getting on for 2 mm.

From the above, I would estimate then the relative resistance of the bead filled paint to be about 2 ohms/mm, so the 2mm coating would give about 4 ohms.

If, as devil's advocate, we say 3 ohms, because the layer may not achieve 2 mm, then the improvement is from 22 ohms to 25 ohms.
25 / 22 = 1.136 or about 13% improvement. This is the ballpark claim made by the manufacturers, and so is NOT unreasonable.

An improvement as small as this could be the difference between condensation forming on an outside wall, and it not forming.

Hi

A very quick observation .... brick suddenly moved within the analogy from a relative 1 Ohm/mm to 0.1 Ohm/mm, which seems to suggest that the material has changed from brick to breezeblock ...

Relative Thermal conductivity
(http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html)
Breeze block 0.10 - 0.20
Brick dense 1.31
Brickwork, common 0.6 -1.0
Brickwork, dense 1.6

.... this would seem to suggest that the benefit of the painted surface with a coating of 2mm would be overstated by a factor of 10 against a 220mm single skin brick wall as originally stated for the analogy ...

Now for the coating ... to enable two coats totalling somewhere around 0.2mm thick, it's pretty easy to calculate that with the volume of dry paint being 0.2l (((1000x1000)x0.2)/(1000x1000)) and allowing for a nominal 33% by volume of water(/solvent) then 0.3litres (0.2/.66) of paint would be required for each sqm of coated surface .... therefore to achieve a 2mm net thickness coating coverage would be ~3 litres of paint for each square metre of painted surface ... considering that this type of paint would seem to typically be ~£10/litre, that's £30/sqm to achieve the claimed performance mentioned in the post above ... this is probably not considered to be a 'reasonable' expenditure for the heat retention performance gain (analogy 2 Ohm), even based on what, due to thermal bridging effect caused by the paint solids, would likely be a very optimistic thermal performance.

In previous discussions reference has been made to specific brands of this type of paint which claim that two coats cover 'up to' 35sqm per 5l, therefore the total thickness could be no more than 0.1mm (((1/3)/(35/5))*2), therefore, even if the the abovereferenced post for a 2mm thick paint covering is in line with saving claims ... quote "about 13% improvement. This is the ballpark claim made by the manufacturers, and so is NOT unreasonable." ... and is considered reasonable, then the manufacturer's claim for two coat coverage of 35sqm per 5l, (therefore 0.1mm thickness), could only achieve 5%(0.1/2) of this potential and therefore the consumer's reasonable expectation of insulating performance/cost would not be correct .... it's not possible to balance the equation for product cost or performance using reasonable parameters, therefore it's simply 'not reasonable' to use an analogy based on Ohms law to apply any form of credibility to a product which can make little difference to overall heatloss unless unreasonable quantities are used, at an unreasonable cost.

Regarding the the painted surface-to-internal air heat exchange relative to the dewpoint at a point in time .... reducing the initial thermal gradient will cause the painted surface to be maintained at a (slightly) higher temperature, but would only delay condensation until the dewpoint differential is reached relative to the increased surface temperature, therefore the only logical solution to condensation/mold would be to reduce the humidity, ie increase ventilation, whether that involves heat recovery or not ...

HTH
Z

c111

Beware of this stuff. I bought quite a lot when I was doing my front room. Put about three coats on and then painted. I didnt really feel much difference in the room, but I knew it seemed unlikely when I bought it. HOWEVER, now 6 months later, the plaster on all my walls has started to pop off the brickwork. It stayed up for 70 years and now its popping everywhere. I am only guessing, but it seems that moisture is getting trapped between the brickwork and the plaster coat. It might be coincidence but I feel there is a good chance that this warmcoat paint is stopping moisture movement, and blocking the moisture behind the plaster. I am having to rip it all off and re-plaster now. beware.

ellajuk

Thanks for that vital information C111 I was reading about this stuff over a year ago, and thought hmm ...., how can something thin keep a room warm, I can understand the reasons behind reflective foil but in this case it seems that this paint is maybe just like putting a layer of plastic over the wall and trapping moisture.

I had a very cold external east wall in my spare room which felt as cold as ice to the touch. But oddly having read things about putting layers on to trap heat and keep oneself warm made me opt putting some thick foam type wallpaper up in that room, the theory being that the particles of foam would trap the air yet being also allowing the wall to breathe be it slowly. Now feeling the wall in the winter months it is certainly lots warmer.

I hope that your experience is of value to others who are considering this type of paint.