Ceiling Insulation

[sometimewoodworker]

9 hours ago, NorthernRyland said:

 

So basically the trade off with the metal roof is you're taking on more heat during the day but releases faster at night. This all relies on the ceiling insulation being of the highest quality also.

No that is not correct. The insulated metal roof doesn’t magically take on more heat than the insulated concrete roof 

 

The heat received by both is equal, the metal roof will reach equilibrium faster than the concrete roof (equilibrium being the point at which heat leaving the roof is equal to that arriving at the roof) take away the heat source (sun down) and the temperature will drop immediately.

 

The concrete roof will reach equilibrium much slower that the steel one due to the much greater thermal mass of the roof, this however is a problem in countries like Thailand where the thermal mass, that is a great benefit in cold climates, stores and releases the daytime heat long into the night.

10 hours ago, NorthernRyland said:

What do you think about the metal roof panels with foam inserted in the middle? I guess that has the same problem of trapping heat though if it does pass through.

We have just recently roofed the outside kitchen and dog house with these. They trap heat generated from under the allow little to be transmitted from above. The significant advantage is that the insulation doesn’t deteriorate as it is enclosed. Our previous roof had the insulation drop off after a few years while the roof rusted through.

[NorthernRyland]

35 minutes ago, sometimewoodworker said:

No that is not correct. The insulated metal roof doesn’t magically take on more heat than the insulated concrete roof 

 

The heat received by both is equal, the metal roof will reach equilibrium faster than the concrete roof (equilibrium being the point at which heat leaving the roof is equal to that arriving at the roof) take away the heat source (sun down) and the temperature will drop immediately.

 

The concrete roof will reach equilibrium much slower that the steel one due to the much greater thermal mass of the roof, this however is a problem in countries like Thailand where the thermal mass, that is a great benefit in cold climates, stores and releases the daytime heat long into the night.

10 hours ago, NorthernRyland said:

 

OK so the roof reaches equilibrium faster and at that point the heat is being transferred in to your house. That's the trade off.

 

I've seen roof tiles that look almost plastic to me (very lightweight at least) which probably have this similar property. Anyone seen these? I can think of one building, I'll try to take a picture next time I see it.

[superal]

20 minutes ago, sometimewoodworker said:

No that is not correct. The insulated metal roof doesn’t magically take on more heat than the insulated concrete roof 

 

The heat received by both is equal, the metal roof will reach equilibrium faster than the concrete roof (equilibrium being the point at which heat leaving the roof is equal to that arriving at the roof) take away the heat source (sun down) and the temperature will drop immediately.

 

The concrete roof will reach equilibrium much slower that the steel one due to the much greater thermal mass of the roof, this however is a problem in countries like Thailand where the thermal mass, that is a great benefit in cold climates, stores and releases the daytime heat long into the night.

We have just recently roofed the outside kitchen and dog house with these. They trap heat generated from under the allow little to be transmitted from above. The significant advantage is that the insulation doesn’t deteriorate as it is enclosed. Our previous roof had the insulation drop off after a few years while the roof rusted through.

Happened to me too . Inferior materials do not last . Cheap materials may save money initially and appear to be similar to the more expensive ones . That is why I would only buy Bluescope insulated roof panels .

     Fact , metal roof noise from the rain depends on the steepness of the roof I.E. A flat metal roof will be much noisier than a steep roof . What surprises me is that in Thailand there is little consideration given to venting the hot air from the attic , even with new buildings .  Solar powered whirly bird vents fitted on the roof would have reduce the loft heat substantially and in turn make the house cooler plus reduce Aircon running costs . 

[sometimewoodworker]

1 hour ago, NorthernRyland said:

OK so the roof reaches equilibrium faster and at that point the heat is being transferred in to your house. That's the trade off.

You miss understand the meaning of equilibrium.
 

A roof has in essence 2 sides the top receives heat, the bottom (if you are sensible has insulation so radiates little heat.

Once equilibrium is reached the top side will be loosing heat by radiation and convection at almost the same rate as the sun is radiating heat to it, not quite the same as some is being lost into the roof.

 

The quality and thickness of the insulation on the underside some heat will be transferred to the house though the percentage will be much smaller than the heat lost from the top.

The heat transfer from the metal roof stops very shortly after it stops being heated by the sun.

_—————-_

with a concrete roof the amount of heat being transferred into the house is smaller at the beginning of the day while the roof is heating up. However the heat transfer to the house extends hours into the night while the thermal mass of the roof cools down

Edited April 20 by sometimewoodworker

[NorthernRyland]

1 hour ago, sometimewoodworker said:

with a concrete roof the amount of heat being transferred into the house is smaller at the beginning of the day while the roof is heating up. However the heat transfer to the house extends hours into the night while the thermal mass of the roof cools down

 

well if you can prevent the house from heating during the day using insulation on the ceiling than it's a win. I'm very skeptical you can insulate the ceiling well enough to cope with a metal roof but in theory it's possible.

[CharlesHolzhauer]

On 4/17/2024 at 9:33 AM, NorthernRyland said:

What's a better solution? I guess you can do foam insulation metal sheeting but that's kind of ugly if nothing else.

I, for one, prefer the most efficient and practical solution, which involves metal sheeting with appropriate insulation material. Personally, I would opt to live in a safari tent-type house rather than a dwelling covered in cement tiles

[sometimewoodworker]

22 hours ago, NorthernRyland said:

 

well if you can prevent the house from heating during the day using insulation on the ceiling than it's a win. I'm very skeptical you can insulate the ceiling well enough to cope with a metal roof but in theory it's possible.

Of course it’s rather expensive to insulate any Thai roof so that you get no daytime heat gain.

 

However it’s not at all difficult to insulate any roof be it metal or concrete to reduce the heat gain to a manageable level. The problem with concrete is that you get the heat gain during a rather unfavourable period.

 

My roofing is all metal and I can assure you that it is not only a theoretical possibility to insulate to a good level but I have done so and my roofing is an example of how easy it is to do it.

 

FWIW Without AC the interior of the house is on average 10C lower than the daytime high, and with an AC unit that most would consider to be significantly undersized (316 BTU sqm) it’s not difficult, given enough time, to drop the temperature by 20C, I don’t drop the temperature to be polar bear or penguin friendly but could if I wanted to.

Edited April 21 by sometimewoodworker

[NorthernRyland]

7 hours ago, sometimewoodworker said:

My roofing is all metal and I can assure you that it is not only a theoretical possibility to insulate to a good level but I have done so and my roofing is an example of how easy it is to do it.

 

 

As mentioned I got a picture of that roof last night. It's in the mountains at about 1000m elevation. This material looks light and probably doesn't store much heat. Looks good to me but I don't know what it is even.

 

 

[4MyEgo]

On 4/19/2024 at 6:12 PM, sometimewoodworker said:

You did rather ignore the fact that a concrete roof will continue to radiate heat for a much longer period than metal one. And while insulation will reduce the amount radiated into the roof spaces it doesn’t eliminate it. 
 

The rain noise will be greater on metal than concrete but you will still get some.

 

The heat is in the attic/roof space, it doesn't come through the insulation batts and insulation blanket, the whirly birds do a great job extracting the heat from the attic/roof space and if you have a gable roof, having those saloon door style vents assists in allowing the air to move around, therefore creating a sort of vacuum for the air to get sucked up and out of the whirly birds.

 

I am not here to convince you, suffice to say if I stick my head up into the manhole, I can feel the air moving at a pace and I can see the whirly birds spinning. Someone once said to me, but you need wind to move the whirly birds to which I replied, mine spin 24/7, no need for wind, as long as there is hot air in my attic/roof space, they spin.

 

You say, the metal roof doesn't heat up as fast as the concrete tiles, or doesn't hold the heat for as long as the concrete tile does, to me it doesn't matter, when I tested all 3, the concrete tiles took the longest, I didn't test if it would hold the heat for longer, I was looking for something to take longer for the heat to penetrate, couple that with thermal reflective sissolation, insulation batts, whirly birds, vented eaves and those saloon style door slates, the hot air is being removed from the attic/roof space and I don't get the sound of rain coming into the house, let alone know when it's raining because we here nothing having concrete tiles.

 

At the end of the day, everyone researches things according to what they want, that said, we are very comfortable and glad we went the way I decided to go, and if you asked me if I would replace the concrete tiles with metal sheeting tomorrow if needed, my answer would be no, because the rain noise issue was looked into as well when I was looking into the roof tiles.   

[sometimewoodworker]

45 minutes ago, 4MyEgo said:

You say, the metal roof doesn't heat up as fast as the concrete tiles,

Again you are misquoting I said Exactly the opposite 

 

45 minutes ago, 4MyEgo said:

or and doesn't hold the heat for as long as the concrete tile does

Corrected wording 

45 minutes ago, 4MyEgo said:

when I tested all 3, the concrete tiles took the longest

 

That is absolutely true but irrelevant 

45 minutes ago, 4MyEgo said:

I was looking for something to take longer for the heat to penetrate

Again it is true but it fails to address the point

 

45 minutes ago, 4MyEgo said:

I didn't test if it would hold the heat for longer

It not only holds the heat for very significantly longer but because of that it gives a greater total heat load into the roof space.

 

If your insulation, ventilation etc doesn’t allow your ceiling to heat up at all the fact that you get a greater heat load above the ceiling means that any roof material is perfectly OK. That however would be a very unusual situation as usually nobody bothers with that level of insulation 

Edited April 21 by sometimewoodworker

[4MyEgo]

On 4/21/2024 at 8:50 PM, sometimewoodworker said:

If your insulation, ventilation etc doesn’t allow your ceiling to heat up at all the fact that you get a greater heat load above the ceiling means that any roof material is perfectly OK. That however would be a very unusual situation as usually nobody bothers with that level of insulation 

 

Most foreigners that I have spoken to don't bother with insulation, let alone sissolation, and their reason being, it costs money and they are better off with the air conditioner going all day and night.

 

Now who would I be to try and educate the uneducated, so to speak.

 

You are correct when you say it is very unusual, however as I mentioned, it is not only the sissolation and insulation that gets rid of the heat load, you also have to have whirly birds, vented eaves and those saloon style looking slated door vents on a gable roof, mine having an attic clearance of 5 metres at its peak, also I didn't mention, we have high ceilings, i.e. 3.3 metres, which also helps. 

 

 

 

Edited April 26 by 4MyEgo

[superal]

16 hours ago, 4MyEgo said:

 

Most foreigners that I have spoken to don't bother with insulation, let alone sissolation, and their reason being, it costs money and they are better off with the air conditioner going all day and night.

 

Now who would I be to try and educate the uneducated, so to speak.

 

You are correct when you say it is very unusual, however as I mentioned, it is not only the sissolation and insulation that gets rid of the heat load, you also have to have whirly birds, vented eaves and those saloon style looking slated door vents on a gable roof, mine having an attic clearance of 5 metres at its peak, also I didn't mention, we have high ceilings, i.e. 3.3 metres, which also helps. 

 

 

 

Solar whirly birds ? , did you fit yourself ?