R Values And Roofing "foil" Insulation

[gdhm]

I visited HomePro today to check out what is best for my new home and am totally confused.

I looked at the offerings expecting the R Values to be the significant factor of which was best. However

one make sold two versions BOTH had identical emissivity figures of 0.03 and reflectively of 97% but their R values were different.

I expected them to be the same if those two figures were identical. Please can someone tell me what I am not understanding and what IS/ARE the MOST relevant figure for stopping HEAT transmission.

AM I correct in thinking that a "foil" under the roof tiles AND a "foil" on the floor of th attic would be beneficial or do members think having BOTH is a minor advantage for keeping out heat

Thanks

Dave

[Rimmer]

Foil under the tiles but no ceiling insulation as heat from the walls rises through the ceiling into the roof roof space where it should be vented outside.

If you have ceiling insulation the upper part of the rooms must be vented to prevent heat build up in individual rooms.

That's the way I have done it and the place is like a meat locker

[gdhm]

Foil under the tiles but no ceiling insulation as heat from the walls rises through the ceiling into the roof roof space where it should be vented outside.

If you have ceiling insulation the upper part of the rooms must be vented to prevent heat build up in individual rooms.

That's the way I have done it and the place is like a meat locker

That's good news Rimmer thanks I did not think of that. It will save me money as well or I can pay for a better quality foil under the roof tiles.

Any suggestion on R value that is best whilst being relatively cost effective before I pay big for each tiny improvements (law of diminishing returns I think its called)

Regards

Dave

[lannarebirth]

Foil under the tiles but no ceiling insulation as heat from the walls rises through the ceiling into the roof roof space where it should be vented outside.

If you have ceiling insulation the upper part of the rooms must be vented to prevent heat build up in individual rooms.

That's the way I have done it and the place is like a meat locker

That's interesting and absolutely the opposite of what I would have thought. I would have thought that the tile insulation would be of marginal value, but deep ceiling batt insulation would have been of great benefit to stop the transfer of heat from the ceiling space to the home. I would think forced ventilation of that space would be a must as well.

[johnliu]

Foil under the tiles but no ceiling insulation as heat from the walls rises through the ceiling into the roof roof space where it should be vented outside.

If you have ceiling insulation the upper part of the rooms must be vented to prevent heat build up in individual rooms.

That's the way I have done it and the place is like a meat locker

That's interesting and absolutely the opposite of what I would have thought. I would have thought that the tile insulation would be of marginal value, but deep ceiling batt insulation would have been of great benefit to stop the transfer of heat from the ceiling space to the home. I would think forced ventilation of that space would be a must as well.

[johnliu]

Foil under the tiles but no ceiling insulation as heat from the walls rises through the ceiling into the roof roof space where it should be vented outside.

If you have ceiling insulation the upper part of the rooms must be vented to prevent heat build up in individual rooms.

That's the way I have done it and the place is like a meat locker

That's interesting and absolutely the opposite of what I would have thought. I would have thought that the tile insulation would be of marginal value, but deep ceiling batt insulation would have been of great benefit to stop the transfer of heat from the ceiling space to the home. I would think forced ventilation of that space would be a must as well.

foil will only works if it is not covered with dust,but in bkk,within 3 months,the top layer of the foil will be covered with dust,as such,it will not reflect any heat,be it up the roof or down the ceiling...thus i think most important is ensure there is a gap between the roof and the false ceiling and do not seal up the edges so that air can flow through

[gdhm]

Foil under the tiles but no ceiling insulation as heat from the walls rises through the ceiling into the roof roof space where it should be vented outside.

If you have ceiling insulation the upper part of the rooms must be vented to prevent heat build up in individual rooms.

That's the way I have done it and the place is like a meat locker

That's interesting and absolutely the opposite of what I would have thought. I would have thought that the tile insulation would be of marginal value, but deep ceiling batt insulation would have been of great benefit to stop the transfer of heat from the ceiling space to the home. I would think forced ventilation of that space would be a must as well.

foil will only works if it is not covered with dust,but in bkk,within 3 months,the top layer of the foil will be covered with dust,as such,it will not reflect any heat,be it up the roof or down the ceiling...thus i think most important is ensure there is a gap between the roof and the false ceiling and do not seal up the edges so that air can flow through

What about the UK style fibre glass insulation which does nto rely on reflection. I believe you can buy it here sealed (be it only 5 cms or so thick) so vermin (if they get into the roof area cannot shred it.

If no dust settling on the foil surface is essential then I assume the thicker foils with plastic bubble wrap inside are more desirable than thin reflective foil because dust is bound to settle on foil very quickly and few will go into the loft space ever to clean it.

Personally guessing on Rimmer's comments I would have thought concerns over heat transfer from upstairs rooms to the attic were minimal being that I would expect the roof area (with ventilation) to be much hotter therefore stopping transfer from attic to bedroom I would have thought was the ideal.

IF cold weather then the attic WILL be colder but then you are likely to be happy with a littel heat heat being retained in bedrooms.

Dave

[Smithson]

Foil under the tiles but no ceiling insulation as heat from the walls rises through the ceiling into the roof roof space where it should be vented outside.

If you have ceiling insulation the upper part of the rooms must be vented to prevent heat build up in individual rooms.

That's the way I have done it and the place is like a meat locker

That's interesting and absolutely the opposite of what I would have thought. I would have thought that the tile insulation would be of marginal value, but deep ceiling batt insulation would have been of great benefit to stop the transfer of heat from the ceiling space to the home. I would think forced ventilation of that space would be a must as well.

I think you are correct, insulate the ceiling rather than the roof. Heaps of ventilation in the ceiling is a must also. The idea to not insulate the ceiling so that hot air can pass thru doesn't sound to good, but I would definitely have heaps of ventilation in the highest parts of the room.

The dust issue is also blown out of proportion. There has been a lot discussion about color bond roofing and foil insulation on www.coolthaihouse.com.

I wouldn't copy what they're doing in England, because the climate is nothing like here.

[gdhm]

...Heaps of ventilation in the ceiling is a must also. The idea to not insulate the ceiling so that hot air can pass thru doesn't sound to good, but I would definitely have heaps of ventilation in the highest parts of the room...

Hi ,

I don't see how I can ventilate the highest parts of the upper rooms as that will defeat the air conditioners in the bedrooms Have never seen it in new build houses here either. I think normal windows will have to do.

To be honest even in my rental I find the outside often hotter (just) than the upper rooms EXCEPT a while after sundown comes then it reverses and only then would one like to let some heat out but the aircons remove it within tow minutes anyway.

However, our upper bathroom that has open vented windows all the time is hotter (most of the time) than the bedrooms (except after sun down).

I personally am unconvinced that on balance ventilation in upper rooms is desirable vs undesirable. Up here in Khon Kaen City outside temperature are high much of the year and I do not want to give outside heat direct access to the bedrooms.

Just MHO

Dave

[Smithson]

...Heaps of ventilation in the ceiling is a must also. The idea to not insulate the ceiling so that hot air can pass thru doesn't sound to good, but I would definitely have heaps of ventilation in the highest parts of the room...

Hi ,

I don't see how I can ventilate the highest parts of the upper rooms as that will defeat the air conditioners in the bedrooms Have never seen it in new build houses here either. I think normal windows will have to do.

To be honest even in my rental I find the outside often hotter (just) than the upper rooms EXCEPT a while after sundown comes then it reverses and only then would one like to let some heat out but the aircons remove it within tow minutes anyway.

However, our upper bathroom that has open vented windows all the time is hotter (most of the time) than the bedrooms (except after sun down).

I personally am unconvinced that on balance ventilation in upper rooms is desirable vs undesirable. Up here in Khon Kaen City outside temperature are high much of the year and I do not want to give outside heat direct access to the bedrooms.

Just MHO

Dave

If you're using air con in the rooms then you definitely want insulation in the ceilings and you're correct about the problem of adding ventilation in an air con room.

While I use air con, I like the idea to minimize it's necessity. The problem with your upstairs bathroom may have to do with the sun hitting the windows or maybe it's something to do humidity from the water, because my bathroom always seems hot. If you've found a way to keep your upstairs bedrooms cooler than a shaded area outside, I would be interested to hear how it's done.

If you look at the traditional way of building here, you'll see bedrooms are upstairs but ppl don't use them in the day, as they're too hot. In Issan most ppl spend the day outside in the shade, then at night when things cool down they head indoors. Having ventilation in the upper rooms will allow the rooms to cool down at night and you may not need air con so often.

IMO there's too much western influence in building here. The only shaded areas in modern Thai houses is the carport, kitchens are located next to living rooms adding to the heat and all that concrete used stores heat which keeps the house hot at night.

[gdhm]

If you're using air con in the rooms then you definitely want insulation in the ceilings and you're correct about the problem of adding ventilation in an air con room.

So you think 2 lots reflective in the rafters and a blanket on the floor. I see sometimes people say reflective foil side down. I don't understand the logic. I know dust cannot settle but how can reflective foil reflect if not facing the direct of the heat source.

Despite what has been said about European insulation thinking not being appropriate here, I do not understand why not. For instance I still tend to think insulation is insulation (cold or hot) be it different types are more suitable for different situations. Apart from vermin nesting and chewing I still think glass fibre wool (if available here) is a very good cheap blanket and with a good R value if sealed and 6ins plus thick R value of 22 ish I believe.

It also should not be bothered about dust. This way what heat gets into the attic from above is blocked by the attic floor insulation. The vents in the attic should remove any heat trapped between the two.

We plan to use Qcon 7.5 cms thick brick inside and out our house and tinted windows (not too great a tinting).

Consequently "rightly or wrongly" I do not expect the bedroom temperatures to rise greatly from within or form downstairs so I do not fear insulation on the upper ceilings which I think will be plaster board or similar.

While I use air con, I like the idea to minimize it's necessity.

I am the other way round I like air-con very much, and being 146kilos now I need it. My desire with all these insulation ideas is to keep the house relatively cool and the consequent big savings needing the aircons to being cooling flay out all the time. I have not adapted to the sitting outside in the shade (still seems much too hot (and humid at times to be a pleasure). Its only the cost of electricity that prevents me using my air cons more (and the cost of aircons in Thailand - expensive compared to Spain's cold AND hot aircons.

The problem with your upstairs bathroom may have to do with the sun hitting the windows or maybe it's something to do humidity from the water, because my bathroom always seems hot. If you've found a way to keep your upstairs bedrooms cooler than a shaded area outside, I would be interested to hear how it's done.

I think it is as you say, plus outside air temperature getting in as well. You must have open windows some or all of the tiem to reduce smells and let humidity out.

I am placing my hopes on the Bathroom Q con walls being an effective barrier between the bathrooms and adjacent rooms. Should be as the inside of the house will not have as much heat on the internal walls as the outside

If you look at the traditional way of building here, you'll see bedrooms are upstairs but ppl don't use them in the day, as they're too hot. In Issan most ppl spend the day outside in the shade, then at night when things cool down they head indoors. Having ventilation in the upper rooms will allow the rooms to cool down at night and you may not need air con so often.

As mentioned above I myself like aircons (wife does not says it gets too cold - but good excuse for a cuddle then ). I do not fancy ventilation into the bedrooms as I feel the heat exchange would be outside to inside (except maybe at night when the aircons would be less efficient with vents to the outside.

IMO there's too much western influence in building here. The only shaded areas in modern Thai houses is the carport, kitchens are located next to living rooms adding to the heat and all that concrete used stores heat which keeps the house hot at night.

Well I designed the kitchen well then two outside walls and the other two are part hall and mostly two bathrooms. Have to be honest LUCK (did not think about heat (only cooking smells)

At least the roofs here usually have metre (or close) overhangs which act as a good shelter with the sun being so close to overhead most of the heating hours due to our proximity to the Equator

Regards

Dave

[Smithson]

So you think 2 lots reflective in the rafters and a blanket on the floor. I see sometimes people say reflective foil side down. I don't understand the logic. I know dust cannot settle but how can reflective foil reflect if not facing the direct of the heat source.

Despite what has been said about European insulation thinking not being appropriate here, I do not understand why not. For instance I still tend to think insulation is insulation (cold or hot) be it different types are more suitable for different situations.

Seen as you'll have air con the whole time then I can't really advise on exactly what type of insulation to use. What I meant about Euro insulation was don't simply copy what they have been doing, because the climate is much different. Generally they're trying to keep heat in, while you're trying to do the opposite. Your power bills will be high and elec charges will rise in the future, maybe dramatically.

Using Q blocks is definitely a good idea.

[gdhm]

So you think 2 lots reflective in the rafters and a blanket on the floor. I see sometimes people say reflective foil side down. I don't understand the logic. I know dust cannot settle but how can reflective foil reflect if not facing the direct of the heat source.

Despite what has been said about European insulation thinking not being appropriate here, I do not understand why not. For instance I still tend to think insulation is insulation (cold or hot) be it different types are more suitable for different situations.

Seen as you'll have air con the whole time then I can't really advise on exactly what type of insulation to use. What I meant about Euro insulation was don't simply copy what they have been doing, because the climate is much different. Generally they're trying to keep heat in, while you're trying to do the opposite. Your power bills will be high and elec charges will rise in the future, maybe dramatically.

Using Q blocks is definitely a good idea.

Yes I appreciate your comments and I was not trying to oppose them. I was not precise enough I meant I felt European type insulation for attic floors may be suitable but not for roof rafter insulation.

My logic (maybe wrong and simplistic). In the UK we try to keep the heat inside and cold in the attic out. I just tried applying reverse logic. Keep the heat inside the attic and keep the cool in the bedroom out of the attic. (upside down to UK -but not in summer- but seems to the same logic applies with glass fibre insulation anyway either way it works) I of course appreciate roofing insulation foils etc. are TOTALLY different as hot countries like Thai rely on reflective insulation (no good at all in a colder climate.

Regards

Dave

[Smithson]

So you think 2 lots reflective in the rafters and a blanket on the floor. I see sometimes people say reflective foil side down. I don't understand the logic. I know dust cannot settle but how can reflective foil reflect if not facing the direct of the heat source.

Despite what has been said about European insulation thinking not being appropriate here, I do not understand why not. For instance I still tend to think insulation is insulation (cold or hot) be it different types are more suitable for different situations.

Seen as you'll have air con the whole time then I can't really advise on exactly what type of insulation to use. What I meant about Euro insulation was don't simply copy what they have been doing, because the climate is much different. Generally they're trying to keep heat in, while you're trying to do the opposite. Your power bills will be high and elec charges will rise in the future, maybe dramatically.

Using Q blocks is definitely a good idea.

Yes I appreciate your comments and I was not trying to oppose them. I was not precise enough I meant I felt European type insulation for attic floors may be suitable but not for roof rafter insulation.

My logic (maybe wrong and simplistic). In the UK we try to keep the heat inside and cold in the attic out. I just tried applying reverse logic. Keep the heat inside the attic and keep the cool in the bedroom out of the attic. (upside down to UK -but not in summer- but seems to the same logic applies with glass fibre insulation anyway either way it works) I of course appreciate roofing insulation foils etc. are TOTALLY different as hot countries like Thai rely on reflective insulation (no good at all in a colder climate.

Regards

Dave

You might want to take a look at some of the research done in Australia, which has a tropical climate in some parts. I understand what you mean about reversing how it's done in the UK, it sounds logical to me, but I'm no expert.