How To Insulate/ventilate A Simple Thai House

[Bpraim1]

Chow

My roof is vented with soffits all the way around following the roof line. So air can enter in all along the roof line.

With the Ceramic coating and PU Foam I don't plan on have'n huge attic temps, so I don't need huge air movement to cool this space. This space is also very small, between the two lines of insulation is less then an 1m on one side and 1.5 on other.

As shown I will insulate roof and ceiling.

2" of PU Foam = 4" of Batt, sprayed onto the underside of roof plus 3'' staycool batt on the ceiling, So total of 7" of insulation in roof, and 3" of PU Foam = 6" of Batt in the walls.

PU Foam is water and air tight so heat flow is better controlled then useing batt, as corners and all edges are open to heat and air movment in batt applications.

As we have planed for the PU Foam and Ceramic coating to deal with the heat from the sun, A smaller layer of insulation will be needed to deal with keeping the home cool, Turning the house into two areas,

One the livin area( walls and ceiling insulated to keep cool air in and hot air out) PU provides the vapor/air barrier.

Second the Attic and roof area, Ceramic coating and Pu Foam will keep heat from entering adding again a vapor/air barrier. So air is only needed to move to remove moisture and what heat does build in the attic space betwwen the two mediums.

I added a pic of my build plan so you can see the roof lines.

Vented Soffits will follow under all the overhangs around complete roof lines as state above.

I also added some info on different Insulating mediums.

A material’s R-value is the measure of its resistance to heat flow. It is important to know the R-value because many states or regions require that a roof system have a minimum amount of thermal resistance on commercial, industrial, and/or institutional buildings. The way it works is simple: the higher the R-value, the more the material insulates.

Some common roofing materials and their corresponding values for Thermal Conductance © and Thermal Resistance ® are shown in the following table.

Material

Thickness In Inches

C-Value

R-Value

Metal

N/A

0.000

0.00

Concrete

1.0

3.333

0.30

Gypsum

1.0

1.667

0.60

Wood

1.0

1.099

0.91

Tectum

1.0

0.500

2.00

Inside Air Film

N/A

1.087

0.92

Outside Air Film - Summer

N/A

4.000

0.25

Outside Air Film - Winter

N/A

5.882

0.17

Vapor Retarders

N/A

0.000

0.00

BUR Gravel

N/A

2.941

0.34

BUR Smooth

N/A

4.167

0.24

Fiberboard

1.0

0.360

2.78

Perlite

1.0

0.360

2.78

Phenolic Foam*

1.0

0.120

8.30

Fiber Glass

1.0

0.256

3.90

Polyisocyanurate

1.0

0.180

5.56

Polyisocyanurate Composite

1.5

0.240

4.17

Polystyrene Bead Board

1.0

0.280

3.57

Polystyrene Composite Board

1.5

0.301

3.32

Polystyrene - Expanded (EPS)**

1.0

0.260

3.85

Polystyrene - Extruded (XEPS)***

1.0

0.200

5.00

Sprayed Polyurethane Foam****

1.0

0.150

6.88

Cork

1.0

0.280

3.57

* Problems have been reported with regard to the use of Phenolic Foam roof insulation. Incidents of deck corrosion have been reported in cases where the insulation is in direct contact with steel roof decks and there is moisture present.

** Molded, Expanded Polystyrene Insulation, also referred to as MEPS, can have an R-value that will vary from less than 4.00 to slightly more than 4.00. The amount shown is an average amount used for roof system R-value calculations.

*** Extruded, Expanded Polystyrene Insulation is commonly used in Inverted Roof Membrane Assemblies (IRMA).

****Sprayed Polyurethane Foam (SPF) will have an R-Value of 7.14 when it is newly installed. After it ages a few months, the R-Value will reduce to somewhere around 6.88

[Beachbunny]

I have two friends who have used an Australian company out of Bangkok. They use a spray on material and spray it in the atic on the top side of the cieling. With a vented atic, two vents, no fans both of their homes in the hot season in Pattaya was at 26 degrees when it was 36-37 degrees outdoors.

some people do a good job hiding their aircon units. others are good in spreading fairy tales

So your saying this cannot be true. this shows you do not know what you are talking about. I never make flaming posts, but what you are implying is not true.

Barry

Barry, I have no reason to doubt your veracity, but where exactly does 26 degree cool air come from when it's 36-37 degrees outdoors? When it's that hot outside, it barely gets down to 26 degrees at nighttime in Pattaya. If/when it does, then I could understand the lower floor (or lower to the floor) areas retaining that 26 degree air until about noon. But without air con, are the windows open? If so, doesn't warm air flow in (and up to circulate out the upper vents)? And, if so, how does it remain 26 degrees at ground level? It just sounds incredible. Maybe IS credible, but SOUNDS incredible.

Well, I'm one of the friends Barry is talking about. And certain parts of the year this is true. We have double walls, well ventilated attic space, and blown in insulation from cool or cosy. We also have double glazed windows and a crawlspace under the house. To keep the inside cool I do the same thing I did in San Diego during a Santa Ana. Open the windows at night for the cool air, shut them early in the morning and close the curtains, especially on the sides the sun shines in. Use fans for circulation. In San Diego I'd open the windows as the outside temp got cooler than inside...same here.

I have a thermometer I check and there have been times when it has been 72F while 90F plus outside. On average the house is around 10 degree F cooler than the outside temperature. We do have A/C but rarely ever have it on except to see if it still works....or for people that are used to being in 22C air con room all the time.

You can only cool down the interior as cool as it gets at night.....where we live (two plus years now) On average it's probably 80 at night,(I never thought I'd be pulling covers at 80 degrees) but ambient air might feel cooler. It seems like after the windows are shut the inside temp. equalizes or something and it feels cooler. The only time I leave any windows open an inch or tow isif it's hot outside, but the breeze is still cool.

The only thing different we would have done if possible would be to switch which side the Master Bedroom is on as the best night breezes come from the other direction.

Beachbunny

Edited October 26, 2007 by Beachbunny

[Naam]

With the Ceramic coating and PU Foam I don't plan on have'n huge attic temps, so I don't need huge air movement to cool this space.

wrong assumption. your attic temperature will rise to the same level as the attic under a roof which is not insulated. the only difference is that it will take longer till that temperature is reached and if not properly ventilated the temperature in your attic might be even higher.

[Bredbury Blue]

"Staycool" roof quilt insulation comes in 75mm and 150mm rolls.

What are people using / recommending?

Is 75mm sufficient / insufficient?

Is 150mm required/overkill?

[basilic13]

I am impressed by the details of Swelters' recommendations.

Although the usefulness of ceilings becomes obvious, I cant help but find it a pity to waste so much space (between roof and ceiling) and find it much more beautiful to have a higher living space...

As such do you think a house without a ceiling (that is a room going all the way to the insulated roof) can be really efficiently insulated from the heat?

thanks...

[IraqRon]

I agree with both of Naam's posts. Get the hot air out of the attic or it will stay hot and radiate down into the living space. Even with insulation on top of drop ceiling, the R factor will most likely not completely stop this thermal radiation completely.

To really take advantage of late night and early moring cooling, a thermal mass of sorts, isolated from gaining heat from outside, is needed in the house. This mass captures and stores the cool, releasing it into the house. Most houses contain very little thermal mass to do this.

[doggie888888]

I am impressed by the details of Swelters' recommendations.

Although the usefulness of ceilings becomes obvious, I cant help but find it a pity to waste so much space (between roof and ceiling) and find it much more beautiful to have a higher living space...

As such do you think a house without a ceiling (that is a room going all the way to the insulated roof) can be really efficiently insulated from the heat?

thanks...

I do not have any attic space, just the walls going up to the roof (I think it is called vaulted or cathedral ceilings) so there is little space between the roof tiles and the ceiling. I do have a layer of foil insulation in the narrow space between the roof tiles and the ceiling, which is gypsum (but lined with bamboo sheets underneath for aesthetics). I also have louver windows very high up to let the hot air escape, which I can close when it rains. The house is noticeably cooler than outside, although sometimes I am not sure if it can be even cooler with better insulation. I use ceiling fans almost constantly, supplemented by portable fans on the hottest, most humid days. I do notice the house cools quickly in the evenings though.

I am toying with the ide of getting the LOHR people in Pattaya to spray their stuff (if suitable for the narrow roof space that I have) just for the added insulation as I feel the foil (and gypsum and bamboo lining) may not be adequate and may be allowing some heat through. If it's only one or two degrees, it may still be worth it I thought. In this heat, every degree counts!!!

A related topic, I am also looking for more efficient fans...because I erred by buying attractive looking fans but really they hardly create any breeze whereas the cheap white ones create a lovely breeze. Again, in this heat, bugger the aesthetics!

So some hints about fans and vaulted/cathedral ceilings would be much apprciated

[meyori]

Hello All

I'm new here but had to add something to this post based on personal experiance. We had problems with our leaky roof for 10 years and had to replace the ceilings in our third floor twice due to crappy work done right from the start. Ended up paying Marcus from "SprayMe" from Pattaya to spray 3 inches of foam under the roof. Complain about the cost at the time but now I can not be happier. When the job was finished you could actualy look up at the outside of the roof and see places where the foam had filled the holes from the inside out. Not only is it watertight now we have noticed that our utility from the air-con is down by over 30%. I do not have any fancy gauges or tecky knowledge regarding this topic but I am not blind to the results and the 10 garrenty from a Western company made it well worth the money.

After 2 years now inside our 3 story shophouse roof in Chalong we have contacted Marcus regarding spraying the roof of our 3 story home that we are building Rawai/Nai Harn. www.SprayMepurfoam.com as with any job you get done here it's better to pay a bit more up front and get it done right the first time.

Richard