stop attic heat coming down into the house

[zeekgarcia]

Have a single story house about 130 sq meters during the hot months the heat from the attic/roof space comes down into the house and it is like an oven. We do not have a/c and keep our windows and doors open.  I am attaching a photo of our roof and more details about it below.

 

I was thinking of getting the SCG stay cool insulation and having it put on top of the ceilings but I read this post about the SCG insulation blocking the heat in the house from rising up into the attic/roof space and they had to install fans in their rooms to blow the hot air from their rooms into the roof space.

 

So I am not sure about what to do now and am looking for suggestions.

 

**More details about our roof**

The roofing of the house is not the cpac clay roofing tiles but it is the common long roofing sheets, I peaked my head into the roof space and saw one gable vent on the far right hand end of the roof which I drew a small blue circle around on the attached picture.

 

The large blue circled area is a downward ridge, where two downward sections of the roof meets and goes downwards from the highest part of the roof, I did see some sunlight along this ridge so I am guessing that air can come in or out of these areas but there are no signs of leaks or water coming in etc

 

The black circled part is an addition that was added onto the house and there is a few cm of space between the roof and the room ceiling.

The whited out part is the neighbors roof, our roofs are just a few cm away from each other.

Edited August 14, 2019 by zeekgarcia

[Naam]

3 minutes ago, zeekgarcia said:

I was thinking of getting the SCG stay cool insulation and having it put on top of the ceilings but I read this post about the SCG insulation blocking the heat in the house from rising up into the attic/roof space and they had to install fans in their rooms to blow the hot air from their rooms into the roof space.

the first step you need is not some tech rubbish² (designed by "thermophysical" ignorants as described above) but a proper ventilation (preferably forced) of your attic.

[zeekgarcia]

6 minutes ago, Naam said:

the first step you need is not some tech rubbish² (designed by "thermophysical" ignorants as described above) but a proper ventilation (preferably forced) of your attic.

 

Are you talking about attic vents or maybe putting a fan at the gable vent? 

Edited August 14, 2019 by zeekgarcia

[wgdanson]

13 minutes ago, Naam said:

the first step you need is not some tech rubbish² (designed by "thermophysical" ignorants as described above) but a proper ventilation (preferably forced) of your attic.

Would the whirly-gig things work, either powered or not please?

[Naam]

10 minutes ago, zeekgarcia said:

Are you talking about attic vents or maybe putting a fan at the gable vent? 

fan at gable vent. make sure there's enough intake on the other end. perhaps you have to make an intake in the eaves. your description is not clear.

[Naam]

4 minutes ago, wgdanson said:

Would the whirly-gig things work, either powered or not please?

the whirlies work only efficiently when driven by a breeze. no breeze means they even hamper attic ventilation.

Quote

common long roofing sheets

= diificult to install a whirly.

[Denim]

38 minutes ago, zeekgarcia said:

they had to install fans in their rooms to blow the hot air from their rooms into the roof space.

 

I have one in our open plan living room / kitchen / dining room. However it sucks the air and blows it directly outside, not into the roof space.

 

If you get one , get a big one. Fan in ours is only 1 foot wide and it has to be left on an hour to really be of any use. Problem is that with insulation the house heats up slower but cools down slower. The walls will retain some of that heat so that even with the extractor fan working the walls continue to radiate that heat.

 

Still, in the balance its a lot better to have insulation than not have it. Certainly lowers electric bills.

 

 

Edited August 14, 2019 by Denim

[zeekgarcia]

27 minutes ago, Naam said:

fan at gable vent. make sure there's enough intake on the other end. perhaps you have to make an intake in the eaves. your description is not clear.

are these attic vents with fans in them, what you are talking about?

Does anyone know of anywhere that sells anything like these here in Thailand?

And could you use them with the standard cement roof panels like the red one below

 

Thanks

Edited August 14, 2019 by zeekgarcia

[tifino]

 installing a passive (non-powered) whirly gig does not by itself actually do anything

(I'm totally in concurrance with @Naam on this) Any air rising up through a whirly, is only doing it due to convection. 

so, if you have, say, already bought a whirly gig, ; then it'd be better to now go buy a ceiling extractor like fan , to ensure air gets forced up through the whirly...

Another alternative, is the Bell type venting.  This concept  is no better for simple convection; however these are all powered

These are supplied with a 12 volt based thermostat.

the major other advantage of these, is that it is weatherproof... something a whirly cannot guaranteed against.

 

 

 

 

[Artisi]

This is a repeat of a similar current post that is running, look for it and have a read. 

Idealy the first place to attach the problem is directly under the roof with reflective aluminium foil, get that right and you have a better chance of getting the house a bit cooler with insulation. 

 

[CharlieH]

Discussed here.......

 

 

[tifino]

17 minutes ago, zeekgarcia said:

are these attic vents with fans in them, what you are talking about?

Does anyone know of anywhere that sells anything like these here in Thailand?

And could you use them with the standard cement roof panels like the red one below

 

Thanks

heh heh heh  - like minds thinking alike!! 

Note,  that the bell vent in your photo that you found, hasn't been installed correctly. 

It's downtube, needs rotational adjustment, to counter the angle of the roof.

It is only capable of retaining it's weatherproofing  guarantees, up to 15 degrees from level.

yes the bells are powered...a 12volt 18Watt motor; contolled via a kit-supplied thermostat.

 

 

 

 

[sfokevin]

I would shy away from anything the needs a hole in the roof as you may  create a water problem... I would add a fan to the gable like this...

 

Edited August 14, 2019 by sfokevin

[Naam]

33 minutes ago, zeekgarcia said:

are these attic vents with fans in them, what you are talking about?

Does anyone know of anywhere that sells anything like these here in Thailand?

And could you use them with the standard cement roof panels like the red one below

 

Thanks

a whirly is easily installed in your corrugated sheets as it comes with a fiiting attachment. but as mentioned... no breeze = hardly any ventilation ventilation. airflow intake is required too!

 

the pictures show roof fans which to the best of my knowledge are not available in Thailand. i installed half a dozen temperature controlled in our Florida home.

[tjo o tjim]

Another approach is a “whole house fan” that exhausts to the attic, plus gable vents (non-powered), since you keep windows and doors open. Bigger is better, and adjustable speed is your friend. 

[kokesaat]

My unscientific approach:

We had the long cement panels similar to the op with no ceiling insulation, 14' ceilings, extra large vents on either end of our roof.  On hot days in Mar-May, you could feel the heat radiate down from the ceiling inside the house.  

We replaced the roof with a rolled steel roof with 1/4" insulation attached to the underside of the panels.  We added 4" of insulated batts to the ceiling.  Our windows and doors pretty much stay shut all day on hot days.  We've resigned ourselves to the comfort of 24/7 air conditioning in the rooms that we occupy, max bills are 3000 Baht.  Cooling is near instantaneous.

Not cheap.....we should have done it right when we built our house.....but lesson learned.  

 

[meand]

I honestly cannot believe how fast trees grow here. 

[Kwasaki]

3 hours ago, zeekgarcia said:

I peaked my head into the roof space and saw one gable vent on the far right hand end of the roof

Put another in other end and insulate your ceiling. 

[Artisi]

4 hours ago, Naam said:

a whirly is easily installed in your corrugated sheets as it comes with a fiiting attachment. but as mentioned... no breeze = hardly any ventilation ventilation. airflow intake is required too!

 

the pictures show roof fans which to the best of my knowledge are not available in Thailand. i installed half a dozen temperature controlled in our Florida home.

no wind OK, but the whirly is still an exit for hot air in the roof space- if there is sufficient air passing thru' the whirly it will probably rotate anyway ---  just ensure there is enough gable vents or what ever is needed to allow air to flow into the roof space and out of the whirly -    

[Naam]

32 minutes ago, Artisi said:

no wind OK, but the whirly is still an exit for hot air in the roof space

"no breeze = insufficient air flow"

[Naam]

3 hours ago, meand said:

I honestly cannot believe how fast trees grow here. 

trees which shade roofs are rare and work only planted close to the home which is a dangerous undertaking.

[sirineou]

 Passive cooling  should be sufficient to rectify issues resulting from attic heat.

-Proper insulation between the attic and living space.

-Gable vents at the highest point possible 

-Soffit vents

As the air is heated in the attic it would rise and exit via the gable vents and be replaced by cooler more dense air  from the soffit vents creating a convection cycle.

For additional attic cooling a fan blowing outward at one of the gable vents would also create a vacuum in the attic space drawing cooler outside air from the opposite gable vent and soffit vents, and assist the convection cycle, 

I have a passive Gable vent/soffit vent with proper ceiling insulation system and my ceiling is always cool to the touch.IMO the trick is proper ceiling  insulation.

 

[sirineou]

6 hours ago, Naam said:

trees which shade roofs are rare and work only planted close to the home which is a dangerous undertaking.

 Not only from the obvious dangers of leafs falling on the roof and falling branches etc , but the lifting power of the roots is amazing I have seen it crack a foundation in two . 

[Artisi]

8 hours ago, Naam said:

"no breeze = insufficient air flow"

It's called convection, hot air rises and will exit thru' the whirly resulting in "cooler" air replacing it, that's assuming the roof is not completely airtight, or do you believe that the big hole thru' the roof offered by the whirly, will do nothing to assist in reducing the build up of heat in the roof space? 

 

I would also suggest that the design of the whirly and its so called internal "fan" is useless, the amount of air exhausted by the fan would be zero - sure it looks good spinning around but no more effective than an open tube with a slight venturi effect as any breeze blows across the top of it. All the louvred top does is the spin around to make it look effective and the exclude the birds and keep the rain out (sometimes) 

[justin case]

put tin foil on your roof...reflects the sun...   and maybe a tin foil hat, for the emf

[AAArdvark]

No idea where to find one of these in LOS.

[gunderhill]

17 hours ago, Naam said:

the first step you need is not some tech rubbish² (designed by "thermophysical" ignorants as described above) but a proper ventilation (preferably forced) of your attic.

followed  by this  but too  late as  your roof  is already  on, insulated  metal and also fibreglass  rolls, my ridge is  fully  vented from one side to tuther and  in this the garage also has many vent  bricks

[gunderhill]

16 hours ago, tifino said:

 installing a passive (non-powered) whirly gig does not by itself actually do anything

(I'm totally in concurrance with @Naam on this) Any air rising up through a whirly, is only doing it due to convection. 

so, if you have, say, already bought a whirly gig, ; then it'd be better to now go buy a ceiling extractor like fan , to ensure air gets forced up through the whirly...

Another alternative, is the Bell type venting.  This concept  is no better for simple convection; however these are all powered

These are supplied with a 12 volt based thermostat.

the major other advantage of these, is that it is weatherproof... something a whirly cannot guaranteed against.

 

 

 

 

Made  my  own at the stainless  shop year s  back Im wary of anything here made  of  plastic as it tends in many (  but  not  all)  cases to disintegrate over time

[Tropposurfer]

Yep like other posters have said with attached pics ... roof mounted 'whirly gigs' (Aussie expression) or escaping heat (high pressure to low) turned roof mounted fans are the go.

 

Just make sure you install a few more than you think to really exhaust the hot air trapping under the roof. Another option is to fit a second 'floating' roof over the whole structure, or on the hottest side of the house (west).

[tifino]

28 minutes ago, gunderhill said:

Made  my  own at the stainless  shop year s  back Im wary of anything here made  of  plastic as it tends in many (  but  not  all)  cases to disintegrate over time

 

 

 the Bell models are also made all aluminium. The base square, of an extremely pliable alloy; to allow for very flush moulding shape, to that of the roof tiling/sheeting

 

Going back to the Title, about the preventing gheat back into the house:

I also looked into actively assisting upwards convection flows, from the rooms.

All Shower/Kitchen/Laundry/Toilet ceiling fans, in most case, don't have a flap arrangement, to prevent flow back downwards when the fans are Off.

 

I installed thermostat controlled fans to each of them, working in parallel with the select switches. Once any thermostat (sitting low in the ceiling) reaches a preset temperature; it's respective fan turns on

I even cut a 25cm hole in my ceiling ladder access manhole, and put a fan into it.

 

Setting at 24C degrees at the lower ceiling, is relative to the upper gable of the ceiling reaching 38C degrees. At the same time, the ceiling inside the room is at 21C degrees

 

a good feeling for the effects of just how much airflow there is, simply from convection; is to stand at the top of your ladder, and feel the simple rush upwards of air, from roomspace, to roofspace!

 

Edited August 15, 2019 by tifino