Chat On A Hot Tin Roof

[Dave Hounddriver]

If I can help further dont hesitate to ask.

 

Here is another construction related problem that you could help with, or anyone else can jump in.  My house has a brown metal roof with about a 4/12 pitch.  The roof starts 5 feet up from the floor on the second story.  It means the ceiling follows the 4/12 pitch for a few feet before leveling off at the 8 foot mark.  It means there is about an 8 inch gap between the metal roof and the Hardiflex ceiling panels.  It means the ceiling gets very hot when the sun is beating down on the roof.  VERY hot such that the air conditioner cannot keep the temperature below 30 degrees when the sun is full but works great when the sun goes down. Here are some possible solutions that cross my mind.  Please help me pick the best/cheapest one:

 

1 - Paint the metal roof white to reflect the sun's heat. (May not be allowed by subdivision rules)

2 - Put solar panels on the roof to absorb the sun's heat and turn it to electricity. (expensive)

3 - Fill the 8" space with insulation (hard to do now the construction is finished)

4 - Throw a tarp over the roof to give the metal panels some protection from the hot solar rays (may not hold up in high winds)

5 - Put in a roof exhaust fan to suck out the hot air between the metal roof and the ceiling (grasping at straws?)

6 - All of above

7 - None of above (any other ideas?)

[BrettGC]

Dave, my old place with the ex had 3 and 5, worked a treat.  The insulation was a bit painful to put in as the decision was made post renovation after experiencing exactly what you are but worth it but in your case given the size of the space may be impractical without removing the ceiling;  maybe some of that spray in stuff?  The roof exhaust fans are great, they power themselves and do make a difference (hot air in the cavity pushes out through them) http://www.lulusoso.com/products/Philippines-Roof-Ventilator.htmlis where we sourced ours. 

 

The solar panels are expensive but if you think long-term they're going to pay themselves off.  I guess it just depends on how long you're going to be there and if you do sell would filipinos be willing to pay the extra like they would for any other add-ons to the place? i.e. pool, hot water, etc.

[jpbago]

I suggest 2" of foil backed styrofoam insulation fastened to the inside of the roof and 2 exhaust fans/vents. There is a type of vent that runs the length of the roof at the peak with openings under the eaves/soffits. 

[jon1]

You also need vents under the eaves to allow airflow out of the roof space.

[lonewolf]

I keep hearing about a coating thats used on tall building that reduces the temp inside by 40 degrees f

[Dave Hounddriver]

I keep hearing about a coating thats used on tall building that reduces the temp inside by 40 degrees f

 

I wonder if that is this stuff:

http://www.whiteroofproject.org/faq

 

or

 

A white roof coating is an elastomeric, reflective, thermal barrier, protecting and waterproofing the surface to which it is applied. White roof coating should have a very thick consistency. When applied properly, a white roof coating should be able to expand and contract even with the most extreme thermal cycles and not crack, bubble, lift, chip or peel. The elongation properties of a high quality coating should be in the range of 375 - 400%. A true white roof coating should have a high rating with the CRRC (Cool Roof Rating Counsel) in the areas of Solar Reflectance, Thermal Emittance and Solar Reflective Index. Last, a white roof coating that performs properly will have a warranty that states waterproofing and ponding water coverage. Do not use a so called “white roof coating” that cannot provide you with these types of warranty coverage.

 

SURECOAT and SURE-A-THANE: (WHITE ROOF COATING)

Not all roof coatings are created equal. A lot of roof coatings are just dressed up acrylic white roof paint with little to no lasting reflective, thermal emitting or waterproofing values. SureCoat and Sure-A-Thane are SureCoat Systems’ Super VOC compliant white roof coatings that display superb energy saving and waterproofing properties that are proven! SureCoat Systems’ white roof coating is 10.426 dry mils thick per gallon per 100 square feet (5 - 10 times thicker than roof paint and 2 - 3 times thicker than most other coatings). It has a Solar Reflectance value of 86%, a Thermal Emittance value of 93%, and a Solar Reflective Index of 108 overall. These are outstanding ratings that last for years after application. SureCoat roof coatings also has a perfected elongation of 398%. This is high enough to expand without cracking and still low enough to contract back in the cold without losing its rubber-like elasticity. SureCoat Systems’ is known to solve water intrusion issues that have plagued the industry for years. When installed as part of The SureCoat Roof System (a coating, poly-mesh, coating system) your roof is eligible for a manufacturer’s written warranty stating that it will not fail due to standing/ponding water conditions even on a flat roof. They make it white, we make it LAST!

 

 

- See more at: http://www.surecoatsystems.com/white-roof-paint-vs-white-roof-coating-case-study.asp#sthash.54u8eT2b.dpuf

[Call me bubba]

3 - Fill the 8" space with insulation (hard to do now the construction is finished)

 5 - Put in a roof exhaust fan to suck out the hot air between the metal roof and the ceiling (grasping at straws?)

 

 

Dave your not gasping at straws,, your trying to figure out the best way to solve this so you can be more comfortable,,

I too had the same issue 6yrs ago when 1st moved in my current unit,,

what i did was this,,,

 removed the ceiling, as it was screwed in, installed a 10mm installation w/aluminum backing on 1 side..

 installed it against the METAL roofing,, to keep it in placed I used the BBQ /wooded sticks  .mounted in the gaps

 cut the "foam" so it would fit firmly  in the joints/rafter beams

again used the wooded sticks to keep it in place,

 

then on the HARDIFLEX I installed a 5mm on the areas that didn't already have any installation.(on the inside areas )

  this was the best 2500pesos I spent to make the room more enjoyable for my then 6yr child,

as not only it reduced the HEAT ,it made it more  QUIETER when stormy weather occurred

and of course was able to use the  AIR CON during the day if needed,

 

perhaps this could give you a better idea of how to solve your issue

 

 

It means there is about an 8 inch gap between the metal roof and the Hardiflex ceiling panels.

 

 

 

]

 

You also need vents under the eaves to allow airflow out of the roof space.

 

 

regarding #5.

on the roof , I couldn't find a exhaust fan, & someone to hook up the wiring

so what i did was installed some simple plastic vents under the eave ,

on both edges on the bottom part of the roof, this did help some to increase the ventilation in the roofing area

 

(made sure that i used window screen on them to prevent bugs or other critters to enter)

 

 

 

 

 

 

 

havent seen this here yet i am sure in the larger cities this can be done,,

[robert k]

Termite remediation companies should have the foam. +1 on all suggestions of roof vent. If it's too hard to get the ceiling down to insulate, l would insulate the underside of the ceiling. Maybe you could find ceiling tiles with an R-factor, just glue them to the ceiling. If you aren't 8 feet tall, l don't think you will miss the 25mm.

[Dave Hounddriver]

Thanks for the suggestions so far, budget considerations dictate that it will be January before I make any decision on this.  I am reminded of all the times I park my motorcycle in the hot sun and when I come back the seat is like a stove top unless someone puts a bit of cardboard on it for me, in which case it is fine.  Sure wish I had a big piece of cardboard and a boy to put it on the roof when the sun was out.  :hystery:

[Steve & Myrlita]

Reminds me of the thick coating used on roofs of mobile homes I believe it was called Cool Seal. It goes on like you would paint. Do 2 or 3 coats. It helped tremendously on the mobile home. I don't know if that is available here or not.