Insulation R Values: Dependable In Thailand?

[Greenside]

I see microfibre ceiling insulation in rolls for use above ceilings in a wide range of brands and prices. The principle of R ratings I understand, but the variation seems very wide for the same kind of insulation (fibregalss or microfibre in a mylar bag) that I wonder if you can place any faith in them at all. I also notice that some are giving an R-t rating, rather than simply R; anyone know what that's about? I can't find a reference on Google.

Two products from Global House that I recently bought seem virtually identical and the same thickness, yet one claims an R-t value of 21 and the other an R value of 12, the former being about 30% more expensive.

[Pib]

My understanding is a Rt rating is the Total R valve when installed in accordance with manufacturer's instructions/in combination with the typical insulation properties of a roof, wall or floor compared to just the pure/raw R value of a certain insulation material. Below is an example of determining Rt value in a certain installation taken from this Link.

You really can't compare Rt and R values...it's like comparing Apples and Oranges. Actually the one you identified with an R-12 value will have a higher Rt value if it was rated with a Rt value versus just a R value. Equal to/higher than the Rt-21 rated one?...don't know, it would all depend on what standards/installation the manufacturer would use to determine the Rt value.

[bbradsby]

never heard of Rt, but compare R vs. R or Rt vs. Rt values so you get apples to apples. Also, be wary of advert claims in LoS, as there no meaningful consumer protection in place. If its fiberglass batt insulation, R-11 is 3.5" , not good enough for ceilings in hot Thailand weather; and R-30 (what i really recommend for ceiling insulation value here) is at least 6" . Build up the local skinny batts to get close as you can to this thickness.

Foil faced is best on the top layer, and place the foil on the attic side of the batt. It reflect radiant heat energy.

One thing to remember: insulation is useless if you have un-weatherstripped window & door openings. the hot, outside air infiltrates your occupied space so quickly, even in a light ( ± 10 kM/hour ) breeze, that it completely replaces your cool inside air with hot, outside air in just a few minutes if youre not effectively weatherstripped at all exterior openings in your house/condo.

[muratremix]

Can anybody recommend a good brand that? I saw 2 types, one is very slim and import (from Israel or something) sold in big roll. Another one is made in Thailand, atleast 10 cm high and sold in 2.4 sqm2 rolls (but each roll is big due to size of sheet). Pricing is similar in given RT values.