Hi all,

Some questions for people who have done their roof insulation /radiant barrier after their renovation.

Radiant Barrier
1.) How would the workers install the radiant barrier below the roof tiles. I've checked my attic , doesn't seem to have a place to step on. (See pictures attached)

Insulation
Plan to use rockwool or Cellulose.
1.)How to handle places like downlight openings? rockwool you can cut to avoid, how about cellulose?
2.)Is rockwool meant to be used exposed such as in the attic? Wouldn't dust accumulate ono top of the rockwool? (My attic is already quite dusty)
3.)Anyone here did another layer of plaster ceiling so that the rockwool would be sandwiched instead of exposed?
4.) I notice that the plaster ceiling in my place is supported by those aluminium strips (see picture). Would that be able to support rockwool?

For (1) things ljke Radenshield https://shopee.com.my/Monier-Radenshield-Do...6018.7969103304 see the diagram there, it is below the support battens. To mount foil which is lightweight, either use another set of horizontal batten to support it or just mount it to existing vertical battens.

Reflecting most of the heat back is important. Rockwool used to limit the heat transfer downwards. Rockwool is heavy stuff as the name suggests. So it can be used below radenshield but still supported by the new set of battens..density of 40kgm 60kgm 80kgm anyhow also heavy lah.

I plan to use rockwool on the ceiling and not on the roof, which means putting on top of the plaster ceiling which is being supported by the aluminium strip. Do you think it can support rockwool weight.(see pic)

To expel the hot air / heat accumulated between the roof and ceiling .....

1. Ceiling exhaust fan to circulate the hot air plus

2. Wind turbine ventilator


For the ceiling exhaust fan, install a timer to operate at regular interval esp from noon onwards.

It's not feasible to put on top of plaster ceiling. Weight is an issue, electrical cable and water pipe is another. What ceo684 suggest is good enough. Install turbine ventilator to improve it.

Can consider repainting the roof tiles also, something like nippon solar roof.

Use radenshield sheet is the lightest and more cost effective way already reduce 80-90% of the transmitted IR coz it reflect back into the roof tile.
As these foil sheet will have plenty of mounting to stick to existing strong batten the roof will not collapse lah.

Rockwool heavy I think one meter sq coverage adding on 3kg every meter sq area even at the lightest 40kg/m3 density which will be a question whether existing plaster ceiling will collapse or not.
The plaster ceiling is held on by few tiny drywall screws into the thin aluminum mounting batten only. Need further reinforcements.

As I see if that is the real pic, the roof using cement roof tiles already quiet enough (not zinc roof or plastic roof) so you don't need to put rockwool for sound insulation. Rockwool if you insist to do, the roof joists (flat part where people can walk on) need to enhance summore and link up, maybe with a new set of those "plaster ceiling aluminum batten" specifically to support the rockwool only, INDEPENDENT of existing plaster ceiling. The existing plaster ceiling will not tahan the weight of the rockwool well. Later middle of the night the paper liner of gypsum board breaks at the screw head holding it up (which is the only point load supporting the weight of the gypsum board itself, its OK for its own weight but it is not designed for additional weight) and kaboom downwards.

I plan to do both radiant barrier and insulation, insulation is so that my aircond does not need to work that hard. Currently on a hot afternoon , my aircond is always at full power and it is unable to bring down the temperature. I think the best it could do was 28-29C .
Upon checking to my surprise the plaster ceiling was 36-38c, so plaster ceiling is pretty a bad insulator and that's the reason why I wanted to do it at the ceiling. Even if I had radiant barrier , and with the air cond on, I'm still absorbing heat from the attic as there is a temperature difference.
That's the reason for both radiant barrier at roof and insulator at ceiling.

Noted, can proceed with both
Radenshield to reflect most of the heat out back to roof tile, basically just stick on using construction adhesive to existing roof batten (the vertical battens in the A shape of the roof). In short, easy installation but ypu may want to do the add joists before the radenshield so easier for the installer to stick the radenshield on the rood batten coz to position a ladder or stool in there based on whats available now seems a bit dangerous, not much safe area for them to work with, risk of falling thru the ceiling is there.

Rockwool above plaster ceiling with additional wooden beam (flat joists) to support weight of people walking around, and between these flat joist you can just use flat bar or the alu batten same type as the plaster ceiling folks use, join them up between joists to look like a flat ladder to support the rockwool slab weight.

All the above is passive heat reduction method. Turbine also quite passive despite the monstrous size.
Active method involve boarding up your sides (ie close off your rooftop airspace to be only yours) so youre only cooling your rooftop airspace and not the whole row of 20 houses' airspace. By making a vent to be able to support the size of a ventilation exhaust fan or two unit ventilation fan about 10in KDK it is gonna move 400 to 500cfm so the air inside is not tupperwared long enough to bake (like now). The input you can just make a passive vent above the bathroom ceiling for it to have cold input air. Why i didnt wanna suggest 12in is that the hole is big and burglar can squeeze in. 10in should be small enough for them not to be able to drop in.

This active ventilation is like you park the car in the hot sun and opening all windows. The car cools better in minutes with the window open as compared to it fully rolled up. Even better if there is a fan blowing out all the time when it is baked in the sun. The exhaust fan you can use on timer so it only work on hot hours say 1100-2000hrs. The electric usage of an exhaust fan is very minimal compared to overworking your AC.

This post has been edited by ceo684: Mar 29 2021, 05:31 PM

I planned to extend my kitchen with pitch roof. 1) Any idea what is the angle I should tell my contractor to built so that there is no leak?
2) Should I use Radiance shield or Zinc sheet? Does it prevent water leak and thief break in?

Thanks

1. A steep gradient will be better for water flow. However the angle will depends on the length of extension and neighbouring units. An experienced contractor would know and advise.

2. It helps but water leak can come from anywhere especially during heavy thunderstorm. As for thief breaking in, no comment as it also depends how detetmine he is.

FYI: I am using radenshield under the tiles (make sure you have venting for the hot air - monier is able to help there!) + cellulose insulation on top of plasterceiling like you plan do to. No problem with the weight.

This in combination keeps the plaster ceiling at ever so sightly above ambient temperature even on the hottest of days. Never is it more than 2° degree above ambient and with proper ventilation you wont trap heat in the roof during the day.

What you thought of is probably ideal for Malaysia if you consider ventilation for the roof as well.

Would like to share the outcome of the installation, I used a double sided bubble radiant barrier and then 2 months ago installed a solar fan

Before:-
Plaster Ceiling :- 38.4c, Roof tiles:- 55C, air cond power :- 900-1000w.

With this I estimate attic temperature to be around 40-44c, going up to the room is like a sauna..






After:- Radiant Barrier only
Plaster Ceiling :- 32-33c, Roof tiles:- 36-38C, air cond power :- 400-450W.
A radiant barrier really works, a must have. Made a huge difference in room temperature.
At the same time I started putting temperature sensor at my attic, external (outside my window) and my room to log the temperature.
I notice around 2c difference between external temperature and the attic temperature.


After:- Radiant Barrier + solar fan
Installed a solar fan so it would turn on roughly 8am to maybe 6- 6:30pm. Made a small difference, temperature now within 0.5c compared to external temperature.
Also integrated all in home assistant , to log the temperature and air cond power. Small savings in air cond power (maybe around 50w on average?)






This post has been edited by Drian: Oct 14 2021, 06:11 PM

Can share the brand of your raden shield?
I'm considering to install the Monier AL+FX series but still want to survey around and see what I can get with lower price.

Search for foillaminate2020 in shopee

I'm using BB238FR-10, dual layer foil , air bubble so there is some insulation in the middle

Got it, thanks bro!

1st I choose for this tile side insulation. But later decide not.

As the insulation is too thin for effectiveness. It blocks the airflow between tile and traps the inner roof hot air from going out.

So I decide to DIY insulate the ceiling. Which is what I feel more directly affects me from the room side.

The ceiling is the most heat generate for the room as the ceiling sq ft is as big as the room floor.

Use the foam spray for the insulation. Brought a few box to try on my working room. Brought from shopee.







The foam expands about an inch thick. But if you want thicker, just spray another layer. The thicker, the more heat insulated. Spray some water before and after the foam. It help to expand the foam more.



It is a fast process and dry about 4-5hr. The next day, you are able to feel the difference.

Here is the result of the temperature difference inside the room without an aircon.





I can increase the aircon temperature to 29°C and it already feels cool. And maintain at 29°C for the whole day even it really hot outside.

The left panel is the actual room temperature near the battery. (below the cabinet) And the aircon remote temperature setting. I never get the same reading before that.



That saves my bill a lot when work from home.

Did you vaccuum before putting the foam? I have glasswool but I look at the top so dusty.

Yes. I vacuum clean the ceiling 1st.

Then spray with water before foaming.

Is the glasswool hazard to health?

Using this. I see so many glasswool you tube video. I guess you just need to wear mask when installing.
http://www.ecowool.com.my/ecowool-detail.a...classic_blanket