Roof insulation

[Dannie Boy]

I have just moved into a brand new single storey house that is fitted with the metal foil insulation below the tiles. My previous house was two storey without any insulation, but I am certain that the new house is noticeably hotter than our previous one. I realise that the insulation is meant to keep the house cooler, but it seems that it is actually acting as a barrier and keeping the hot air inside. Do any other forum members have experience of this type of insulation and the impact on temperatures?

[Nereus]

There is a long post about the subject here:

viewtopic.php?f=10&t=14278&hilit=roof+insulation

[Dannie Boy]

Thanks Nereus, quite a long thread although with no real conclusive outcome on the impact of the foil. I can appreciate that if there is insufficient ventilation in the roof space, then the foil could act as a trap and keep the heat in - certainly, that is what it seems like. If anybody has any further experience or advice to offer, gratefully received

[Pleng]

Also what's your definition of 'just moved in'

The temperatures over the last few days have been steadily rising, and noticeably so, so the increase in house temperature might just be down to that?

[dtaai-maai]

^^Very good point!

[Dannie Boy]

Also what's your definition of 'just moved in'

The temperatures over the last few days have been steadily rising, and noticeably so, so the increase in house temperature might just be down to that?

Just under 4 weeks ago, and yes I agree it has got hotter this last week or so, but even when we first moved it did seem hotter, although it was the very recent increase that made me wonder - this house has foil insulation and it appears to trap the heat in, which is why I wanted to ask others if they had experienced the same? I am living in a rented house while I am having a new house built and I have to decide fairly soon whether to have foil insulation installed - the roofing stockist recommends it, but then they have an interest in making a sale!!

[JimmyGreaves]

Below the tiles is fine and recommended as one side faces towards the tiles that refects heat back towards the tiles.

Not sure about above the ceiling tiles however.

[Dannie Boy]

Below the tiles is fine and recommended as one side faces towards the tiles that refects heat back towards the tiles.

Not sure about above the ceiling tiles however.

Yes the plan was for the foil to go immediately under the tiles but nothing between the ceiling and the foil. It seems to be the trend on many new buildings to do the same, but the recent hike in temperatures made me question it?

[Nereus]

As mentioned on the other thread, there are just too many variables involved to be able to state categorically that one type of insulation is the best.

For me, if I had the option during construction I would install the reflective foil under what ever roof material I was using. It cannot be installed after the roof goes on, but it could always be removed at a later date!
To this I would add a fibre type layer directly on to the ceiling, making sure that there is as few as possible gaps left in it, and that any light fittings that protrude into the ceiling space are protected from direct contact with the material.
And finally, some form of cross flow ventilation to allow hot air to escape from the roof space.

[Dannie Boy]

Thanks for that Nereus, sounds like good advice.

[phartley58]

Check if your roof has Air Tiles. If not, it shouldn't be too expensive to have a few fitted all round.



Arte et Marte

[usual suspect]

I've had days/times when I've thought same as you D.B.
The ceiling in my bedroom and in the bar has had foil simply laid on top of the square-tiles... and
IMO this foil layer is damn useless, AND as you say, may well be counter-active. What may have happened with your house is one team put on your roof, while the next team realised team 1 had forgotten to lay the foil on the rafters beforehand, so opted for laying it on your ceiling.. same-same in their minds
I know they're not pretty but we fitted one of those 'swirly-things' on the roof of the bar as an attempt to get hot air out.

[Dannie Boy]

I've had days/times when I've thought same as you D.B.
The ceiling in my bedroom and in the bar has had foil simply laid on top of the square-tiles... and
IMO this foil layer is damn useless, AND as you say, may well be counter-active. What may have happened with your house is one team put on your roof, while the next team realised team 1 had forgotten to lay the foil on the rafters beforehand, so opted for laying it on your ceiling.. same-same in their minds
I know they're not pretty but we fitted one of those 'swirly-things' on the roof of the bar as an attempt to get hot air out.

They are still building houses on this development and the foil is laid directly beneath the tiles and as best as I can tell, nowhere else. Maybe the recent very hot weather has been a major contributor as the last couple of nights haven't been as hot?

[migrant]

And finally, some form of cross flow ventilation to allow hot air to escape from the roof space.

Used to have a house, not in Thailand, that had a large fan installed in the attic. Even in extreme heat the house was always reasonable and no air conditioning

[hhfarang]

^ My parents former home in Tennessee (which has summers much like here) had a huge fan installed in the ceiling in the center of the house that blew into the attic. So you could open windows and that fan would create a breeze throughout the house by sucking air into the windows and blowing it out through the attic which had vents at either gabled end plus a couple of those turbines that let heat rise out. It worked pretty well in a house that only had one room air conditioner.