Cold Weather - Hot Topic : Insulation

[cube]

Hi,

With all the cold weather around, the topic of insulation has come up again.

Specifically, what opinions do you have on the use of underfloor insulation for a wooden floor.

There seem to be three types available, foil, blanket and polystyrene.

Has anyone any experience in installing these - how easy to install and how effective are they?

My basic problem is that heat rises, so there is a strong argument for ceiling insulation, but does insulating the floor actually work!

Thanks

cube

[Rolf]

In our PPOR we have a basement underneath the lounge area. The basement is always relatively warm over winter. So the heat from upstairs clearly escapes through the wooden uninsulated floor down to the basement. We don't mind this as we don't want the basement to be freezing, but it shows that there is definitely a heat loss.

[Bluekiwi]

In our PPOR we have a basement underneath the lounge area. The basement is always relatively warm over winter. So the heat from upstairs clearly escapes through the wooden uninsulated floor down to the basement. We don't mind this as we don't want the basement to be freezing, but it shows that there is definitely a heat loss.

Errr I am no scientist but I havent heard of heat falling ?

[Rolf]

Errr I am no scientist but I havent heard of heat falling ?

Have you heard of heat lamps, and/or tried standing underneath one? They're quite effective even though they tend to be mounted in the ceiling

I think you're mixing up heat radiation with a heated mass of air. The heat (infra-red) radiation will be emitted from the heat source evenly in all directions. The resulting heating of the air around the heat source will cause that air to rise.

So in the example I gave above, the heated air trapped in the lounge emits heat radiation in all directions, also towards the floor. This causes the floor to warm up which in turn emits radiation into the basement underneath, heating the air there.

[cube]

So, apart from draughts coming up through the floor, the problem is one of conduction of the heat through the floor boards - the idea of underfloor insulation being that any such heat gets trapped, reducing the temperature gradient through the wood, preventing further losses?

Does that make sense?

[Rizowz]

Yes, I can still hear my old science teacher now; "Heat does NOT rise, hot elements do". Eventually a room will heat up everywhere including by the floor, but it will get warmer near the ceiling first. Hence why ceiling insulation is so important, followed by walls and then floor (not to mention thermal curtains or double glazing).

Would be keen to hear rea experiences with floor insulation, have been seeing those expol foam ads on tv and wondering if they'd be a good investment in a place I'm looking at doing up.

[Aston]

My basic problem is that heat rises, so there is a strong argument for ceiling insulation, but does insulating the floor actually work!

Thanks

cube

I once owned a house with this problem.

I resolved the problem in the following way.

1. Bats stapled underneath the floor.
2. Foil stapled and sealed under the joists.
3. Building paper taped and sealed on top of the entire floor.
4. Softboard on top of the building paper.
5. Two layers of rubber carpet underlay.
6. Carpet on top.

Expensive but problem solved, the floor was then the warmest part of the house.

[Skruff]

Hi there. I'm going to try a product called Silverzone next week. It's two layers of foil, with air cells in between. We have a small place in Central Plateau (snow on the ground last week), in which we have an area of polished floor boards, and currently have no underfloor insulation. The R rating is supposedly 2.3, and it provides insulation and a vapour barrier all in one. I'll be installing it over the long weekend, so I'll let you know how it goes.

Cheers

Skruff

[spurner]

My property was on Campbell Live last night, on the feature about uninsulated homes.

Just about fell over when I saw my tenants talking about how cold the place was, Doh!

[cube]

Hi there. I'm going to try a product called Silverzone next week. It's two layers of foil, with air cells in between. We have a small place in Central Plateau (snow on the ground last week), in which we have an area of polished floor boards, and currently have no underfloor insulation. The R rating is supposedly 2.3, and it provides insulation and a vapour barrier all in one. I'll be installing it over the long weekend, so I'll let you know how it goes.

Cheers

Skruff

Thanks Skruff.

Welcome to the forum - look forward to hearing of your experiences!

[Bob Kane]

1. Bats stapled underneath the floor.

You cruel bastard.

[Perry]

Does cost-effective = comfort-effective?
And vice-versa?

Would certain insulation actions in Auckland
be quite inadequate for Otago, with the
opposite applying in reverse?

[Stickman]

Errr I am no scientist but I havent heard of heat falling ?

Heat as an energy form is lost easily via conduction. The area underneath the timber floor could be colder than than the inside of the building, thus the timber cools down and cools the room down via conduction.
Those thinking of 'heat rising' are only allowing for convection (or heat that is being circulated on warm air.)

[Stickman]

Expol polystyrene does work reasonably well.

[cube]

Heat as an energy form is lost easily via conduction. The area underneath the timber floor could be colder than than the inside of the building, thus the timber cools down and cools the room down via conduction.
Those thinking of 'heat rising' are only allowing for convection (or heat that is being circulated on warm air.)

Ah-ha - so the problem can be the wood cooling down, and then cooling down the feet, rather than the wood being warmed up and hence trying to warm the area beneath. This I understand.

Perry - yes, insulation in Auckland is more about draft exclusion and being able to walk around bare-foot. In Otago I imagine it's more about keeping the penguins from looking for a new place to stay because the Antarctic has warmed up too much!

I heard from a friend that Expol 'batts' had fallen out after a while (but they were self-installed )