Exterior wall insulation

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Exterior wall insulation

Postby milangee » Mon Aug 26, 2013 10:50 pm

Exterior wall insulation? The exterior walls in my bedroom feel cool to the touch, are they supposed to be like that or is it lack of insulation?
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Last edited by milangee on Thu Aug 29, 2013 7:32 pm, edited 1 time in total.
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Re: Exterior wall insulation

Postby Albrecht Stoecklein » Tue Aug 27, 2013 10:29 am

Hi Milangee,

That's a hard one to answer. Insulation by itself does not generate heat but just reduces the movement of heat through the building envelope. So even if your walls would be super insulated, but you don't apply any heating (including solar gains) into the room, all the internal surfaces will be cold.

"Normal" comfort room temperatures are 20degC. If the air is roughly at that temperature we feel warm. All the objects and surfaces in the room will be at a similar temperature. But our body temperature is about 34degC. So any surface at a lower temperature will be feeling slightly cool to the touch.

The reason why we often don't feel that the surface is cold is that the surface layer itself may have a reasonable insulation value. So the skin of our body heats the surface layer of the object when we touch it. If this surface layer has some insulation value (think of a carpet for example) then the heat from our skin can't escape very easily. The surface therefore heats up to about 34degC and we perceive the surface as warm.

Similar, think of a hard surface in a warm room, such as a granite bench top in the kitchen. Even though that is warm (20degC environment temperature), if you touch it it will feel cold, because all the heat from your skin is quickly conducted into the granite because it has a low surface insulation.

So the quick answer is, that it would be very difficult to determine whether there is enough insulation in your wall just by touching it.

If there are power points or switches in that wall you could take one of them off (of course first pull the fuse on the distribution board) and have a peak inside the wall.

Chances are that if the house was built before 1978 that there is no wall insulation.

I hope that helps.

Sunny regards

Albrecht
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Re: Exterior wall insulation

Postby EarlMay » Thu Nov 21, 2013 11:57 pm

Albrecht Stoecklein wrote:Hi Milangee,

That's a hard one to answer. Insulation by itself does not generate heat but just reduces the movement of heat through the building envelope. So even if your walls would be super insulated, but you don't apply any heating (including solar panel) into the room, all the internal surfaces will be cold.

"Normal" comfort room temperatures are 20degC. If the air is roughly at that temperature we feel warm. All the objects and surfaces in the room will be at a similar temperature. But our body temperature is about 34degC. So any surface at a lower temperature will be feeling slightly cool to the touch.

The reason why we often don't feel that the surface is cold is that the surface layer itself may have a reasonable insulation value. So the skin of our body heats the surface layer of the object when we touch it. If this surface layer has some insulation value (think of a carpet for example) then the heat from our skin can't escape very easily. The surface therefore heats up to about 34degC and we perceive the surface as warm.

Similar, think of a hard surface in a warm room, such as a granite bench top in the kitchen. Even though that is warm (20degC environment temperature), if you touch it it will feel cold, because all the heat from your skin is quickly conducted into the granite because it has a low surface insulation.

So the quick answer is, that it would be very difficult to determine whether there is enough insulation in your wall just by touching it.

If there are power points or switches in that wall you could take one of them off (of course first pull the fuse on the distribution board) and have a peak inside the wall.

Chances are that if the house was built before 1978 that there is no wall insulation.

I hope that helps.

Sunny regards


Albrecht

Ya it will help..I am thinking of insulating all my home walls this winter season and I will take care of above mentioned details..
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Re: Exterior wall insulation

Postby bhattimona » Wed Mar 27, 2019 8:30 am

It is not that easy. If you remove the lining inside and insulate without installing an air barrier on the cladding side you waste your money as the windwash will greatly reduce the performance of the insulation. Also the windwash (cold air) can move the dewpoint into places where you dont want it. This also depends where you are in the country.
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