Insulation of a wood clad house

by **newtonhill** » Sat May 02, 2009 7:58 pm

We have a 1940's wood clad house with, we believe, no insulation. We have been told that we would have to tear out our interior walls, to be able to put in insulation!! They have also stated that we cannot 'blow-in' insulation because of condensation (which we don't understand) Please someone tell me there is an easier, or at least a less messy way to accomplish this.

by **Perry525** » Sat May 09, 2009 5:31 pm

Lets deal with the condensation.
Condensation is due to warm wet air finding a cold surface, the air being chilled by the cold surface and the water vapour condensing onto the cold surface.
This usually happens when the warm wet air inside our home comes into contact with a cold window or perhaps rises inside the home through a badly fitting loft trap door into the loft and condenses on the inside of the cold roof.
If you add insulation to the outside of a solid wall, then the water vapour in the home will not enter the wall, because it is a warm wall and water vapour always moves from warm to cold, so it will condense onto something else.
If you add insulation to the warm room side of a solid wall, you make the solid wall colder and if the water vapour can get into the wall then it will cross the wall to the cold outside surface and blow away on the wind.
Where a solid wall is dry and is protected by cladding then it is a good insulator. How good depends on the thickness of the wall.
Note: Most solid walls are damp most of the time and some are wet some of the time or all of the time. A wet wall will accelerate the heat loos from a home.
Adding insulation to a wall is always worth while but, the better the insulation to start with the smaller margin for saving and the longer the pay back time.

by **newtonhill** » Sat May 16, 2009 3:50 pm

I understand now a bit more about condensation. Thank you Perry525! But what I don't understand is why they say that blown in insulation in a WOOD CLAD house would be more than in the 'traditional' built house?

by **Perry525** » Sat May 16, 2009 5:32 pm

As you now understand condensation does not arrive as of magic, it is there because someone (or the weather over the Gulf of Mexico) made the water vapour that is looking for somewhere to condense.
So, the water vapour in our homes is put there by us, cooking, bathing, breathing, washing - whatever, it is only there by our actions.
Therefore, the type of house doesn't make much difference.
However, the perception by the individual...... that's a different matter.
Go into a hot steamy bathroom on a cold night and the windows are covered in condensation, if the walls and ceiling are painted with gloss paint and are almost water vapour proof, then they will be running with condensation, the toilet cistern full of cold water, will have condensation dripping on the floor.
The same room with treble glazing, a single thickness of plasterboard on the ceiling, perhaps wallpapered where the water vapour can soak into and through the fabric of the building will look dry.