More insulation on a cavity block wall

[Mebs]

Our house is quite exposed. Two bedrooms are at the rear of the house and are north facing. The walls are built of cavity blocks. A few years ago we insulated all of the bedrooms with insulated plasterboards but the two bedrooms at the rear are still cold. We should have used thicker plasterboards probably. Would it make any sense to put external insulation on the back wall of the house? We could not afford to do the whole house.

I just wonder if having insulation on the inside of a cavity block wall would prevent the wall heating up and having the heat retained by the external insulation, defeating the purpose of it. And we really do not want to take down the existing insulated plasterboard. It was messy last time and I do not want to go through all that again. Thanks.

 

[MrEarl]

Hello,

We had the cavities filled with insulation a few years ago.

At the time, they injected the walls with little grey beads, which were apparently covered wtih some form of glue, which would later dry and hold all of the grey beads together.

While I do think the insulation resulted in the house being a little warmer, we still have the little grey beads coming out of our air vents, everytime there is a strong wind. It drives me crazy, as I ultimately have them popping up throughout the house. Perhaps there's an easy solution to this problem, without having to close off all of the air vents which I know I'm not supposed to do.

If you do decide to invest in some form of insulation, have a look at the [broken link removed] first, as you may be entitled to claim a grant towards the work you are intending to get done.

Also, one other thought, as the bedrooms will no doubt have reasonably large windows - perhaps the windows need to be upgrated or checked for drafts. Glass is very poor at retaining heat, so also ensure you have a good pair of heavy curtains covering each window.

 

[Jetblue]

we still have the little grey beads coming out of our air vents, everytime there is a strong wind. It drives me crazy, as I ultimately have them popping up throughout the house. Perhaps there's an easy solution to this problem, without having to close off all of the air vents which I know I'm not supposed to do.

Mr Earl,
Screw off the Vent covers, squeeze a short section of the appropriate size pipe (usually 4" sewer) onto the vent hole and seal the end with a squirt of silicone. Replace the vent cover.

Alas, I think Mebs has "cavity blocks rather that a cavity wall". Pumping beads into cavity blocks is not an option.

 

[MrEarl]

Thank you JetBlue,

Sorry if I have confussed matters regarding Mebs, perhaps I misunderstood.

 

[Leo]

It's not recommended to apply external insulation to a wall that is insulated internally. Also, most reputable contractors will tell you external insulation is at its best when applied to an entire building. As a result, the [broken link removed] available for external insulation only apply where the entire structure is being insulated.

 

[clueless]

I had a similar problem but putting in internal insulation was not an option. I couldn't get insulation into cavity into the walls either. I looked at the price of external insulation but it was very expensive so would have taken years to recoup. Instead I put a lot of insulation into the attic and it helped a lot. You may not need to change the windows if there is a way to replace the seals to stop drafts coming in. Another thing that might help is if you get a dehumidifier. Houses in Ireland are really damp and if you put a good dehumidifier on every level in the house it will draw out the moisture in the air. I think it brings up the temp about 5 degrees in the room its in.