Cavity wall insulation - worth doing?

speedy_gonzalez

Is it worth having a two bed-room mid-terrace house done? Just had our gas & electric bill and the monthly direct debit is going up by £12. Affordable but if cavity wall insulation will make a difference I'll get it done.

vegasvisitor

Hi

See what others say first. I would be reluctant to get it again, because although it does work, it can also cause dampness. I have to be careful not to place anything right tight up against outside walls now (had mould on the back of a bookcase once - maybe that's relatively normal but I was a surprised, and not sure it would have happened before the insulation). I think maybe it stops natural ventilation.

macman

Certainly worth it from the point of view of energy saving, it's heavily subsidised anyway so unlikely to cost you more than a couple of hundred-have a look on your utilility supplier's website for prices.
It does not reduce ventilation.
I assume you have cavity walls?

WestonDave

If anything it should reduce mould on walls as its cold surfaces which tend to attract condensation, and mould grows on the condensed water. In our case it dramatically reduced it - in one north facing room we had vinyl wallpaper (previous owners taste!), and at various points you could brush your hand over the wall and come away with your hand literally dripping wet. That has ceased since having insulation put in.

Regardless of cavity wall insulation, if the relative humidity in your house is too high, you will get condensation in cold corners - behind furniture is classic because often the warm air currents in the room don't get there. Moist air getting into a cold corner will lead to condensation and then mould.

In terms of getting it installed, you can either go via the utility company and get them to arrange it, or alternatively often the contractors can arrange the grants themselves so if you ask around the neighbours and find out who did a good job, you can then get them in to quote. That's the way we did it, because we wanted the bead type of insulation which is less common.

27col

WestonDave is quite right about the causes of condensation. I would not dream of not having cavity insulation. It has been 33years since I built this house and there has never been the slightest hint of dampness. The back of the house is very exposed to the prevailing weather.
If there is dampness inside a house it is far more likely to be due to condensation of some sort, than penetration from the outside. The whole point of insulating the walls, coupled with central heating is to make condensation virtually impossible or at least to reduce the possibility to very remote levels. Its the heat that is preventing the condensation and the insulation that is keeping the heat where it is wanted, Inside the house. An unheated house will form condensation even if it is insulated.