Cavity Wall Insulation ??

[Macster]

Hi, is anyone 'in the know' with regard to Cavity Wall Insulation pls ?
Our House is only about 12years old, and pretty warm to be honest, but today we had a Company round who advised that the Local Authority are giving subsidies toward Cavity Wall Insulation.
Our inner walls are apparently 'Thermablocks', but we still have a cavity that could be filled to give even greater heat savings etc,and its only gonna cost £120 for a 4Bed Detached House.
However, Ive read that some people suffer more Damp problems as a result sometimes - does anyone know if this is likely or a general problem ?

Thx

 

[Leftie]

Cue Clive ???

 

[brendy]

We had ours done with the beads while the extension was done and to be honest was worthwhile. Damp, I dunno, a year on now and haven't got any.
We got a similar subsidy, we paid around 150-200 after assistance.

 

[drawboy]

Right this is up my street as a time served apprentice trained bricklayer. Houses have cavities for a reason. That is to stop damp penetrating through the outside brick to the inside of the house. Tie irons that hold the two skins together have a twist in the middle so any water trying to travel between the two walls falls off before it can get to the inside, therefore filling the cavity defeats the object of having it in the first place. I wouldn't fill my cavity for that reason, also a house can be too warm which can lead to condensation problems. I see this all the time,black mould growth due to no drafts or airflow because of blocked airgrates and double glazing. The only effective remedy for condensation problems is to leave your windows open all of the time. That then works totally against the idea of a warmer house in the first place. I would rather top up my loft insulation to the max, it will do the same job. Just out of interest if anyone has had double glazing installed to save energy in a typical lifetime you will never get back in savings what the DG cost in the first place regardless of what the salesmen tells you.

 

[brendy]

Double glazing is different, it also reduces noise from outside, looks better and is harder to break.
When we built the extension, going without DG was never even discussed. We used damp proof course and vents etc, so far there has been no damp through, we haven't painted yet (issues with builder) so can see the bare plaster.

 

[andiritchie]

You could end up with bridging as the cavity is there for the house to breath.Most new built houses with cavity wall insulation only have 50mm insulation leaving a 50mm cavity

 

[AMcC]

My tuppence on the subject.

Agree that walls have cavities for a reason, but I think the materials blown in are specially chosen for their resistance to the passage of moisture.
The new building regs are continually increasing the amount of insulation required in houses and the airtightness of the construction. At least anything you do voluntarily will mean you are not as far behind todays standards and will reduce the heat loss. Upgrading the loft insulation to at least 250mm total depth will probably help more.

The condensation issues are generally caused by todays lifestyles and the lack of draughts in modern houses. You very rarely see damp in an older house with a working coal fire. Reducing moisture in the air will limit condensation and regular heating all help. Kitchens, bathrooms utiltiy rooms are best served with mechanical extract systems or equal systems, this aids the removal of the moisture in the air. As the energy conservation debate continues some even have heat recovery systems fitted to not loose too much heat.

Quick summary, probably go for it.

 

[Ken_A]

Financially it's worth it- as for risk of dampness, well there is a SMALL chance. If you get damp it is prob due to a small gap and driven rain entering cavity and then moving along void. However IMHO it is a very small chance and well worth the investment. Most of the injected beads are covered with resin which is water proof, thus it activity protects from the wind driven rain.
Cavity blocks are quite a poor product and can lead to problems when not installed correctly, hence, some councils (and countries - Ireland) have refused to allow their use in the domestic market.
IMHO its a large gain from a small cost with little chance of problems (assuming it's a reputable company)

But then again what do I know - I've just spent the last 10 years designing some of the UK's and Ireland's most dynamic and thermally advanced housing.

 

[AMcC]

that will be timber kits then

 

[Ken_A]

that will be timber kits then

I have probably specified and designed enough timber to keep the Scandinavians in business or a few years. Yea timber frame, stick building, platform frame, SIPS and steel frames with a lot of variations in between.