Cavity Wall Insulation Question

som

Following on the theme of old insulation - our current house was done with Urea Formaldehyde in the 1970's. This may shrink over time. We still have the life time guarantee. Is it possible to check the state / effectiveness of the insulation?

For those also asking - We had cavity insulation done in our last house (built 1992) and it made huge difference with no immediate problems in the first 3 years.

Plain_Speaking

som wrote: »

Following on the theme of old insulation - our current house was done with Urea Formaldehyde in the 1970's. This may shrink over time. We still have the life time guarantee. Is it possible to check the state / effectiveness of the insulation?

For those also asking - We had cavity insulation done in our last house (built 1992) and it made huge difference with no immediate problems in the first 3 years.

An Infrared Thermal imaging survey would be the best way to check on the effectiveness of your existing installation.

However in a "money saving" spirit I would suggest its not necessarily worth the survey cost unless you think you have a problem with dampness/condensation/mould growth etc.:)

peterbennett26

I suppose it depends on the reason why air bricks were installed in the first place.

Say it was just to provide fresh air from the outside into the room, which had a fire in it that needed the air supply. (or to keep a wooden ground floor from rotting)

Then if the air brick was installed properly, i.e. as a system, it should have the following components in a cavity wall build.

On the outer wall (known as the outer leaf by builders etc.) it will have the special brick with the air holes. Spaning the inner and outer leaves (the cavity) should be a fired clay 'tube/pipe' with the same section/shape as the air brick, and on the inside/inner leaf, the hole will typically be covered by a louvered vent.

As you are bridging the cavity it is very important that liner/tube slopes very slightly downwards towards the outer leaf, perhaps slate packing can be employed under the liner to raise the inner side slightly. (any moisture runs to outside)

When properly mortared in place, in theory at least it shouldn't be an issue.

On suitability of retrofit cavity wall insulation, supposedly that depends upon the exposure of the property to the elements, and keeping the inner leaf dry was originally one of the touted advantages of the open cavity wall construction.

On exposed sites one of the new build solutions can be the partially filled cavity. Here the insulation bats are fixed to the inner leaf, and still give an air gap to the outer leaf to try to prevent water transfer when the outer leaf gets saturated.

Don't know if that helps, as there is no blanket answer on suitability. A sales driven organisation might install it in properties where it really shouldn't, but a surveyor subject to enforceable penalties might be expected to err on the side of caution when judging property suitability.

How can you quantitatively judge this aspect ? Feedback on failures, root cause analyses, where's the data on the wetting cycles the properties have been subjected to, is there an official procedure to be followed during the suitability survey from the government's Building Research Establishment ?

Dunno.

Plain_Speaking

peterbennett26 wrote: »

I suppose it depends on the reason why air bricks were installed in the first place.

Say it was just to provide fresh air from the outside into the room, which had a fire in it that needed the air supply. (or to keep a wooden ground floor from rotting)

Then if the air brick was installed properly, i.e. as a system, it should have the following components in a cavity wall build.

On the outer wall (known as the outer leaf by builders etc.) it will have the special brick with the air holes. Spaning the inner and outer leaves (the cavity) should be a fired clay 'tube/pipe' with the same section/shape as the air brick, and on the inside/inner leaf, the hole will typically be covered by a louvered vent.

As you are bridging the cavity it is very important that liner/tube slopes very slightly downwards towards the outer leaf, perhaps slate packing can be employed under the liner to raise the inner side slightly. (any moisture runs to outside)

When properly mortared in place, in theory at least it shouldn't be an issue.

On suitability of retrofit cavity wall insulation, supposedly that depends upon the exposure of the property to the elements, and keeping the inner leaf dry was originally one of the touted advantages of the open cavity wall construction.

On exposed sites one of the new build solutions can be the partially filled cavity. Here the insulation bats are fixed to the inner leaf, and still give an air gap to the outer leaf to try to prevent water transfer when the outer leaf gets saturated.

Don't know if that helps, as there is no blanket answer on suitability. A sales driven organisation might install it in properties where it really shouldn't, but a surveyor subject to enforceable penalties might be expected to err on the side of caution when judging property suitability.

How can you quantitatively judge this aspect ? Feedback on failures, root cause analyses, where's the data on the wetting cycles the properties have been subjected to, is there an official procedure to be followed during the suitability survey from the government's Building Research Establishment ?

Dunno.

The "air brick system" with sleeving, you describe above, is typical for current new build housing, where thermal insulation levels are high to comply with building regulations.
Such a detail would be very rare for the vast majority of the country's poorly insulated housing stock built between approx. 1930-1970. There is normally no air brick sleeving across the cavity in these houses.
Historically most air bricks are fitted to vent underfloor suspended timber ground floors. If cavity wall insulation is done by "cowboys" who block such air bricks there is a real and serious risk of a dry rot outbreak in the ground floor timbers.
House owners should be aware of this risk and ensure the work is carried out by professional insurance backed installers.
Currently the latest "platinum" bead insulation provides the most effective thermal values for retrofit cavity insulation. Mineral wool has less "fire risk."

pixie__girlie

Can anybody advise pretty please ?

I live in a 70's bungalow, we had airbricks fitted when we moved in as it was advised in the survey ( suspended timber floor)

Had a surveyor come to check if we could get the government funded cavity wall insulation, they said we already have it (proof being some small cement filled holes at the front of the house ) but I can't help feel that the cavity isn't filled. The heat just doesn't stay in the house (we have plenty loft insulation). Plus- when the builder fitted the airbricks, wouldn't all the cavity wall stuff have fallen out.... ??

Wish I knew more about building and what not and I don't have any handy friends / fam!! Any advice most welcome. x

MX5huggy

Your suspended timber floor is likely to be one of the major reasons for your heat loss.

Your cavity would most likely be filled with mineral wool fibre this does not fall out. Alternatively polystyrene beads may have been used these would fall out but they are supposed to be glued in, it's a mix of glue a beads pumped in.

captainhindsight_2

If you crawl across your loft space you maybe able to look down the cavity wall and see if you have insulation in the cavity, other option is to drill a hole in the wall.

For floor insulation HHCRO and CSCO (parts of ECO) grants will help pay for this or even all of it in some circumstances (CSCO is not means tested but pays less than HHCRO), also there is a cashback scheme coming which may include help for floor insulation.

jazzydom

Having researched this previously, I know Thermabead Ltd can save up to £140 annually on your CO2 bills. They offer Cavity Wall Insulation which can be funded via their partners. All in all, it seems like a win-win to me!table { }td { padding-top: 1px; padding-right: 1px; padding-left: 1px; color: black; font-size: 12pt; font-weight: 400; font-style: normal; text-decoration: none; font-family: Calibri,sans-serif; vertical-align: bottom; border: medium none; white-space: nowrap; }.xl64 { vertical-align: middle; white-space: normal; }