Advice please on cavity wall insulation using polystyrene beads

emc

I am considering having cavity wall insulation installed, and would be grateful for advice from people on insulation using polystyrene beads.

The installation firm recommends Thermabead Diamond, which costs £99 but is said to be 15% more efficient than the alternative Thermabead Carbon Saver, which is free with the EDF funding.

Has anyone had either of these products installed and can give a view of their effectiveness?

Thanks.

grizzly1911

emc wrote: »

I am considering having cavity wall insulation installed, and would be grateful for advice from people on insulation using polystyrene beads.

The installation firm recommends Thermabead Diamond, which costs £99 but is said to be 15% more efficient than the alternative Thermabead Carbon Saver, which is free with the EDF funding.

Has anyone had either of these products installed and can give a view of their effectiveness?

Thanks.

We had a thermal wool blown into ours. A bit like loft insulation but softer and shorter strands, which was supposed to be the best:(

I have heard tell of the beads falling out if any large holes are made in the wall e.g. fan ducting or when doors windows are replaced.

tony6403

Polybeads are a very good option for insulation of your cavities. I have had no problem with my installation except an expected increase in condensation on the windows in cold weather.
I have no experience of Thermabead Diamond or the other one but I can't imagine that they will not make a noticeable improvement.
The beads should be installed together with an adhesive which prevents their escape when making any holes.

MiserlyMartin

The thermal conductivity of each type:
0.040 Wm–1K–1 Thermabead
0.033 Wm–1K–1 Thermabead Carbon Saver
0.031 Wm–1K–1 (density 13 Kg/m3) for Thermabead Diamond

from www.bbacerts.co.uk/PDF/4300ps1i1_web.pdf

As you can see there it not a lot in it between the Diamond and the Carbonsaver. As I see it, there is a 25% improvement between the Thermabead standard and the diamond but only a 6% improvement between the carbonsaver and the diamond, although if anyone would like to correct me, feel free. I have been doing a lot of homework. Watch out! I have yet to find a company who ISN'T doing something dodgy or misleading. I would recommend familarising yourself with the BBA certs and getting some building knowledge, then on the day of the installation supervise the workmen thoroughly, making sure they are doing the job properly. The temptation for companies to make maximum profit out of these grant funded schemes by doing a large number of installations in a day and taking shortcuts in doing so is immense so do your homework and be careful of shoddy work.

rustyboy21

No Experience as cavity wall insulation, however I have experienced them in work as a fireplace shop.

Fitters one day went out to a new house to fit a balanced flue fire. With fitting one of these, you have to knock out the internal brickwork to get to the cavity in order to fit the fire depth.

I got a frantic phone call this day, screaming for help, saying the wall was falling apart. I rushed to the property to see one guy with polystyrene balls stuck to his whole body and the other with his arm in the hole trying to stop the balls falling out, He was like the little boy putting his finger in the dyke ! The whole room was full of balls !

4 Bin bags later, they had stopped the flow and fitted the fire, they then had to go in the loft with the bin bags and refill the wall with the beads !

I now ask new home owners who are buying a balanced flue fire, to ask the builder if houses are insulated this way.

Never again ! :rotfl:

phead

The beads are of course bonded these days, so the story above doesn't apply. Is there any reason, such as narrow cavity, why the normal blown fibre isn't being used?

ragga_2

which ever company do it, as previously stated make sure you keep an eye on them, My parents had it done on their house about 5 yrs ago and now have damp near the eaves of the house, make sure they insulate this area around the wallplate as there is usually only one skin of brickwork for about 8" and is prime for a cold spot, but make sure there is still air circulation still possible for your roof.

emc

Belated thanks, folks, for your very helpful replies.

I did not monitor this thread at the time, and wish I had, because some of the warnings, from MiserlyMartin, rustyboy21 and ragga, turned out to be particularly pertinent.

EDF's contractors passed the installation to a related firm, whose installation team arrived on the appointed day but well before the agreed time, and did the work in my absence, loooong story. I was therefore not consulted and could not giving consent nor see and check any of the work being done.

I am therefore not confident the work was done properly, and have put in a complaint, so the matter is currently being investigated.

emc

MiserlyMartin

Thanks for your pm, which I saw and replied to today. Hope the info is still useful to you.

ajw4tts

We had the for mentioned polystyrene beads (Thermabead Diamond) and were assured by the salesman that the beads are essentially glued so it becomes a solid substance. This is not the case, we omitted to open our boiler cabinet during the installation, little polystyrene balls are now coming from the back of the boiler. We have called the company (Domestic General Insulation) twice and although we were assured someone would return our call. So far no one has, under no circumstances, in my personal view, should anyone consider this method of insulating your walls. We are anticipating having building work done in the future and are sure we will have a similar nightmare to others with the balls escaping. You have been warned.............. I have had 3 other homes insulated using the conventional white foam with no issues, If this is still available that would be my personal recommendation.

MartinN_2

Observations on this:
1. Miserly Martin helpfully gives the thermal conductivity of the 3 types of Thermabead. The alternative is Rockwool which has a conductivity of 0.037, between ordinary Thermabead and Thermabead carbon saver.
2. Ragga mentions damp near eaves after insulation. A likely cause is that the wall was not insulated right to the top; this will allow any penetrating rain to move down the inner surface of the outer leaf until it reaches the top of the insulation. The insulation material is chosen to be water repellent, so water will collect on top of it and thus wet the inner leaf creating a line of damp. The cure is to add more insulation to bring it right up to the eaves which are kept dry by roof overhang.
3. Free insulation does seem to carry a higher risk of sloppy work, since the organisation paying for it, not being the true customer, has little incentive to complain about bad work.
4. My understanding is that the beads are and always were meant to be blown in along with glue, but the glue is expensive, so contractors sometimes put in too little or even none at all.