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Energy /
Wall Insulation QuestionsBack to Cheap Wall Insulation | Email me your question 12 Oct 2008 Found your article very helpful but for a different insulation problem. I have a modern penthouse flat with insulation in the flat roof construction not the ceiling 2ft below the roof. There is a lot of heat loss. Several insulation contractors have been to quote and because its small the price is expensive (£4k for one!) I\'m going to use your vacuum solution to do it myself. How far do you think the vacuum cleaner will blow beads into the roof space ie if I put a 10 ft extended noozle on the Y section. Simon Taylor in UK Hi Simon
I never measured the blowing distance.
The main challenge you may find is avoiding them blowing back towards you as you work. The beads are incredibly light - when you release them in a small space with a blower going I suspect they fly all over the place. Make sure you have a very good mask - the polystyrene dust is probably a very bad thing to get stuck in your lungs.
How could you prevent them drifting back out the man-hole as you work?
Cheers, Paul
Hi I'm really impressed with your work and it looks like you just managed to finish before the baby arrived! Do you think your system would work from the inside? ie cut holes in plasterboard, fill with beads then re-fill the plasterboard? Does polystyrene degrade PVC used in electrical wiring? I also have dwangs so I\'ll need 3 times the number of holes too! Anyway thanks again for the inspiration Tom Mulholland (Scotland, UK) Hi Tom
Yes - polystyrene does "eat" PVC electrical wiring - so you need to avoid it at all costs! I was also fortunate that most of my wiring is on interior walls. There were only three places were I had to leave the section empty. I've been thinking about blowing in some other sort of filling - maybe wool?
I think going from the inside walls should work. (I suspect my wife may not have tolerated that much hassle.)
Cheers, Paul
Hi Paul, Did the EPS beads get a static charge from all the handling? How did you keep the beads from creating a "chimney effect" in the wall when the static charge creates a void in the middle of the wall cavity? Any regrets yet? Most houses in Southern California built before 1975 (mine) don\'t have insulated walls, and your retrofit solution sounds better than the expanding foam or celulose (shreaded newspapers!) blown in. Regards, Hi Garth
Must confess I hadn't thought about static charge. It's a very good question.
The frustrating thing is... I don't know of an easy way to measure the thermal resistance.
One thing I have noticed is condensation on the outside of the walls in the areas where my insulation is (between the studs) - and no condensation where the studs run up the walls.
That suggests to me that the area between the studs is cooler than the stud area. Therefore the studs are conducting heat out of the room better than the polystyrene filled spaces. And that's another way of saying the polystyrene is a better insulator than the solid wood stud.
By comparison - I have a few columns that I have not filled (because they contained electrical wiring - and polystyrene melts wiring insulation). These sections do not show condensation.
So all that tells me is that the polystyrene sections are better heat insulators than the non-filled sections. But how much better? - I just don't know.
In the year after the wall insulation went in my power usage (all my heating is from a electric heat pump) was down a wee bit - right up until we had a baby. Looks like were going from 5000 kWh last year to about 6500 kWh this year.
Cheers, Paul
What about electrical wires - doesn't the polystyrene react with the plastic around the wires? I'm lucky that our house has almost all it's wiring on the interior walls (ie between rooms) not the perimeter walls. There are about 4 spots with wires - so I just left those empty. At some later stage I'll think about filling those with something non-reactive, like wool or paper fibre.
Is it fire retardant? Yep. Poly Palace only use fire retardant polystyrene in their underfloor products (so I made sure they gave me fire retardant beads).
In the UK polystyrene wall insulation is blown in with a glue. Why is that? My guess is:
I don't have an answer to any of these issues with what I've done.
I've heard that polystyrene absorbs water over time. Given that your house has wooden walls - will any leaks mean your walls become water logged over time? I've heard that too. Which is one reason why if you have underfloor polystyrene blocks it's very important to have a vapor barrier too - so that they don't collect the water vapor expiring from damp ground. polystyrene blocks used in floating marina's have to be replaced eventually when they become waterlogged. I'm not sure how long "eventually" is.
In my case I'm currently just hoping that my walls are waterproof.
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