Watching Holmes on Homes tuesday evening on a Shed channel he was fixing some freezing plumbing which had been half insulated with what he called 'half pound foam' (which I guess is the expanding foam we get here in cans). He said in cold weather it shrinks and creates gap through which cold air can flow. He coated it with a blue foam, which he called 'Two pound foam'. What is this stuff?
Instinctively, i'd say it was foam of a different (higher) density
The two most commonly used spray foam products are low-density, open-cell SPF (nominally referred to as ?1/2 pound?) and medium-density, closed-cell foam (?2 pound?). Foametix offers both types of SPF, dubbed Blue Max 050 Open-cell and Blue Max 200 Closed-cell.
Google does if you look...
Open cell foam will absorb moisture from the air whenever the pipe is at the dew point, which will then freeze should the opportunity arise. Closed cell foam by its nature will not.
Armaflex is a preformed pipe insulation which is closed-cell.
i've googled: oh dear,
2 days ago i filled the gaps at the top of an exterior wall with foam, was going to cap it with a thin layer of concrete, (before the slates go back on).But the foam may move with heat variations, the concrete may crack, and water seep in, so i guess that to do a long-lasting job when the snow's gone i'll have to clear it all out and use concrete to infill. [g]
Hardly a critical location. Even on my gable end wall, which faces SW and has a minimal slate overhang, I only used mortar. Stick some pva in the mix if you're woried.
Armaflex is also neoprene, so that the cells flex if they do happen to be wet and frozen. Stiffer foams (PU, PIR) will tend to crumble gradually over the years.
One of my favourite things in the workshop ever is a roll of "Armaflex gaffer tape", 3mm sticky-backed neoprene. It makes non-slip pads under furniture, anti-vibration handle wrappings on power tools, draught excluders on windows, the works.
there were huge gaps in the top of the wall (north facing) filled with straw from decades of birds. It will take perhaps 20 buckets of cocrete lugged up the ladder, and a few hour removing the foam, but i think i'd better do it as the foam wouldnt last many decades.
[g]
I've seen Holmes on Homes mentioned a few times and kept wondering WTF does Eamonn know about houses ...but now I know This might be of interest
today i started ripping the interior foam from the top of the wall where I put it last week, and i've ordered this:
which I hope is the correct kind of exterior closed cell foam for using where water might dribble in.
george [dicegeorge] wrote:
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