You bloody plasterers, changing building regs
it’s 50mm air flow in cavity work, not 25mm, before insulation came into play wall were 250mm overall, 2 skins of 100mm + 50mm. With the introduction of insulation (at first the shite polystyrene Jablite), the 50mm always has to be maintained, insulation width has increased ridiculously over time ( ask Splott-Light about this), walls are now 325mm overall, 100mm + 100mm for the walls (unless a 140mm inner skin is specified) with 75mm cavity insulation (usually celotex or Kingspan at the moment) + 50mm air flow. The increases in insulation widths has caused havoc with material costs specifically I.G. lintels as their overall width have to be increased each time to take the inner & outer skins resulting in previous stock becoming obsolete, same with cavity closers, wall ties etc. Someone is making a right killing with changing building regs. As regards injected cavity insulation I would tend to avoid it, the installation is very much down to the operative, blank spots will result in cold spots eventually turning your interior walls in those areas a horrible shade of black. If possible perhaps exterior insulation bats could be fixed, with an expanding metal key prior to rendering. I’ve been in the game since 1971 and the emphasis to us during my 4 years at Llandaff Tech was that cavities must be kept clean & clear, our tutors, Howard Phillips & Mike Hart would be horrified at the thought, 40 odd years later, after the introduction of cavity work after years of solid wall structure folk were planning on filling them.
Originally Posted by Tuerto
That's the stuff where they pump it in from the outside? I don't like it. I presume that your property is getting on for 50 years old and therefore was never fitted with a celotex type of insulation board? The reason that i don't like it is because a cavity needs to have air flow. Todays wall cavities are 100mm-That would be 75mm of celotex insulation tight to the internal skin of brickwork with a 25mm void that allows movement of air. When insulation is pumped in then it fills the Cavity and you no longer have that air flow which can lead to the cavity sweating and eventual salting on the internal plasterwork, although you may get lucky and none of this happens. The little balls are designed so that they don't take on moisture. Have a look outside of your house and see if you have cavity vents, usually 120mm from ground level, if you do then the purpose of them is to help your cavity circulate with air which greatly reduces any issues with moisture build up. Personally, i like the idea of my walls being vented and would probably consider a scarfe and jumper in winter as oppossed to the loose fill blocking my cavity. good luck
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