blown insulation into an existing insulated wall

woody1

so existing dwelling
current wall build up
white sand render
100 block
50 air
65 eps insulation
100 block
35mm insulated plasterboard

what do people think of blowing expanded polystyrene beads into the air cavity ( this has probably been asked before )

ive done a condensation risk analysis for it ( as much as i can, i cant find blown beads on the material list so i substituted expanded polystyrene, i know theres bound to be a percentage of an error involved but ive gone thru a variety of materials and thicknesses and condensation is still only occurring on the inside face of the external wall )

condensation occurs on the inside face of the external wall .. as it does under current construction apparently.. but there is no danger of mould growth apparently in either construction

there actually looks to be marginally more condensation occurring under the present construction.. but it occurs in an air cavity so shouldnt be any great problem

so, do i trust that the blown bead insulation will not carry moisture ( be it penetrating rain or condensation ) across the cavity to the existing insulation, from what i gather wet insulation boards are worse than useless
this is the crux of the issue..

does anyone have any experience , has anyone already done this and can they see any improvement

BryanF

woody1 wrote: »

ive done a condensation risk analysis for it

may i ask what software did you use? and how did you find it, time to learn it etc

what are the other parameters ie, exposed site, damp site, any probs at the moment.

for what its worth imo the better Bead products seem ok, BUT DONT TAKE MY WORD FOR IT OR THE CONTRACTORS get the:

• correct guarentees
• and insurances,
• followed by a thermal image (before and after)

you could always do a bit of research and stick a humidity monitor into the cavity ( costs about 50€) and if you have the patience for the analysis software then this imo would be the way to go.

woody1

sorry brian , i didnt see your question till now, i used the build-desk u software, a trial version,
never used it or anything of this type before and i found it very easy to pick up..

site is very exposed.. not coastal..but there is pretty much nothing between it and the west coast approx 25 miles away..
no site isnt damp
there are no signs internally of any damp related problems

there is one issue with cracking white-sand render..basically a bad plastering job..hairline cracks only this makes me nervous of the beads as well, no fault of the beads themselves but i dont want them getting any wetter than they need to be

yeah the moisture meter is an interesting idea..could do that in a few spots.. and see what comes up... unfortunately and somewhat ironically seening as im trying to save money, i dont see us doing this anytime soon as we dont have the money to do it anymore, really annoying situation where you need to spend to save but dont have the initial spending money, but we'll have to buy kerosene at some stage instead..mental isnt it..

had a couple of installers down looking at it and they wont guarantee anything because of the insulation already in the cavity, they cant guarantee the quality of the installation of this insulation, which is fair enough as they cant see it...