Cavity insulation or not.

kabakuyu

I have the opportunity to get cavity wall (bead) insulation installed at a reasonable cost.The house is a 2 storey detached with attic conversion.House was built in 1981/2 and no cavity insulation installed, all exterior walls have plaster board with 28mm insulation backing attached to walls by dot and dab method, all windows D/G(4 yrs old) with trickle vents, all bathrooms have extractors fans linked to light switch.Attic insulation is 300mm.No other room vents in house except in utility(dryer)kitchen( Hood)and two blocked fireplaces.

Installer has said I would be ok to install bead,he has produced agrement cert(regarding ingress of water in exposed areas) that certifies bead is suitable for rendered walls but not brick,my exterior walls are rendered.

I have a few questions, hopefully ye can offer some guidance.

1.Will the bead insulation make a difference, are uninsulated cavities an absolute no no nowadays?

2.I am worried about condensation, do I have enough ventilation at the moment?will the insulated board currently in house impact on cavity insulation as regards to condensation?

3.One of my gables gets some s/w showers and is more exposed to weather than the others which are more sheltered(I am in urban location so some shelter from neighbours) should I be worried about water ingress?

Any guidance or tips very much appreciated.

Water John

Definitely go for the cavity insulation. One area, as in my house, where airflow is a problem, could be between the dabbed on insulated board and the wall.

MicktheMan

OP, in order to answer your 1st question can you give more information:

a: does your house heat up sufficiently when your heat turns on?

b: assuming the answer to a is yes, then do you notice that the heating has turned off within, say, an hour of it going off?

kabakuyu

https://www.boards.ie/discussion/comment/120113574#Comment_120113574

Hi Mick, it heats up very quickly,it cools down within a couple of hours, some rooms more quickly than others like the sitting room which has large bay window.Airtightness would not be the best IMO.

MicktheMan

https://www.boards.ie/discussion/comment/120117336#Comment_120117336

Airtightness would not be the best IMO.

You just answered your own question (well, question 1 anyway). If air tightness is poor, pumping the cavity won't make much of a difference.

kabakuyu

https://www.boards.ie/discussion/comment/120118167#Comment_120118167

Thank you Mick,I presume that means airtightness should be looked at first.Any ideas on the other questions?