Solid Wall Insulation Options..

[darms]

Hi all

I've done some searching already on previous posts, but cant seam to find the answer.

Here goes........I live in a 3 bed 1930’s semi in N.London which has solid walls (no cavity walls) with a ground floor extension. The extension was completed approx 19yrs ago with NO insulation being applied to the walls.

I believe the walls were constructed using those large grey bricks (sorry not sure on their official name). Plasterboards were then dotted and dabbed and then skimmed.

External insulation is not really an option as the property is end of terrace with garden fences very close.

From what I've read am I right - I need to for go something like Kingspan K17/K18?
Does the existing plasterboards have to come off?
Are their any specialist installers anyone recommended?

Thanks in advance

 

[chappers]

basically you need a decent plasterer to dot and dab the insulated board on then skim over for you.

 

[darms]

ok but does the existing plasterboard need to come off, or can it be fitted on top?

 

[ajrobb]

19 years ago, your extension should have been built with cavity walls. You might get a grant to install CWI.

For the main house, Kingspan K17 is not supposed to be an option for external solid walls and Kingspan recommend K18 on battens - have a look at the link.

I suppose the ideal seems to be to remove existing plaster and create a 50mm vented cavity using galvanised steel battens, then K18. Don't use any impervious coatings. This will avoid most damp problems. You don't HAVE to skim; they tend not to in other countries. You could use drywall sealer if you want to be able to use a steam stripper at a later date, or drywall primer if you just want paint.

Alternatively, you could just have a 19mm unvented cavity with treated timber battens (or galvanised steel). The low-emissivity foil on K18 gives an extra 0.6 R-value next to an unvented cavity (equivalent to 15mm PIR insulation).

 

[^woody^]

Think about what you are trying to achieve or what problem you are trying to solve.

There will be a lot of disruption to insulate internally - including the need to remove plaster (or mechanically fix battens) and bring all the electrical sockets switches forward. And then there is the loss of space of up 50-75mm to make it worth while.

So weigh up the costs and payback times as opposed to a few extra £'s in heating bills

 

[tfish]

i take it you havent living in one of these houses Woody?

Its either improve or move, no option.

I batterned and filled inbetween with Kingspan foam board then plastered. Much improved warmth and damp.

 

[chapeau]

Yes, I have a similar 'problem' in that the mrs feels cold in the warmest room so sometimes you have to add insulation which us sensible chaps might feel unneccessary.

But I have a question which has always puzzled me.

The solution above and in the literature is to dot and dab insulation onto a solid wall. We also read about cold bridging and condensation issues.

So when dot and dabbing onto a solid wall, you will have areas with adhesive between wall and interior, and areas with air between wall and interior. Obviously two different heat transfer properties, one guesses the adhesive part will be a cold spot. Why is possibility of condensation on interior wall not considered an issue?

 

[ajrobb]

The solution above and in the literature is to dot and dab insulation onto a solid wall.

I am intrigued now. I haven't seen manufacturer's instructions saying to dot and dab onto external solid walls. I think K17 product sheet says specifically not to be fixed by dot and dab to external walls but to use K18 on treated wood or galvanised steel battens instead.

EDIT: by "external wall" I meant "external solid wall" ('cos K17 can be dot-and-dabbed on external cavity walls)

 

[chapeau]

Well it looks like you are right and I am wrong. Thanks for the answer!

 

[daveo78]

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