Internal insulation

allycavs

Hi guys

I'm renovationing 2 rooms upstairs. There are a total of 4 rooms upstairs. While doing this I'm considering putting in internal insulation in those 2 rooms on external walls. Would this force other rooms to be colder as flow of air will move elsewhere..

Basically can I do internal insulation in steps or does this have knock on effect else where in house.

Alan

mike_2009

One primary concern with internal insulation is unexpected outcomes - you're changing the buildup of the wall and could get condensation buildup between the new insulation and the old internal wall surface. This might not be apparent for a while but bring about mold problems etc. External insulation is preferred but more expensive. Wrap the whole house up and deal with air tightness etc - SEAI have a grant for it but it's not cheap. Search for forums here for more advice as it's a common topic. But basically proceed with caution and only with Professional advice and even then you should fully understand where your new moisture / thermal layer will be. It's a cheaper but riskier strategy.

Sleeper12

allycavs wrote:

I'm renovationing 2 rooms upstairs. There are a total of 4 rooms upstairs. While doing this I'm considering putting in internal insulation in those 2 rooms on external walls. Would this force other rooms to be colder as flow of air will move elsewhere..

I've done this myself over 10 years ago. It made a huge difference to the comfort level of the house.

I used plasterboard with 4 inch foam attached. This went directly onto the existing wall. As Mike says this type of insulation may cause problems. I haven't found any yet but in theory there could be mould growth between the insulation and the original wall and I don't know about it.

greasepalm

i have also got internal insulation on some outer walls be it only 28 but anything is better than nothing and also got ceiling done in those rooms and is warmer and plenty of breezes

Calahonda52

greasepalm wrote: »

i have also got internal insulation on some outer walls be it only 28 but anything is better than nothing and also got ceiling done in those rooms and is warmer and plenty of breezes

The mould issue here is driven by how far inwards in the wall the dew point [DP]
is moved as a result of the II.
it will move a lot more with 100mm vs 28 mm

http://www.dpcalc.org/

DP is when water vapour condenses out to moisture

Sleeper12

Calahonda52 wrote: »

The mould issue here is driven by how far inwards in the wall the dew point [DP]
is moved as a result of the II.
it will move a lot more with 100mm vs 28 mm

http://www.dpcalc.org/

DP is when water vapour condenses out to moisture

Im not sure I'm understanding this correctly. Am I more at risk because I have 100mm or less at risk?

Lumen

If it's airtight on the warm side you presumably only have to worry about moisture permeating through the wall from the outside, from cracked render, porous brick, moisture entering top of cavity etc.

Calahonda52

Sleeper12 wrote: »

Im not sure I'm understanding this correctly. Am I more at risk because I have 100mm or less at risk?

I was trying to explain the science, not give a view on risk.
I don't have time to do a sketch so lets write it a bit.
Internal wall temp: 18 C
Outside wall temp: 5 C
So the temp gradient in the wall is from 18 to 5.

The normal view here in Ireland is that the DP is 12.5 C

So where is that point in the wall?

Logically 100mm will bring it further in than 28 mm.

HTH

Lumen wrote: »

If it's airtight on the warm side you presumably only have to worry about moisture permeating through the wall from the outside, from cracked render, porous brick, moisture entering top of cavity etc.

A BIG IFF for normal houses

MicktheMan

Sleeper12 wrote: »

Im not sure I'm understanding this correctly. Am I more at risk because I have 100mm or less at risk?

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