Internal insulation

[adamjseed]

Hi,

I am about to start work on internal insulation on my old, solid wall house. Its quite damp on one wall in particular and I have some ideas on solving the damp (french trench, chemical damp proof course, fixing render etc) but my question is:

What would be the best method of internal insulation for a damp house?

I have heard many different ideas but would love to ask on here, whats worth doing and what should I avoid? Links to products would be great.

 

[JamieCelotex]

Hi Adam.

Where a wall has the possibility of being damp it would be best to leave an airspace of 25mm between the wall and then construct an independent timber frame.

Assuming a 9” (215mm) solid wall then typically 75mm Celotex GA4000 between these studs would meet the required 0.3 U value for a wall refurbishment.

It is then important that a continuous vapour control layer such as 1000 gauge polythene is placed across the inside face of the studs before the plasterboard is fixed up.

Hope that's of some help.

 

[adamjseed]

Thanks for your reply Jamie (sorry delayed). While I fully agree that your solution is viable, I have an issue with the amount of space im going to loose. I then discovered a product by Marmox.

Im not 100% sure on a few things so im going to ask a few questions:

1) I think I can attach these boards straight onto the damp wall (after doing my best to sort out the damp issue) as they are water proof. This means I can reduce the space taken up dramatically. Has anyone attached these boards in damp conditions?

2) I am still very confused about how to calculate U values and what values should I be looking to achieve. I have a 225mm sold wall with outer render. Can anyone explain how I work it out? The R value of Marmox 40mm is 1.22 and 50mm is 1.53

 

[AronSearle]

No point having a 25mm cavity between the insulation and wall, unless this is ventillated to the outside.

https://www.english-heritage.org.uk/publications/eehb-insulating-solid-walls/

You can download a free trial programe called build-desk to calculate u-values.

Assuming the damp is not from external sources (or this is fixed) and it is caused by condensation, then it may be possible to affix insulated plasterboard which incorporates a VCL direct to the internal wall surface.