Internal and External Insulation

[JamesRP]

Hi, I am new to this forum and need some help and advice.

I have a single skin extension on the back of my house, it needs insulating and I am considering insulating both internal and external walls with 50mm Ecotherm PR50 Versal board.

Can this be applied direct to the single skin brickwork, separated only by 47 x 100 studs on each side and then covered on the outside with featheredge and on the inside with plasterboard?

Any advice is gratefully received.

Thanks,

James.

 

[jeds]

I wouldn't advise both internal and external. Just dry-line the internal with a thermal laminate board. 85mm Kingspan k17 board will bring is close to current thermal regulations. Easy to do, no fuss and a good finish.

 

[JamesRP]

Hello Jeds,

Do you have time to explain why it is not a good idea to sandwich the single skin brickwork between two layers of 50mm ecotherm?

Thanks,

James.

 

[Agile]

My view is that any external cladding runs the risk of damp ingress and would not be advisable quite apart from the significant extra work and cost for little gain.

I gather that any serious insulation addition like this needs building control approval and inspections.

Tony

 

[jeds]

Apart from the extra work it is better if a wall can evaporate moisture to the external. Internal insulation is the best option in the situation you describe. Some people advocate external insulation because of the notion of the wall acting like a huge battery of heat. That may have some value in certain situations but it is completely false in the case of a half brick thick wall. Internal insulation is easy to do, provides a warm wall which avoids condensation and is thermally efficient.

 

[Bouba]

Just been on a website selling k17 and 18. They are saying avoid using k17 as it can lead to problems due to water penetration possibly condensation. They recommend k18 on timber batten or metal furrings. How efficient would they be as compared to a proper cavity build wall