# Internal v's External Insulation



## kaza (12 Nov 2013)

Hi,

I have a rented property, three bed semi with flat roof kitchen extension, and small flat roof porch. The attic is well insulated, but the walls are 9 inch cavity blocks with no insulation. The house is very cold and there are problems with condensation and mold in some places.

We've have a few people look at it and the main problem is insulation (along with upgrading the vents). So we are looking at insulating the three external walls, kitchen extension and porch. We have gotten a few companies out to look at pricing internal and external insulation and we are getting a lot of conflicting advice over which option is better in the long run. 

Obviously I would prefer to go with internal insulation as it's much cheaper, but I do not want to do that if it's going to produce problems down the line (condensation on cold external side of wall, thermal bridges). As it's rented my main aim is not to reduce the heating bills (although obviously want the house warmer), but to remove the condensation/mold problems before they get worse. But I want to ensure I don't then need to address new problems because of the insulation in 5/10 years time, and have to invest a chunk of money again at that stage.

The tenant is fine with moving out for a week if we do the internal insulation, and we have someone that will do it in that time frame.

We have the house for a foreseeable future as it's in bad negative equity and want to ensure it's a decent house for tenants to live in, and easy to rent. However, money is tight and we want to avoid having to spend big sums money if possible. I am trying to organize an architect to come out and give some independent advice. But does anyone here have any sound advice or experience with internal or external insulation?

Thanks


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## lowCO2design (12 Nov 2013)

kaza said:


> *walls are 9 inch cavity blocks*
> *there are problems with condensation and mold
> *
> *upgrading the vents*
> *problems down the line (condensation on cold external side of wall, thermal bridges).*


 read relevant links in post 4
id recommend external insulation, i appreciate its expensive, and it has to be done by the right people who'll give it due care and attention. dry-lining will be problematic for the reasons you give above 


http://www.askaboutmoney.com/showthread.php?t=164680


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## kaza (13 Nov 2013)

*lowCO2design *thanks for responding. I am just not sure if financially external insulation is an option for us. As I said the house is rented but we have to top-up the mortgage considerably every month, along with our own mortgage and childcare etc... Getting the external insulation would mean a loan for us and I am just not sure that's an option at the moment.

But external might be our only option if internal is going to cause big problems down the line?

We have an architect coming out to look at the place this morning, he specializes in building insulation etc.. So hopefully we will have a good idea if there is any cost effective solution for us to implement. I really hope there is as I don't want to leave the house as is.


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## kaza (13 Nov 2013)

We had the architect out and he was money well spent - walked through all the issues with the house and prioritized all the problems and talked through solutions for each.

Turns out our main problems are the windows, then the ventilation and thirdly the walls.


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