EPC solid wall insulation by render

oxonsaver84

Hello there, I searched the keywords of this question on the forums and couldn't find an answer so hoping this is note a duplicate query (even if it is a stupid one).

We've recently purchased a mid-terrace victorian home with solid walls, and one of the top EPC recommendations is per the below. However, the external walls are rendered in cement.  Does that not count as insulation?

Advice much appreciated, as it looks like this is the major obstacle to us being able to apply for the Boiler Upgrade Scheme grant...   

Step 2: Internal or external wall insulation

Typical installation cost

£4,000 - £14,000

Typical yearly saving

£103

Potential rating after completing steps 1 and 2

nofoollikeold

1. Cement is not a heat insulating material in the general sense.  
2. With an average installation cost of £9,000, you have a payback period of 87 years at current prices.  

FreeBear

nofoollikeold said:

1. Cement is not a heat insulating material in the general sense.  
2. With an average installation cost of £9,000, you have a payback period of 87 years at current prices.  

1) Render has a thermal conductivity of around 0.57 W/mK, so you would need a very, very thick layer to provide any real level of insulation. You also end up with a huge thermal mass that needs heating up before the room would feel warm. On the plus side, it would take an age to cool down again.

2) If you are paying someone to do the work, £9K could be a reasonable ballpark depending on the size & complexity of the building. If you were to do the work yourself (internally is by far the easiest), it might cost less than £1K.

Regardless of cost, insulating a property can improve the quality of life. Stopping all those cold draughts, and making it easier to heat & keep warm should be considered. The work will also go some way in improving the EPC rating and might make it easier to sell at some point in the future.

oxonsaver84

nofoollikeold said:

1. Cement is not a heat insulating material in the general sense.  
2. With an average installation cost of £9,000, you have a payback period of 87 years at current prices.  

Thanks - though re 2, doing so would make me eligible for a separate grant of £5k hence entertaining the idea

oxonsaver84

FreeBear said:

nofoollikeold said:

1. Cement is not a heat insulating material in the general sense.  
2. With an average installation cost of £9,000, you have a payback period of 87 years at current prices.  

1) Render has a thermal conductivity of around 0.57 W/mK, so you would need a very, very thick layer to provide any real level of insulation. You also end up with a huge thermal mass that needs heating up before the room would feel warm. On the plus side, it would take an age to cool down again.

2) If you are paying someone to do the work, £9K could be a reasonable ballpark depending on the size & complexity of the building. If you were to do the work yourself (internally is by far the easiest), it might cost less than £1K.

Regardless of cost, insulating a property can improve the quality of life. Stopping all those cold draughts, and making it easier to heat & keep warm should be considered. The work will also go some way in improving the EPC rating and might make it easier to sell at some point in the future.

Thank you. Regarding internal insulation, do you know if an internal liner like wallrock kv600, which seems to have positive reviews generally in the real world sense, would tick the boxes on EPC world? 

Doozergirl

oxonsaver84 said:

FreeBear said:

nofoollikeold said:

1. Cement is not a heat insulating material in the general sense.  
2. With an average installation cost of £9,000, you have a payback period of 87 years at current prices.  

1) Render has a thermal conductivity of around 0.57 W/mK, so you would need a very, very thick layer to provide any real level of insulation. You also end up with a huge thermal mass that needs heating up before the room would feel warm. On the plus side, it would take an age to cool down again.

2) If you are paying someone to do the work, £9K could be a reasonable ballpark depending on the size & complexity of the building. If you were to do the work yourself (internally is by far the easiest), it might cost less than £1K.

Regardless of cost, insulating a property can improve the quality of life. Stopping all those cold draughts, and making it easier to heat & keep warm should be considered. The work will also go some way in improving the EPC rating and might make it easier to sell at some point in the future.

Thank you. Regarding internal insulation, do you know if an internal liner like wallrock kv600, which seems to have positive reviews generally in the real world sense, would tick the boxes on EPC world? 

In a word, no.  

grumbler

oxonsaver84 said:

FreeBear said:

nofoollikeold said:

1. Cement is not a heat insulating material in the general sense.  
2. With an average installation cost of £9,000, you have a payback period of 87 years at current prices.  

1) Render has a thermal conductivity of around 0.57 W/mK, so you would need a very, very thick layer to provide any real level of insulation. You also end up with a huge thermal mass that needs heating up before the room would feel warm. On the plus side, it would take an age to cool down again.

2) If you are paying someone to do the work, £9K could be a reasonable ballpark depending on the size & complexity of the building. If you were to do the work yourself (internally is by far the easiest), it might cost less than £1K.

Regardless of cost, insulating a property can improve the quality of life. Stopping all those cold draughts, and making it easier to heat & keep warm should be considered. The work will also go some way in improving the EPC rating and might make it easier to sell at some point in the future.

Thank you. Regarding internal insulation, do you know if an internal liner like wallrock kv600, which seems to have positive reviews generally in the real world sense, would tick the boxes on EPC world? 

Thermal lining paper? Ha-ha.

Anything thinner than 25mm is pretty much useless, but normally it's 50-100mm    foam insulation boards.