How to modify a new extension to reduce future energy consumption.

highnelly

Hi all,

I have recently built an extension onto a 1 bedroom mid-terrace cottage. Unfortunately I did not start to read this forum until after the construction, so I was not well informed on how to build for energy efficiency.

For the superstructure I used a 300mm cavity wall and now that the blocklayer has completed the job, and taken his money, I have seen some instances of thermal bridging, which occur as a result of:

A. Concrete blocks were used to close the cavity wall (length = circa 24m)
B. A steel catnick over the back door + window opening
C. The foundation and the internal wall

Bearing in mind that only concrete blocks were used in the construction; how do I now modify the structure to reduce the bridging effects. For example, can I put a strip of insulation on the external wall just beneath the eaves to reduce the heat loss from the cavity closer, and the same at the door and window opes? What can be done about the bridging at the foundation at this stage considering only the subfloor hs been poured so far?

Also when it comes to plastering a cavity wall, I guess I should prevent the wall from breathing as much as possible, in order to maintain the U-value of the cavity. Is this a correct assumption? Does anybody have advice on the materials I should use to plaster both inside and out?

Thanks in advance for any help

sinnerboy

highnelly wrote: »

Hi all,

I have recently built an extension onto a 1 bedroom mid-terrace cottage. Unfortunately I did not start to read this forum until after the construction, so I was not well informed on how to build for energy efficiency.

For the superstructure I used a 300mm cavity wall and now that the blocklayer has completed the job, and taken his money, I have seen some instances of thermal bridging, which occur as a result of:

A. Concrete blocks were used to close the cavity wall (length = circa 24m)
B. A steel catnick over the back door + window opening
C. The foundation and the internal wall

Bearing in mind that only concrete blocks were used in the construction; how do I now modify the structure to reduce the bridging effects. For example, can I put a strip of insulation on the external wall just beneath the eaves to reduce the heat loss from the cavity closer, and the same at the door and window opes? What can be done about the bridging at the foundation at this stage considering only the subfloor hs been poured so far?

Also when it comes to plastering a cavity wall, I guess I should prevent the wall from breathing as much as possible, in order to maintain the U-value of the cavity. Is this a correct assumption? Does anybody have advice on the materials I should use to plaster both inside and out?

Thanks in advance for any help

dry lining is probably the way to go

make sure the floor and wall insulation layers touch

Spread

If you chase your cables, you can then fix eurathane-backed plasterboard onto the wall before skimming. These can be fixed using plastic mushrooms. Alternatively, batten out and screw boards on.