Bungalow Conversion - Brickwork/Cavity Insulation

[richo106]

Hi All

 

We are hoping to add another story to our bungalow to make it a house, footings are Ok for this and due to budget constraints we won't be knocking it down (as much as I would love too but had plenty in depth conversations with builders) 

 

We want all brick design with new brick, the plan was for me to take of the outer skin to the blues and then the builder would start from there, however due to it being a 1960's bungalow there is only around 70-80mm cavity. My idea was to fill this with 50mm PIR insulation and obviously in the new walls as these will have the same thickness cavity. Does this sound sensible? Would you still insulate on the internal walls too?

 

One idea we was torn with was external insulation and render but we really not so keen on all rendered house even though it might be the most cost effective/easiest method

 

What are peoples opinions on this? Any other recommendations/ideas?

 

Many Thanks

[richo106]

 

Been trying to do a lot of my own research and a lot of comments go against having rigid insulation within the cavity so would it be better just to have standard wall insulation at 70/80mm or full fill insulation. Then insulate internally using pir rigid insulation?

 

Thanks 

[joe90]

I think having rigid insulation within a cavity is it’s difficult to seal the sheets together, if you are removing the outer brick skin you could stick the insulation to the inner brickwork, sealing the joins with foam then get your builder to add the outer skin. If you are renewing the outer brick skin is your foundation wide enough to give you a greater cavity? If not then insulating inside is your only option. You may already know this but if you did demolish and re build you can clams the VAT back on everything. (and give you the bigger cavity for insulation like I did, I had 200mm rockwall batts).

[Brickie]

The chances of your cavity side of your inner leaf wall being free from mortar snots and generally clean & tidy to receive rigid sheets is low. Are you taking down the outer skin because you don’t like the appearance of of the existing bricks? 
 

[tonyshouse]

Other ideas, maximise insulation while you have the chance. Hundreds not tens of millimetres 

[richo106]

10 minutes ago, Brickie said:

The chances of your cavity side of your inner leaf wall being free from mortar snots and generally clean & tidy to receive rigid sheets is low. Are you taking down the outer skin because you don’t like the appearance of of the existing bricks? 
 

Yes that's correct we want to change the outer skin so all of the house is of the same brick

 

Thanks

[Brickie]

2 hours ago, richo106 said:

Yes that's correct we want to change the outer skin so all of the house is of the same brick

 

Thanks

So you’re taking down to DPC(I presume)?

Has anyone considered the possibility of taking right down to footing level & starting from scratch with a much wider cavity? 

[richo106]

26 minutes ago, Brickie said:

So you’re taking down to DPC(I presume)?

Has anyone considered the possibility of taking right down to footing level & starting from scratch with a much wider cavity? 

Yes taking it right down and new DPC installed

 

Please see attached image of our foundations

 

Thanks again