Insulation Thoughts - External v Internal

BryanF

What about a mixture of blown insulation and ewi

kev1234

BryanF wrote: »

What about a mixture of blown insulation and ewi

So are you suggesting EWI on the front and back of the house where it is accessible to install and then blown insulation into the cavity wall where the side extension joins the neighbours house? I was under the impression that if doing EWI then I would need to do it around every wall or its a waste of time?

BryanF

kev1234 wrote: »

So are you suggesting EWI on the front and back of the house where it is accessible to install and then blown insulation into the cavity wall where the side extension joins the neighbours house? I was under the impression that if doing EWI then I would need to do it around every wall or its a waste of time?

the insulation layer should be continuous.

kev1234

BryanF wrote: »

kev1234 wrote: »

So are you suggesting EWI on the front and back of the house where it is accessible to install and then blown insulation into the cavity wall where the side extension joins the neighbours house? I was under the impression that if doing EWI then I would need to do it around every wall or its a waste of time?

the insulation layer should be continuous.

Just to clarify, are you saying a single type of insulation layer should be continuous (eg. External around whole house) or can there be differing insulation methods on walls provided that there is some form of insulation continuous around the house? Can I join a wall with EWI to a cavity filled wall without EWI or will this be ineffective or result in cold bridging?

Dont Be at It

Has anyone in here any experience/thoughts of combining a surface applied, impregnating sealer (e.g. Meta Creme) with IWI on a brick wall?
Joseph Little puts it forward as something definitely worth considering in his Breaking the Mould series of articles.

BryanF

kev1234 wrote: »

1. Just to clarify, are you saying a single type of insulation layer should be continuous (eg. External around whole house)
2. or can there be differing insulation methods on walls provided that there is some form of insulation continuous around the house?
3. Can I join a wall with EWI to a cavity filled wall without EWI
4. or will this be ineffective or result in cold bridging?

1. A continuous ‘zone’ / ‘layer’ / ‘path’. Type can vary
2. Yes in theory,
- What If you built a block on flat say 150mm in from the neighbors boundary walls and filled this cavity with beads
- insulation & quinlites at base for foundation insulation continuity
- then where the boundary wall stops (ie above it, or on external walls facing the garden) you could then go with ewi.
- You could have a cavity on the walls facing the garden and just use ewi above the boundary walls - ie up to overlap with roof insulation
3. Yes, as above, in theory subject to your Arch tech detailing all these junctions
4. This comes back to the importance of ‘continuous insulation ‘layer’ / ‘envelope’ - All junction should be considered in detail. This is why fees for extension can be just a high as new builds, as your in the business, think about the amount of details to be worked out for a builder, you can see why your approach to just having an engineer is not really enough designer input.

Kev that’s it from me. Best of luck with your build

BryanF

Dont Be at It wrote: »

Has anyone in here any experience/thoughts of combining a surface applied, impregnating sealer (e.g. Meta Creme) with IWI on a brick wall?
Joseph Little puts it forward as something definitely worth considering in his Breaking the Mould series of articles.

How old is the brick wall, was lime used in the joint mix?


Are you repointing externally?

Dont Be at It

BryanF wrote: »

How old is the brick wall, was lime used in the joint mix?

Are you repointing externally?

Nearly 120 years old - originally it was lime but was re-pointed with normal cement in the last 20/30 years.
I'm guessing that the joints would have to be redone with lime cement again, to allow moisture escape, if sealer was to be applied?
Just trying to get an idea of the benefit of doing this?

BryanF

Dont Be at It wrote: »

Nearly 120 years old - originally it was lime but was re-pointed with normal cement in the last 20/30 years.
I'm guessing that the joints would have to be redone with lime cement again, to allow moisture escape, if sealer was to be applied?
Just trying to get an idea of the benefit of doing this?

Freeze thaw cycle : brick is porous, cement not so much

Dont Be at It

BryanF wrote: »

Freeze thaw cycle : brick is porous, cement not so much

So you don't think there's any benefit to sealing the brick?
Or that there is benefit if you re-point with lime cement?
Struggling to decipher your comment!:pac:

BryanF

Not sure sealing the brick would create a continuous vapour barrier

Dont Be at It

BryanF wrote: »

Not sure sealing the brick would create a continuous vapour barrier

Agreed.
But even if it keeps 50/60/70/80% of driving rain from penetrating the wall, surely it's a plus (as long as it allows any moisture that does penetrate the brick to escape freely - which most of these products claim to do)?
By the way, my thinking was to still use breathable IWI (not non-breathable)!

whosedaddy?

Hi BryanF, and all,
Could I just jump in here for a clarification please.
I've seen number of houses in neighborhood with EWI upstairs only. I'm thinking main reason is brickwork on ground level (an no planning). They must mix EWI updstairs with IWI downstairs (or no insulation).
Mixing of IVI and EWI is ok, as long its in different area's of the house and overlaps/junctions etc are detailled enough to reduce cold bridging to a minimum.
I've been fending off some general building contractor tryin to push IWI all the way saying mixing both "just doesn't work". With no substantiation of the claim. And i'm not buying it, but am somewhat confused. Surely it it doesn't work, there would be no point in doing an upstairs only wrap.
The only no-no is EWI and IVI at same wall, right?
/daz

BryanF

BryanF wrote: »

1. A continuous ‘zone’ / ‘layer’ / ‘path’. Type can vary

So ewi or Iwi would be best in your instance.

Can’t you just get external insulation with brick slips?

the importance of ‘continuous insulation ‘layer’ / ‘envelope’ - All junction should be considered in detail.Best of luck with your build

whosedaddy?

Thanks
Need to check about EWI with brick slips. And talk to neighbours why they didn’t do it.
I’d be happy for IWI for new extension (EWI issue with boundary wall ) and rest of downstairs (concrete floors) but EWI upstairs as bathroom can’t take IWI without moving door, loosing bathtub and other rooms. Or if money stretches do extension with IWI and rest EWI.
I‘m open minded to what works and doesn’t. But it needs to be explained to me properly.