Insulation Question New Build

silverdecks

I am in the process of finalising things before building and am wondering about insulation. My engineer allowed for pumping the cavity, but assigned certifier has said there are risks or dampness through the pumping and he has recommended the boards rather than pumping. Was wondering if any of your guys have any thoughts on what is the better route these days?

sydthebeat

silverdecks wrote: »

I am in the process of finalising things before building and am wondering about insulation. My engineer allowed for pumping the cavity, but assigned certifier has said there are risks or dampness through the pumping and he has recommended the boards rather than pumping. Was wondering if any of your guys have any thoughts on what is the better route these days?

Both methods are certified.

Where is your build?

silverdecks

sydthebeat wrote: »

Both methods are certified.

Where is your build?

Thanks for the reply, a my build is in Cork, mid Cork. When you say certified? Who certifies it? Pardon my ignorance about this.

BryanF

Cavity Beads or cavity boards there are products with iab/bba certs for both

silverdecks

BryanF wrote: »

Cavity Beads or cavity boards there are products with iab/bba certs for both

Does this certification mean that the issues of dampness and water entering the cavity from rainwater to the external wall are not relevant anymore?

sydthebeat

silverdecks wrote: »

Does this certification mean that the issues of dampness and water entering the cavity from rainwater to the external wall are not relevant anymore?

I'm sure it's just the assigned certifier giving their opinion.

Cavity Bead isn't suitable behind un rendered brickwork in areas of server exposure. ... but fine everywhere else.
Read the iab cert to satiate your fears.

dathi

http://www.nsai.ie/Our-Services/Certification/Agrement-Certification/Search-Agrements-Certificates.aspx in case you don't know where to find certs

Corkblowin

I'd always specify pumped insulation if possible.

Ask the assigned certifier if he's concerned about the difficulties of ensuring the boards are tightly fitted into the inner face of blockwork and that theres no gaps - particularly at corners and the extra wall ties at opes. Blocklayers often don't pay as much attention as they should.

silverdecks

Corkblowin wrote: »

I'd always specify pumped insulation if possible.

Ask the assigned certifier if he's concerned about the difficulties of ensuring the boards are tightly fitted into the inner face of blockwork and that theres no gaps - particularly at corners and the extra wall ties at opes. Blocklayers often don't pay as much attention as they should.

Ya I think the certified was wondering about the problems of dampness gettin to the insulation as in the early days!

RORY O CONNOR

BryanF wrote: »

Cavity Beads or cavity boards there are products with iab/bba certs for both

The installer should provide you with the certs showing compliance with Part L required U values for the walls-which is 0.21. or lower. Or the BER assessor who has provided the preliminary BER cert should also do this.

Personally I think you should insulate inside the cavity with board and then insulate inside the house-just the way Id do it myself.

hexosan

RORY O CONNOR wrote: »

Personally I think you should insulate inside the cavity with board and then insulate inside the house-just the way Id do it myself.

If the insulation is fitted correctly in the cavity why would you need to insulation internally (I assume you mean insulated slabs on external walls) your doing away with the internal mass and run the risk of condensation behind the boards.

Plus people who use insulated slabs are often unaware that you'll need to scratch plaster behind the boards for Airtightness.

If it were me I'd go with 200mm pumped bead full fill (I used 250mm on my build) engineers can get fussy over 200mm plus it's harder to get lintels (Steelites) for large opening

sydthebeat

Basic principles of insulation mean that you should keep all your insulation in the one layer/plane.

Splitting then up significantly increases areas of localised interstitial condensation.

Insulated boards on the internal of a standard new build are not a good idea.

BryanF

RORY O CONNOR wrote: »

The installer should provide you with the certs showing compliance with Part L required U values for the walls-which is 0.21. or lower. Or the BER assessor who has provided the preliminary BER cert should also do this.

Personally I think you should insulate inside the cavity with board and then insulate inside the house-just the way Id do it myself.

Where is your air-tightness layer? Or does the blockwork get a good coat of plaster before drylining?
Why create a situation where every wall/floor/ceiling/ope is not as insulated as the drylined areas?

MicktheMan

RORY O CONNOR wrote: »

Personally I think you should insulate inside the cavity with board and then insulate inside the house-just the way Id do it myself.

^^^^^ this is a very poor spec.

OP, have you considered block on flat +ewi?

If going with cavity wall, than widest cavity feasible paying attention to thermal bridging at opes, coming out of the ground and top of walls, then pump with bonded bead.
As others have said, don't neglect a good air tightness plan/strategy.

Charlie Charolais

With full fill cavities, are there issues with dpcs? The damp has no means of escape via glued beads?

sydthebeat

Charlie Charolais wrote: »

With full fill cavities, are there issues with dpcs? The damp has no means of escape via glued beads?

Where does the damp come from?

Charlie Charolais

sydthebeat wrote: »

Where does the damp come from?

hi syd,
the traditional routes; window heads reveals etc?
or can we omit the dpc's?

sydthebeat

Charlie Charolais wrote: »

hi syd,
the traditional routes; window heads reveals etc?
or can we omit the dpc's?

no, my point is... where does the damp youre referring to above come from ?


if its weather driven moisture it cannot cross the cavity

if its condensation it runs down the face of the inner leaf until it hits the dpc courses and is directed outwards....

Charlie Charolais

sydthebeat wrote: »

no, my point is... where does the damp youre referring to above come from ?


if its weather driven moisture it cannot cross the cavity

if its condensation it runs down the face of the inner leaf until it hits the dpc courses and is directed outwards....

My understanding of traditional DPCs was where the external head/reveals leak with driven rain ingress, damp hits the dpc on external face of internal leaf & flows down & out on the dpc
I agree with driven rain not been a problem now
On condensation: if the cavity is fully filled is there space for the downward run?

Side question: what causes the condensation?

Doorcase

architect has sheeted insulation in cavity, builder is saying blow insulation in because it is much cheaper. is blown in insulation as good?

MicktheMan

Doorcase wrote: »

architect has sheeted insulation in cavity, builder is saying blow insulation in because it is much cheaper. is blown in insulation as good?

It's better when you take into account the fact that installing insulation boards in the cavity properly is rarely achieved.

BryanF

Doorcase wrote: »

architect has sheeted insulation in cavity, builder is saying blow insulation in because it is much cheaper. is blown in insulation as good?

What stage are you at? If this is a tender stage great. If your on site, it's too late for this discussion.

Blown bead: best will be ~0.033w/MK
Insulation sheets: can get down to ~ 0.22w/MK

Have the opportunity to widen your cavity by 30/50% ? And ask the builder who pays for that..

s2sap

sydthebeat wrote: »

Basic principles of insulation mean that you should keep all your insulation in the one layer/plane.

Splitting then up significantly increases areas of localised interstitial condensation.

Insulated boards on the internal of a standard new build are not a good idea.

I had an initial meeting with an architect today to try and choose the right architect for our new build I asked him if we are trying to achieve high standards of air tightness what insulation he would be recommending.

Having read this post last night I was surprised at his answer - beads in the cavity and internal wall boards as an additional means of insulation. I assume he means dry lining. Should his response then give me cause for concern or is localised interstitial condensation not a big / regular occurrence.

Thanks

893bet

s2sap wrote: »

I had an initial meeting with an architect today to try and choose the right architect for our new build I asked him if we are trying to achieve high standards of air tightness what insulation he would be recommending.

Having read this post last night I was surprised at his answer - beads in the cavity and internal wall boards as an additional means of insulation. I assume he means dry lining. Should his response then give me cause for concern or is localised interstitial condensation not a big / regular occurrence.

Thanks

Yes. See below thread for some info

http://www.boards.ie/vbulletin/showthread.php?t=2057563730

MicktheMan

s2sap wrote: »

I had an initial meeting with an architect today to try and choose the right architect for our new build I asked him if we are trying to achieve high standards of air tightness what insulation he would be recommending.

Having read this post last night I was surprised at his answer - beads in the cavity and internal wall boards as an additional means of insulation. I assume he means dry lining. Should his response then give me cause for concern or is localised interstitial condensation not a big / regular occurrence.

Thanks

Borrowing an acronym from my daughter .... OMG!

BryanF

MicktheMan wrote: »

Borrowing an acronym from my daughter .... OMG!

Ah Mick! no need for the dramatics! Half the BER 'experts' (considering it's a one week course) in the country would recommend the same, as would many architect/engineers.

There is a lack of understanding of building physics as we seek to insulate our homes. Some day I hope we get to a point of actual energy/ co2 reductions after we manage to keep the internal temp at a comfortable level, and avoid 'breathing' colonies of mould.

MicktheMan

BryanF wrote: »

Half the BER 'experts' (considering it's a one week course) in the country would recommend the same, as would many architect/engineers.

Yep ... these "experts" etc keep me very busy:)

sydthebeat

s2sap wrote: »

I had an initial meeting with an architect today to try and choose the right architect for our new build I asked him if we are trying to achieve high standards of air tightness what insulation he would be recommending.

Having read this post last night I was surprised at his answer - beads in the cavity and internal wall boards as an additional means of insulation. I assume he means dry lining. Should his response then give me cause for concern or is localised interstitial condensation not a big / regular occurrence.

Thanks

:eek:

to put it simply YES, it should cause you concern

to be over dramatic... DEAR GOD run away !!!!!

mrsWhippy

sydthebeat wrote: »

:eek:

to put it simply YES, it should cause you concern

to be over dramatic... DEAR GOD run away !!!!!

Is dry lining always a case for concern? It came up in a conversation with our architect too - he said 'it did work for some' - though he didn't necessarily suggest it for our situation.

What is the solution then, if dry-lining isn't it?

sydthebeat

mrsWhippy wrote: »

Is dry lining always a case for concern? It came up in a conversation with our architect too - he said 'it did work for some' - though he didn't necessarily suggest it for our situation.

What is the solution then, if dry-lining isn't it?

it is a bad construction.... especially for a new build where you have the opportunity to do things properly.

It is more suited for renovations and upgrade works where its financially or otherwise not possible to to locate insulation anywhere else.

IF it absolutely has to be used on a new build, it should be modelled up so as not to cause interstitial condensation behind the dry lining. The rule of thumb in this is that you shouldnt have more than 1/3 or insulation internally and 2/3s in the cavity.... though there is software out there which will model the construction.
I specified it on a build of a house a few years over a basement as it made financial sense to keep the wall width as thin as possible due to mass concrete retaining walls.

s2sap

sydthebeat wrote: »

:eek:

to put it simply YES, it should cause you concern

to be over dramatic... DEAR GOD run away !!!!!

Ok - Now I am back to square one again then. Whilst I want to be involved naturally in the design and input re insulation products etc - to the ordinary guy in the street it is a little confusing to say the least. It is like listening to our politicians in a debate - both sides are always right!!! Each manufacturer tells you theres is best.

Keep this simple for me please - what is the general consensus of opinion on here about best method to achieve good air tight values without the need to OVER spend on cavity insulation. Is it blown beads? What depth of cavity?

This will help with my architect decision process if I know that they are at least getting the fabric of the build right at outset.

Thanks

sydthebeat

if your new build is a new dwelling, the very first thing you have to get done is a Preliminary DEAP assessment to assess what specification you need to comply with building regulations.

without this you are shooting into the mist.

Whomever you get to do this should have good experience in the physics of domestic construction ie be an architectural technician or engineer and should have experience in compiling these reports. 5 mins with someone will tell how good they are, as every single specification choice will have may options, and every options will have pros and cons and knock on effects.

Water John

Built 25 years ago and partially lined the cavity and insulated dry lining inside. Would not do it again. No heated mass so house cools quickly. I'd only consider it if I was using UFH as the floor would have the mass.
Sealing the house envelope and insulation are two linked but separate tasks and objectives.
Ask around, among friends and relatives, talk to builders. Even on sites you see being built. Names will soon come up as being reliable and know what their doing. Any contacts in any of the trades. They won't be long telling you who to keep away from.

s2sap

Thanks for the responses guys - it really is much appreciated.

I spoke to another architect today who tells me most of his new builds are coming in with airtight results of between 1 and 2. Is that good, bad or indifferent? He did clarify that if better results were required by the client he would design for that but naturally cost has to be taken into account.

MicktheMan

s2sap wrote: »

I spoke to another architect today who tells me most of his new builds are coming in with airtight results of between 1 and 2. Is that good, bad or indifferent? He did clarify that if better results were required by the client he would design for that but naturally cost has to be taken into account.

Aiming and achieving between 1 to 2 regularly is very good. The lower the better.