# Insulation - haven't a clue and need advise



## Pinky&dBrain (16 Feb 2009)

Hi All,

Starting a new build and am so confused about insulation, probably the most important part of the build. Any advise welcomed.

The blocks I will be using is standard 4" solids and I guess the standard cavity is between 100 -110mm, my question is would much have to change in order to have a wider cavity lets say 120mm or 130mm? Would the extra width mean different foundations, more pressure on weight of roof etc. I was thinking of going with the pumped insulation in the walls, however I have no idea even after reading posts here of which type to go for? If I did decide to go with pumped insulation is there then a need to dryline the walls?

Also what kind of insulation do you need in the floors, the house is a bungalow, the guy doing my groundwork has not mentioned insulation is it standard to put insulation in the floor. 

Roof insulation then is another question would you be better to use pumped or rolls of sheeps wool? I really am confused!!!


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## sydthebeat (16 Feb 2009)

pinky,

you are asking very valid questions..... but you will always be confused until you have professional input.

You are embarking on building a house that i hope will stand for 100 years, this house has to comply with current building regulations, and to date you do not know if it will comply or not.
since 2005, an energy calculation has to be done on a build to see if it complies or not with part l of the building regulations. It is extremly dangerous to embark on a build without knowing if it complies or not, as it can be very very expensive to retro fit a build if it is shown not to comply.

what you need is to hire an architectural technician that is also a Building energy rating assessor to do this calculation, and specify for you they type and thickness of insulation you need to comply... and any upgrade you may wish as well...

this service can cost in the region of 400-500, well worth it in my opinion.


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## Pinky&dBrain (16 Feb 2009)

Hi Sydthebeat,

I have an engineer hired but obviously I need to hire an architectural technician, as my engineer has not discussed much with me at all in the way of insulation. I will look into getting such a person as I think it would be well worth €400/€500 thanks for this advise.


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## sydthebeat (16 Feb 2009)

pinky....

id be very wary of an engineer that was willing to sign off a build without knowing first what was going into it....

but go with the technician to complie an insulation specification for you, and to do a prelim BEr assessment, and price for the final BER cert on completion...


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## Birroc (16 Feb 2009)

Pinky&dBrain said:


> Hi All,
> 
> Starting a new build and am so confused about insulation, probably the most important part of the build. Any advise welcomed.
> 
> ...


 
I starting building 10 months ago. Built a 150mm cavity and filled it with beads. I have to say that the house feels toasty even though we're not in yet and there is no insulation in the attic yet. Only problem with the 150mm cavity was the 'cavity closers' at top but you can buy bigger ones. Not dry-lining. I like solid walls.


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## baldyman27 (16 Feb 2009)

Working on the foundations of a house at the moment with a 150mm cavity which requires an extra 4" block in the rising walls, so that's an extra cost.

If you're installing underfloor heating then the minimum standard is 125mm floor insulation, which should be laid in 2 layers to cross over the joints.


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## Pinky&dBrain (16 Feb 2009)

Hi Birroc, thanks for reply, using a 150mm does this mean I would not have to change my foundations as everything there is standard or would I have to tell the man whos doing my groundwork that I need the 150mm cavity as I am getting the site cleared today, breaking an entrance and stripping soil, Maybe its too late for this?

Also baldyman27, thanks for your response also, however I am not using underfloor heating, sticking with stove + back boiler + oil and solar panels.


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## Birroc (16 Feb 2009)

Pinky&dBrain said:


> Hi Birroc, thanks for reply, using a 150mm does this mean I would not have to change my foundations as everything there is standard or would I have to tell the man whos doing my groundwork that I need the 150mm cavity as I am getting the site cleared today, breaking an entrance and stripping soil, Maybe its too late for this?


 
Doubtful. Ask your engineer. Its only 50mm extra - you will save room by not dry-lining anyway. I am not a fan of dry-lining.

Tell the guy doing the raft that you're putting in a wider cavity so that he build a decent step and definitely tell the blocklayer !

Best of luck.


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## sydthebeat (16 Feb 2009)

Pinky&dBrain said:


> Hi Birroc, thanks for reply, using a 150mm does this mean I would not have to change my foundations as everything there is standard or would I have to tell the man whos doing my groundwork that I need the 150mm cavity as I am getting the site cleared today, breaking an entrance and stripping soil, Maybe its too late for this?
> 
> Also baldyman27, thanks for your response also, however I am not using underfloor heating, sticking with stove + back boiler + oil and solar panels.



pinky,

as you are only increasing the cavity, and adding no real weight to the wall, then in theory you do not need increased foundation.... but your engineer has the last call on this...

the foundation design is also based on your site conditions....


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## baldyman27 (16 Feb 2009)

Pinky, you need to tell the guy doing your groundworks as the risissng walls will have to be wider than the 300mm that is standard fro a 100mm cavity. Also, some insulation under the floor would be advisable, underfloor heating or not.


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## sydthebeat (16 Feb 2009)

put 80mm pu or pir insulation under the floor..


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## threebedsemi (16 Feb 2009)

bear in mind also that there are better option to partial-fill cavity wall construction out there, ie, full cavity fill, timber frame, external insulation on single leaf blockwork... 
in my experience partial fill cavity wall construction does not in practice work to the designed efficiency a lot of the time. 
i would echo the above post regarding avoiding drylining if possible (i think its preferable to locate all the insulation in the same zone, be it inside, outside or in the middle)


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## VByrne (16 Feb 2009)

Hi Pinky,
There's no problem making the cavity 20-30mm wider, the foundation needs no further reinforcement, as for the insulation, there are many systems you can use, but as you are building from new you want something that works and lasts for the life time of the building, because of moisture most fibrous material will degrade, some quicker than others, and also the moisture will mean that the advertised U-value will not be achieved. The insulation that's made from foam seem to fit the bill, they are not effected by moisture and they last a long time, there is a system they use in Canada where they spray a closed cell foam below the foundation and also in the cavity, it's sprayed in the cavity at about 70mm and they leave a 50mm gap for air flow, but because it is all one piece there is no air leakage, and then they use it in the attic to construct what is called a warm roof construction, with this system they also use a heat recovery ventilator, if your building from new I'd look into it, it should not be to dear as there is no need for air or vapour barriers, I hope this helps.


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## sydthebeat (16 Feb 2009)

always remeber to use materials that have been certified for use in ireland, under irish conditions....

if a material does not have proper certification it must be ignored from a building reg compliance and BER point of view....


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## VByrne (17 Feb 2009)

Hi sydthebeat,
You are right it should be certifide, Closed cell foam in both board and spray form does hold agrement, in the UK they test it in spray form, the IAB do not have a system yet so they send it on to the BBA for testing, it's mineral fibre in an attic that holds no test results for this use, BS, ISO, and EN are not tests for fitness for a particular purpose.


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## BarneyMc (17 Feb 2009)

Birroc said:


> I starting building 10 months ago. Built a 150mm cavity and filled it with beads. I have to say that the house feels toasty even though we're not in yet and there is no insulation in the attic yet. Only problem with the 150mm cavity was the 'cavity closers' at top but you can buy bigger ones. Not dry-lining. I like solid walls.


 
Can I ask Birroc if you used a standard concrete block for the inner leaf or a 'QuinnLite' type one and what width?


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## Birroc (17 Feb 2009)

BarneyMc said:


> Can I ask Birroc if you used a standard concrete block for the inner leaf or a 'QuinnLite' type one and what width?


 
Standard 100mm blocks on both walls.


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## Pinky&dBrain (18 Feb 2009)

Hi Guys,

Thank you all for the help and advise. I was talking to my engineer, builder and they were saying to me that the bead type insulation can fill the cavity to much and not leave room for air flow thus causing water to seep through the blocks and other materials. I'm thinking I might just go with Kingspan range, I will definitely look into that foam insulation also. Its a hard decision which I want to get right as I only want to have to do it the once.

Thanks again all


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## BarneyMc (18 Feb 2009)

Pinky&dBrain said:


> Hi Guys,
> 
> I was talking to my engineer, builder and they were saying to me that the bead type insulation can fill the cavity to much and not leave room for air flow thus causing water to seep through the blocks and other materials.


 
The beads are IAB certified that this water seeping will NOT take place. Are you sure your engineer/builder are up to scratch with insulation technologies?


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## hughr (6 Mar 2009)

Pinky&dBrain said:


> Hi All,
> 
> Starting a new build and am so confused about insulation, probably the most important part of the build. Any advise welcomed.
> 
> ...



 no much would not have to change if the foundations are width enoungh,and you dug down to the right depth.insulation is important ,so yes use 38mm broads on all exteranl walls and 18mm on reveals also insulation is very important for sound proof.under floor heating is very good now adays it is standard,rolls of insulation used in artic are 150mm thick so find out the thickens of the pumped insulation, also use foilback plasterbroad slabs it also helps stopping the heat escape throught the roof ,hope that was some bit of help for you hugh the plasterer


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