Cavity Insulation Question

stephentbb2000

Built in a new house in 2009 to comply with current building regs. The cavity wall is a 100mm with 60mm of insulation. I have two questions;

1 Is it ok to fill the remaining gap with cavity insulation?
2 Would it pay off financially in the long run?

(Upstairs down stairs bungalow B2 rating)

Thanks in advance.

BryanF

stephentbb2000 wrote: »

Built in a new house in 2009 to comply with current building regs. The cavity wall is a 100mm with 60mm of insulation. I have two questions;

1 Is it ok to fill the remaining gap with cavity insulation?
2 Would it pay off financially in the long run?

(Upstairs down stairs bungalow B2 rating)

Thanks in advance.

2009 built, 60mm insulation complys with the regs?

to answer your question

1. depends on the product, some require 50mm of a gap - but plenty of installers will go ahead and do it - id be looking for or treating a thermal imaging survey following the work, just to be sure
2. yes - there are people with a 100mm full-fill cavity putting extra EWI outside this! so I think your safe enough to assume it will payback to pump your walls:)

Frank Black

I have a related question.
We're building at the moment - the specification that our architect has for the walls is 60mm insulation - should we up this to 100mm?

BryanF

black francis wrote: »

I have a related question.
We're building at the moment - the specification that our architect has for the walls is 60mm insulation - should we up this to 100mm?

people that are retro-fitting have more insualtion than your architect is proposing:eek:

you should employ a better architect;)

to answer your question, the current regs require a holistic view of insulating your build, so its not as simple as providing a certain thickness but 100mm of the best PIR/phenolic insulation is the very minimum you should be installing but that may not even be enough, I would need more info on your design

1. what stage are you at?
2. have you carried out a provisional BER?
3. have you seen 'about the the house' lately
4. and are you aware that people are building with 5 times the insulation thickness your architect has specified. see here

Francis, start looking for an energy consultant to advise on your insulation, air-tightness, thermal bridging (really all your construction details), specification of windows/doors, ventilation and heating

Frank Black

BryanF wrote: »

people that are retro-fitting have more insualtion than your architect is proposing:eek:

you should employ a better architect;)

to answer your question, the current regs require a holistic view of insulating your build, so its not as simple as providing a certain thickness but 100mm of the best PIR/phenolic insulation is the very minimum you should be installing but that may not even be enough, I would need more info on your design

1. what stage are you at? - Just coming up to pouring floor slab next week.
2. have you carried out a provisional BER? - Nope
3. have you seen 'about the the house' lately - Nope
4. and are you aware that people are building with 5 times the insulation thickness your architect has specified. see here - I am now

Francis, start looking for an energy consultant to advise on your insulation, air-tightness, thermal bridging (really all your construction details), specification of windows/doors, ventilation and heating

Hi Bryan, answers above - the architect has specified "min 60mm HD/PIR rigid insulation" - in fairness to him, the design was carried out a couple of years ago (we had problems with Planning Permission).

BryanF

black francis wrote: »

Hi Bryan, answers above - the architect has specified "min 60mm HD/PIR rigid insulation" - in fairness to him, the design was carried out a couple of years ago (we had problems with Planning Permission).

Francis see page p24 (the horizontal sheet) I'm not a fan of the DOE's chosen method, but its a start for you to look at. also see here and if i were you i would get a provisional BER asap, before continuing on site.. you have a bit of time as with the cold weather expected you may no be able to poor anyway..

Innish_Rebel

BryanF wrote: »

Francis see page p24 (the horizontal sheet) I'm not a fan of the DOE's chosen method, but its a start for you to look at. also see here and if i were you i would get a provisional BER asap, before continuing on site.. you have a bit of time as with the cold weather expected you may no be able to poor anyway..

From that document am I right in seeing the DOE suggest 150mm cavity with 100mm PIR or 140mm EPS and 50mm PIR internal insulation to achieve 0.14 U-value.

If you are not a fan what would your preferred arrangement be?

BryanF

black francis wrote: »

Hi Bryan, answers above - the architect has specified "min 60mm HD/PIR rigid insulation" - in fairness to him, the design was carried out a couple of years ago (we had problems with Planning Permission).

Innish_Rebel wrote: »

From that document am I right in seeing the DOE suggest 150mm cavity with 100mm PIR or 140mm EPS and 50mm PIR internal insulation to achieve 0.14 U-value.

If you are not a fan what would your preferred arrangement be?

please note that the link does no tell you 'if you do this, you will pass B'regs'

i and others on one of many threads, have gone into the this discussion in great detail. the outcome imo was/is there are many options and the one chosen by the DOE was to suit the existing concrete industry and a senior lazy labourers who needed a familiar option. my opinion is why do both cavity and drylining? you loose the thermal mass for a start, and you'd really need to consider the air-tightness meaning you may be plastering the inner block wall and whats the difference between 150 & 300 cavity, how progressive your engineer is seems about the size of it:rolleyes:

I'm a fan of timber frame, but if you like the idea of a bomb proof structure:) then go either ewi or a wide cavity. deciding/considering who's building it, costing it, ease of construction/ lifespan/maintenance, air-tightness and thermal bridge etc. where you or your family have health issues/concerns or environmental preferences, id specify natural renewable materials - maybe even a hemplime mix:eek:

muffler

BryanF wrote: »

I'm a fan of timber frame, but if you like the idea of a bomb proof structure:)

To ensure a level playing field here can I ask you if you have any association with the TF industry?

BryanF

muffler wrote: »

To ensure a level playing field here can I ask you if you have any association with the TF industry?

hi muffler. no i dont:), but i like a walk in the woods now & again:D

kboc

Francis,

I would not go another inch until you have spoken to people who can advise you on a cost effective and extremly heat efficient/air tight house.


What part of the country are you in?

Regards
K

Frank Black

kboc wrote: »

Francis,

I would not go another inch until you have spoken to people who can advise you on a cost effective and extremly heat efficient/air tight house.


What part of the country are you in?

Regards
K

In the midlands.

Our contact with the builder is that he has to comply with the current building regs and he's registered with Homebond.

Why would I need to employ another advisor?

BryanF

black francis wrote: »

In the midlands.

Our contact with the builder is that he has to comply with the current building regs and he's registered with Homebond.

Why would I need to employ another advisor?

I think you answered this, in your opening post:

We're building at the moment - the specification that our architect has for the walls is 60mm insulation - should we up this to 100mm?

MicktheMan

black francis wrote: »

In the midlands.

Our contact with the builder is that he has to comply with the current building regs and he's registered with Homebond.

Why would I need to employ another advisor?

A few reasons off the top of my head.

You're building you own house which you will live in for the forseeable future while energy prices rise and rise.

Does your builder know the about the new Part L (2011)?

The current air tightness regulation is still very draughty - you need to be a very bad builder to fail it!

Did you happen to see "Primetime" tonight about self certification etc.

Frank Black

BryanF wrote: »

I think you answered this, in your opening post:

That's true - and it's what the specifications says. Our contract with the builder does say that works are to be in accordance with the current (at time of contract signing) building regulations - which I'm presuming is 2010? If the 60mm doesn't comply with these regs in terms of the u value achieved, I would be hoping that any upping of this thickness is covered.

I don't want to sound ungrateful for the advice being offered, because it is useful, interesting and appreciated - but when people are suggesting that I call a halt to works on site until I've spoken to an advisor - I'm going to be looking at a claim by our builder straight away.

There's a limit to how much I can go changing the design at this stage - I'm certainly stuck with a 110mm cavity wall.

Given the above would the advice be to re-visit the design?

DOCARCH

black francis, who will be certifying the work/issuing opinions on complaince at the end of the work?

First, ask them what regulations/what version of Part L they will be certifying to?

It will not be Part L 2011 as you obviously applied for (and got) planning permission prior to December 1st.

Frank Black

DOCARCH wrote: »

black francis, who will be certifying the work/issuing opinions on complaince at the end of the work?

First, ask them what regulations/what version of Part L they will be certifying to?

It will not be Part L 2011 as you obviously applied for (and got) planning permission prior to December 1st.

We have an Engineer looking after the build who will certify, the builder is also a memeber of Homebond and they send out an engineer at various stages to sign off that home is being constructed in accordance with their criteria.

I will check into the Part L regulations with our Engineer.

DOCARCH

Let us know when you got planning permission and when you expect the build to be complete. Somebody here will then be able to tell you what version of Part L should apply to your build.

Frank Black

DOCARCH wrote: »

Let us know when you got planning permission and when you expect the build to be complete. Somebody here will then be able to tell you what version of Part L should apply to your build.

PP was received in March 2011 - just had a look through the notification of grant, and there's nothing regarding complying with any particular Building Regs.

The builder estimates that build will be complete around May next year.

BryanF

black francis wrote: »

That's true - and it's what the specifications says. Our contract with the builder does say that works are to be in accordance with the current (at time of contract signing) building regulations - which I'm presuming is 2010? If the 60mm doesn't comply with these regs in terms of the u value achieved, I would be hoping that any upping of this thickness is covered.

I hope I win the lotto - unfortunately were talking about the same level of hope

I don't want to sound ungrateful for the advice being offered, because it is useful, interesting and appreciated - but when people are suggesting that I call a halt to works on site until I've spoken to an advisor - I'm going to be looking at a claim by our builder straight away.

no one wishes this upon you, what i was saying earlier is - its xmas, so get someone in to do some construction details to the regs that deal with thermal bridges, insulation, air-tightness etc now, and they can be be looking at the issues while the builder can work with the snow and his holidays etc..

There's a limit to how much I can go changing the design at this stage - I'm certainly stuck with a 110mm cavity wall.

Given the above would the advice be to re-visit the design?

not the design, as your relatively stuck with that from planning. but given your situation I'd be recommending construction drawings. with the first critical floor insulation and thermal bridge junction upon you now, as your about to poor the slab poor.

Frank Black

Well, we've already agreed underfloor insulation - we've underfloor heating and from speaking with the suppliers, they said we needed to achieve a u-value of 0.15 - so we have agreed a 100mm thick insulation board which does this, it's my understanding that this u value also comples with the latest building regs.
Our original spec only called for a 0.25 u value, so might be paying a bit extra to the builder for the upping of insulation.

I'll have a look through some of the literature you've posted over the next few days and consider speaking to someone - we're trying to control costs as much as possible, so don't want to go adding in extras left, right and centre, but we're obviously looking for as energy efficient house as possible.

boatbuilder

Don't fall into the trap of relying on building regs to ensure your builder puts in decent insulation.

In my opinion, anyone building a new house should put far more insulation in.

Remember that the building regs are the MINIMUM requirements.... you'll be kicking yourself later if you just do the minimum.

Also consider air-tightness...all the insulation in the world is useless if you have draughts blowing everywhere.

Frank Black

boatbuilder wrote: »

Don't fall into the trap of relying on building regs to ensure your builder puts in decent insulation.

In my opinion, anyone building a new house should put far more insulation in.

Remember that the building regs are the MINIMUM requirements.... you'll be kicking yourself later if you just do the minimum.

I guess what I'm confused about is - 'what's the appropriate amount?'

I mean, there presumably comes a tipping point with insulation, where the money you start spending on extra doesn't show a return on the investment.

Now, I know that any future value attributed to the insulation will depend on energy prices in the future, which are an unknown - but how do people work out how much to spend on beefing up insulation at construction stage?

BryanF

black francis wrote: »

I guess what I'm confused about is - 'what's the appropriate amount?'

I mean, there presumably comes a tipping point with insulation, where the money you start spending on extra doesn't show a return on the investment.

Now, I know that any future value attributed to the insulation will depend on energy prices in the future, which are an unknown - but how do people work out how much to spend on beefing up insulation at construction stage?

have a read of the literature i gave you.. the reason you hire an architect or engineer is to work this stuff out on your behalf.

where UFH is being installed don't scrimp on the insulation as you'll be heating up everything but the house for the rest of the buildings life - remember its set in concrete so its hard to retro-fit. imo 200mm is not wasteful:)

MicktheMan

black francis wrote: »

That's true - and it's what the specifications says. Our contract with the builder does say that works are to be in accordance with the current (at time of contract signing) building regulations - which I'm presuming is 2010? If the 60mm doesn't comply with these regs in terms of the u value achieved, I would be hoping that any upping of this thickness is covered.

I'm regularly called out to homes which, although built/renovated to the regulations by "reputable" builders, are still cold, uncomfortable and/or very expensive to heat and am asked "why didn't we talk to you before we started building". Nuff said. You pays your money and you take your chances:rolleyes:.

beyondpassive

black francis wrote: »

I guess what I'm confused about is - 'what's the appropriate amount?'

I mean, there presumably comes a tipping point with insulation, where the money you start spending on extra doesn't show a return on the investment.

Now, I know that any future value attributed to the insulation will depend on energy prices in the future, which are an unknown - but how do people work out how much to spend on beefing up insulation at construction stage?

There is a individual 'appropriate amount' of insulation for every house, its about 3- 4 times what your team are proposing. After about 300mm of insulation the returns become negligible.

You'll likely to be building to Part L 2008, which looks for a 40% improvements on 2005 regs. Most "Architects" and Builders haven't got a good understanding of these regulations which require a DEAP calculation to work out the level of insulation required. Many use the backstop values, which don't comply and manufacturers brochures are very optimistic.

Fuel prices have doubled in the last 2 years, despite recession and the price is only going one way, most likely in an exponential curve. Its widely accepted that 8% increases are now very conservative. Using DEAP or Passivhaus software you can work out ways to reduce your energy demand, Insulation being the best option. As others have said Insulation is no good without attention to detail at junctions and airtightness.

We're at a period of transition where the building industry is becoming very quality and evidence based. Many of the 'auld lob it up sure she'll be grand' builders are getting out or are forced out. At a CIF meeting last week, many of those there said that Part L 2011, marked the time to get out. This morning I tested a house built in '09, where the occupants were frozen, plagued by drafts even with the heating on.

So it looks like you'll need to go back to the drawing board. Avoid insulated board lining as a quick fix its not an ideal solution.

Frank Black

An informatibve post Beyondpassive, but 'going back to the drawing board' is not an practicable option - our floor slab's being poured next week.

Do-more

black francis wrote: »

our floor slab's being poured next week

Watch out for the long range weather forecast, freshly poured concrete still contains lots of water and if there are sub-zero temperatures and the residual water in the concrete freezes at any point in the first 10 days it will prevent the concrete from setting correctly and can weaken the concrete by as much as 50%.

Frank Black

Do-more wrote: »

Watch out for the long range weather forecast, freshly poured concrete still contains lots of water and if there are sub-zero temperatures and the residual water in the concrete freezes at any point in the first 10 days it will prevent the concrete from setting correctly and can weaken the concrete by as much as 50%.

Jaysus - like I'm not worried enough about the insulation

Qualitymark

Avoid insulated board lining as a quick fix its not an ideal solution.

I'm thinking about getting cavity wall insulation (if it turns out to be possible - not sure if my 1930s house has cavity walls or not); someone has advised me that warm board, external (probably impossible - pebble-dashed house) or internal, would be more efficient. Are they wrong?

And is there any way of finding out roughly how much the cavity wall insulation should cost? I don't want to pay non-mickey surcharge.

Also, my house has some 1930s original Crittall windows (http://heritagewindowsacademy.co.uk/images/HeritageWindows/SunTrapBayWindowsMain.jpg) which I love and won't get rid of, but which are kind of ice traps. I'm told that some of the museums have a kind of heavy plastic blinds that they can hang over the windows in winter, which makes them effectively insulated, but can't find any information on these. Would anyone know what they are, how much they cost, and where to buy them?

kboc

PM sent. Please call that man.

Carlow52

black francis wrote: »

An informatibve post Beyondpassive, but 'going back to the drawing board' is not an practicable option - our floor slab's being poured next week.

Next week is next week so you have time to re-group. Its not over till the....

Unless you like, and can afford, really fast cars and even faster women, then this project is the most expensive investment you will make and dont get frog marched into making rash decisions that will cost you over a life time.

It seems u have an arch and an engineer on ur payroll so its time to get them earn their mula

I haven't read all the items here as its a mixed thread and dont have time to see whats what, so just on the frost issue what exact stage is the construction.

This may sound crazy,[ I may be a clown but am not a fool,] so if u have elected to go UFH and find the slab detail allows for less insulation than u want to meet 20XX specs, then drop the UFH and insulate the slab more.

I am not an expert here but I understand that UFH requires more underfloor insulation than if not UFH

just do it

black francis wrote: »

An informatibve post Beyondpassive, but 'going back to the drawing board' is not an practicable option - our floor slab's being poured next week.

Great, it's not poured yet. Now is the time to act and take all the advice you're getting on here.

I'm in a relatively new house that has had the energy upgrade last winter (cavities pumped, extra layer of attic insulaiton, heating control upgrades, stove installed, draft-proofed) and it is still cold!

A few hundred euro now on a competent energy assessor will be saved in your first year's energy bill! A few good ones are regulars on this forum by the way...

Frank Black

Cheers for all the advice - quick update.
Just to be clear - the architect who carried out the design is no longer involved in the project, though we can contact him if we need to clarify something.
We have got a good few references for the builder - he has built a house for my wife's cousin which we been to a few times - the house is very cosy and warm and her cousin has no complaints about draughts or the need to have heating running constantly.

Had a chat with the Engineer and Builder about the issues suggested on the thread - we will go with a full cavity fill and also a 37.5mm thick Kingspan insulation board fixed to the internal blockwork - the will bring the u-value down to about 1.5 - 1.6.

We have yet to agree a price for this, but it would seem sensible given the feedback I've received here.

BryanF

Francis hows the provisional BER looking?

Frank Black

BryanF wrote: »

Francis hows the provisional BER looking?

Will ask our enginner to carry out an assessment over christmas - he's a registerted ber assessor.

Frank Black

If I could trouble you guys with another quick question.
As mentioned we're going to go with a board to the inner side of the block work.
Would we be better going with board insulation or a pumped bead insulation to the cavity?

sydthebeat

black francis wrote: »

If I could trouble you guys with another quick question.
As mentioned we're going to go with a board to the inner side of the block work.
Would we be better going with board insulation or a pumped bead insulation to the cavity?

my preferred option would be pumped... more chance of it being done correctly.. just ensure that the installation is done in compliance with the IAB cert

Qualitymark

sydthebeat wrote: »

my preferred option would be pumped... more chance of it being done correctly.. just ensure that the installation is done in compliance with the IAB cert

What's the IAB cert, please, and how do you ensure compliance?

Do-more

Qualitymark wrote: »

What's the IAB cert, please, and how do you ensure compliance?

IAB = Irish Agrément Board.

You can search for certificates here.

The certificate will detail how the product is to be installed so it is up to your engineer to ensure that the product has been installed correctly before they sign off on the build.

beyondpassive

Qualitymark wrote: »

I'm thinking about getting cavity wall insulation (if it turns out to be possible - not sure if my 1930s house has cavity walls or not); someone has advised me that warm board, external (probably impossible - pebble-dashed house) or internal, would be more efficient. Are they wrong?

Unlikely you have a cavity if its a modernist house, External insulation would be the best option, but you'd need to be very careful with the design to keep the building character consistent with the original.

Qualitymark wrote: »

Also, my house has some 1930s original Crittall windows which I love and won't get rid of, but which are kind of ice traps. I'm told that some of the museums have a kind of heavy plastic blinds that they can hang over the windows in winter, which makes them effectively insulated, but can't find any information on these. Would anyone know what they are, how much they cost, and where to buy them?

Ya those steel windows are class. In germany and austria they move the windows out and install a double glazed screen on the inside. See the CPAS forest renovation on Architects A2M website http://www.a2m.be/home/ go to projects and then under bureau, see CPAS forest.

Qualitymark

Talked to one of the neighbours, who said he'd put in external insulation and it made a minimal difference.

Yes, adding a double-glazed screen on the inside of the 1930s windows would be ideal for winter, but not possible at the moment. (Thanks, bloated bankers.)

Modernist? Not sure. Art deco styling throughout.

BryanF

Qualitymark wrote: »

Talked to one of the neighbours, who said he'd put in external insulation and it made a minimal difference.

I think you need to give some context here. Insulation installed correctly, in the right situation, will improve the performance of a home.
But was a holistic approach taken?
Did your neighbour simply take the cheapest insulation option with out consulting an architect (with BER experience). Its often best to consider the windows, ventilation, thermal bridges, heating system etc at the same time (i'm only naming a few of the possible issues)

Many homes from this era get 'insulation only' solutions, then the clients find they have increased problems with condensation/mould.
This is not the insulations fault, but the fact that there is a lack of joined-up thinking by some tradesmen/ installers and a large proportion of our BER assessors..

as BP stated:

you'd need to be very careful with the design to keep the building character consistent with the original.

So imo employ an arch who has an understanding of buildings - someone who has actual building conservation as well as energy conservation experience. you might say that 1930's is not quite conservation work but the Art deco style commands architectural respect and generally a premium sale price..

best of luck with it

Qualitymark

Hm... employ an architect, danger of mould... sounds as if insulation is for the rich.

BryanF

its interesting that from the entire peace I wrote outlining why your previous statement was insufficiently considered, you chose this response

Qualitymark wrote: »

Hm... employ an architect, danger of mould... sounds as if insulation is for the rich.

I'll put it another way
I meet home owners regularly that have gotten poor advice or inappropriate work carried out on their homes. They generally blame the installer, when imo it was partially their lack of knowledge in choosing that installer which was the problem.
We have little or no regulation of how building products are used in our homes. yes, we have IAB certs and even a notional building control, but these mean nothing without the installers and products being chosen properly. imo due to our desire for cheaper services, inappropriate materials/products/installations are happening across the country retro-fitting and building industry. at least if installers are chosen with the help of an independent client representative, that has been descriptive in what works are appropriate and required, then you the client will have some assurance and will be less likely to say things like

Qualitymark wrote: »

Talked to one of the neighbours, who said he'd put in external insulation and it made a minimal difference.

sydthebeat

Qualitymark wrote: »

Hm... employ an architect, danger of mould... sounds as if insulation is for the rich.

this is a completely unhelpful comment to make.
posters here are imparting their own knowledge and experience on their own time. if you cannot add anything helpful then dont post

continue in this fashion and you will find yourself banned.