Pumped Cavity versus Xtratherm rigid Insulation

Fuseman · 15-04-2015 2:53pm #1

Hi Folks

There is so much information around I am a little overwhelmed and need some guidance.

We are in the process of just starting an extension for an existing dwelling. The architect spec'd out a 300mm Cavity Wall for the extension. So that would be 100mm Brick, 100mm Insulation and 100mm Brick

Chatting to the builder today, he said that if he was building the extension for his own house he would pump the cavity and then put up a 50mm Insulated plasterboard inside.

I am lost :-(

FM

893bet · 15-04-2015 2:56pm

Fuseman wrote: »

Hi Folks

There is so much information around I am a little overwhelmed and need some guidance.

We are in the process of just starting an extension for an existing dwelling. The architect spec'd out a 300mm Cavity Wall for the extension. So that would be 100mm Brick, 100mm Insulation and 100mm Brick

Chatting to the builder today, he said that if he was building the extension for his own house he would pump the cavity and then put up a 50mm Insulated plasterboard inside.

I am lost :-(

FM

Ignore both and ask for a 150mm cavity and pump it.

Strolling Bones · 15-04-2015 3:10pm

893bet wrote: »

Ignore both and ask for a 150mm cavity and pump it.

+1

BryanF · 15-04-2015 3:22pm

893bet wrote: »

Ignore both and ask for a 150mm cavity and pump it.

Seconded

Plastered block internal finish with an eye on air-tightness, your designer should be specifying air-tightness measures

DOCARCH · 15-04-2015 3:32pm

@Fuseman. For balance, there is nothing wrong with what your architect has specified (for an extension to an existing house).

Full fill cavity insulation is tricky to install correctly, so, I would suggest the builder may (or may not) have a reason for offering his thoughts?

Personally, if it is brick outer leaf, I would prefer to use (a certified) full fill cavity insulation over bead (not matter what the bead is certified for).

Fuseman · 15-04-2015 3:53pm

DOCARCH wrote: »

@Fuseman. For balance, there is nothing wrong with what your architect has specified (for an extension to an existing house).

Full fill cavity insulation is tricky to install correctly, so, I would suggest the builder may (or may not) have a reason for offering his thoughts?

Personally, if it is brick outer leaf, I would prefer to use (a certified) full fill cavity insulation over bead (not matter what the bead is certified for).

Its not a brick outer leaf. Its just a standard 4" block as far as I am aware. The builder wouldnt do it himself. He would sub contract in a certified insulation company to do the pumping

Strolling Bones · 15-04-2015 4:58pm

DOCARCH wrote: »

@Fuseman. For balance, there is nothing wrong with what your architect has specified (for an extension to an existing house).

Actually - if the existing house is drylined then it would make sense to dry line the extension too.

DOCARCH · 15-04-2015 7:04pm

Fuseman wrote: »

Its not a brick outer leaf. Its just a standard 4" block as far as I am aware. The builder wouldnt do it himself. He would sub contract in a certified insulation company to do the pumping

Fair enough. I would not fill a 100mm cavity with bead and dry-line.

Just to say, your architect will not be too happy if you go back, at this point, and suggest a 150mm cavity and/or 100mm with bead plus dry-lining (as suggested by your builder) as it will change the overall wall thickness (add approx. 50mm to the wall thickness). That could have a knock-on in relation to structure, general detailing and/or space internally.

Fuseman · 16-04-2015 4:50pm

DOCARCH wrote: »

Fair enough. I would not fill a 100mm cavity with bead and dry-line.

Just to say, your architect will not be too happy if you go back, at this point, and suggest a 150mm cavity and/or 100mm with bead plus dry-lining (as suggested by your builder) as it will change the overall wall thickness (add approx. 50mm to the wall thickness). That could have a knock-on in relation to structure, general detailing and/or space internally.

Is there specific reason for not filling the cavity with bead and dryline?
example Mould problems etc

thatslife · 16-04-2015 4:57pm

I'm currently looking into this same thing.
I was told to avoid bead. He was explained to me that overtime bead will degrade in the cavity.
Like a football, air inside beads would slowly seep out and ur insulation thickness wud become less and less

DOCARCH · 16-04-2015 5:03pm

Fuseman wrote: »

Is there specific reason for not filling the cavity with bead and dryline?
example Mould problems etc

Always try and keep your insulation in one layer...if at all possible.

hexosan · 16-04-2015 5:03pm

thatslife wrote: »

I'm currently looking into this same thing.
I was told to avoid bead. He was explained to me that overtime bead will degrade in the cavity.
Like a football, air inside beads would slowly seep out and ur insulation thickness wud become less and less

Told by who ?? Timmy in the pub or Johnny down the road

thatslife · 16-04-2015 5:06pm

hexosan wrote: »

Told by who ?? Timmy in the pub or Johnny down the road

Johnny told me on the road to the pub and Timmy seconded it. Whats your opinion Hex?

mikeymouse · 16-04-2015 5:15pm

In same boat here,
what's the price diff?

sydthebeat · 16-04-2015 5:37pm

thatslife wrote: »

I'm currently looking into this same thing.
I was told to avoid bead. He was explained to me that overtime bead will degrade in the cavity.
Like a football, air inside beads would slowly seep out and ur insulation thickness wud become less and less

in my opinion, thats rubbish

polystyrene is already air blown so so teh air has no need to go anywhere
also its a pretty rigid material... polystyrene boards havent sagged so why would beads?

quilted material, yes definitely.

who told you? a foam insulation seller by any chance?

Strolling Bones · 16-04-2015 5:41pm

thatslife wrote: »

I'm currently looking into this same thing.
I was told to avoid bead. He was explained to me that overtime bead will degrade in the cavity.
Like a football, air inside beads would slowly seep out and ur insulation thickness wud become less and less

Well nothing lasts forever. All materails degrade over time. In this case - centuries.....

thatslife · 17-04-2015 12:32pm

Relax lads, I'm just repeating what was explained to me. My engineer recommends a 150mm cavity therm. No dry-line. Thoughts? here is the link to it http://www.xtratherm.com/wp-content/uploads/2012/01/CavityTherm2011irl.pdf

Superdaddy · 18-04-2015 2:18pm

thatslife wrote: »

Relax lads, I'm just repeating what was explained to me. My engineer recommends a 150mm cavity therm. No dry-line. Thoughts? here is the link to it http://www.xtratherm.com/wp-content/uploads/2012/01/CavityTherm2011irl.pdf

Ive used it in mine. Major hassle with getting blocklayers to install it as per instructions. Great product when installed correctly in my opinion.

thatslife · 22-04-2015 12:15pm

Superdaddy wrote: »

Ive used it in mine. Major hassle with getting blocklayers to install it as per instructions. Great product when installed correctly in my opinion.

Any tips on installation?

soccercrew · 22-04-2015 9:38pm

thatslife wrote: »

I'm currently looking into this same thing.
I was told to avoid bead. He was explained to me that overtime bead will degrade in the cavity.
Like a football, air inside beads would slowly seep out and ur insulation thickness wud become less and less

I have opened up 25 yr old walls with beads and no change whatsoever.

Superdaddy · 24-04-2015 1:13am

thatslife wrote: »

Any tips on installation?

Get a Blocklayer that's happy to build from the outside on scaffold. If they don't follow instructions, sack them without hesitation.

murphy31ie · 25-04-2015 12:55am

Hi,
Currently in the process of a self build, starting the roof next week. I have a 150 mm cavity that I am going to pump, did not want to build in insulation as you need to be standing over the builders to ensure joints are being taped. Anyway was planning on dry lining along with the 150 mill pumped cavity, is that a bad idea. Cheers for any info

murphy31ie · 25-04-2015 1:10am

murphy31ie wrote: »

Hi,
Currently in the process of a self build, starting the roof next week. I have a 150 mm cavity that I am going to pump, did not want to build in insulation as you need to be standing over the builders to ensure joints are being taped. Anyway was planning on dry lining along with the 150 mill pumped cavity, is that a bad idea. Cheers for any info

Sorry I should have added it is 50mm dry lining.

BryanF · 25-04-2015 6:58am

murphy31ie wrote: »

Hi,
Currently in the process of a self build, starting the roof next week. I have a 150 mm cavity that I am going to pump, did not want to build in insulation as you need to be standing over the builders to ensure joints are being taped. Anyway was planning on dry lining along with the 150 mill pumped cavity, is that a bad idea. Cheers for any info

This is debated to death here, try typing variations of key words into the advanced search.

insulation is best kept in the cavity. Why dry line? You lose the thermal mass of the Blockwork and potentially air-tightness. What is your expected air-tightness figure stated in the building contract?

murphy31ie · 25-04-2015 8:14am

BryanF wrote: »

This is debated to death here, try typing variations of key words into the advanced search.

insulation is best kept in the cavity. Why dry line? You lose the thermal mass of the Blockwork and potentially air-tightness. What is your expected air-tightness figure stated in the building contract?

We were advised by the BER man to dry line, my dad is looking after the job as he is a retired contractor but from him there will be a scratch coat and the boards will be mechanically fixed. I would need to look up the expected air tightness figure, we are trying for as air tight as we can. Thanks for any info again

_Brian · 25-04-2015 8:23am

When we built our main house 8 years ago we pumped the 100 mm cavity and put 50mm board on the inside.

Our cavity is pumped with certified bead. In the loft space where I can access the top Of the cavity the head is still rigid and in place. This is near 3 stories up and there is no evidence if sag. The bead still feels rigid as the week it was done.

Rigid insulation in cavities is easy to fit but difficult to fit properly and detail so as to prevent air ingress, and many are so poorly detailed around corners and windows to render them useless.

murphy31ie · 25-04-2015 8:26am

_Brian wrote: »

When we built our main house 8 years ago we pumped the 100 mm cavity and put 50mm board on the inside.

Our cavity is pumped with certified bead. In the loft space where I can access the top Of the cavity the head is still rigid and in place. This is near 3 stories up and there is no evidence if sag. The bead still feels rigid as the week it was done.

Rigid insulation in cavities is easy to fit but difficult to fit properly and detail so as to prevent air ingress, and many are so poorly detailed around corners and windows to render them useless.

Hi Brian

Are you happy you went with the dry lining?

eoinvden · 28-04-2015 7:27am

Just wondering if anyone has any experience of using xtratherm cavity fill rigid board insulation. We're considering it for a new build but its very expensive.The architect had originally specified it for 150mm cavity but is now suggesting we could use Quinn 110mm insulation which would give u values close to but not quiet as good as xtratherm. There is a significant price difference (almost double). Any help would be appreciated

sydthebeat · 28-04-2015 7:39am

Have you had your preliminary DEAP assessment done to find out what spec you need to comply with regs?

Exactly what product AND thickness did the architect specify.
And exactly what product AND thickness are you considering as an alternative

The R Tech · 28-04-2015 11:37am

What do people think about, the level of workmanship deteriorating when block layers don't have to deal with insulation in the cavity. Such defects as mortar dropping down to the DPC, un-scrapped joints etc. In addition for pumped insulation the deap software requires thermal imaging to ensure there are no air pockets in the corners etc. to use the y-Value.
Any thoughts guys

DOCARCH · 28-04-2015 11:45am

Mod Note: Decided to merge two threads on same/similar topic.

sydthebeat · 28-04-2015 1:54pm

The R Tech wrote: »

What do people think about, the level of workmanship deteriorating when block layers don't have to deal with insulation in the cavity. Such defects as mortar dropping down to the DPC, un-scrapped joints etc. In addition for pumped insulation the deap software requires thermal imaging to ensure there are no air pockets in the corners etc. to use the y-Value.
Any thoughts guys

i wouldnt agree, its actually much easier keep a 150+ cavity cleaner than having to deal with partial fill insulation.

the success of any in-homogenous construction such as a cavity wall is dependent on the workmanship... be it with partial fill, full fill, or pumped insulation.

The R Tech · 28-04-2015 2:33pm

Sorry i was referring to full fill insulation as partial fill is more or less gone now!
However it is still very difficult to remove fallen debris or cement from 100mm or 150mm
Also just a note a 150mm full fill cavity has a u-value of 0.13 Vs 0.19 for pumped bead.
Sorry just the other point of the thermal imaging for air pockets in the bead or foam insulation what do people think.

sydthebeat · 28-04-2015 2:47pm

The R Tech wrote: »

Sorry i was referring to full fill insulation as partial fill is more or less gone now!
However it is still very difficult to remove fallen debris or cement from 100mm or 150mm
Also just a note a 150mm full fill cavity has a u-value of 0.13 Vs 0.19 for pumped bead.
Sorry just the other point of the thermal imaging for air pockets in the bead or foam insulation what do people think.

no its not, a brush will clear most dpcs ????

as i said, its all down to workmanship, regardless of the insulation method.
Full fill insulation certainly requires a strong attention to detail and care as well.

the 0.08 thermal bridging factor is applicable for new builds once the

relevant drawings be signed off by the developer, builder, site
engineer or architect

why do you think thermal imagining would have to be carried out in order to input this value?
or are you talking about a calculated thermal bridging factor?

DOCARCH · 28-04-2015 2:51pm

I can see where R Tech is coming from.

No matter how many times you drum it into block layers, it is very hard to get them to use some/any form of mechanism to prevent mortar snots dropping down the cavity as the wall is built up.

A lot easier/fail safe, to a certain extent, to be installing full full insulation at the same time the wall is being built up and clean top of each panel of insulation as they go.

sydthebeat · 28-04-2015 2:58pm

DOCARCH wrote: »

I can see where R Tech is coming from.

No matter how many times you drum it into block layers, it is very hard to get them to use some/any form of mechanism to prevent mortar snots dropping down the cavity as the wall is built up.

A lot easier/fail safe, to a certain extent, to be installing full full insulation at the same time the wall is being built up and clean top of each panel of insulation as they go.

agreed, its easier to keep the cavity clean with full fill insulation.

however where 'workmanship' comes into the picture here is the installation of the insulation boards themselves. Ive seen probably 5 different house builds using this over the last few years and NONE have been perfect.

Problems have ranged from gaps between boards horizontally due to mortar on the wall ties, vertical gaps due to boards being 10-20 mm short due to an opening so the gaps are just spaced between the boards, a lack of understanding as to the need to start the insulation 225mm below the finished floor level.

that being said, its definitely a better system than the partial fill... but its far from a perfect system.

edit: the cleanest cavities ive seen are the ones where the clients themselves are clued in and remove the mortar droppings themselves.

murphy31ie · 20-05-2015 1:35pm

Sorry if this has already been talked about somewhere else, any advice on the best bead to use for pumping the cavity, the cavity is 150mm. Any suggestions are most welcome.

staff1986 · 03-01-2016 7:53pm

Hoping to start a direct labour built bungalow in March. Decided to go with 150mm full fill board insulation.

Is it necessary to tape the joints of the insulation boards?

Thanks

Calahonda52 · 03-01-2016 8:46pm

staff1986 wrote: »

Hoping to start a direct labour built bungalow in March. Decided to go with 150mm full fill board insulation.

Is it necessary to tape the joints of the insulation boards?

Thanks

yes but the other question is how will u manage the air gaps around the wall ties?

What made u decide on this solution?
What did u dismiss and why?

staff1986 · 04-01-2016 4:15pm

I dont know is the honest answer. I will contact the Xtratherm agent who I'm dealing with and try get some information/installation details from him. They are the experts of their own products.

Initially I was going with bonded bead. I did a good bit of research and one issue which was repeated in a few places was with driving rain on exposed sites. My site is very exposed and this was a concern. My BER guy and a family friend who builds high-spec houses in Dublin both had the same concern over bonded bead (I didnt prompt the question). This made my mind up. If my site wasnt exposed I'd probably still be undecided.

Regarding options (limited to a budget), there was full fill rigid board v.s. partial fill rigid board and insulated slab on internal wall. It was a lifestyle choice really. insulated slab offers a quick heat up / cool down while the full fill utilises the thermal mass of the blocks which will hold the heat, slowing the heat up / cool down time.

Hope this helps.

Eleni2015 · 04-01-2016 5:05pm

Hi Staff, just curious as to how driving rain affects the bonded bead insulation?

staff1986 · 04-01-2016 9:53pm

From what I have read/heard driving rain can cause water infiltration through the external leaf into the insulation. The concern is the water will travel across the bonded bead and make contact with the internal leaf. The full fill rigid board insulation acts as a barrier preventing this water ingress. As far as I know this is issue is not a problem / proven fact with bonded bead, but more of a concern shared by some.

BryanF · 05-01-2016 1:17am

staff1986 wrote: »

From what I have read/heard driving rain can cause water infiltration through the external leaf into the insulation. The concern is the water will travel across the bonded bead and make contact with the internal leaf. The full fill rigid board insulation acts as a barrier preventing this water ingress. As far as I know this is issue is not a problem / proven fact with bonded bead, but more of a concern shared by some.

Unless this is a brick facade:

Where have you read this?

This was covered to death here a few year ago, I think the regular posters are just tired of discussing it.

Beads In Principle are better at avoiding water infiltration over boards

JonathonS · 05-01-2016 2:50pm

BryanF wrote: »

Beads In Principle are better at avoiding water infiltration over boards

+1. You should also consider BASF Walltite, although it is considerably more expensive than beads.

Murphy14 · 05-01-2016 10:17pm

staff1986 wrote: »

From what I have read/heard driving rain can cause water infiltration through the external leaf into the insulation. The concern is the water will travel across the bonded bead and make contact with the internal leaf. The full fill rigid board insulation acts as a barrier preventing this water ingress. As far as I know this is issue is not a problem / proven fact with bonded bead, but more of a concern shared by some.

Water should not travel across bonded bead the adhesive thats used to bond the beads is also a water repellent plus the shape of the bead if water enters cavity it would run down to dpc rather than across

staff1986 · 06-01-2016 10:47pm

Thanks for the heads up on BASF Walltite.

Ok fair enough there has been loads of discussions on this before and there's no point in flogging a dead horse, but what would be really helpful to me (I need to make a decision on insulation in next few weeks) would be peoples first hand experience who have constructed houses and lived in houses over the past 1-4 years that have been insulated with bonded bead or xtratherm cavitytherm.

What was the construction experience like?

What has comfort level/heating been like in the house?

Thanks in advance as this would be really helpful to me

BarneyMc · 06-01-2016 11:58pm

Just at the plastering stage so can't comment on comfort levels yet. The beads took the insulation installation out of the hands of the blockies which was a blessing. I've seen insulation boards on site and between the blockies and the weather the quality of the rigid board construction was poor. Anyway, just my experience!

qaz123 · 06-02-2016 11:24am

Currently trying to decide to go for 110mm partial fill board with 50 mm thermal board sand and cemented or 150mm full fill xtratherm insulation.

Looking for people with experience of either with underfloor heating run by heat pump.
How do you find it

BarneyMc · 06-02-2016 2:34pm

qaz123 wrote: »

Currently trying to decide to go for 110mm partial fill board with 50 mm thermal board sand and cemented or 150mm full fill xtratherm insulation.

Looking for people with experience of either with underfloor heating run by heat pump.
How do you find it

If it's down to those 2 choices then the latter. Keep your insulation in 1 layer.

bravojohnny · 07-02-2016 10:48pm

^^^^
This

In my opinion insulation should be in kept in the same location.

Elsie161211 · 10-03-2016 11:01pm

How about a 110mm partial fill with a 6" Quinnlite block, scratch coat and plaster. No need for insulated board on the inside then?

Pumped Cavity versus Xtratherm rigid Insulation

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