Blown bead cost comparison

[Gorlando]

Depending on the number crunching, I seem to be settling on a 155mm full fill cavity with eps beads for a number of reasons, fast install, builder free installation etc to name a few.

 

With Thermabead's Carbon Saver for example brick outer, 155mm full fill, med dense block inner and plaster finish gives back a u-value of .18.

 

To cost out Thermabead have said to work on the basis of £10pm/sq for a 155mm fill.

 

I was just wondering if anybody had there insulation costs to hand to easily try and draw some comparisons to other methods (I realise this may difficult so cost per meter squ would be easiest)

 

 If anybody can suggest other eps bead providers also. Finally, would like to hear people's options on the figures achieved above. I like it as it appears a respectable value for a modest cavity size.

 

Climabead doesn't seem to perform as well (185mm needed to achieve the same), waiting to hear back from Poly-pearl and energystore (all taken from the national bead blowers association website)

 

thanks in advance

[Jeremy Harris]

Is it worth looking at a 200mm cavity to get a better insulation level?  The beads are pretty cheap, most of the cost is in blowing them in with PVA, I think, and a 200mm cavity doesn't cost any more to build than a 155mm cavity.  The payback time for the small extra cost would probably be pretty reasonable, too.  0.18 W/m².K isn't really great, and a little better would ensure you meet the SAP requirements with a small performance buffer in the event that some other aspect of the as-built construction doesn't quite meet the as-designed assumptions.

[Oz07]

Make sure you report back with your findings as I'm interested. Last job I had 150mm cav, aircrete blocks and blown in wool. .18 u value but I would of preferred using denser block with beads like yourself. I just found it hard to get reliable prices for eps blown bead.

 

as jsh says if living in property for some time and your not restricted with your plot size it would be interesting to see payback on 200 cav u value  

[PeterW]

200mm cavity brings some serious increase in tie costs - my 275mm are £47 a box vs £26 for standard, and 325mm ones are nearly £80 a box ..! 

 

Try one of the ones blowing a graphite EPS bead as they are not too bad - think mine was £11sqm but would need to check for 150mm

[Declan52]

Not true that a 200mm cavity won't cost more. Your block founds will need to be wider for  a start. You will have to build the blocks 450mm wide to suit a 200mm cavity instead of 350mm Foundation block. You will have the extra cost of the mortar as well plus the cost to lay the extra blocks as you will Def use more. If you are already planning to build your founds 450mm wide then it won't matter.

You will have the cost of longer wall ties.

Depending on how wide your openings are you could maybe get away with using a 65mm concrete lintel to close the cavity at windows and doors. A standard bootleg head will close a 150mm cavity.

[bassanclan]

I had approx 115sqm of grey eps bonded beads blown in a 100mm cavity for £853 plus vat at 5% - (dense concrete block construction) by Miller Pattison last summer.

I looked at installation of insulation during the blockwork build, but decided that as the price was pretty similar I may as well have it blow in after and avoid errors in putting the insulation in etc

[ADLIan]

Problem with blown insualtion is that any defects (voids, density variations, clumping) are hidden - the method for 'guestimating' the adequacy of fill is woefully innacurate and would not identify any of the above.

With retrofit in old walls I take the view that anything is better than nothing so the odd void may not be an issue. In new build this is not the case - at least with built in cavity batts you can see any issues/problems and correct them.

 

[Jeremy Harris]

We have blown insulation.  300mm in the walls, 400mm in the roof.  The blowing method is very well controlled, with pressure sensing, remote control, etc, and has all the required approvals.  I think there are significant risks in blowing into small cavities, like the typical 50mm of an old cavity wall, and the sensor-type machines won't even work reliably on such a small cavity, which is another indication that they may be problematic.

 

When you get to 150mm + wide cavities there is pretty much zero risk of voids or exclusions.  The insulation behaves like a very free flowing fluid (think fluidised bed, as it's the same principle) and will, without any doubt whatsoever, produce a better job, in terms of insulation integrity, than rigid or rockwool batts fitted as the walls are built. 

 

I watched our insulation being blown in, and saw first hand exactly how it flows, and how much of an overkill the manufacturers minimum fill hole spacing is - the stuff flows easily for around three times the fill hole spacing.  In our roof, the fill was visible up the pitch, as the internal Intello membrane is translucent.  If there was anywhere where voids were more likely it was the roof, as it was filled in bays, with only limited crossflow though the small thermal break gaps.  The blown insulation was absolutely solid, right up to the ridge, with no trace of any voids.  It's blown in with such pressure that even now, three years later, the exposed areas of the filled membrane still feel strongly under pressure.

 

So, to sum up, I'd say that it is probably one of the best ways of insulating a decent sized cavity.  It's a  very well-controlled and measured process, there is no "guestimating" at all and there is no "woeful inadequacy" whatsoever.  There is simply no comparison between the type of equipment and fill system used for a wide cavity new build and some of the cowboys that have been doing shoddy jobs with poor equipment in the retrofit market.

Edited May 9, 2017 by JSHarris

[Ian]

for anyone considering full fill masonry cavity walls there's a useful guide inc maps and diagrams to the geographic rain exposure limits v types of wall construction in Part C of the Building Regs. The link below is to the English Regs and you need to go to pages 32 - 36.

 

http://webarchive.nationalarchives.gov.uk/20151113141044/http://www.planningportal.gov.uk/uploads/br/br_pdf_ad_c_2013.pdf

Edited May 9, 2017 by Ian

[ADLIan]

See also individual manufacturers BBA certs - these will give more details of type of construction and max exposure limits.

 

@JSHarris - I am aware of the procedures for injected CWI having developed blown in cavity products, taken them through the approval process and approved contractor status.

[Gorlando]

On 2017-5-8 at 15:35, JSHarris said:

 0.18 W/m².K isn't really great, and a little better would ensure you meet the SAP requirements with a small performance buffer.

 

@JSHarris it is an interesting point you make surrounding the buffer it provides. To be completely honest we have always sought to try and achieve a value equal to or less than .15. A 200mm cavity for example, using the above stated wall construction would achieve .14. I got talked out of it by my designers viewpoint initially, but providing the budget can handle the extra wall tie costs and cavity closings then I may well settle on 200mm. I think it's time I became more assertive! The build won't be starting for a good while also so I have plenty of time to shop around.

 

On 2017-5-8 at 20:09, Oz07 said:

Make sure you report back with your findings as I'm interested. Last job I had 150mm cav, aircrete blocks and blown in wool. .18 u value but I would of preferred using denser block with beads like yourself. I just found it hard to get reliable prices for eps blown bead.

 

as jsh says if living in property for some time and your not restricted with your plot size it would be interesting to see payback on 200 cav u value  

 

@Oz07I will report back no problem, but like I said above we won't be building until this time next year at the earliest. Also, we never intend on selling, with the intention being to pass it onto the kids. Prob more reason to spend that bit extra money on the fabric. I think a more dense block will require an even bigger cavity to acheieve .14 for example, may be wrong. My preference is medium dense, but all card are on the table at present. Can I ask your reasons for not wanting to aircrete/thermalite next time around? 

 

On 2017-5-8 at 21:29, PeterW said:

200mm cavity brings some serious increase in tie costs - my 275mm are £47 a box vs £26 for standard, and 325mm ones are nearly £80 a box ..! 

 

Try one of the ones blowing a graphite EPS bead as they are not too bad - think mine was £11sqm but would need to check for 150mm

 

@PeterW that would be the 325mm for me then, With a quick look last night I found them at approx 2.30 per wall tie, for a branded kind. I'm sure with a little shopping around we could shave a bit of that, and a bulk buy of course. I read somewhere that there is a company in Ireland who do cheaper alternate basalt composite ones, but I can't find where I read it now. Any idea how many is used per sqm of wall?

 

On 2017-5-8 at 21:30, Declan52 said:

Not true that a 200mm cavity won't cost more. Your block founds will need to be wider for  a start. You will have to build the blocks 450mm wide to suit a 200mm cavity instead of 350mm Foundation block. You will have the extra cost of the mortar as well plus the cost to lay the extra blocks as you will Def use more. If you are already planning to build your founds 450mm wide then it won't matter.

You will have the cost of longer wall ties.

Depending on how wide your openings are you could maybe get away with using a 65mm concrete lintel to close the cavity at windows and doors. A standard bootleg head will close a 150mm cavity.

 

@Declan52 all valid points that I have logged for discussion and costings, thank you. Lets just hope the ground doesn't hold any nasty surprises to boot!

 

On 2017-5-8 at 21:32, bassanclan said:

I had approx 115sqm of grey eps bonded beads blown in a 100mm cavity for £853 plus vat at 5% - (dense concrete block construction) by Miller Pattison last summer.

I looked at installation of insulation during the blockwork build, but decided that as the price was pretty similar I may as well have it blow in after and avoid errors in putting the insulation in etc

 

@bassanclanOn the face of it, (£7.78pm/sq) that's pretty cheap. That is my main reason to have it blown in, to avoid the errors.

 

On 2017-5-8 at 22:35, ADLIan said:

Problem with blown insualtion is that any defects (voids, density variations, clumping) are hidden - the method for 'guestimating' the adequacy of fill is woefully innacurate and would not identify any of the above.

With retrofit in old walls I take the view that anything is better than nothing so the odd void may not be an issue. In new build this is not the case - at least with built in cavity batts you can see any issues/problems and correct them.

 

 

@ADLIan points noted, but surely as your building from scratch than the opportunity to engineer out said voids is present? I can see how clumping and variations will be harder to overcome, or builders bodging/hiding installation defects whilst I'm not there when employing the use of batts/eps boards. Ultimately for me, its choosing the lesser of the two evils. I'd be interested to read any articles you may have surrounding the issues you have highlighted.

 

On 2017-5-9 at 07:57, JSHarris said:

We have blown insulation.  300mm in the walls, 400mm in the roof.  I watched our insulation being blown in, and saw first hand exactly how it flows

 

@JSHarrisThe roof...never even considered at this stage that we could get it blown in there also as we are looking at warm roofs (house and annex) more volume should hopefully mean better price and more saved time and money for the initial super structure build. And a useful first hand insight, thanks.

 

21 hours ago, Ian said:

for anyone considering full fill masonry cavity walls there's a useful guide inc maps and diagrams to the geographic rain exposure limits v types of wall construction in Part C of the Building Regs. The link below is to the English Regs and you need to go to pages 32 - 36.

 

@Ian plot is in Stoke-on-Trent, about 16 miles north of Stafford. From my understanding of the document, and please correct me if I'm wrong. We should be okay with tooled flat joints @+150mm. This joint will give us the farmhouse look of the local area also.

 

20 hours ago, ADLIan said:

See also individual manufacturers BBA certs - these will give more details of type of construction and max exposure limits.

 

I am aware of the procedures for injected CWI having developed blown in cavity products, taken them through the approval process and approved contractor status.

 

@ADLIan I'll check the BBA certs for the one we settle on when the time comes. In your opinion then, is there a top performer?. My research so far is highlighting the Thermabead Carbon saver as the best performer, but I haven't had the chance to research a great number. 

 

 

thanks to all for some really interesting points, I'm sure this thread will help many others too.

 

Giuseppe

 

Edited May 10, 2017 by Gorlando
Update

[Gorlando]

@Oz07 @JSHarris Calculations for the u-value of .14 were done with fibolite, another bonus!

[Ian]

33 minutes ago, Gorlando said:

 

@Ian plot is in Stoke-on-Trent, about 16 miles north of Stafford. From my understanding of the document, and please correct me if I'm wrong. We should be okay with tooled flat joints @+150mm. This joint will give us the farmhouse look of the local area also.

 

@Gorlando

yes, you'll be okay with that spec.

[Ian]

40 minutes ago, Gorlando said:

Any idea how many is used per sqm of wall?

 

@Gorlando

typical cavity tie spacing works out at 2.5 ties per m2 of wall area.

[Oz07]

.14 with your original plan? I.e. Medium block and 150 cav?

[Gorlando]

3 hours ago, Oz07 said:

.14 with your original plan? I.e. Medium block and 150 cav?

 

No sorry that's a 200mm cavity; .18 with a 155mm cavity. 

 

FYI Energystoreltd have come back to me this morning also, their product has only a slightly worse r-value and are stating approximate per sq meter costs as £6-8 for 155mm cavity. A 155mm cavity with the above spec is rounded up to .19 with ESltd as oppose to .18 with thermabead's CS. 

 

Hope that helps? 

Edited May 10, 2017 by Gorlando
Wrong figures stated

[Declan52]

Have you priced up using lightweight/thermal blocks for the inside skin to improve your u value.

[Gorlando]

1 hour ago, Declan52 said:

Have you priced up using lightweight/thermal blocks for the inside skin to improve your u value.

 

When you say light-weight, do you mean thermalite or med dense/light-weight concrete such as fibolight?

 

Preferance is for fibolight, which is the block spec'd in the valies above, or similar. I want to avoid thermalight etc for the many snagging issues they can bring on further down the line.

 

But in answer to you question, no. I can't price anything up, as such yet, as we are still agreeing the final design. The initial design put forward was a non starter from our point of view so we threw it out. Now waiting for a more suitable initial floor plan to work off.

[Declan52]

No matter what block you choose you will have cracks to fill 18months later. 

I used lightweight aircrete blocks on mine and have had no issues. As long as you fully soak the wall prior to wet plastering then it will be fine.

Are you wet plastering or bonding plasterboard to the blocks.

You have the sqm worked out to price the insulation so from that work out how many blocks you need,you use 10 blocks per sqm. Phone round all the suppliers and see what suits the budget.

 

[PeterW]

I would properly model your design using the spreadsheet that @JSHarris put together and play with the numbers. 

 

We have more roof than wall, and going from 0.15 to 0.18 in the walls made the square root of naff all difference. What made the big difference was the airtight layer and reducing the number of ACH. It was a huge difference and is where I'm concentrating the detailing on 

[Gorlando]

31 minutes ago, Declan52 said:

No matter what block you choose you will have cracks to fill 18months later. 

I used lightweight aircrete blocks on mine and have had no issues. As long as you fully soak the wall prior to wet plastering then it will be fine.

Are you wet plastering or bonding plasterboard to the blocks.

You have the sqm worked out to price the insulation so from that work out how many blocks you need,you use 10 blocks per sqm. Phone round all the suppliers and see what suits the budget.

 

 

That's it I don't. The insulation quotes above are just for 'a' sq meter @ 155mm cavity. I have no actual floor plans or elevations to work a total off. To use the initial design put forward would be a waste of time as we have changed it so much.

 

Plastering. I know I will still get expansion cracks whatever. I'm bearing an open mind still towards thermalite and it's good to know about your positive results. I do know to just soak the bejesus out of em, first lesson in plastering from me old man!

 

Suppose it just comes down to costs and like @PeterW says whether the difference is actually costs effective. 

 

Hopefully have some better plans by the end of the week

 

Cheers

[Brickie]

There is a two part tie system I've used previously for larger cavities (you bed one part in to the skin you're building & the other part locks into it for the other skin.) No idea of cost,but what I've found when building a 150mm cavity (the largest I've worked on) is that,with all the will in the world,a lot of the ties topple out before you've laid on them. The extra length & weight of them makes them extremely difficult to keep in position before your brickwork goes on your bed joint,so inevitably a few (or a lot) end up being pushed in afterwards,seriously impacting their effectiveness. 

Another option might be to build in Abbey channel slots,&I use the sliding ties. Again,no idea on cost.