Best value External Insulation

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Dansouthcoast84

Private Member
For green deal you need to achieve u value of 0.030 wmk or 0.30 cant remember which One. This is achieved with 90mm eps. Which all our jobs are used
 

owls

Private Member
0.30 is the standard building regs,
but you can use others to get that instead of eps such as phenolic at 70mm or pir
 

bobspread

Well-Known Member
i done a small ewi a couple of months ago , single skin wall with 50mm phenolic,i was told that the phenolic gives better u values than the grey 90mm
 

Dansouthcoast84

Private Member
i done a small ewi a couple of months ago , single skin wall with 50mm phenolic,i was told that the phenolic gives better u values than the grey 90mm
Yeah they are good on values. Some.manufacturers dont like them and would prefer to use the eps though. Think been few failures with phenolics
 

owls

Private Member
it does, that's why you can use thinner insulation to get the same values,
but using its a bugger and it turns to mush when it gets wet, parex have stepped away from it but I fitted a warranted enewall system with it recently.
 

vfr12

MOTORC*NT
Nothing wrong with the phenolic, it's the way we use it.The boards can handle anything just like the eps, but there is one difference between phenolic and eps- rasping and bending. They will break before you can change the lines, where with the eps you have no problems. K5 used only with fixings can be real disaster. If the walls are not strait you will end up with not so good looking EWI, therefore I always recommend wet and dry fix. This way you have strait wall and don't have to worry about the edges of the boards.
 

Rigsby

TPF Special Forces
Phenolic is fine for already flat walls otherwise you have to be perfect at boarding as you cant rasp. Like said getting a warranty can be a problem. I always go for eps, unless the customer demands K5 and accepts the risks.
 

plasterjfe

Private Member
Phenolic breaks down slowly after production so the uvalue can actually drop off very slowly in time. And another issue with it not being stable is it can shrink or curl on the wall weeks after its fitted behind the render leaving some terrible showing in the walls after the work is complete.

Sto, JUB, parex, dryvit certainly try their best to avoid after series of reactions. Sto won't use whatsoever anymore.

That said better value per thickness. I think 60mm phenolic gets u around 0.32
 

Plasterers1StopShop

Private Member
We stay well away from Phenolic. Will do our best to change the spec due to the reasons mentioned by JFE.

EPS is the most readily available, cost effective and best to work with
 

warriorupnorth

Private Member
Substrate types and thickness, finishes etc will affect the overhaul dimensions of the product applied but as a general rule of thumb solid 9 inch brick construction with 90mm platinum eps achieves the min requirement but it's always advisable to get this checked by the system supplier . We avoid phenolic.
 
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