External insulation v Fullfill Cavity

agrostar

Not sure if this is the correct section if not pls move.
New build house starting soon was seriously considering 200mm external wall insulation but after talking and looking at some of the work done by afew contractors I'm not blown away with their knowledge or workmanship. Trying to get information as regards finish window/door detailing, warranties and general finishing has been very sketchy at best, there seems to be a lack of knowledge as regards to the detail needed to finish to achieve the maximum result in terms of thermal efficiency and durability. I have read about Ewi to death here on boards and I'm sure if done correctly is a very good way of insulating a house but I'll admit I'm slowly losing confidence in this method.
The other option we were considering was to go with 150mm cavity and to use 150mm xtratherm full fill insulation. (No internal insulated slab) Our block layer has used this on many jobs in the past and believes if done properly would be as good as the ewi when all the proper corner pieces and closers are used.
Sorry now for ranting but what would people's opinion be on using the full fill versus ewi?

Morini

I had an extension put on my house last year, and had external insulation applied to the full house. I can't compare to the cavity fill insulation, but I'm very happy with the results. I can PM you the subcontractor details? They were chosen by the main contractor, who had used them before, and our architect (who was watching closely) is pleased with the work they did.

All windows were replaced, so the new windows had to be set further out than the originals. That didn't seem to cause a problem for the insulators.

The only thing I'd have done differently would be to have a satelite dish bracket put on first!

Calahonda52

IMO, cavity construction [back/front partial/full/No] Fill is largely a construction methodology that I have little to no confidence/faith in for the simple reason that it is impossible to supervise.

Morini, in his post, has made reference to a number of professionals he used, something that seems absent in the OP

agrostar

Calahonda52 wrote: »

IMO, cavity construction [back/front partial/full/No] Fill is largely a construction methodology that I have little to no confidence/faith in for the simple reason that it is impossible to supervise.

Morini, in his post, has made reference to a number of professionals he used, something that seems absent in the OP

One of the Ewi installers went to view their work was recommended by our engineer, the other was also one of the main contractors doing Ewi in our local area. They seem to be focusing on retrofitting to existing houses only having done a small number of new builds. Having looked at one of the projects the favoured Ewi installer was working on we were less than impressed, fixings were in sporadically and loose and the general work area was very untidy.
So are you saying that unless you use a building contractor and get your architect to choose and oversee your ewi installers it cannot be done effectively?

BryanF

agrostar wrote: »

One of the Ewi installers went to view their work was recommended by our engineer, the other was also one of the main contractors doing Ewi in our local area. They seem to be focusing on retrofitting to existing houses only having done a small number of new builds. Having looked at one of the projects the favoured Ewi installer was working on we were less than impressed, fixings were in sporadically and loose and the general work area was very untidy.
So are you saying that unless you use a building contractor and get your architect to choose and oversee your ewi installers it cannot be done effectively?

Pick a well known ewi system and call the manufacturer (ask to speak to the 'local technical rep' - and make out like your building a housing estate:) )ask them for their typical details and go through any questions . After that its an arch/arch tech who should consult. This is outside of the expertise/interest of most traditional civil/structural engineers (with some notiable exceptions to this massive generalisiation lurking around boards )

agrostar

BryanF wrote: »

Pick a well known ewi system and call the manufacturer (ask to speak to the 'local technical rep' - and make out like your building a housing estate:) )ask them for their typical details and go through any questions . After that its an arch/arch tech who should consult. This is outside of the expertise/interest of most traditional civil/structural engineers (with some notiable exceptions to this massive generalisiation lurking around boards )

I suppose the main reason why I'm straying away from using ewi is the need to have to use (and lack of) people with the relevant expertise that seems to be required to get ewi done correctly. I was hoping that by hiring professional installers to install the the ewi it would be done correctly as it's not rocket science by no means. Once basic details around plinth, soffit, corners and widows and doors are done correctly it should be exactly that basic as most ewi installations should be similar without any great variations as insulation can only be fitted to the wall in a limited number of ways depending on system and insulation thickness. Why so much of a mystery about it?

The reason I'm being swayed towards the fullfill cavity at the moment is that our blocklayer who has used it on a lot of projects and knows how to fit it correctly with all the proper accessories suggested it. I have full confidence in him to get the job done 100% as he has done work for myself, friends and family and is very exacting in his workmanship. (TBH I'd have more confidence in him fitting the insulation correctly in the cavity than the ewi I have seen installed)
He will be laying the blocks regardless if their on edge or flat so he has little to gain one way or the other.

agrostar

So I suppose back to the original question,
If I was to use 150mm fullfill in the cavity and it is fitted correctly would it perform on a par with 200mm ewi?

BryanF

agrostar wrote: »

So I suppose back to the original question,
If I was to use 150mm fullfill in the cavity and it is fitted correctly would it perform on a par with 200mm ewi?

Show us the plynt, eaves, window, threshold details for the cavity option ? will they be any better than the ewi companies?

agrostar

BryanF wrote: »

Show us the plynt, eaves, window, threshold details for the cavity option ? will they be any better than the ewi companies?

Sorry for coming on here for an opinion of which of the two options might be better or equal if done CORRECTLY to the manufactures recommendations and standards. We don't have the detail for the cavity option but I was just wondering whether the cavity with the correct corners and accessories would be on a par. All my drawings through from planning has been drawn to use ewi and all of our research has been based on using ewi. Ewi done correctly is a good system but if the professionals fitting it cannot be trusted to install it correctly unless the are supervised by an archtech it's very worrying. I'm not trying to get the house built for nothing and save some pennies at the sacrifice of the fabric of the building, I was all for using ewi even though it was more than likely going to the more expensive option but from looking at some work and talking to the fitters and from what I'm getting from here it's a non runner on a self build. I only intend to have this house built once and if the main fabric of the house is not right it will not perform over the lifespan of my family or the building. That's why i was asking if both systems are done to the letter of the law which system is better?
Which of the two horses would ye place yere €250k-€300k bet on?

listermint

I'm looking at retrofit and after research. Best option for me would be cavity pumped and ewi outside. Sure more expensive but it removes the convection loss in the cavity and clads the external for thermal bridging.

Windows to move out into ewi also.

There is no right answer to all of this frankly , how long is a length of string.

The option above is the best for that particular house may not fit others

Calahonda52

This might be worth 15 euro
http://www.adverts.ie/other-diy-renovation/complete-guide-to-external-wall-insulation/12165791

The argument here is about the standard of workmanship that is available to you as opposed to any technical discussion.
There are alternatives to the stick on EWI

I will geo get a link.
In passing, whats the airtightness target and how will it be achieved?
Are you using an insulated footing?

Dudda

The EWI guy in my opinion doesn’t have to be supervised as much as the blocklayer. You can see from the road or comfort of your own car every EWI board before external render starts. You can see joints, fixings, how plum it is. If you see a small 5mm gap between boards you can instruct them to squirt some expanding foam into the gap. With the blocklayer and full fill cavity all you can see is the top line of insulation by looking down into the cavity. You’ve no idea what gaps are present or how well it’s fitted. Even the best intentioned blocklayer in the world will fit a board poorly on a wet windy day when he’s hungry and looking at the clock and still has an hour to lunch and the wife was giving out all morning about how the hair stylist didn’t get her fringe right.

Which is better? 150mm full fill or 200mm EWI? This all depends on the insulation product you’re using. The more money you pay the higher quality the insulation and the thinner it can be. For example if it’s the new 150mm Kingspan Kooltherm cavity insulation with a u-value of 0.018 and you’re having 200mm Standard Aerowall externally then the cavity will perform a lot better but it’s a very expensive insulation in comparison. If you use similar quality insulation for the 150mm full fill and 200mm EWI then obviously the EWI will be better as it’s 50mm thicker. It all depends on the products you use and that depends on what you can afford.

I had 150mm EWI added to my 1970’s house as it only had a 50mm cavity but involved in projects where we used full fill cavity also.

corcadorcha

To follow on from that any suggestions on the best EWI system to use? Amy consensus on this. I'm in the same position and am probably going with am EWI system.
Thanks

BryanF

agrostar wrote: »

i. Ewi done correctly is a good system but if the professionals fitting it cannot be trusted to install it correctly unless the are supervised by an archtech it's very worrying.... bet on?

both options have pros & cons and are only as good as their detailing.

And There are other wall options such as aerated concrete block for example.

My point was, and I don't mean to antagonise, - how do you know a cavity wall 'professional' can be trusted to install insulation/all air-tight & water tight details correctly with out appropriate detailing and supervision