External Insulation for a New Build

BarneyMc

I'm currently looking into external insulation as an insulation method for a new build.

One method I've come across is to firstly build with standard concrete blocks on their flat. Then apply the external insulation and render.

Can anyone comment on this and give me an idea of:
Insulation thickness
Overall wall thickness
Wall U value
Pros and cons

conor2949

I have gone the external insulation route on my house.

Its a new build house, 3000 sq feet over two floors.

I went with 215mm concrete block on flat for all external walls.

I am putting on 200mm of Polystyrene (EPS 70/Platinum i think) insulation on the outside and finished in a silicate render in a colour of my choice.

I have been told I will have a wall u value of 0.15.

I went for the system for a number of reasons:
- It was new and looks to be the business on paper (practical application is a bit different though)

- I got an excellent price on it and it will be done by tradesmen that have been doing this for twenty years

- I feel it will give a much better solution than cavity wall insulation by almost eliminating thermal bridging


There are some small considerations to think about though before you go this route such as:

1) where to put you ESB meter cabinet

2) how much of an overhang on your rafters will be needed to allow for the insulation depth and then a soffit/fascia

3) Window cills - i think i have to go with aluminium cills to cover such a big depth of insulation

4) blocklayers understanding the importance of having very clean joints between courses

5) the experience of the tradesmen installing the system

6) the practicalities of the system - i'm not sure how much of a force the render/insulation could take before getting damaged - i.e. someone belting a sliotar off it wouldn't be the best for it in the long term.

etc
etc

MicktheMan

Can you PM the contact details of the ewi installers and what price you got quoted. Thx.

BarneyMc

MicktheMan wrote: »

Can you PM the contact details of the ewi installers and what price you got quoted. Thx.

Yes me also please Conor.

Also, how does external insulation work with a real stone finish - how is the stone fixed to the insulation or is it possiblw at all?

conor2949

pm's sent lads

as regards the stone - thats a very good point.

i've got a protruding porch and i'm gettin the guys to put on phenolic foam insulation just for this bit of the house so that i can use a shallower depth and still achieve the same u value.

Ideally the best way of approaching it is to put in extra long wall ties at blockwork stage and let them protrude out through the finished external insulation and render and that way you can tie in the stone work.

one consideration is that you might need slightly wider footings to allow for all the increased depth of the exterior .

I omitted these wall ties from my blockwork so now i think i am faced with having to use expanding metal and leave that protrude out through the insulation and the render and tie in the stonework that way.

C.

Out Of Order

MicktheMan wrote: »

Can you PM the contact details of the ewi installers and what price you got quoted. Thx.

Can you PM me too please Conor.

I'm going down this road myself and am trying to learn what I can about it.

I have been quoted €90 /sq mtr inc VAT for supply + fit of 200mm EPS platinum and sills.

There are only two IAB approved EWI systems at the moment but I have spoke to two others who expect to have it shortly.

I'm told that two 100mm layers with staggered joints would be better than one 200mm layer but wouldn't this increase thermal bridging from the mushroom fixings?

I'm also looking at 215 quinlite blocks instead of standard block on flat, but they work out about three times the price. Has anyone experience with these?

Do-more

I was speaking to someone recently who is involved in passive house design and they mentioned that there is a new block being produced in Germany which is similar to a Poroton block but has a finer honycomb structure which allows it to achieve passive haus standard of wall insulation without the need for any external insulation. Seems there is a range of blocks available for all the various details required.

I've no idea how the costs compare to alternative methods but would like to investigate further. I've searched the net but can't find details on this block.

If anyone has details would you please PM me.

sas

Do-more wrote: »

I was speaking to someone recently who is involved in passive house design and they mentioned that there is a new block being produced in Germany which is similar to a Poroton block but has a finer honycomb structure which allows it to achieve passive haus standard of wall insulation without the need for any external insulation. Seems there is a range of blocks available for all the various details required.

I've no idea how the costs compare to alternative methods but would like to investigate further. I've searched the net but can't find details on this block.

If anyone has details would you please PM me.

More likely to be

http://www.greisel.de/index.php?id=4&type=0

than

http://www.gisoton.de/de/main/architekten_ingenieure/gisoplan_therm/

but both are interesting.

Mods, I assumed it was ok to post these as they don't have an irish agent and I have nothing to do with them.

As regards price, the last time I priced the poroton T8 (u-value 0.18) the materials delivered to my site were 85k for 300m2 house. I don't expect these to be any different and ultimately will prove a non runner...

sas

Out Of Order wrote: »

I'm told that two 100mm layers with staggered joints would be better than one 200mm layer but wouldn't this increase thermal bridging from the mushroom fixings?

2 layers as suggested greatly increase the labour and hence the price. The PHI have stated that gaps up to 5mm make little difference as long as each EPS board is properly sealed to the blockwork. So the advice is without merit. The 5mm gaps should of course be filled with expanding foam.

At 200mm you will be using mushroom fixings anyway.

Avoid quinnlitess unless absolutely necessary. Even the strongest are impractically brittle.

sas

Out Of Order wrote: »

There are only two IAB approved EWI systems at the moment but I have spoke to two others who expect to have it shortly.

I'm likely to get stick for this but I wouldn't go losing sleep about IAB certification on EWI systems.

There was a great article in Construct Ireland magazine recently which proved that if you followed the construction details in the IAB cert for one of those systems, you wouldn't satisfy the 2008 building regulations regarding thermal bridging.

The IAB are absolutely up in arms over the article. No one likes to be made foolish looking.

They know nothing about EWI systems, yet as long as you can afford it they are willing to stamp approval on a product.

They also recently had to withdraw an insulation option in a cert they had only issued 2 years previously. Obviously their certification process leaves alot to be desired.

If ETA is in place and your superviser is happy, I would fire ahead.

However, IAB certification is important as I understand it if you are applying for the grant though.

PCPL

As an installer for a newly approved EWI system i can say that the process for such certification is a joke, i had some of my work scrutinised and i reckon the certification rep wouldnt know when he had enough eaten, we found out that he used to work as a clerk in the offices and now he's certifying systems with no experience in construction, go figure. The system has been used in the UK for the last 30 years with BBA certification and has been installed on many new builds in the UK and is starting to take off here,they also produce a honeycomb panel which is fixed to the exterior of timberframe structures, it is rendered onto directly and replaces the need for a 100mm block outer leaf.

lud

conor2949 wrote: »

- I got an excellent price on it and it will be done by tradesmen that have been doing this for twenty years

Hi,
Could you pm the details of the tradesmen please?

Thank you

BarneyMc

Just going back to my original question. If using EWI plus natural stone, would the insulation need the waterproof render before the stonework is applied or would the stonework be sufficient as a water proof skin?

conor2949

Barney,

It is the acrylic/silicate/silica render that makes the house waterproof, without it, you won't be watertight. The render has to be applied to give you the protection you need.

Stonework isn't waterproof.

all the best

c.

BarneyMc

That was the answer I was afraid of Conor - thanks for the info.

This then would be a very costly build then: internal concrete block, insulation, acrylic/silicate/silica render plus natural stone. Has anyone gone down this route or any suggestions?

conor2949

Barney,

Its surprising how the breakdown of the cost of EWI splits out.

The vast vast majority of the labour cost is on the actual insulation and mesh and base coat work.

Each wall to finish it in finish coat, takes about 1 day (obviously depending on the size of the wall and the detailing involved like how many windows, doors, etc.)

It took about 40 man days to put all the insulation and wide reveals on my 280 sq metre house.

It took about 10 man days to put on the finish coat.

Naturally you have the extra cost of the materials but it isn't that significant an amount in the total cost of the EWI system.

Naturally it all depends on the surface area of your house and how much of it you intend covering in stonework.

Conor

gooner99

conor2949 wrote: »

I have gone the external insulation route on my house.

Its a new build house, 3000 sq feet over two floors.

I went with 215mm concrete block on flat for all external walls.

I am putting on 200mm of Polystyrene (EPS 70/Platinum i think) insulation on the outside and finished in a silicate render in a colour of my choice.

I have been told I will have a wall u value of 0.15.

I went for the system for a number of reasons:
- It was new and looks to be the business on paper (practical application is a bit different though)

- I got an excellent price on it and it will be done by tradesmen that have been doing this for twenty years

- I feel it will give a much better solution than cavity wall insulation by almost eliminating thermal bridging


There are some small considerations to think about though before you go this route such as:

1) where to put you ESB meter cabinet

2) how much of an overhang on your rafters will be needed to allow for the insulation depth and then a soffit/fascia

3) Window cills - i think i have to go with aluminium cills to cover such a big depth of insulation

4) blocklayers understanding the importance of having very clean joints between courses

5) the experience of the tradesmen installing the system

6) the practicalities of the system - i'm not sure how much of a force the render/insulation could take before getting damaged - i.e. someone belting a sliotar off it wouldn't be the best for it in the long term.

etc
etc

Hi Conor.I assume that you are probably in your house at this stage.Could you share with us how the EWI turned out for you and how your house is performing during this cold spell?

uptowngirly

I'd be really interested in this as well - also looking for ideas on how to incorporate stone facing on one part of the building with this method of insulation...

BarneyMc

uptowngirly wrote: »

I'd be really interested in this as well - also looking for ideas on how to incorporate stone facing on one part of the building with this method of insulation...

Me too regarding the stone.... also anyone with an EWI system like to share their experience through this and last year's winter???

soldsold

Just had 150mm EWI installed over 15 year old cavity wall with old 50mm aerobord and recently pumped cavity. Ive also fitted a load of windows and doors into a 225mm cavity extension with full fill beads.

Compared to the cavity wall build the EWI was miles simpler, has no obvious cold bridging around windows, as I checked with an infra-red gun and there is a minimal temp drop around the window edges. EWI was also very simple, I just pointed out the walls to the plasterers and off they went.

Compared to cavity walls where I had to check the wallties were clean of mortar droppings, and clean a lot of them myself, clean the bottom of the cavity, close the cavity at wallplate level, work out how to close the window reveals, etc, EWI would be very tempting for a new build.

However, I like the wide window reveals that cavity walls give, am not convinced how soundproof one block wall with EWI is, I have also natural stone on three faces so cavity walls suit this finish. Finally cavity walls worked out on my build at 74 euro per m2 including insulation and plaster, paint, lintols, DPC, etc which is a lot cheaper than the EWI cost. However I have spent a lot of time and money on airtightness across the wide cavity, in my case its not an issue as my time doesnt cost me but if paying for labour it adds up. Also EWI window sills are insulated and these cost 38 euro per linear meter plus vat and delivery.

So if I was building a new build, and I didnt have time to do any DIY or the knowledge/ time to check the workmanship on the job, I would most likely go the EWI route.

If I was building again and did have the knowledge and time to monitor the build (which I'm sure I would), I'd most likely go for a wide cavity again.

M5QUATTRO

Hi Guys
I have been doing a fair bit of research now regards a new build< I would like to get concrete floors first, second and possibly attic, also concrete walls etc so what i am thinking is a house with the ICF Kore system -polystyrene concrete formwork blocks that you build, fix steel in and pour your concrete into to form your walls in mass concrete with insulation in and outside.
Has anyone done this, if so can it be done yourself? or does it work?

hunggaur

soldsold wrote: »

. Also EWI window sills are insulated and these cost 38 euro per linear meter plus vat and delivery.

hi i am doing a refurbishment and would like to know where i can get sill extensions from any helps would be greatly received.

many many thanks

jon

soldsold

hunggaur wrote: »

soldsold wrote: »

. Also EWI window sills are insulated and these cost 38 euro per linear meter plus vat and delivery.

hi i am doing a refurbishment and would like to know where i can get sill extensions from any helps would be greatly received.

many many thanks

jon

I got mine from Redmond acrylic In dublin

S.

dfader

soldsold wrote: »

Just had 150mm EWI installed over 15 year old cavity wall with old 50mm aerobord and recently pumped cavity. Ive also fitted a load of windows and doors into a 225mm cavity extension with full fill beads.

Compared to the cavity wall build the EWI was miles simpler, has no obvious cold bridging around windows, as I checked with an infra-red gun and there is a minimal temp drop around the window edges. EWI was also very simple, I just pointed out the walls to the plasterers and off they went.

Compared to cavity walls where I had to check the wallties were clean of mortar droppings, and clean a lot of them myself, clean the bottom of the cavity, close the cavity at wallplate level, work out how to close the window reveals, etc, EWI would be very tempting for a new build.

However, I like the wide window reveals that cavity walls give, am not convinced how soundproof one block wall with EWI is, I have also natural stone on three faces so cavity walls suit this finish. Finally cavity walls worked out on my build at 74 euro per m2 including insulation and plaster, paint, lintols, DPC, etc which is a lot cheaper than the EWI cost. However I have spent a lot of time and money on airtightness across the wide cavity, in my case its not an issue as my time doesnt cost me but if paying for labour it adds up. Also EWI window sills are insulated and these cost 38 euro per linear meter plus vat and delivery.

So if I was building a new build, and I didnt have time to do any DIY or the knowledge/ time to check the workmanship on the job, I would most likely go the EWI route.

If I was building again and did have the knowledge and time to monitor the build (which I'm sure I would), I'd most likely go for a wide cavity again.

SoldSold,
How exactly did you close the cavities, support the heavy windows and achieve airtightness?
Thanks,
dfader