EWI - Detailed Questions

[Ferdinand]

Branching off from my Little Brown Bungalow thread, I am doing EWI which will probably be 90-120 EPS and a thin film render, to give me a U-Value for the wall of between 0.19 and 0.23. Good so far.

 

But I have a number of questions about "how to do" to make sure I get the detail right, and I thought it would be a good separate thread so others can pile in their Qs in future.

 

Over at the Green Building Forum (GBF) there is an extensive literature of scores of threads about this, but digging there is like excavating Troy with a toothpick. Hence this focused thread.

 

These are my current queries:

 

1 - How to Mount things on the outside of the EWI

 

There are three categories - a) - light things (say less than 5kg), b) heavy things (5kg+), (c) really heavy things (eg porch canopy).

 

(a) might be something like an outside light, while (b) might be something like a satellite dish.

 

What are the current suggested best practice for this?

 

(a) used to be "drill a 25mm hole with a shovel bit, insert a piece of pipe, fill with a stronger gun-foam, and plug/screw into that". Or alternatively to "insert and glue a plug of stronger insulation, such as a different grade EPS or Extruded Polystyrene, and mount into that". I note that there are now "EWI Spiral Insulation Anchor" fittings, like large versions of plastic plaster spirals and claim 5kg capability.

 

(b) used to be "accept the cold spot and drill into the wall with a long fixing", but I have also seen "insert a batten or sheet of plywood under the insulation when doing it". My preference is for an alternative - eg provide a 6" diameter 6" post elsewhere for a satellite disk and a precreated cable route inside.

 

(c) has usually been "use lighter anchors and a post against the wall that passes the load into the ground" or "freestanding post"

 

Clearly the more complex it is made at the beginning the more cost that will be added to the install up front, but that is probably worthwhile to avoid complications later.

 

This is the best thread I have seen over at GBF: External fittings on EWI.

 

2 - Gas and Electric Meters

 

Separate thread here.: Shallower Gas Meter Boxes.

 

3 -  Ventilation via Ceiling rather than Fans

 

On the "minimise holes in EWI" principle, I plan to take these out through the roof. Are there any difficulties or limitations on taking bathroom and kitchen extract fans (probably not the Hob Extractor Hood) out through the ceiling and a ventilation tile, other than length of duct run etc? I need a model of heat recovery fan that will do this (usually I use through the wall Vent-Axia Lo Carbon Tempra models).

 

4 - Gas flues

 

I know nothing about this wrt EWI. My small bungalow does have an old flue which goes up to a chimney. Can I use this for my boiler exhaust etc? I suspect that it will not meet the modern inspection requires for Gas Flues (ie hatches everywhere). I think I can find a way around this reasonably easily.

 

5 - Controlling mad men with drills (Hello Virgin)

 

This is tricky since my property will be rented. I need to stop the visiting driller killers from putting holes in my nicely warm and airtight walls.

 

I can do things such as a clause in the rental contract, tenant education etc - that will work with longer term tenants. I suspect the best way will be that plus a pre-determined duct with a drawstring coming (eg) into an airtight, insulated built in cabinet in the appropriate location. Another option is to have the cable runs in place first.

 

I would be most interested to here comments or variations on any of the above.

 

Thanks

Ferdinand

 

Edited April 16, 2017 by Ferdinand

[ProDave]

I wish I had more time, but only on a borrowed internet connection for a while, so don't bank on me seeing any replay straight away.

 

Having a brick wall means any light objects (lights etc) can just be fitted with long screws

 

I have a cunning plan worked out for heavy things like car ports but that needs more time and drawing some pictures, but I have worked out how I propose to do it.

 

TV aerials, satellite dishes etc will be mounted away from the house not onto it.

 

Feed plenty of satellite grade coax runs from every tv point, back to a marshalling / distribution point, then provide a "route out" im my case a hockey stuck down through the floor, and the sky man will never need to get his drill out. BUT you will probably have to attend and connect it for him. 

[Steptoe]

I've always just used oversized worms/pigtails/whatever their name is,

But, I've never had to hang anything more than maybe 15kg ,

You get a few different sizes of them, so obviously for a light a smaller one would do, but something like a sat dish is going to need maybe a 2 or 3" one.

 

For a new build, I'd prefer Dave's idea though.

Edited April 17, 2017 by Steptoe

[Ferdinand]

14 hours ago, Steptoe said:

I've always just used oversized worms/pigtails/whatever their name is,

 

@SteptoeYou mean the things that look like mini washing machine agitator spirals? This is a plasterboard one not an EWI one.

 

 

Long screws are doable, but are a cold bridge so are perhaps Plan B. Though having a filled cavity wall inside will help that.

 

@ProDave

Looking forward to your further comments when you have the time !

 

Ferdinand

 

Edited April 18, 2017 by Ferdinand

[Ferdinand]

OK. Just had chat to EWI supplier on the phone. Their responses seem to be quite best practice. The main thing is about planning in advance.

 

1 - How to Mount things on the outside of the EWI

 

Standard technique is to cut the foam so that sections of 2x4 can be spliced in ==> no cold spots. They leave with a screw stocking out to show where it is.

 

Heavy stuff is better on freestanding poles if possible.

 

3 -  Through the Wall Fans eg Vent-Axia Lo Cardon Tempra

 

Make sure they are long enough, then they will cut a hole for them in the insulation and finish.

 

(Note: emphasises need to make sure that a sleeve .. eg piece of soil pipe ... is fitted in the wall and will span the EWI too, and fan is mounted into that so it can be taken out easily for maintenance or replacement.)

 

4 - Gas flues

 

Have it in place first, and they will fit around it, with a patch of rockwool insulation.

 

5 - Controlling mad men with drills (Hello Virgin)

 

Various solutions, which maintly involve standing over intallation engineers with a cup of tea and some instructions as to what you have fitted to help them. 

 

F

Edited April 18, 2017 by Ferdinand

[Steptoe]

3 hours ago, Ferdinand said:

 

@SteptoeYou mean the things that look like mini washing machine agitator spirals? This is a plasterboard one not an EWI one.

 

 

Long screws are doable, but are a cold bridge so are perhaps Plan B. Though having a filled cavity wall inside will help that.

 

@ProDave

Looking forward to your further comments when you have the time !

 

Ferdinand

 

Yes, things like that, but, bfo plastic ones, quite a small centre, but really big 'thteads' ,

Personally, for a new build, I'd be looking for an alternative though.

[Ferdinand]

Quote

 

Personally, for a new build, I'd be looking for an alternative though.

 

 

Agree. The main priority should be to design them out.