Airtightness, tape before or after the grey coat

oldhead

Hi to all,

just looking for some advice. i am puting a grey coat of plaster on the internal walls before i put on my insulated 50mm board. the reason i am putting on the grey coat is to help airtightness. now does the airtight tape go on between the exposed block and window/doorframe or does it go on over the grey coat before i put the slab around window. i have heard both. just looking for your thoughts if there is anyone out there that came across this

many thanks

Gulliver

Is this the fleece tape that is plastered in? If so I found that a sand/cement (grey) plaster does not stick too well. You need to use a gypsum-based plaster. What I did was stick tape to window, gently bend fleece part away from the wall (towards the centre of the window) apply layer of bonding coat* to the bare block, stick down fleece part of tape and put another coat of bond over this. Scratch the bond as it's getting hard to provide a key for the sand/cement coat.

I'm not using insulated slabs, though, so that might not be of any use to you.

*Bonding coat is like the pink finishing skim. It is gypsum based. I tested a piece of the tape in both sand/cement plaster and bonding and the sand/cement just popped off when dry. The bonding was much better.

heinbloed

now does the airtight tape go on between the exposed block and window/doorframe or does it go on over the grey coat before i put the slab around window

Questionmark....

Neither nor. Ask your architect/designer/salesmen why this is the case.

cuculainn

heinbloed wrote: »

Questionmark....

Neither nor. Ask your architect/designer/salesmen why this is the case.

Can you elaborate please???

heinbloed

Concrete and lime-PVC or timber window frames have different expansion and contraction rates. For the standard PVC frame that is about 2 %. No tape would move at this rate, imagine a 1m wide frame then-if it is fixed correctly- it would move 1cm at each end. Meaning that not only the tape would have to move at a 1cm rate.

So no, no tape there.

Perma-elastic compression 'tape' please.

But contact your architect/civil engineer, he/she will tell you about mixing different materials and avoiding gaps and cracks.

Note: once the tape comes off no one will stick it back.
These amateur remedies look good for the blower door test results, like blocking kitchen hoods and chimneys. But when it comes to real long term performance they're useless. And never to be cured, unless the windows are taken out and the compression 'tape' been brought in, finally.


PS

See (partial) correction in my next post

sinnerboy

uPVC expands at a rate of 0.00006mm/C

So lets take an extreme

-20C (last winter ) to say 30C ( here's hoping for a great summer ). So delta T = 50

Take a 1800mm window

1800 x 50 x 0.00006 = 5.4mm / 2 = 2.7mm either side.

So apply the tape with a gentle curved fold (hard not to anyway)

The fleece part is "buttered" onto the block and then skimmed over sandwich like.










...... I'm hungry now :pac:

oldhead

thanks for all the advice, there are pvc windows, is the usual practise to put the tape between the window and the exposed block, then plasterboard then skim it or window and scratch coat for airtightness, then tape, plasterboard and then the skim

heinbloed

I stand to be corrected, thanks Sinnerboy!

Not 1-2 % shrinkage/expansion for the lime/PVC frame but 1-2 o/oo (permille).
Or in simple dimensions : 1-2 mm per meter under standard temperatures.

But:

NEVER taping !
I stick to that, following continental standards.

I try to elaborate. The frame will expand +- 1-2 mm when white and +-2-3mm per meter when black/dark.

The wall will do so as well,at a lower rate.

This means we have to leave a gap of 6 mm with the standard sized window. To allow for the expansion and contraction of both materials.
We have to increase this gap to take up movement of forces, like the load on hinges and locks when opening and closing the window under full thermal and windload stress.

Which leaves us with a minimum gap between white PVC frame and concrete wall of 10mm !
For dark PVC frames this would be 15 mm !

The tape as used by the amateurs would cover these 10mm or 15mm, no problem, it is much wider.
But it would not be flexible enough to allow for movement in itself over +-6mm once fixed. It has simply no 25% flexibility !!
It would either tear itself or pull the plaster off. End of the airtightness !


Details on how to install PVC windows here(in German language)

http://www.niederhofer-fenster.de/montageanleitung-pvc-elemente.pdf

The picture on page 12 shows details for a filled cavity wall (picture 11-6).
The mesh pattern (#) shows the compression tape. The diagonal pattern (\\\) shows the weather proofing sealant covering the compression tape.

The wave pattern shows the insulant.

These are EU standards based on the laws of physics.

Of course if someone developes a rubber tape which will get as old as the windows and walls and sticks all the time despite being pulled and pushed then this could be used as well.
But I'm not aware that something like that exists...

So boiled down :

An insulated gap between frame and wall must be there.
This has to be covered to keep the wind out.
This coverage must allow for movement.
This movement is 25% of the gap.


The plaster and EWIS company Weber insists on the compression tape.
And so does the STO company.
And all PVC window manufacturers.

So I have 2 questions myself for the speciallists:

Which regulation allows or recommends for the 'folded' sticky tape when installing PVC windows in concrete structures ?

Which sticky tape has a guaranteed shrinkage/ expansion of 25% ?

Thanks.

heinbloed

Now I have checkked the www. for all tape manufacturers I could find. But can't find a tape offering 25% elasticity.

What is used by our specifiers on the forum? What is the tested, at least the stated elasticity of this tape?

A German manufacturer offers a butyl rubber lip/strip for the issue: the frame facing edge glued onto the frame and the concrete facing edge plastered onto the wall.....

heinbloed

Some live data, taken 2 minutes ago:

Sunny but hazy weather, outside air temperature 2m above ground in the shade 12 degrees Celsius.

White PVC frame (touching the white wall), temperature at the un-shaded soutside of the house at 2m height: 27 degrees Celsius at center frame.
The same white PVC frame shows 32 degrees Celsius at the horizontal section, 1.5 inches above the cill, 1.5 feet above soil level.

So Delta T 20 Kelvin (!)meassured. That's the temperature difference between air temperature and frame temperature (at the warmest point).

Note that the windows/frames/cills had been cleaned only recently, that it is a hazy day and not summer yet.
So more movement is to be expected.

A window cill with little thermal mass, facing upwards in a clear night will get how cold? Shrinkage?



PS

I should mention that ALL my larger PVC windows have leakage problems along the sides and at the top. I can't get the external gap -between plaster and frame- airtight. to much movement.
When I build in the frames I listened to 'specialists' advice and did NOT use compression tape.
Own fault.

Gulliver

Maybe the tape itself doesn't expand but by putting a fold in the corner as I have already done and Sinnerboy suggested, then there should be no problem. See my pitiful diagram. Most of the manufacturers suggest to allow a bit of "give" on corners for tape, fleece, membrane etc.

sinnerboy

nice one G.

heinbloed

Thanks!

A lot of work I suppose, dosing the (canned?) foam, striping or cutting it back to create a gap? How will it be avoided to push the plaster tight into the gap?
What happens on the outside?

Gulliver

heinbloed wrote: »

Thanks!

A lot of work I suppose, dosing the (canned?) foam, striping or cutting it back to create a gap? How will it be avoided to push the plaster tight into the gap?
What happens on the outside?

The foam took some time. It was canned (couldn't get the fresh organic stuff ). I used a pointing trowel and piece of flooring laminate (we're real high-tech here in Leitrim!) to scrape out the gap. As I was doing the bonding, I "buttered" the block almost all the way in. Pressed down the fleece whilst maintaining the fold in the corner and carefully applied the top coat, making sure not to pull the fleece towards me (and thus the fold out of the corner) as I worked. As there is now a hollow(ish) bond-covered gap, the plasterer can do what he wants.

I'm afraid I don't know what you mean about the outside. I was only concerned about air ingress around the inside edge of the window frame to the interior of the building.

This sounds like a lot of work - and it is. The application of the fleece to the frame takes the longest, as you are trying to get a straight line whilst keeping as close to the edge as you think the plasterer will cover. The application of bond took less time. Don't forget to make the top coat a bit thicker and give it a light scratch to provide a grip for plaster.

creedp

Hi. Have I just had a Bobby Ewing dream situation here? Am I to understand form the above that thespecific tape sold by the major airtightness companies for windows/doors and seemingly recommended as the riguer for this purposes by it seemed everyone is now completely useless? If so this is just too bad as many many people have acted on this advice in good faith.

By the way I notice all calcs re expansion of windows relate to PVC windows. Would wooden/aluclad windows be more or less problematic in this context? Also if the window tape is useless what about all the other tapes supplied by SIGA etc?

Thanks

Gulliver

creedp wrote: »

Hi. Have I just had a Bobby Ewing dream situation here? Am I to understand form the above that thespecific tape sold by the major airtightness companies for windows/doors and seemingly recommended as the riguer for this purposes by it seemed everyone is now completely useless? If so this is just too bad as many many people have acted on this advice in good faith.

By the way I notice all calcs re expansion of windows relate to PVC windows. Would wooden/aluclad windows be more or less problematic in this context? Also if the window tape is useless what about all the other tapes supplied by SIGA etc?

Thanks

I don't think the products are at fault per se. It's the installation of those products that needs to be carried out correctly. There has been much talk about theories of expansion etc., however IMHO if the expansion in real life was that bad, windows and doors would never be weatherproof.

heinbloed

@ Gulliver:

You wrote:

I'm afraid I don't know what you mean about the outside. I was only concerned about air ingress around the inside edge of the window frame to the interior of the building.

My concern with the PVC windows I have in place is actually raised at the extyernal part. The wind blows rain water between silicone sealant and plaster/frame. Where there are 'never-sealing' gaps, mainly at the hinges where the frame has to carry the load of the windows and doors.
The top is bad as well, but here rain ingress is no problem.

No matter what I put on onto these very small gaps, the movement of the PVC sooner or later causes cracks to apear.

So my next job there would be to remove what is there, including the plaster, replaster around the windows but leaving a gap of ca. 5mm to be filled with a compression tape. Which should give wind tightness as well as water tightness. So I hope.

As far as I understand the theory the internal sealing should be diffusion tight and the external sealing diffusion open. To avoid build-up of condensation around the cold frame within the wall.
Once the windows are in place (faulty,as in my situation) this seems to be impossible to achieve.

I put a course on HELE and all the other window sellers for giving wrong advice.

Thanks for your posting, one never stops learning!





@ creedp:

The problem arises not only with PVC windows.
PVC frames have a much larger thermic reaction, movement due to thermal expansion and contraction compared to timber frames.
But timber frames take up water, they might move even worse due to swelling and shrinking.
And PVC does not take up water.
So the final situation (movement) has to be looked at when placing the frames. Allow them to move. Any stiff filler, be it plaster or PU foam will give in and is not a long lasting sealant.
Put in compression tape, a long lasting type. The standard PU foam is only a filler or fixing method, not a durable sealant against water/moisture or wind impact. It simply deterioates with aging and physical impact.

The Germans refer to a so called " RAL method ", recognised building technology concerning door and window installations. The door and window manufacturers refer to it, the architects and civil engineers as well.
I used the methods descibed there on building sites abroad without realizing how important these are. Here in Ireland in my own home I used the "Irish method", being an amateur who listened to the window seller.
No method that was !

Here the German window and door association

http://www.window.de/ral.html

and their non-binding rules

http://www.window.de/762.html

Gulliver

heinbloed wrote: »

@ Gulliver:

You wrote:



My concern with the PVC windows I have in place is actually raised at the extyernal part. The wind blows rain water between silicone sealant and plaster/frame. Where there are 'never-sealing' gaps, mainly at the hinges where the frame has to carry the load of the windows and doors.
The top is bad as well, but here rain ingress is no problem.

No matter what I put on onto these very small gaps, the movement of the PVC sooner or later causes cracks to apear.

So my next job there would be to remove what is there, including the plaster, replaster around the windows but leaving a gap of ca. 5mm to be filled with a compression tape. Which should give wind tightness as well as water tightness. So I hope.

As far as I understand the theory the internal sealing should be diffusion tight and the external sealing diffusion open. To avoid build-up of condensation around the cold frame within the wall.
Once the windows are in place (faulty,as in my situation) this seems to be impossible to achieve.

I put a course on HELE and all the other window sellers for giving wrong advice.

Thanks for your posting, one never stops learning!





@ creedp:

The problem arises not only with PVC windows.
PVC frames have a much larger thermic reaction, movement due to thermal expansion and contraction compared to timber frames.
But timber frames take up water, they might move even worse due to swelling and shrinking.
And PVC does not take up water.
So the final situation (movement) has to be looked at when placing the frames. Allow them to move. Any stiff filler, be it plaster or PU foam will give in and is not a long lasting sealant.
Put in compression tape, a long lasting type. The standard PU foam is only a filler or fixing method, not a durable sealant against water/moisture or wind impact. It simply deterioates with aging and physical impact.

The Germans refer to a so called " RAL method ", recognised building technology concerning door and window installations. The door and window manufacturers refer to it, the architects and civil engineers as well.
I used the methods descibed there on building sites abroad without realizing how important these are. Here in Ireland in my own home I used the "Irish method", being an amateur who listened to the window seller.
No method that was !

Here the German window and door association

http://www.window.de/ral.html

and their non-binding rules

http://www.window.de/762.html

Heinbloed, you might be able to save yourself a load of bother if the gap isn't too big. Someone on another thread mentioned there is a silicone-type sealant that never fully "goes off" and as such has some elasticity in it. If you remove the old sealant and replace it with this stuff you might be sorted!

sydthebeat

The airtightness tapes are NOT useless. They are use-specific and proven

Please see the wood for the tress here.... one person argues that a tape wont expand 1 cm, is then mathematically proven erroneous.. and solution added.

then argues the tape needs to expand 25% :rolleyes:

creedp

sydthebeat wrote: »

The airtightness tapes are NOT useless. They are use-specific and proven

Please see the wood for the tress here.... one person argues that a tape wont expand 1 cm, is then mathematically proven erroneous.. and solution added.

then argues the tape needs to expand 25% :rolleyes:

Sorry if I overreacted as I read this thread last night and just thought bloody hell even when I actually try to get something right its wrong!!

Anyway it seems on mature reflection the discussion is more to do with externally sealing the windows with silicone or this compression tape which seals the window to the ope externally to stop water ingress.
I accept your point concerning expansion rates. I would also have thought that if window frames could move 1cm or even 1.5cm there would be a high risk of frames simply buckling and cracking the glass. Is this a more common problem that what I'm aware of?

sinnerboy

no

heinbloed

Gulliver wrote:

Heinbloed, you might be able to save yourself a load of bother if the gap isn't too big. Someone on another thread mentioned there is a silicone-type sealant that never fully "goes off" and as such has some elasticity in it. If you remove the old sealant and replace it with this stuff you might be sorted!

Well, I used a sealant which is supposed to best on the market. The sealant is still fine, elastic, not deterioating. But the water in the plaster - to which it was adhered to - froze. With the result that small ice cristals developed between sealant mastic and plaster. And off it came.
The sealant (Henkel, made in the UK for € 13.- per cartridge!) is still fine. But now there are cracks between sealant and plaster, allowing wind and water to get into the hair-fine gap.


Creedp wrote:

I would also have thought that if window frames could move 1cm or even 1.5cm there would be a high risk of frames simply buckling and cracking the glass. Is this a more common problem that what I'm aware of?

You would have to check with frame manufacturer's specifications.
To avoid the glas panes bursting these are kept 'floating ' in the frames. Meaning they don't touch the frame, are kept away from it by the means of spacers at the botttom. And held in place with the sealant strip.

The pane must be allowed to stand on the footing, the bottom rail of the frame. There it has to be adjusted, brought into balance/level before the rubber sealant holding part is fixed to the frame. Using "spacers" to make it level.
This way the frame can move without impacting the pane.

PVC does indeed move by 2-4 %....
But the material used for window frames isn't a pure PVC, it is PVC mixed with additives, usually lime up to 30%. The more lime there is in the mix the less it moves. But the harder/ more brittle it gets as well. And it will agen as well faster with more lime, unless other aditives counteract this....

About timber frames:

The old timber frames consisted of a single routed piece of timber, the single pane set with putty.
Small panes in soft mastic ( "putty"), the "Georgian" window.
And the glas bursted when the frames became wet and where old, since aging of the putty made it hard and un-elastic. The putty needed regular treatment with linseed oil to keep it elastic, at least that did help for a while.

Nowadays the timber frames are made of various layers of timber. The better the quality the better the manufacturer had choosen the timber before glueing them together.
The pieces of timber counteract there inherent movement, if one layer warps to the left then the next layer should warp to the right right. In theory this would level out.
As long as the glue holds them together no problem.

But the expansion and contraction in length (temperature and moisture impact) can not be counteracted.

Therefore the German window manufacturers recommend the compression tape around the frame, before setting it into the opening of the wall..

A stiff filler (like for example plaster) between frame and wall will cause the modern frame to buckle. Since the frame wants to expand/contract length wise. If restricted it will do so side wise, the 'buckling' effect.

Using perma-elastic fillers will allow for the frame to move. And perma-elastic sealant strips around the panes will protect them.

Most PU foams aren't suitable for this purpose of filling the gap between wall and frame.
If they take up water and the water freezes they aren't elastic anymore. And are a breeding ground for moulds.
And they have a limited life time, turning brittle after a while of pulling and pushing forces. Then allowing air to circulate behind, between frame and wall and PU powder. If this air contains water the wall will get wet, the timber frame rottening.
So this water/dampness ingress has to be recognised.
Reduce the ingress of vapour by sealing the gap towards the room and allow for the vapour (which will make it there anyhow!) to leave the structure.


Hence my question @ Gulliver:

How is the gap's breathability guaranteed? How will the vapour leave the cold gap before it condenses on the cold frame/wall?

What material is used at the outside, at the external part?
What seals the gap against vapour ingress?

Or maybe the tape is vapour tight? And the PU foam doesn't take up vapour, is perma-elastic and vapourtight ? And at the outside a 'breathable' layer covers the gap?

I'm not happy with the mastix solution there myself.
The wall at the bottom of the frames is wet. Mould is apearing in the corners. Coldest spot, collection point of condensation.
I'm afraid the whole thing needs to be redone.

What is "wufi" saying about the issue?

Gulliver

heinbloed wrote: »

Gulliver wrote:
Well, I used a sealant which is supposed to best on the market. The sealant is still fine, elastic, not deterioating. But the water in the plaster - to which it was adhered to - froze. With the result that small ice cristals developed between sealant mastic and plaster. And off it came.
The sealant (Henkel, made in the UK for € 13.- per cartridge!) is still fine. But now there are cracks between sealant and plaster, allowing wind and water to get into the hair-fine gap.

Oh dear. That's unlucky.

heinbloed wrote: »

Hence my question @ Gulliver:

How is the gap's breathability guaranteed? How will the vapour leave the cold gap before it condenses on the cold frame/wall?

What material is used at the outside, at the external part?
What seals the gap against vapour ingress?

Or maybe the tape is vapour tight? And the PU foam doesn't take up vapour, is perma-elastic and vapourtight ? And at the outside a 'breathable' layer covers the gap?

I really don't know. I thought we were talking about airtightness inside the house. I have no idea about condensation and such. Sorry.

heinbloed wrote: »

I'm not happy with the mastix solution there myself.
The wall at the bottom of the frames is wet. Mould is apearing in the corners. Coldest spot, collection point of condensation.
I'm afraid the whole thing needs to be redone.

heinbloed wrote: »

What is "wufi" saying about the issue?

I can't get the idea of an engineer dog out of my head.

heinbloed

Gulliver wrote concerning (interstitial) condensation, between window frames and walls:

I really don't know. I thought we were talking about airtightness inside the house. I have no idea about condensation and such. Sorry.

The airtightness would include the vapour tightness. Air is a mixture of various things, water is part of it.

Maybe your specifier/ tape agent has an answer?

Thanks.

Gulliver

heinbloed wrote: »

Gulliver wrote concerning (interstitial) condensation, between window frames and walls:



The airtightness would include the vapour tightness. Air is a mixture of various things, water is part of it.

Maybe your specifier/ tape agent has an answer?

Thanks.

I'm confused, Ted. The airtightness the OP and I were talking about is applied to the inside of the window, on the inside of the house.

You seem to be talking about the outside.

heinbloed wrote: »

How is the gap's breathability guaranteed? How will the vapour leave the cold gap before it condenses on the cold frame/wall?

What material is used at the outside, at the external part?
What seals the gap against vapour ingress?

Or maybe the tape is vapour tight? And the PU foam doesn't take up vapour, is perma-elastic and vapourtight ? And at the outside a 'breathable' layer covers the gap?

I think we have our wires crossed. I'm only talking about my personal experience installing the fleece on the inside of the walls to make the house airtight. The fleece has a vapour resistance of 7.75 NMs/g. Their documentation states that it "enables the airtight sealing of doors and windows according to RAL recommendations (airtight on the inside, higher diffusion resistance on the inside compared to the outside)."

Oh and I know what air is. It's that stuff I'm trying to keep out of my house unless it comes from the HRV. "Air" is by definition: Nitrogen 78.084%, Oxygen 20.947%, Argon 0.934% and Carbon Dioxide 0.033% with small percentages of Krypton, Helium etc. The water vapour content is entirely variable, dependant on your environment.

heinbloed

Gulliver wrote:

I'm confused, Ted. The airtightness the OP and I were talking about is applied to the inside of the window, on the inside of the house.

You seem to be talking about the outside.

Not at all, Gulliver. I'm talking about a wholesome aproach.
Damp air penetrating the gaps around the cold window frame ( gaps which you left for a purpose, claiming Sinnerboy had told you to do so), for example via the internal wall, will cause condensation.
If it can't get out out at a rate at least as fast as it gets into.

So again: how is this condensation dealt with ?

Just forgotten, like the installers of my windows did ?

Timber window frames might deal with this. PVC certainly not.

Gulliver

heinbloed wrote: »

Gulliver wrote:



Not at all, Gulliver. I'm talking about a wholesome aproach.
Damp air penetrating the gaps around the cold window frame ( gaps which you left for a purpose, claiming Sinnerboy had told you to do so), for example via the internal wall, will cause condensation.
If it can't get out out at a rate at least as fast as it gets into.

So again: how is this condensation dealt with ?

Just forgotten, like the installers of my windows did ?

Timber window frames might deal with this. PVC certainly not.

OK.

1) Sinnerboy did not tell me to do this, I already had this done, he had thought of the same thing as me. Let's not drag him into this. That sounded like the blame game.

2) The condensation will never reach the cold frame - the fleece is between the plaster and the frame and as such not really a cold surface. The "gap" is a small fold in the fleece to allow for movement/expansion.

3) I'm an unemployed IT tech who is doing a few jobs around the build to save money - I know nothing about building until I have to learn it for the next job. I was only trying to give the OP my experience with airtightness.

Good luck with the build OP, hope it all goes well!

heinbloed

Sorry, Gulliver, you said

2) The condensation will never reach the cold frame -

This is wrong.
The frame is the coldest part of the wall. It is exposed to moisture trying to get from the block/brick/wall out. Outwards to the point of lowest rel. humidity. If this moisture hits a cold surface it will condense. And form droplets.
So with the construction detail shown on your pictures there is a guaranteed moisture=condensation problem. Around the frame.

That's simple building technology, interstitial condensation.

The only way to reduce this effect is to eliminate air ingress. A diffusion tight felt will help. But not in the detailing shown on your pictures, there is a gap, meaining the construction isn't diffusion tight.

No matter what type of 'felt' is used, as long as it is punctured there is moisture getting through it. Onto a cold surface....

And an air gap surrounding the entire frame as shown on your picture will guarantee plenty of build-up of water droplets.




So I see so far two major faults with this type of window installation:
1.) the ingress of damp air is not hindered.
2.) the existence of a water collector, a condenser channel

And we haven't spoken yet about the deterioation of the PU foam with time and movement and the construction details towards the outside.

The destruction of the PU foam can be tested in a simple manner. Put two planks of timber at a distance similar to the distance between your frame and the wall.Fill this gap with foam, let it cure.
Now shift the planks paralel to each other at a similar rate as to be expected with your door or window frame. Forwards and backwards for a few times
For example 3-4 mm when looking at a door frame of 2.5 m height.
Most PU foams won't survive this test.

So there will be not only the build-in gap for now but the PU foam will split over it's entire length.

There are special PU foams for the purpose, but these are expensive and have a limited warranty as well.

The only way - so it seems to me as an amateur - is to use a permanent elastic filler, sealed diffusion tight at the room facing side and diffusion open at the outside.

That's plain logic. But one has to think about it.

brendan_donegal

Getting pretty detailed, I have 3 questions:

My windows are already installed, so:

1. Tape applied internally for airtightness is ok as long as you leave it with plenty of expansion? which means cutting back foam to leave a gap for the extra/fold tape to sit in?

2. Tape should be applied after scratch coat but before drylining and skim coat?

3. Externally my window installers just put in expanding foam and now my plasterer is going to come along and plaster the outside, do I need to do anything else outside to seal from weather i.e. rain? If so does the plasterer normally do this??

BryanF

1. yes - sometimes you may find that a tape to membrane strip to caulk generously on to scratch coat, ensuring no air gaps - see http://www.boards.ie/vbulletin/showpost.php?p=71318188&postcount=11 same principle (not dealing with thermal bridge of course)
2. yes
3. sealant as recommended by window manufacturer (silicon sealant and backing rod)

also see

heinbloed wrote: »

Details on how to install PVC windows here(in German language)

http://www.niederhofer-fenster.de/montageanleitung-pvc-elemente.pdf

see page 16 of inside and 17 for outside

consider using the specialist tapes, membranes, silicones and seals that offer a decent guarantee/lifespan

has your architect not specified and detailed this work for you?

are you at least following the accredited details on the DOE website?

muffler

Please note that heinbloed has had his posting privileges removed from this forum and hence will be unable to answer.

brendan_donegal

you mentioned sealant + backing rod, what is a backing rod?