Which airtight tape is needed?

[ruggers]

Which airtight tape is best for window reveal cavity closers to blockwork?

 

I need to start buying air tight tape for various areas of the build, but first up, i need to order some asap to seal the plastic cavity closers to the internal block work reveals before the windows get fitted next week. 

 

I've just realised I'm going to need to tape one side of the closer before the frames go in. I'm having the frames set back into the cavity by 25mm, so window reveal fixing straps are being used, these will over lap the closer, meaning taping later wont make a decent seal.

 

Siga fentrim was suggested for some areas but its very expensive.

 

Just to add, all block work reveals are painted in airtight paint and closers will be modified to be thicker.

[Nickfromwales]

You don't tape to blockwork.

 

You need to parge the blockwork, to get it flat and uniform, and then paint it with liquid airtight membrane (assume Passive Purple from Intelligent Membranes?) and then you tap to that.

 

If you've PP the bare blockwork then that's less than great as the pours of the blockwork will allow air to pass behind the tape.

 

A pic of what you have would help, but, tbh, you just get the windows installed and then airtight afterwards, which reduces unnecessary work and effort.

 

 

This was one where I got the builders to fully parge the woodcrete ICF, as it's pretty dogshit unless you do the lot, and then PP over. Then they foamed, then they taped.

 

Very difficult project where I was principal consultant, but the builders were really good guys and we got an initial 0.88 ACH, then a bit of 'go find the leaks', and then a final test at 0.66 ACH (as built, end of project test) which was really not expected.

[MikeGrahamT21]

7 hours ago, Nickfromwales said:

You don't tape to blockwork.

 

You need to parge the blockwork, to get it flat and uniform, and then paint it with liquid airtight membrane (assume Passive Purple from Intelligent Membranes?) and then you tap to that.

 

If you've PP the bare blockwork then that's less than great as the pours of the blockwork will allow air to pass behind the tape.

 

A pic of what you have would help, but, tbh, you just get the windows installed and then airtight afterwards, which reduces unnecessary work and effort.

 

 

This was one where I got the builders to fully parge the woodcrete ICF, as it's pretty dogshit unless you do the lot, and then PP over. Then they foamed, then they taped.

 

Very difficult project where I was principal consultant, but the builders were really good guys and we got an initial 0.88 ACH, then a bit of 'go find the leaks', and then a final test at 0.66 ACH (as built, end of project test) which was really not expected.

 

Would it make a difference if the blockwork was being wet plastered? Fully embedding the airtight tape into the plaster. This is what i did, with the fabric type tape, was what the guidance suggested was the right thing to do. Blocks were primed with airtight primer before the tape. Just curious really, not much i can do about mine now if it is wrong lol

[ruggers]

Hi, I'll reply to you both.

 

Correct me if theres a better order to do this before or after the windows are fitted next week. I was thinking i need to do some upfront work. See picture for my window reveal.

 

Its 100mm dense block inner, 100mm pir set back by the depth of the plastic cavity closer 25mm. 50mm air gap, 100mm facing brick.

 

I'm going to fit the cavity closers this weekend before the windows go in. Im modifying them and adding 50mm thick pir to make them 75mm total, the extra bit wont bridge the cavity, but will overlap the set back window frame.

 

I'm using soundal soudatight brush on around the reveals, the rest of the walls will later be sprayed after chases are completed Cant get anyone to wet plaster so dot and dab boards.

 

I planned to paint the reveals this weekend to seal up pores in the blocks, then add the cavity closers over lapping, then tape closers to blocks, then windows fitted with the straps drilled into the inner block work, and then touch up over the brackets and screws with tape or more membrane. That way any air tight tapes are adhering to painted blockwork and will adhere much better than to bae dusty blockwork.

 

I thought if i fit closers, then windows in, then try to paint over it all and tape closers to blocks it will get messy.

 

It sounds like i need to parge coat the reveals with sand a cement asap, then add soudal liquid membrane paint, then cavity closers, then windows fitted, then tape over? @Nickfromwales

 

 

[ruggers]

I want to ensure the laps/wings of the plastic closer have a good seal to the inner block work and need the closers fit before Tuesday windows.

 

The brush on soudal lq has reinforcement fibres in and is a paste and much thicker than what will be sprayed onto the inside block work later on using their sp version.

 

Its already bought. Passive purple is great but the price was far too expensive.

[Nickfromwales]

4 minutes ago, ruggers said:

I thought if i fit closers, then windows in, then try to paint over it all and tape closers to blocks it will get messy.

 

It sounds like i need to parge coat the reveals with sand a cement asap, then add soudal liquid membrane paint, then cavity closers, then windows fitted, then tape over?

Use flexible tile adhesive instead of sand / cement, you’ll thank me later   

Use the standard set not rapid, and mix it to quite a stiff consistency. You don’t need a 5mm thick layer so don’t go wasting time / money getting these perfect and uniform. Just get it on, do a couple of reveals, go back to the first and trowel it to get it half decent, and then go over with a wet sponge an hour later to get a ripple free finish.

 

Couple of hours later you can paint the liquid AVCL over the parge. Moisture will soak into the mortar so don’t worry about it not having fully dried out.

 

I do about 150-200mm of parge, then about 100mm of liquid AVCL, minimum 2 coats, leave to fully dry (this is very important) then tape to that.
 

How much of the cavity closer will be exposed between the frames and the tape / parge? 

[Nickfromwales]

15 minutes ago, ruggers said:

I want to ensure the laps/wings of the plastic closer have a good seal to the inner block work and need the closers fit before Tuesday windows.

 

The brush on soudal lq has reinforcement fibres in and is a paste and much thicker than what will be sprayed onto the inside block work later on using their sp version.

 

Its already bought. Passive purple is great but the price was far too expensive.

The brush on stuff is good, just when you use it it tends to either need to be lathered on to allow the fibres to bridge stuff (which means it takes days to dry) or you brush most of that back off. It’s a bit of a fiddle to get used to applying it, plus you then use a lot more than perhaps you needed. One benefit, as it says it’ll plug 5mm pores, is you could miss the parge work out, but it needs more coats lathered on and lots of drying time vs parge and thin coats of the liquid AVCL. 
 

If times against you, I’d parge. 

[ruggers]

 

1 hour ago, Nickfromwales said:

I do about 150-200mm of parge, then about 100mm of liquid AVCL, minimum 2 coats, leave to fully dry (this is very important) then tape to that.

What does the 150 - 200 mean?

 

Most of my vertical block reveaals are 1050 to 1275mm high. I've used the brush on around the full house perimeter before i built the masonry hangers into the block work diring construction and its quite an easy product to apply and it does fill a lot of the grainy holes, a parge would give this a better finish but i thought the liquid avcl would have a better lifetime bond to the blocks rather than adhesive then painting over that?

 

 

1 hour ago, Nickfromwales said:

 

 

How much of the cavity closer will be exposed between the frames and the tape / parge? 

The cavity is 150mm, frames set back 25mm. Ill assume the closers wings are 25mm, so there will be 150mm of plastic to cover.  

 

I didnt think theres a need to paint over the whole closer. I proposed to tape the inside closer edge to the parged or liquid sealed inner leaf block, then use a folded tape to tape the window frame to the closer 15/50mm or similar.

 

Then adhere my plasterboard to the reveals over everything.

 

If i don't vertically tape the closers edge to the inner block before the windows are fitted, ill be taping over metal window straps too so the tape wont be continuous betwen plastic and masonry, it will be taping over metal too.

Edited 5 hours ago by ruggers

[Mr Punter]

17 minutes ago, ruggers said:

 

The cavity is 150mm, frames set back 25mm. Ill assume the closers wings are 25mm, so there will be 150mm of plastic to cover.  

 

I didnt think theres a need to paint over the whole closer. I proposed to tape the inside closer edge to the parged or liquid sealed inner leaf block, then use a folded tape to tape the window frame to the closer 15/50mm or similar.

 

Then adhere my plasterboard to the reveals over everything.

 

If i don't vertically tape the closers edge to the inner block before the windows are fitted, ill be taping over metal window straps too so the tape wont be continuous betwen plastic and masonry, it will be taping over metal too.

 

I think you need check reveal cavity closers as one of the wings will clash with your brickwork.

 

These https://insulationgo.co.uk/150mm-xt-cl-close-r-checked-fit-pir-cavity-closer-brick-outer-pir-core-insulation/

 

or if you want fire rated, which may be a better fit with the rigid insulation:

 

https://www.insulationsuperstore.co.uk/product/arc-ecocloser-150mm-fire-rated-cavity-closer-2-4m-length-pack-of-6.html

[Nickfromwales]

4 hours ago, ruggers said:

What does the 150 - 200 mean?

A 150mm to 200mm ribbon, continuous around every opening. The pic above shows about 300mm as the clients went loop the loop with liquid Barney.... The danger when a self-builder becomes beyond obsessed with one particular thing, and then can't stop themselves ordering a few pallets of something......then some more.....and some more......

 

4 hours ago, ruggers said:

a parge would give this a better finish but i thought the liquid avcl would have a better lifetime bond to the blocks rather than adhesive then painting over that?

Not imo, the parge with tile adhesive is a much better surface for the liquid AVCL than rough blockwork, and gives a far more uniform surface for tape to be applied to. I got a <0.2 ACH with the last one, a masonry refurb of a 1960's POS. Blasted that past EnerPHit, and out the other side 😎.

 

4 hours ago, ruggers said:

Then adhere my plasterboard to the reveals over everything.

You'll need to use foam over the closer, and dab over the masonry / Soudal / tape.

 

4 hours ago, ruggers said:

If i don't vertically tape the closers edge to the inner block before the windows are fitted, ill be taping over metal window straps too so the tape wont be continuous betwen plastic and masonry, it will be taping over metal too.

Which is fine, as then the fixings of the plates will be behind the tape / foam, and be sealed nicely. This is how every job gets done that I've seen. Tape last.

 

 

And yes, the window company "could" have used bloody cranked plates....... they just thought it would be good to make like difficult.