Airtight Tape to Block

KerrySurfer

Quick couple of questions for all you knowledgeable folks. Currently researching Airtight tape for sealing the hardwood doors/windows to the concrete block inner leaf. The reveal finish is going to be sand & cement plaster/render. Windows are in.

Should the reveal be pre-plastered with a light coat of bonding or sand & cement (or some other paint-on material) to ensure a smooth surface to aid adhesion of the tape to the reveal. Can't imagine tape will stick well to a concrete block?!

Can anyone recommend a good airtight tape? PMs would be great if brands can't be mentioned.

Any advice appreciated!

Dudda

Pro Clima and Siga are the big brands found in most hardware shops like the Nike and Adidas of the sports world but lots of other brands are available which can be cheaper. I think the biggest difference is the more expensive can have up to 50 year guarantee. Cheaper ones can be paper based or not reinforced and can be fine depending on where and how they're used. If the tape isn't fitted right and put in with care it doesn't matter which you use.

If plastering internally you usually you fit the tape to the blockwork and window frame first. The tape is usually 100mm wide and it has a fleece side that can be plastered over. This creates the airtight bond between the window and wall.

Is this a new build? What about the rest of the house? Have you airtight junctions around pipes, radon barrier, ceiling, roof, at first floor level, etc? If you're at the window fitting stage in a new building and only thinking of airtightness now it might be a bit late

BryanF

smooth coat plaster around reveals, primer and contega, then plaster over.

What about insulation continuity? Where is the wall insulation? How do it overlap with window frame? Did arch not do a detail?

rampantbunny

On my self-build I used a fleece based tape (Contega SL) at any junction where raw blockwork was present. This required a thin bead of flexible glue (Orcon F) on the blockwork first.
Primer was used on smoother plaster type surfaces to stabilize them. At junction between screed floor and wall I used OrconF on top of the primer as the tape for that joint is not self-adhesive. In other places, I taped directly onto the primer.
I used ProClima products throughout (I've no connection).

KerrySurfer

Thanks for the replies guys, very useful info there. Contiga SL and Fentrim 20 were the two products I had seen online.

Dudda, unfortunately not a new build, it's an extension to a 50 year old bungalow. My main objective with the tape is draught prevention as I think it'd be a losing battle trying to make such an old building airtight. I'll get it well insulated and I think I'll be happy enough with that.

Bryan, the extension has full fill rigid insulation (100mm) and the old section has 60mm unfilled cavity. I installed rigid PIR insulation and DPC in the cavity around the window openings once I had the old windows taken out. I plan to fill the old cavity with pumped insilation, possibly something like Walltite as my cavity width is so narrow. I see what you mean regarding insulation continuity but the inner leaf wasn't stepped back to allow for this.

It's a slow self build and I'm only researching these tapes at the moment so I have time on my side. I'll be chatting with my engineer and plasterer before I do any work on the doors/windows.

Again, thanks for the info, it's well appreciated.

Calahonda52

insulation without air tightness is a waste. period