Air tightness tape yes, no?

[Selfbuildsarah]

Morning all, having read a fair bit about taping windows for air tightness I am still not sure if there are circumstances where you wouldn’t use it. We are having Norrsken windows in our timber frame build but they don’t include it as standard. Everything I’ve read says don’t rely on just foam and silicone. I have to tell them yes or no today. It is a considerable amount of money to add to the build (I even thought I’d do it myself!) but we have 17 windows and 5 doors! 😅 

[Nickfromwales]

11 minutes ago, Selfbuildsarah said:

Morning all, having read a fair bit about taping windows for air tightness I am still not sure if there are circumstances where you wouldn’t use it. We are having Norrsken windows in our timber frame build but they don’t include it as standard. Everything I’ve read says don’t rely on just foam and silicone. I have to tell them yes or no today. It is a considerable amount of money to add to the build (I even thought I’d do it myself!) but we have 17 windows and 5 doors! 😅 

If using AeroBarrier then I’m confident to say it wouldn’t be needed, but if you’re using the likes of MBC TF then you’ve got nothing to worry about as they will tape these for you in their price. 
 

Have you checked that in the contract? Not seen one yet where they didn’t tape them

 

Double-check, and then tell Norrsken to stand down and just foam and mastic seal for weathertight, and be on their way.

 

 

[Gone West]

16 minutes ago, Selfbuildsarah said:

Everything I’ve read says don’t rely on just foam and silicone.

All I can say is, on my timber frame build, i didn't use any tapes or membranes for airtightness. For windows and doors I used two strips of Combriband and the Soudal SWS foam system on the inside. It achieved  an average 0.47 ACH without any tweaks. It just requires care.

[Selfbuildsarah]

10 minutes ago, Nickfromwales said:

If using AeroBarrier then I’m confident to say it wouldn’t be needed, but if you’re using the likes of MBC TF then you’ve got nothing to worry about as they will tape these for you in their price. 
 

Have you checked that in the contract? Not seen one yet where they didn’t tape them

 

Double-check, and then tell Norrsken to stand down and just foam and mastic seal for weathertight, and be on their way.

 

 

Thanks Nick, I will check that before I reply to Norrsken. 

[Thorfun]

Did all the window and door taping myself. Norrsken didn’t offer it from what I recall. 
 

it’s not too bad once you get the hang of it. 

[SBMS]

13 hours ago, Selfbuildsarah said:

Morning all, having read a fair bit about taping windows for air tightness I am still not sure if there are circumstances where you wouldn’t use it. We are having Norrsken windows in our timber frame build but they don’t include it as standard. Everything I’ve read says don’t rely on just foam and silicone. I have to tell them yes or no today. It is a considerable amount of money to add to the build (I even thought I’d do it myself!) but we have 17 windows and 5 doors! 😅 

How much is it to add to the build?

 

we’ve just finished doing it ourselves. Probably overkill because we are planning on aerobarrier as well… but it’s one thing that wasn’t expensive in materials but was time consuming. Soudatight membrane with fleece over all cavity closing joints and then airtight tape on window to cavity junction. 

[Nickfromwales]

17 hours ago, SBMS said:

How much is it to add to the build?

 

we’ve just finished doing it ourselves. Probably overkill because we are planning on aerobarrier as well… but it’s one thing that wasn’t expensive in materials but was time consuming. Soudatight membrane with fleece over all cavity closing joints and then airtight tape on window to cavity junction. 

If you’ve got MVHR and you’re going with AB then make sure you seal everything up, so the airborne sealant can’t get into it and exit through the unit internals to outside. 

[saveasteading]

49 minutes ago, Nickfromwales said:

exit through the unit internals 

From what I've seen of heat exchanger construction  it might completely block it.

[Nickfromwales]

1 hour ago, saveasteading said:

From what I've seen of heat exchanger construction  it might completely block it.

Indeed!

 

My only reservation about AB is I think they need to up their game here, in terms of looking more meticulously at what potential damage could be done and to mitigate against it before doing the treatment. 
 

For eg, on the job I posted about here recently, the underbelly of the MVHR unit had 2 open ports and I hadn’t yet connected the condensate, so these were ports where air would have flooded in, gone right through the unit internals, and out through the 2 roof vents. That would have been catastrophic imho.

 

I think they need to have a checklist for any time they attend partially completed projects, to seek and identify these types of things. Possibly a pre-visit email stating where these possible leaks / faux pas may exist and asking the client to prepare these accordingly, ahead of their visit.

 

I'm seriously impressed with AeroBarrier, and I will be using them into the future with my new and future self build clientele, as it’s a very, very good system and the results were amazing. However, they do need to button this loose end up as it’s only my diligence (in putting 2 layers of duct tape over these MVHR ports) that stopped that unit from being (potentially) wrecked.

 

I also blocked off every single room vent very robustly too, as obviously you cannot have any open MVHR ceiling terminals during this treatment.

 

That’s my only criticism. 
 

 

 

edited to add:

 

I assume AB would have blocked off all the MVHR vents as standard practice, I’m just happier if I know these are done ‘my way’.