Sealing Window Openings in Timber Frame

[Triassic]

The exterior membrane is in place, next I need to seal around the window appatures. Looking online there are a number of ways of doing this, with some suggesting specialist membranes.

 

How did you do yours? Is there a right way of sealing around the window appature? Do you use special tape, or a combination of membrane and tape?

 

I had this approach in mind.

 

 

Edited March 3, 2019 by Triassic

[Russell griffiths]

From my research when I was going to do timberframe that looks spot on

what I would say is use a specific product for the cill pan, just wrapping your external membrane into the opening will not do, it needs to be fully waterproof. 

 

A lot of literature i read said a good belt n braces approach was to tilt your cill plate 5degrees down so any water getting to the cill pan gets gravity to pull it outwards. 

[Mr Punter]

I have used Tyvek FlexWrap for cills and also for pipes through walls. Works well as it is elasticated enough to stretch around corners.

[Triassic]

3 minutes ago, Mr Punter said:

FlexWrap

Wow, that’s expensive stuff, £280 for a  152mm x 75m roll.

[Cpd]

1 hour ago, Russell griffiths said:

A lot of literature i read said a good belt n braces approach was to tilt your cill plate 5degrees down so any water getting to the cill pan gets gravity to pull it outwards. 

Hmmmm I built my own windows in my shed and an error in my glazing seal resulted in water getting onto the cill plate that was not tilted outwards and water made its way into the building...... bloody annoyed at my error as it was a fairly big job to sort it out, now I just need re to do the other side........  it faces east so does not get much weather but still needs to be done..... 

[Crofter]

I used Siga Wigluv tape for sealing around the frames. Expensive, but not somewhere that you really want to scrimp.

I was advised (can't remember by who) to only seal the sides and top, though- this leaves a pathway for water to escape if any moisture condenses inside the wall. It sounds a bit counterintuitive, but the way the rest of the detailing worked, it wasn't going to cause any problems as the alu sill forms the actual weathertight layer across the bottom of the window.

[Triassic]

18 minutes ago, Crofter said:

I used Siga Wigluv tape 

I was advised (can't remember by who) to only seal the sides and top,

I read it was the bottom and sides?

[Crofter]

OK I might have mis-remembered a wee bit there.

I think what I actually did was to seal the bottom, but the way the window frame was shaped you ended up with a gap that would allow any condensation to drain out. Can't really explain it without a photo, and it's all hidden behind cladding now!

[Cpd]

2 hours ago, Crofter said:

I used Siga Wigluv tape for sealing around the frames. Expensive, but not somewhere that you really want to scrimp.

Yup that’s what I used second time around..... great tape - repaired a rip on my quad bike seat as an experiment to see how long it holds up, been on over a month and still going strong.