Ground floor to wall airtightness

[SBMS]

I have made a bit of a sequencing error with my airtightness strategy. I had planned to use a liquid membrane at the ground floor slab to wall junction before the insulation was laid and screed was poured. I neglected this and the 175mm insulation and then a latex screed with foam perimeter was poured. 
 

I am dot and dabbing so wet plastering cant help me. Can I use a liquid membrane to seal the finished screed to the wall? There’s the annoyance of the foam perimeter strip to get over and the plastic sheet under the screed would need trimming right back as currently that’s been left long lapping onto the block wall by couple hundred mm. 
 

Am I good to just try and seal this junction with liquid membrane (soudatight lq prob) as best I can?

[Oz07]

Could illbruck foam the gap once boarded if you leave the boards an inch or so off floor gives a good gap to make a nice bead. Cut back flush with board once gone off 

[SBMS]

1 hour ago, Oz07 said:

Could illbruck foam the gap once boarded if you leave the boards an inch or so off floor gives a good gap to make a nice bead. Cut back flush with board once gone off 

Thanks - will get plasterer to do full perimeter dab etc, but don’t I still need to worry about airtightness at the floor wall junction itself?

[Oz07]

That foam will cover the gap. I got a good air score last time and didn't worry too much about this junction. Think I just used the foam as above. I would guess its one of the less crucial airtightness details on traditional construction 

[Russell griffiths]

I did exactly the same

floor screed down

boards on walls

big fat squirt of foam all around entire house

let it cure and cut flush 

fit skirting. 
don’t be buying one tin, get a box of 12 at a time and use it everywhere. 

[SBMS]

2 minutes ago, Russell griffiths said:

I did exactly the same

floor screed down

boards on walls

big fat squirt of foam all around entire house

let it cure and cut flush 

fit skirting. 
don’t be buying one tin, get a box of 12 at a time and use it everywhere. 

You squirting this up behind the board you mean At the bottom? Is this needed if dabbed correctly? 
 

No one done airtight paint on the screed wall junction then?

[Onoff]

4 minutes ago, SBMS said:

You squirting this up behind the board you mean At the bottom? Is this needed if dabbed correctly? 
 

No one done airtight paint on the screed wall junction then?

 

I'll bet Illbrück FM330 is a darn site more flexible at this junction where you could have settling/movement.

 

It's like no other expanding foam tbh. Forms an airtight almost rubber like skin.

 

Reassuringly expensive too. 

[crispy_wafer]

6 hours ago, SBMS said:

You squirting this up behind the board you mean At the bottom? Is this needed if dabbed correctly? 
 

No one done airtight paint on the screed wall junction then?

yeah, i did...  Soudatight lq, onto floor and wall, then soudaltight membrane squashed in with a couple more coats of lq over the top, paying attention to the edges.  if you are geared up to spray, then there is a sprayable paint that will cover the junction.  Thinking about it, if the dpm and dpc is taped correctly all round, should this junction even an issue?

[SBMS]

3 hours ago, crispy_wafer said:

yeah, i did...  Soudatight lq, onto floor and wall, then soudaltight membrane squashed in with a couple more coats of lq over the top, paying attention to the edges.  if you are geared up to spray, then there is a sprayable paint that will cover the junction.  Thinking about it, if the dpm and dpc is taped correctly all round, should this junction even an issue?

Think I might do this. Not sure if dpm/dpc was taped…

[Oz07]

15 minutes ago, SBMS said:

Think I might do this. Not sure if dpm/dpc was taped…

Why would you want to make your life harder? If you've already boarded I'd just use the foam. 

[crispy_wafer]

57 minutes ago, Oz07 said:

Why would you want to make your life harder? If you've already boarded I'd just use the foam. 

to be honest this is the quicker, and possibly more wallet friendly option.  Tenner a tin, he'll get the VAT back, and also be able to use it for sealing those penetrations for lights, cctv cameras, external taps, outside sockets etc.

 

1 hour ago, SBMS said:

Think I might do this. Not sure if dpm/dpc was taped…

I get the 'Got to be sure' thoughts you are having, sometimes to just have to have the feeling that you've done all you can.  All in, it's probably a couple of pots of paint and a couple of hours of time.

 

I don't think there is really a right or wrong here, both methods will do a job for you.

 

I haven't foamed the base of the boards, but I might do, it would stop the crap accumulating under the boards!  Sort of job that could be done in 20 minutes whilst I'm pressure testing plumbing...