Airtightness & kitchen unit baseboards

[WWilts]

Airtightness test people coming on Tuesday.

Plasterboard to floor sealed everywhere except behind kitchen units. How to mitigate? Something to seal above and below kitchen unit baseboards.
(Pls assume that for various reasons mitigation is needed)

Something not too demanding time wise.

[Radian]

5 minutes ago, WWilts said:

Something to seal above and below kitchen unit baseboards.

Is this to achieve more plasterboard to floor sealing? I ask because the way you put it sounds like you could mean sealing the top and bottom of the baseboard instead. This would obviously leave a large volume of unconditioned air under the units - the inside of which would also be cold.

[ProDave]

You need to pull the kick boards off and reach under to seal the PB to the floor properly.  At least it does not need to be done neatly as it will not be seen.

 

Is there not proper air tight layer behind the plasterboard?

[Radian]

37 minutes ago, ProDave said:

You need to pull the kick boards off and reach under to seal the PB to the floor properly.

When I was installing our new dishwasher in the summer, I had the kick panels off under the sink unit and marvelled at the ~20mm ragged edge gap between screed and bottom edge of the dry lining. I was going to foam it but the gun had seized so made a mental note to come back and do it later. Yeah, right.

 

Of course now I think about it the gun and canister wouldn't have fitted under there anyway. I can just imagine it.

[j_s]

Base boards off and can of expanding foam to pb/wall/floor junction? 

 

I did this in mine although I couldn't get access to it all. Gun didn't like being in the side on position much either. 

 

How quick can you get hold of compriband? 

[WWilts]

2 hours ago, Radian said:

you could mean sealing the top and bottom of the baseboard

yes

 

[WWilts]

2 hours ago, ProDave said:

Is there not proper air tight layer behind the plasterboard?

Belt and braces.

No parge, but Celcon blocks (negligible air permeability) and 5:1 mortar well pointed, all sitting on near-raft concrete foundations which in turn rest on hard brash. In short, very little likelihood of movement.

Plus joist ends on first floor have tony tray.

[Radian]

1 hour ago, j_s said:

I did this in mine although I couldn't get access to it all. Gun didn't like being in the side on position much either. 

 

 

Thinking about how to revisit this job and I think I'll try a length of PVC tube on the end of the nozzle. Two man job - one to operate the gun the right way up and another reaching under the cupboards. When I say man...

[WWilts]

2 hours ago, ProDave said:

reach under to seal the PB to the floor properly.

airtight membrane joined with orcon airtight adhesive sounds like a possibility. At worst, seal top of base boards with that and silicone seal from bottom of baseboard to floor? Perhaps easier than reaching across the 600mm to the wall, under the units.

Airtight membrane with orcon was what went under one problem bath, sealing pb to floor. Feasible but not enjoyable experience.

 

Edited December 17, 2022 by WWilts

[Radian]

2 minutes ago, WWilts said:

At worst, seal top of base boards with that and silicone seal from bottom of baseboard to floor?

 

But how airtight are the carcasses for your units? They're usually made from flimsy stuff at the back dry slotted into rebates. Liberal application of Ilbruck FM330 (doesn't have to be pretty) along the wall/floor interface would be my plan.

[j_s]

56 minutes ago, Radian said:

 

Thinking about how to revisit this job and I think I'll try a length of PVC tube on the end of the nozzle. Two man job - one to operate the gun the right way up and another reaching under the cupboards. When I say man...

 

Speedfit 10mm ch pipe fits on my gun plus taping it with electrical tape to stop it forcing the pipe off as the foam flows. Only issue with the longer tube runs is the pressure needed on the gun. The foam does come out a bit differently too, at least with Soudal blue flexi airtight foam. 

[MJNewton]

Yeah I've had only limited success using extension pipes with expanding foam. Have usually just about got things to work, although like @j_ssays it does seem to come out slightly different - perhaps less aerated and so doesn't expand quite so well. Worth a try though. 

[Ferdinand]

14 hours ago, Radian said:

 

Thinking about how to revisit this job and I think I'll try a length of PVC tube on the end of the nozzle. Two man job - one to operate the gun the right way up and another reaching under the cupboards. When I say man...

 

[WWilts]

Time short, clever solutions difficult to attempt at short notice.

So, cheated. Blobs of expanding foam cut into strips, reached under the units and pushed them into gap between plasterboard and screed. Not 5 star work, but if there were gaps before then they are at least less "open" now. Let's see how the test goes.

Thanks for all the ideas.

[WWilts]

16 hours ago, WWilts said:

Let's see how the test goes.

3.75 m3/m2/h
Target for SAP pass was 4.
Phew

Started at 4.6, leaky trickle vents were main culprits. Some sockets on first floor stud walls too, because polythene membrane not put under rafters & roof membrane highly permeable. (Will have to put bungs in the unused sockets on cold days).
Was on floor by kitchen units shoving in the foam bits even as the test was on. Some air flow perceptible there. 
Extractor fan plastic seals - some had come undone during test, but sealing them up would probably have taken score below 3 (with risk of expensive MVHR requirement)

All in all, relieved.