Insulating basement walls

[Steveb21]

Semi Basement constructed from 325mm concrete blocks and infilled with C35 concrete and rebar.

Walls have been tanked using KA Tanking Slurry. The floor has 100mm rigid insulation and a concrete slab. Wet UFH heating will be installed.

Next step is to add in some insulation. Which would be a good choice here:

1.Dot n Dab insulated plaster boards directly onto the tanked walls. (any one had any experience of D&D over tanking slurry?)
2.Create a stud frame and install rigid board insulation, cover with vapor a barrier and then plaster board on top. (the timber frame will breach the tanking in the areas it will need to be fixed to the walls).
3. any other suggested method(s)?

Being a basement general concern is to keep condensation to a minimum.

Many thanks.
Steve

 

[foxhole]

Insulated plasterboard fixed with fixing foam, impervious to damp, unlike dot and dab.

 

[Steveb21]

Insulated plasterboard fixed with fixing foam, impervious to damp, unlike dot and dab.

Was just watching a video on youtube about this. Appears to be simple method however do the insulated plaster boards come with a vapour barrier? As it is a tanked basement there will be condensation, therefore a vapour barrier of some sorts will be required. Thoughts?

Just read that the PL4000 comes with added VCL.

Celotex PL4000 features a vapour control layer built in. It is positioned between the plasterboard and Celotex foam insulation. When the boards are tightly butted together, the tapered edges of the plasterboard are sealed with scrim tape and jointing compound to form an effective vapour control layer with a high vapour resistance.

 

[foxhole]

Condensation occurs when moist air meets cool surface , no air , no condensation .

 

[Deleted member 174758]

As an altermative you could got to metal studwork (see British Gypsum or Lafarge sites for details) with plasterboard cladding. This would be fixed at floor and ceiling, is relatively thin and doesn't pierce your tanking (very important, that). Having tanked the walls surely you don't want to go undoing the work by fixing anything to it or through it?

 

[Steveb21]

What about using glue to fix batons on to the tanked walls?

 

[Deleted member 174758]

But you are still attaching something to the tanking. Always best not to do this and instead have a physically separate wall - which is how a professional would approach the task

 

[Steveb21]

With the metal studwork would it be best practise to have foiled back insulation board right up against the tanked walls, or should a gap be left?

Am I correct in thinking that metal stud walls are designed to have plasterboard directly attached? unlike a battened wall where you would install rigid/wool insulation between the timbers.

 

[Deleted member 174758]

When I've installed these there was always a gap between the tanked wall and the MF/insulation. I inderstand that this trapped air space also acts as insulation. MF is easy to cut with a pair of straight tin snips (aircraft snips).

Plasterboard is directly fixed into the MF studs using drywall screws (order a decent brand like Fischer, Hilti or British Gypsum rather than going to SFX or Wickes - metal requires fine thread, not coarse thread). Rigid insulation or mineral wool can also be installed in the same way you do with timber stud, although in that case it is recommended that your studs sre fixed to the track using either wafers (wafer head self-drilling screws) or crimped (using a crimping tool).

BTW drywall screws are invariably Philips #2 head, so you would need some appropriate bits (Pozi bits don't work well), and an impact driver is better than a combi drill as it really is a lot faster and will drive into metal a lot easier fie to the higher speed