Is aluminum flashing under bottome plate a good idea?

[fred2]

I'm building an extension on a concrete slab...i forgot to put down a water proof membrane...its too late now (as the slab is done)...but i haven't put the wooden frame up (its a brickveneer extension)...I was just wondering..if it would be a good idea to
put the bottom plate on a strip of aluminum flashing, rather than directly on the concrete...
just as a bit of insurance.... is this sensible?

[echnidna]

plastic flashing is good enough and easier to work with

[thebuildingsurv]

I am assuming you forgot to put down your poly under the slab ? is this right ? How did your steel inspection get passed for your slab ? You will probably get rising damp problems ?

[fred2]

Well the extension started off as a vehrander (so no poly under slab)...and now i put a new building permit in to add walls to it...to make it part of the house.. anyway, its on a little slop...with nice drainage away from the slab, and the slab is reasonably high...about 30-50 cm, so i'm hoping that i don't get too much rising damp... anyway, i'll put some flashing under the bottom plate..just as a bit of extra insurance....if anyone has any better ideas...let me know...thx for all responses...

[Barry_White]

Maybe a good coating of epoxy paint over the slab would help.

[echnidna]

If the slab is lower than the house floor you could batten it over a membrane and fit a sheet/timber floor at the same level as the house floor

Stay with the flashing under the walls.

[rat52]

Don't use alu as it will corrode out in less than a year. Use a plastic viscourse under the timber plates to stop any rising damp

There are a number of surface paints that can be used to seal the concrete which would be advisable to use especially if you are going to lay carpet or vinyl.

[rileyp]

Maybe a good coating of epoxy paint over the slab would help.
This is what I was thinking .
Seal the slab with 2 part epoxy and any holes with sikaflex or simular.