1

I want to attach fiber cement siding planks to furring strips over concrete wall. My understanding is that I need some moisture barrier to prevent water from getting to the wood. So can I staple 6mil plastic for that purpose? The surface I am covering is very small - around 30sqf.

4
  • Do I understand you want to staple the plastic to concrete?
    – mikes
    Apr 22, 2012 at 23:05
  • Plastic goes to wood furring strips as described in question. Thanks.
    – Uncle Meat
    Apr 22, 2012 at 23:22
  • I'd consider using something like Azec for the furring strips (PVC). That way you have no wood at all to worry about.
    – DA01
    Apr 23, 2012 at 16:11
  • You might look into a product like Deck Flash™ Barrier, that you could just sick to the furring strips.
    – Tester101
    Apr 23, 2012 at 16:43

1 Answer 1

1

The moisture barrier would generally go between the furring strips and the concrete and would be attached to the wall simply by attaching the furring strips to the concrete. If you wanted to really seal the area you could run a bead of adhesive sealant between the moisture barrier and the wood.

6mil plastic is a "vapor" barrier, not a "moisture" barrier. The difference is that a moisture barrier allows air to permeate it but prevents liquid water from going through. A vapor barrier prevents water AND air being transmitted through it. Moisture barrier is used between porous materials like concrete and wood to allow the various materials to acclimate to changing temperature and humidity without exchanging liquid water (the concrete will absorb a lot of liquid water from the ground, and then pass it into the wood which is a sponge for water, which will cause the wood to rot). If vapor barrier is used, moisture will be trapped on either side of the barrier, which can cause puddles of condensation on the moister and/or warmer side of the barrier.

So, to answer your question, you should probably use a product like Tyvek or TyPar, or an older material like roofing felt, between the furring strips and the concrete. For an installation like this, you can just cut strips of the barrier to prevent direct contact between the materials, and then simply place them behind the furring strips as you attach the strips to the wall.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.