Advertisement
Help Keep Boards Alive. Support us by going ad free today. See here: https://subscriptions.boards.ie/.
If we do not hit our goal we will be forced to close the site.

Current status: https://keepboardsalive.com/

Annual subs are best for most impact. If you are still undecided on going Ad Free - you can also donate using the Paypal Donate option. All contribution helps. Thank you.
https://www.boards.ie/group/1878-subscribers-forum

Private Group for paid up members of Boards.ie. Join the club.

Diluted PVA under tiles.

  • 29-09-2025 03:15PM
    #1
    _Brian
    Registered Users, Registered Users 2, Paid Member Posts: 19,319 ✭✭✭✭


    Ok.
    In my first build I sprayed floors with dilute PVA and tiled over and had no problems, still good after 30 years.

    We’re doing some renovations to a house at the moment and I have the floors again sealed with dilute pva. Maybe 4:1

    Now I’ve read this is considered a no-no as there is a risk of problems with the bond. That I should use SBR instead.

    What now ??



Comments

  • #2
    Calahonda52
    Registered Users, Registered Users 2 Posts: 12,959 ✭✭✭✭Calahonda52


    Really down to the quality of the substrate. was 4:1 the first go this time?

    I generally go 10:1 on concrete floors a few times before going a bit stronger

    The ? now is will SBR add any value as the PVA is the "weakest link"

    Is there an obvious coating of PVA, ie shiny, smooth to touch?

    “I can’t pay my staff or mortgage with instagram likes”.



  • #3
    _Brian
    Registered Users, Registered Users 2, Paid Member Posts: 19,319 ✭✭✭✭_Brian


    https://www.boards.ie/discussion/comment/123861415#Comment_123861415

    The floor looks the same maybe a little darker, just no dust coming off it. Not shiny at all.

    Should I coat with dilute SBR now or leave as is ?

    Post edited by _Brian on


  • #4
    10-10-20
    Registered Users, Registered Users 2, Paid Member Posts: 9,650 ✭✭✭10-10-20


    Like Claahonda was saying, PVA is probably more of an issue if it left a skin on the substrate than if it dispersed into the concrete. If it was light enough and it's only preventing dust then bond between the tiling adhesive and concrete should be quite good. If it was a thick layer then the PVA would be preventing the adhesive from bonding directly with the concrete. That's more of a problem if damp penetrates the underside of the tile as it reactivates the PVA and the tiles can get unstuck. Next time use a tiler's adhesive - which is a dilute SBR.

    I'd leave it as is and not worry about it.



Advertisement