Thread: Backing rod problem - can YOU help????

Get hold of some 6 mm or 10mm (which ever suits the gap) closed cell foam as used in construction joints. the white one can be compressed with little effort to fill smaller holes and save a lot of compound.
Sikaflex is good but very expensive, I use the 11FC for waterproofing .

Go to K-Mart and purchase a few of the white plastic kitchen spatulas, they are nice an stiff and at a couple of dollars each do a great job. You need one cut down to a chisel shape to control the depth and the other to remove any excess produced.

1. The areas being treated MUST be dry.

2. Clean out any old caulking.

3. Apply a small amount of compound and Insert the closed cell rod with a 50 mm blunt scraper, it will compress into gap.

4. Apply more caulking and use the chisel spatula to get an even and smooth depth, then ceal off any excess with the standard spatula.

What's behind the ply, is it a stud wall with bottom plate? (and if so what are you doing about moisture under it - treated pine or.. ?) You can also buy alum angle and screw it to the concrete at a few spots with screws into plastic plugs. Before you screw it down finally, run just a bead of sikaflex and then bed the angle into it and screw it down. If the slab is nice and even you could even forego the screws.

Bunnings sell a product called Foam Fill comes in a pressure can. It expands to 3 times its original volume as you spray it. It is suitable for interior and exterior use. Once dry it can be sanded, cut and painted. It is waterproof. I used it to seal the holes (about 4 years ago) on the greywater tank around the discharge pipe.

Regards
Harold