Adhesive sealant

Well, Folks

Over the last 4-5 days I have finally had the serendipitous combination of the right weather and reasonably conducive health required to seal around the base of SWMBO's kiln shed where the crappy thing joins the crappily laid concrete slab it sits on.

Every time it has rained since it was done last Feb-Apr, it has leaked like a bloody sieve.

Our lovely plumber, electrician and gas plumber each fixed some of the really lousy (Australian) "design" that it represented.

I have needed to research how best to seal where the steel fails to accurately meet the concrete.

The weather also needed to be bone dry for about a week prior to starting the job, and for the duration. I even considered using Dunlop Tile-All Plus, which will even adhere and set under pool water. However, at nearly $40 a tube, this was looking to be prohibitively expensive. I have used it to glue water line tiles back on in our pool. Sticks like baby poo to a nappy ...

Finally settled on Sikaflex-11FC. It is a polyurethane based adhesive sealant.

This stuff also sticks like baby poo, but requires a clean, firm, dry substrate. It also costs a bomb - $18 a tube. Have used 4.5 tubes to finish the main job.

The Sikaflex comes in a small variety of colours, and will glue and seal most materials except the usual suspects of PE and some other plastics.

It is exceptionally tough once properly set (about 3 days IME). I have put a standard bog gun tube nozzle down on a half brick after using it to pierce the internal seal of the Sikaflex tube with. I can lift the half brick by the old nozzle.

Cutting off the dags with an Olfa knife shows how tough it is. More so than normal silicon-based products.

The part of the shed that had the worst leaks was the door sill for the double doors. It had a gap of around 5+ mm between the bottom of the sill and the concrete. I have filled this gap and glued 25x20x1.6 mm aluminium angle on each side of this, with the legs facing away from the sill. I did the outside part some days ago, then fitted the internal piece today. When the Sikaflex has set a bit, I will rivet these bits to the door sill. These will provide the mechanical strength so that the adhesive/sealant only has to seal the sill rather than holding it against rotational forces if someone stands on it (as one does ... ). It also makes this part some 60 mm wide, giving plenty of surface area for adhesion, and a stable platform to resist twisting motions.

Not sure how suitable this stuff would be for automotive use, but it seems a better choice than silicone, which can tend to rot steel.

as far as using sikaflex on cars goes, I've been using it for 4+ years and have never had any problems

Was that the Sikaflex-11FC, Twink.

There are so many varieties of these things ... reigns ... .

I use the sikaflex sold at the local auto one! :biggrin: I know for a fact that there is an "automotive" spec Sikaflex, that is used in windscreen fitment.

Hahaha. What did I just say? Confusion reigns supreme in this stuff, Twink!

Is the auto grade an adhesive/sealant, an adhesive, or a sealant?

BTW, the seals I laid down today are going off quite nicely. I should be able to do the riveting tomorrow morning. Then leave it for about a week to out-gas fully. After that, I will paint the floor with heavy duty paving paint (first coat diluted with 10% mineral turps; second coat straight. I intend to run the coat up over the base and sealant to provide as much protection from water penetration into the adhesive/sealant from both inside and outside. A bit like the 'skirting' in modern hospitals.

Ah, it's an adhesive... terrible if you get it on your hands!

^ Too right!

I had a box of Kleenex and a big garbag to hand. Every single bit of dross got wiped off immediately. Of course, there is nothing quite like a finger/thumb for tooling off this stuff, but this needs to be removed from fingers, work and the nozzle immediately.

After each session - it took about 8-12 sessions in all - I washed the remnants off my fingers with methylated spirits and then Sard Wonder soap. Seemed to work OK.

I might add that the Sikaflex-11FC is exceptionally viscous. I have an old sealant gun that managed it, but if buying a modern gun, go for a professional one off the blocks. This stuff is so viscous that squeezing a fine bead will quickly destroy a domestic grade gun, if it manages it at all!

I use Sikaflex products (adhesive and sealant) and they work really well.

^ Good to know, thanks.

If most of these products were half as good as they say on the packaging, we would be living in adhesive/sealant paradise.

I have previously found that Bostick acrylic gap sealant works OK for things like around windows, but no good for perennially wet areas.

Butyl Mastic is also good for wide gaps between dissimilar materials like brick/anodised aluminium. Again, no good for wet areas.

After my current experience with the Sikaflex-11FC, and the recommendations here, I think I will use Sikaflex products in future. Most are nowhere near the cost of the 11FC. So far I can highly recommend this for wet and difficult situations and dissimilar materials.

The bond to the crappy concrete is not as good as it could be, but much better than I expected. I have tried to make up for the poor surface by using a double pass (inside + outside), and completely filling the bigger gaps across the 20 mm width, and making the doorway into a 60 mm width. Hopefully this will be successful. I did water the outside with a hose this morning, and there was zero penetration. So far, so good ... :ebiggrin: :biggrin:.

The old tradie saying goes, "Do your best, Sika the rest".
When I install my snorkel I will probably use sikaflex to seal the tubing and airbox.

The biggest problem with adhesives/sealants is the huge range and the severely limited capability of the sales droids to provide a credible recommendation for a particular task.

Gidday Zippo & Au

Thanks for your comments and thoughts.

I finally got the sills riveted in place this arvo.

Apparently we are supposed to be getting some rain over the next week, so I will get the chance to see how successful (or otherwise ... ) all the pain and work has been. Fingers crossed ...

Usually 24-48 hours drying is enough for waterproofing. Full strength I think is after a week.

Sikaflex is magical stuff.

I needed something that would stick polycarbonate windows onto a fibreglass boat after removing the tarnished leaky 1960s crappy ones and their leaky rubber seals. Everyone I spoke to in the marine industry and one industrial designer said Sika was the least likely to fail.

Rather than use rubber seals, I got the windows made about an inch oversize out of UV stabilised tinted polycarbonate and Sikaflexed them to the outside of the boat. Looks much more modern. That was 10 years ago with regular salt, sun, heat, cold, flexing, torsional stresses, no cleaning and the occasional impact - they still ain't going anywhere.

Hoping they stay on for another decade.....they cost a bloody fortune!:lol:

That really is a tribute to the stuff, Tweak.

And Sikaflex-11FC is still only half the price of Dunlop Tile-All Plus - a misnomer: the Dunlop product sticks like buggery to everything it touches. It can even be used to stick tiles to the bottom of a full swimming pool! The chemicals in swimming pools make plain old sea water look positively benign. Pool "water" bears more similarity to a galvanising plant's pickling baths ...