Cracking Down, or up

[tonyg]

I am just in the process of quarter and side decking with marine ply, and Master Joiner I am not. What is the best material to fill in any little joints and fillets please?
Plastic wood? If so, which type?
The finish will be three million coats of Sadolin Mahogony, so I hope that covers the little indiscretions. Thanks, Tonyg

 

[chippie]

I would suggest an epoxy filler, and also make sure that all edges of sheets are sealed with epoxy as water can track through the layers of ply very qickly from the edges. In my opinion plastic wood is for interior work only.
Good on you for having a go!
Good luck

 

[graham]

Have you considered coating the deck with epoxy resin and fiberglass cloth?

It would help keep out the moisture from soaking into the plywood and give a long lasting nonslip finish.

Either way I would soak all the plywood edges with epoxy resin and fill gaps with epoxy filler.Dearer but 20 times better.

 

[Gaffer]

All well and good, but epoxy can be very brittle and may crack after time particularly if there is any movement or flexing, and there may be problems with adhesion. I would suggest considering something along the lines of a sealant/ adhesive such as Sikaflex to actually fix the ply down which will at the same time seal the cracks and gaps

 

[AndrewB]

3M filler is marginally preferable to Sikaflex in that its much the same stuff but they do a tan colour which should be less visible. (I noticed some going cheap in Ocean Leisure at Charing Cross a couple of weeks ago). Use Thinners no 9 to clean.

The alternative is wood plugs and fillets in the gaps. Plastic wood is really only good for very tiny cracks and holes.

 

[oldharry]

I agree with Gaffer: Epoxy is a hard glue, and used as a filler breaks away from butt joined timber (actually the timber breaks away from the glue join as epoxy is so much stronger). A felxible glue like Sikaflex gives a much more durable joint as the glue can move with the timber. While the timber is still new and its moisture content really low, sheathing with epoxy and glass cloth will give excellent results, and a good durable finish.

Make quite sure that water can not penetrate under the sheathing once it is in place, as it the ply will rot away merrily and surpisingly quickly once the sheathing integrity is compromised.

 

[oldsaltoz]

G’day TonyG.
If you are sure the joints are strong enough you could fill them with closed cell balloons (Micro-balloons). If you need to make them strong, use epoxy resin; brush some into the gap first and let it soak into the timber this will reduce the risk of cracking later. Add some ‘fibre’ filler to more epoxy resin and fill as req’d. You can add some colour if you plan a clear coat later. After it sets wash it with fresh water and some wet and dry paper to remove the deposits left by the chemical reaction of the epoxy. Well no doubt, others will have other fixes but your objective must be to maintain strength and prevent water getting in. Hope this helps.

Avagoodweekend Old Salt Oz……

 

[tonyg]

Well, thanks everyone for all the info. I don't really want to epoxy over the timber, and would rather use something which behaves like plastic wood in ease of use-Sikaflex is great but messy(or maybe it's me!) and there is the odd dimple which I would like to fill, smother with stain and fool everyone that I hadn't made an arse of it in the first place. Cheers, TonyG

 

[Gaffer]

As an after thaught, if your deck is wood, make sure that whatever you bond the new decking with is flexable enough. Also, you may find that Sadolin will be rather slippery when wet. For a few pounds extra use teak faced ply, and just sand it. Even better, when all the pieces are cut out lay them on the floor, rout grooves 2 inches apart parallel with the gunwale, fill the grooves with black epoxy and the end result will look like you have teak laid and paid deck....very nice....