Sealing/finishing a wooden gate without paint

Hi All,

I'm a complete amateur woodworker, as the rest of my post will no doubt make abundantly clear.

I made a wooden gate a couple of months ago and construction-wise it seemed to go well and I was happy with the result.

It is made out of 20x85mm jarrah decking planks. I was intending to seal it with decking oil, thinking that if that's good enough for decks, then it should be good enough for something made out of decking material.

Note that I specifically did not want to paint the gate as I love the natural wood grain look.

I noticed in the instructions for the decking oil that it said to let the deck weather for 4-6 weeks before applying the first coat to allow tannins and so forth to be washed out.

So I waited...

The first problem was that when the weather was very hot and sunny, the gate bent inwards a bit (when looking from the front) as the individual planks shrunk. But it wasn't major, I could live with it.

However the second problem has now occurred since the weather recently has been very rainy. The planks have soaked up the moisture and expanded, causing the gate to bend outwards so much so that I can barely get the gate bolt in the wall anymore.

Yes I'm a doofus and clearly I've done something wrong. I would greatly appreciate some advice on what I should do, or should have done first:

1) Applied coats of sealant to the individual planks before assembling the gate.

2) Assembled the gate, then applied the coats immediately before any changes occur.

3) Something else altogether???

Also now that I've got this problem I've just taken the gate down to give it time to dry again, with the intention of sealing when it is back to "normal" shape. Is that worthwhile? Or idiotic?

Thanks in advance for any advice.

Well a gate is a little different to a deck. The main difference is one is horizontal and the other is vertical. The deck would have the planks nailed or screwed down where the gate is suspended by hinges. Although I am not able to see in the photos but I think normally a deck would have a small gap between planks. Mainly for a way for the water to disperse but I also think for wood movement.

Which brings me to this point. Wood by its own nature expands and contracts by the level of moisture it retains. I would allow for that movement when you build the gate. So you might want to take a little off the gate for this reason. Will I take it apart and put a space between each plank I am not sure I will see what others think.

In regards to decking oil I would read the can and you may find that it also contains some polyurethane.

My personal perspective I will wait for the gate to dry out and once dry I will coat it with the decking oil that you already have. I would keep the gate as flat as possible while waiting for it to dry. If it is exposed to the weather then I would look at an incline to stop the water from pooling on the gate.

I also await other's opinion.

No need to be hard on yourself. We all make errors and this is just one way to learn. And good going on giving this a go.

Thanks for your reply Christos,

You're quite right I haven't allowed for movement of the planks. They are butted up against one another. However I've seen other solid wooden gates so there must be a way to do it - perhaps those gates rely upon being painted and thus there is no movement of moisture in/out of the wood?

You mention that the decking oil may contain polyurethane - is that good or bad? Apologies for my ignorance I simply do not know the significance of that.

I have already taken the gate down and it is drying flat in my shed. I'm wondering if I need to take it apart completely - and THEN coat each individual plank in oil, finally put it back together. Or just coat the whole assembled gate.

You're right I shouldn't be too hard on myself - I know I've made some basic mistakes but knowledge doesn't just spring out of nowhere :)

Thanks again for your response.

Polyurethane is not natural like your oils. So the polyurethane is a sort of barrier for moisture.

See what happens to the gate once it is dry, before taking the steps of pulling everything apart. It might just be that it has taken on water and soaked up enough to swell the wood. If it settles to what it was before it just might need the coat of the decking oil that you already have.

Aside from the problems you are having that gate really needs a diagonal. If you don't put one on, within a couple of years it will be dragging on the ground at the outside corner. I know it seems like you could swing an elephant on it now, but over time it will, like most things, sag and droop. Have a look out how wooden gates in a hardware are made and they aren't that good either.

The other thing is if you want to retain the wood grain look I hope you are prepared to sand and recoat it every 12/24 months as there is no clear finish on earth that can stand up to the Aussie sun.

Most solid wooden gates I've seen aren't butted together like yours, but are rather gapped like a deck or overlapped like fence palings. In effect the latter gives each board a "3/4 board gap" in which to expand.

As is, the only really viable option would be as Christos suggests; trimming one side to leave a larger gap between the gate and the post.

BobL is also correct that you need a diagonal brace. From the pix it looks like it'd be a simple enough matter to retrofit one or two between your rails.

If you do retrofit one, just remember that the low end of the brace(s) goes on the hinge side... otherwise it wouldn't work properly.


Apart from all that, personally I'd go with the decking oil. It's as good a choice as any clear finish and it's much easier to give it a light sand & recoat every year or two than PolyU, which needs removing before applying a new coat!


BTW, the gate is looking good apart from these 'technical' issues. :2tsup:

Great looking gate.

As the others have said - it does need a diagonal brace.

Decking oil sounds good so long as you ensure that the ends, top and bottom are absolutely saturated with the oil. Think a bunch of straws held vertically [end grain] - this is where the weather will enter - even the bottom as the rain splash will wet the bottoms. Also be aware that decking oil requires "frequent" coats to keep it looking its best.

Thanks very much guys for your comments and advice - greatly appreciated.

The decking oil I have does say it's good for decks and gates, and does not appear to mention the word polyurethane anywhere. It says I can coat and re-coat without removing previous coats. In fact it suggests that multiple coats are good, or even required in some cases.

With regards to oiling, I did not realise that I needed to re-sand before each new coat of oil! I thought simply re-applying once a year would be sufficient. I will carefully consider whether I want to have a gate that must be re-sanded and re-oiled every 12 months. I might even end up painting it as that would likely offer the best and longest lasting protection.

With regards to the diagonal brace - my understanding is that a conventional gate with gaps in between the planks is held together pretty much entirely by the rails, thus the brace is necessary to prevent sagging over time.

However with my gate it is effectively a single board. I've got each individual plank attached to the next one via 6 pocket hole screws - done in pairs, that end up being hidden by the rails. (15 planks = 14 butt joins, each with 6 pocket hole screws = 84 joints in total, hidden in pairs under the braces). In the light of there being no "slippage" between planks I deduced that no brace was required. The only way the gate could sag is if 6 pocket hole joints in a row failed completely and allowed a plank to slide downwards.

Naturally I could be utterly mistaken in my conclusions! I'm more than happy to put a brace on regardless.

I was also considering dismantling the entire gate (having pocket hole joints allows me to do that) then re-joining them all with biscuit joints + gorilla glue instead, to make a super strong board. Having access to each individual plank again would allow me to coat all surfaces with oil too. (Going too far perhaps?)

Again, thanks for your help.

I think without paint door is not safe and no longer it will work properly.. so if wooden door you preferred for your homes then use paint depends it would be wooden color or others. :B

Hi Everyone,

I built timber boats for 20 years and now run a timber refurbishing business that specialises in outdoor timber treatments, deck restoration, varnishing etc.. and can say in confidence most of the above information is correct.

The timber would have been better if it was left outside for a couple of months in the area you will eventually install the gate to season. It will season inside but not as well.

Yes, make sure there is some room for expansion around the edges(5-10mm will be fine). Dont butt and biscuit join them though, it will still open up over time and the boards will also tend to cup more as well. A gap of 3-5mm between planks would have been perfect for this job, but if you are going to leave it butt joined as is it now it will be okay but the fasteners might work loose over time and need tightening or replacing. Just give it that expasion room on the edges and it should be okay as is. Over time it will cup but just sand those raised edges down when it happens and it will stabilise over a few years.

A cross brace/diagonal is essential long term no matter how solid it feels now.

As far as coatings go i can only say don't go with any cheap products and definately don't use a polyurethane. They don't last anywhere near as long. We, sydneyclearcoatings.com.au only ever use Sikkens or Intergrain products. The easiest to apply in your case will be Intergrain 'Natural Stain'. It should give you 3-4 years if you do 4 good coats. They call it an oil but it does clean up with water(warm water is best).

When applying the product do 2 coats, let it dry for a day or two. Then a light hand sand(carefull not to sand through on the edges) with some 180G paper and then 2 more coats. If it does start to weather or wear, touch it up asap or give the whole gate a service coat.

If you need any more advice get our contact details from sydneyclearcoatings.com.au and give us a ring anytime. Happy to give anyone advice gratis about deck restorations, varnishing, exterior timber sealing etc..

Good luck