I wasn't happy with how my merbau deck came up last year even after cleaning and oiling. It's really patchy. It's nearly 10 years old and I think its time to get back to the bare wood. Just wanting to get as much advice as possible before embarking on the project. It's a pretty big area. I'm thinking I need to buy a hand sander and maybe also buy paint stripper to use first? I don't want to take too much wood off. I will also need to attack the nails as many nail heads have popped out a little. I wish the builder had used screws! Any advice appreciated.
Oops. Forgot to add a pic I took of the deck so you can see how ordinary it currently looks.
@Baz is under the deck accessible? I hope so, because even then, it could be a big job.
In my experience there's no getting around having to sand back the surface until you get back to the raw wood surface, especially if it's been oiled.
Wood oils promise much, but for them to be successful, you must reapply it, strictly to the manufacturer guidelines (ours was a penetrating wood oil & seal coat, every 6 to 8 months). Unfortunately it's almost impossible to do it over the damper months. Firstly you need several rain free days for it to dry out, then you have pray that it doesn't rain within 24 hours of applying it. Long story short, we had a beautiful Western Red Cedar Tiltadoor, & I got caught out, & it's painted now. Sure it looks OK, but it's a shame that I had to cover such a beautiful wood.
The bad news as I see it, is that your boards need to be sanded back, or they'll still be blotchy (I'd recommend a belt sander), & due to the nails being close to the surface, the boards should be lifted.
Once that's done, I'd use a quality Marine Clear coat on all sides. It'll protect the wood, & not darken it like the wood oils do.
Sorry I'm not the bearer of good news, but hopefully another Workshopper has an easy fix for you.
Thanks Andy. Half of the deck isn't accessible underneath as it is on top of an old concrete slab (the old small deck). Why would that make it easier? I thought I'd just punch down the nail heads with a nail punch first. So you would hire a big belt sander?
Yeah, you are going to need to get the nails below the surface of the timber.
If you were able to access underneath the deck then you would want to consider replacing the nails with screws. To do this you just give the boards a hammer tap from underneath to lift the nail a bit, tap the board back down which exposes the nail head, remove the nail, then screw the board down again.
@Baz, unfortunately, I fear that all of the boards have to come up, so that they can be sanded back to the raw wood finish, then clear coated on all surfaces, so that they're fully protected & won't tend to warp.
I was initially thinking that you'd need to lift the boards from underneath, but if you have access to some, you'll be right, you only have to lift 1 board from underneath, the rest can be lifted from above.
I'd recommend getting a belt sander, it doesn't have to be heavy duty or massive, as in reality, it isn't a big job, so should be affordable, & you'll have it available for other jobs later down the track. The belts that you use, are what determines how agressive the sander will be, so experiment with different belt grits. The beauty of removing the boards, is that you can lay them down, & let the weight of the sander & grit size to do the work for you.
Whether you use nails or screws to secure after, isn't important, but do go with Marine Clear (it's made for tough environments & is hard wearing), rather than persisting with wood oils. I'll be upfront & admit that I haven't used Marine Clear Coat, but I wish I had, so ask around & research different applications to help make an informed decision.