Water pooling on deck

Forums › Home Workshop DIY › Water pooling on deck - solutions?

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jonathan18

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#3118892 22-Aug-2023 08:01

tchart:

I have the same problem, the guy who built our deck was "too good" and the spacing is minimal. The gaps get filled with dirt etc and then block the water from draining. If the deck has been water blasted recently then I have minimal pooling.

What Ive found is that using a oscilating multi tool is a good way to clear the blocks without destroying the deck - as the side of the blade doesnt cut.

Cleaning out the gaps with a water blaster and a craft knife blade certainly made a big difference - here's the before and after, with the only water pooling being where I haven't cleaned.

Good idea on the multi-tool; I do have one and hadn't thought of using it. [Edit - though at this stage the blade won't fit in the gap, as the wood is so swollen! It was difficult enough to fit the craft knife in there...]

johno1234

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#3118893 22-Aug-2023 08:05

concordnz:
mattwnz:

I thought most people put the grooves on the underside, as it allows water to drip off the underside? I personally am not a fan of grooves on the top surface, as it reduces the surface area your foot is in contact with and can be slippery in the longitudinal direction, especially when it gets algae growing on it.

I did heaps of research into this when designing & building my Deck.
In short, 'both ways are right'.

Often in commercial installs or damp spots you will be required to put them grooved side up, for traction.

Some people also put them grooved side up for texture/look.

Others put them grooved side down because they like the smoother finish. (note, if painted, the smooth side up can get quite slippery when wet) - but if stained or left to silver off naturally, it's fine.

I would never put the grip tread grooves up. They just capture water and gunge and are hard to clean. The only place I would ever do that is the end edge of deck stair treads.

https://www.stuff.co.nz/life-style/homed/garden/123971912/grooves-up-or-down-nzs-fierce-decking-debate-finally-settled#:~:text=Decking%20should%20be%20groove%2C%20or,get%20a%20lot%20of%20sun.

jonathan18

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#3118895 22-Aug-2023 08:06

trig42:...

The next time we did it, someone suggested that Hit the Deck is pretty much just Napisan, so we tried with that. Worked just as well.

Dissolve Napisan into hot water in a sprayer, spray liberally over deck and leave for a bit, scrub the part you've just done, rinse and repeat on another section. Wood comes up like new. We've done it on a pine deck and a kwila one, same results on both.

This is what I'm debating buying vs a product with a different active ingredient (oxalic acid); rather than buy Napisan I'd probably just buy calcium percarbonate, which is the active ingredient in Napisan - $48 for 5kg off TM which will do a lot of decking.

I'm thinking mould remover for the worst patches, followed by the whole deck using calcium percarbonate.

jonathan18

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#3118896 22-Aug-2023 08:12

mdf:

Where does the water run off to? We had flowerbeds at the end of a previous deck and it quite significantly constrained what we were able to use. I'm pretty sure we ended up with one of the Bunnings concentrated deck clearner options, but had to do the version that you scrubbed on with a broom because it was less toxic to plantlife.

Just onto lawn, and not a quality lawn I particularly care about, plus a fence at one end.

eracode:

@jonathan18 May I ask where are you based?

Palmerston North.

jonathan18

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#3118898 22-Aug-2023 08:17

johno1234:

@jonathan18 are the boards screwed down or nailed?

Nailed, unfortunately; if it had been screws I'd not have had any problems with lifting the boards.

If we're still in this house at a point it's time to replace the deck, we'd get it done quite differently!

johno1234

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#3118899 22-Aug-2023 08:32

jonathan18:

johno1234:

@jonathan18 are the boards screwed down or nailed?

Nailed, unfortunately; if it had been screws I'd not have had any problems with lifting the boards.

If we're still in this house at a point it's time to replace the deck, we'd get it done quite differently!

Ooh, now I understand not wanting to lift them!

eracode

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#3118902 22-Aug-2023 08:45

IANAChippy but IMO I'm a pretty skilled DIY'er and have successfully built many decks over a 45-year period - pine, hardwood and composite. As seen in this thread, there's several solutions that could be used here. I believe the best practical solution in your case is one of those suggested above - run a circ saw along the 'join' in the affected boards to create a normal sort of drainage gap between them.

Set the saw so that the cut depth is barely more than the thickness of the boards so that you're not cutting into the joists. This will create a gap of about 3mm which is fairly standard for most new decks. Lightly sand to round-over (or bevel) the tops of the new cuts so that they don't look so newly-modified. Even though these boards may not match the gaps (or lack of gaps) in the other boards, it's probably a small price to pay if you want the deck to drain - and it will work well.

It's a really simple job. The reason I asked where you are located is because if you were near us in Auckland, I would be happy to do it for you - but it sounds like you will have a builder on hand shortly anyway.

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jonathan18

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#3118909 22-Aug-2023 09:03

eracode:

IANAChippie but IMO I'm a pretty skilled DIY'er and have successfully built many decks over a 45-year period - pine and hardwood. As evidenced in this thread, there's several solutions that could be used here. I believe the best practical solution in your case is one of those suggested above - run a circ saw along the 'join' in the affected boards to create a normal sort of drainage gap between them.

Set the saw so that the cut depth is barely more than the thickness of the boards so that you're not cutting into the joists. This will create a gap of about 3mm which is fairly standard for most new decks. Slightly sand to round-over (or bevel) the tops of the new cuts so that they don't look so newly-modified. Even though these boards may not match the gaps (or lack of gaps) in the other boards, it's probably a small price to pay if you want the deck to drain - and it will work well.

It's a really simple job. The reason I asked where you are located is because if you were near us in Auckland, I would be happy to do it for you - but it sounds like you will have a builder on hand shortly anyway.

Thanks, @eracode, that's an awesome offer, and a pity I don't live in your neck of the woods! Also, appreciate the tips on how to go about it; I do have a circular saw, but am not the most adept at using it - I think I'll be ok provided the blade fits cleanly into the gap where it's wider, as I'd not be comfortable if this wasn't the case. Depending on when the builder's going to start his work I may see if it's feasible for me to do.

So you don't reckon I need to use a relatively narrow blade? I'd have thought that may minimise how different this part of the deck looks from the rest.

eracode

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#3118911 22-Aug-2023 09:13

jonathan18:

eracode:

IANAChippy but IMO I'm a pretty skilled DIY'er and have successfully built many decks over a 45-year period - pine, hardwood and composite. As evidenced in this thread, there's several solutions that could be used here. I believe the best practical solution in your case is one of those suggested above - run a circ saw along the 'join' in the affected boards to create a normal sort of drainage gap between them.

Set the saw so that the cut depth is barely more than the thickness of the boards so that you're not cutting into the joists. This will create a gap of about 3mm which is fairly standard for most new decks. Lightly sand to round-over (or bevel) the tops of the new cuts so that they don't look so newly-modified. Even though these boards may not match the gaps (or lack of gaps) in the other boards, it's probably a small price to pay if you want the deck to drain - and it will work well.

It's a really simple job. The reason I asked where you are located is because if you were near us in Auckland, I would be happy to do it for you - but it sounds like you will have a builder on hand shortly anyway.

Thanks, @eracode, that's an awesome offer, and a pity I don't live in your neck of the woods! Also, appreciate the tips on how to go about it; I do have a circular saw, but am not the most adept at using it - I think I'll be ok provided the blade fits cleanly into the gap where it's wider, as I'd not be comfortable if this wasn't the case. Depending on when the builder's going to start his work I may see if it's feasible for me to do.

So you don't reckon I need to use a relatively narrow blade? I'd have thought that may minimise how different this part of the deck looks from the rest.

A narrower blade would definitely be a nice-to-have but not essential IMO.

Yes - making a plunge-cut with a circ saw is probably not an easy thing if you're not an experienced user.

Sometimes I just sit and think. Other times I just sit.

eracode

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#3128797 17-Sep-2023 18:30

@jonathan18 Interested to know if you found a solution.

Sometimes I just sit and think. Other times I just sit.

jonathan18

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#3128801 17-Sep-2023 18:55

As I suspected, waterblasting the deck got rid of a good amount of @#$$#% between the boards, and using a multitool as suggested above helped clear out even more where I did it, which was focusing on the worst parts where the water was pooling. This has led to less water pooling, allowing the boards to dry further, so not so much swelling, so… you get the idea!

The builder starts work on the fence and car pad tomorrow, and I’m still planning on asking him about increasing the gap with a circular saw for a long-term solution. Will report back in a few weeks on how successful it’s been.

In the interim, I’ve made much more important improvements - namely putting up 60m of LED fairy lights!

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