deck joists - moisture protection?

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aucklander

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#268081 27-Feb-2020 08:31

Hi,

I have come across an idea that it is worthwhile to protect the top of the deck joists before installing the decking boards, to prevent or at least minimise water ingress into the top of the joists. At the same time, this method might also prevent quick drying of the top of the joists... so the opinions might be divided between different builders...

have anyone used such method, and was the Council inspector in agreement with using such method?

Most products for this purpose are the type of self-adhesive bitumen tape, I am also consideirng using some bitumen paint (waterproofing) for the top of joists before installing the decking.

Any ideas or advice, please?

thanks.

eracode

Smpl Mnmlst
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#2427981 27-Feb-2020 09:14

IANABuilder but I simply would not bother - standard pine joists with the correct and specified treatment level will last for decades. Depending on what you use, you may create more issues than you avoid. No need to overthink this.

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

sqishy

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#2427985 27-Feb-2020 09:20

I agree with above, wood get wet, drys out in sun and if correct treated it won't have an issue.

I guess there could be some changes if the deck doesn't get much sunlight or always damp.

But these things can cause a new problem 10 years later no one though of at the time.

Bung

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#2428048 27-Feb-2020 09:33

I suspect some of the extra protection ideas are from areas where untreated hardwood is more common. With pine you can often go up a treatment level to H4 or 5 for not much extra cost depending where you buy.

I rebuilt a 30+ year old deck that had a lot of damp sand sitting on the joists in the gaps between boards. Of 12 joists 3 had soft spots. Maybe current treatment wouldn't be the same.

Dugimodo

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#2428052 27-Feb-2020 09:39

My deck is 23 years old and the decking timber is getting to the point where I'm considering replacing it. The joists however show no signs of rot or water damage at all. I recently lifted a section to build a step into my deck, everything under the deck is in good condition.

I think you've found a solution for a problem nobody has.

There may however be situations where it might help, a deck with poor air circulation maybe, or very close to ground level?

aucklander

478 posts

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#2428085 27-Feb-2020 10:36

OK,

I agree, I might have tried to find a solution to a problem nobody has...

Deck is approx 2.5 - 3m above ground, and in full sun after 11:00 a.m. so poor ventilation or damp / shaded area is not applicable.

thank you all for your opinion, timber is H3.1, so I was just worried for nothing...

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Jase2985

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#2428086 27-Feb-2020 10:39

i suspect localities were this is common have things like standing snow, where the wood would be constantly wet for long periods of time. its unlikely to be the case in the vast majority of NZ

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SATTV

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#2428568 28-Feb-2020 07:39

We have been wanting to do our deck and have seen some Aluminium framing systems and they look amazing, no warping, twisting and most of all no rotting.

https://www.outdure.com/?gclid=EAIaIQobChMIiJ6Cj7Dy5wIVE6mWCh20OA56EAAYASAAEgLMlfD_BwE

There is another company

http://proframe.co.nz/

I think the Outdure looks like the better system.

I have lots of rotting wood here so we are avoiding wood where possible in our back yard.

John

I know enough to be dangerous

SATTV

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#2428569 28-Feb-2020 07:39

We have been wanting to do our deck and have seen some Aluminium framing systems and they look amazing, no warping, twisting and most of all no rotting.

https://www.outdure.com/?gclid=EAIaIQobChMIiJ6Cj7Dy5wIVE6mWCh20OA56EAAYASAAEgLMlfD_BwE

There is another company

http://proframe.co.nz/

I think the Outdure looks like the better system.

I have lots of rotting wood here so we are avoiding wood where possible in our back yard.

John

I know enough to be dangerous