DIY Deck Build - Advisable?

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Paul1977

5047 posts

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#2637510 18-Jan-2021 18:40

wally22:
OK.

Make a bridge at right angles to the pipe that the bearer can rest on. If the horizontal piece of the bridge ends up below ground at all, use a pile(H5) for it.

Earlier you mentioned cutting piles. Always paint the cut ends with Metalex Concentrated Timber Preservative using appropriate safety precautions.

Alternatively and preferably, don't cut any piles. Some builders will happily cut piles and not treat the cut ends. The treatment is an envelope system so any break in the outside of the envelope should be retreated, but will not necessarily be as effective as the original commercial pressure treatment.

Shouldn’t be below ground level, but would be close. Using an H5 pile on its side as a bridge as you suggested is a good idea.

I was planning on on painting any cuts, but hadn’t looked up what product was required so thanks for that.

geoffwnz

1593 posts

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#2637717 19-Jan-2021 08:18

Useful thread. I've been looking at putting a decking over the top of a shoddy concrete path between my house and garage and was looking at the grooves up vs down thing. Turned out that because it will be a main access way, I need to meet the slip resistance so will have to put the grooves up and at 90 degrees to direction of travel. So that solved that conundrum for me.

As far as keeping it clean, I guess the deck brush attachment for the waterblaster will get plenty of use. :-)

MotorDrive Rallying

chevrolux

4962 posts

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Inactive user

#2637736 19-Jan-2021 08:38

Why would some concrete over a pipe matter at all... I think that's some serious over thinking.

Seems like a hell of a lot of piles too.. But I guess if you're using light timber, makes sense.

Paul1977

5047 posts

Uber Geek

#2637829 19-Jan-2021 10:14

chevrolux:
Why would some concrete over a pipe matter at all... I think that's some serious over thinking.

Seems like a hell of a lot of piles too.. But I guess if you're using light timber, makes sense.

Probably overthinking a lot of it, but since I haven’t done it before I’d rather overthink it than underthink it and get it wrong. My concern was having a weight bearing concrete footing directly on the pipe could crush it if too much weight was applied.

It is a lot of piles. Because of limited ground clearance can really only use 90x90 bearers and 90x45 joists which limits the maximum allowable span of each.

I’ve arranged for another builder to come over for an hour or so to check over the site and plan and answer any questions I’m still not 100% sure about - and give me some pointers. I think it will be money well spent (for peace of mind with nothing else).

WinNZ90

196 posts

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#2638396 19-Jan-2021 18:43

chevrolux:

Why would some concrete over a pipe matter at all... I think that's some serious over thinking.

Seems like a hell of a lot of piles too.. But I guess if you're using light timber, makes sense.

I have a conversation with the plumber just yesterday about this fact. He said that you can can push the piping around so long as the fall of the direction of flow remains the same but due to how concrete dries the pipe could get damaged.

I had a talk with him again today and he said that you should avoid putting it directly over the pipe all together as it could cause issues with the direction of flow and instead of having a slight fall for the direction of flow, it might cause the fall to change and then you'd be having to dig everything up and redoing the pipe.

However he did say that if you want to do a little extra work dig up more of the pipe, enough to gently shift it out of the way so you can get the pipe where you need it.

Jase2985

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#2640708 23-Jan-2021 20:58

chevrolux:

Why would some concrete over a pipe matter at all... I think that's some serious over thinking.

Seems like a hell of a lot of piles too.. But I guess if you're using light timber, makes sense.

because the weight of the deck is on it.

Froglotion

208 posts

Master Geek

#2640725 23-Jan-2021 23:44

I'd just put in an extra row of piles where they impact on the drainage. Cost isn't much in the scheme of things and it removes any stress on the pipes. Then just run an extra bearer and run the joists as per plan. I did a similar setup for my deck, and had to avoid a bunch of pipes so had piles in odd places. Didn't matter in the end as once finished you'll never know. I also used that metalex stuff when I cut all the piles in half. I made sure to have the uncut end in the ground and treat to top end. I also cut 45 degree bevels on the top where they sat either side of the bearer so water can't sit on the top of the pile.

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