Replacement for overshadowed outdoor deck that is rotting

7 years ago

last modified: 7 years ago

We have an overshadowed outdoor deck area that replaced a large portion of our small back garden where grass would not grow. Despite being in Sydney, Australia and facing north, in winter our deck does not dry out. Planks are now rotting and the deck is dangerous in parts. About 5 years after it was first built the decking boards need replacing - but not the substructure we hope. We are looking for advice and experiences of alternative decking materials that:

1. are attractive

2. will hold up to the wear and tear of 2 Staffordshire terriers (rules out products which scratch easily like Modwood)

3. are low maintenance (not keen on painting it yearly, though staining it may be ok if the boards don't need to be removed and stained or painted both sides)

4. will not become slippery when wet or become mouldy or mossy.

The current structure is low to the ground and over dirt with steel posts, H4 treated pine bearers that do not touch the ground, and H3 treated pine decking boards attached to the posts. Treated pine was an economic choice. We hoped the boards would grey but they have largely turned green, slippery and unattractive. Ag piping is laid throughout the deck substructure and leads into a drain installed when we built the deck. Despite what we have done to retain porosity and improve drainage, we fear it is not enough and we need to increase this. However, we are not certain this will be sufficient to stop the decking boards from rotting.

To maintain sufficient porous area in our garden we are unable to concrete the ground beneath the deck or to cover the deck. We have a large covered deck abutting this deck, built of spotted gum decking boards and bearers (a hardwood), stained and built over a concrete base which slopes gently towards a the same drain. This deck is great and has no problems.

Photos show the problematic deck and trees which overshadow it. The photos were taken at 5.30pm 22/1, with sun from the west getting to the deck. All trees are to the north and NE of the deck, so fully block winter sunlight. Note that we do not have control of any of the large trees - they are on neighbours land. We previously explored pruning the trees but this would be costly and ongoing, we believe.

Any ideas? Any experiences that might help us? We'd love to hear from you...

BTW, we would have loved to use a high quality artificial grass in this area but our high amount of leaf/tree litter, lower porosity of AG than our current deck and tendency for shaded AG to grow mould or algae (we hear) probably means this is not a viable option.

Featured Answer

oklouise

7 years ago

last modified: 7 years ago

sounds like the area wants to be a garden for shade loving native bog plants and a mixture of stones and gravel...do you need the extra hard surface of a deck that doesn't want to co-operate?

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Comments (14)

bigreader
7 years ago
The not drying out is surprising. Are you sure there is no problems underneath?
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Susan Clark thanked bigreader
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Susan Clark
Original Author
7 years ago
last modified: 7 years ago
bigreader, not sure at all though we did quite a lot when building the deck to aid water flow into the drain. We will explore that soon by pulling up parts of the decking boards and can address water pooling, but given the size of the deck we can't imagine it's a deck wide problem. As the problems we see on top of the decking boards are all over it, we assume the over-shadowing we experience is a major issue in itself... hence seeking an alternative decking surface.
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Susan Clark
Original Author
7 years ago
last modified: 7 years ago
oklouise, in one sense no, we don't need a monster deck. We avoided it for 10 years but got sick of alternating between mud and dust. Our staffies are dedicated gardeners unfortunately... as fast as we put plants into the ground, they dig them out. We had a very sorry excuse for a backyard before we fenced off part of it - despite spending thousands undoing their damage. I'm not sure I can properly envision what you are suggesting, but I fear it would return us to an unfriendly, barren garden.

UPDATE: I looked up 'bog gardens' and they can be spectacular. Wow. As the dogs need space to move around - and would destroy a dense planting in record time - I don't think we could do it right now, but it's certainly a thought for another time. Thanks
brixnmorta
7 years ago
My 1st thought was pavers, but your well defined question rules that out due to the possible mould. So, how about a radical solution, if budget allows - a patio roof with a translucent sheet or 2 (& no gutters where possible to avoid leaf litter clogging it) ?
Susan Clark thanked brixnmorta
wuff
7 years ago
Hi Susan, we used millboard, that does not scratch like modwood. It is expensive, however it is tough, major con is that it is very hot underfoot if it is in the sun, ours is all under cover so that does not affect our use of it. It is partially self healing. It is a far superior product to mod wood, more realistic looking and hard wearing. Bonus, no maintenance
Susan Clark thanked wuff
wuff
7 years ago
I think maybe leaving the pine deck to age without oiling may have contributed to its down fall,also that is a very heavy ( But nice) pot on the deck, pine is a softwood and that would be a lot of strain on decking boards. We had treated pine Decking that was wet or damp and in shade most of winter, we oiled it with good quality oil two or three times a year and it was an arduous task but pine stayed strong and water would bead off it, we endeavoured to do a coat in autumn before rain started. You may be able to change a few of worst boards and bring it back using an oil with a stain, it would need several coats to start with, don't use the water based coating use the proper decking oil for best results , good luck
Susan Clark thanked wuff
PRO
User
7 years ago
Hi

Love the setting!

From what you are describing, it sounds like you have a ventilation issue. A deck lower than 400mm off the ground needs to have ventilation just like the house.

This typically means the sides are open (doesn't happen) and the spacing is around 5-6mm between boards.

If you don't have this, the water that gets in cannot evaporate and will keep the ground and the underside of the deck moist, even with your drainage as it can pool in sections. This in turn means your deck is always wet.

Once that happens, it is only a matter of time before fungus growth/soft rot etc occurs.

We always excavate a low to the ground deck to ensure we have 400mm of clearance to the underside of the bearers.

Another way is to ensure there is a moisture impermeable membrane across the ground (plastic) covered with gravel and graded down with vents placed all around.

Cheers
PRO
MB Design & Drafting
7 years ago
My old treated pine deck held moisture as well even though it was regularly oiled, partly covered, etc. It got reincarnated as a privacy screen, some battens on our front fence, etc. Treated pine is good but I don't think it's ideal for decking, it seems to deteriorate after a few years. Probably great for veranda's though.

Hardwood even though not treated only oiled seems to outlast it pretty well. The new treated hardwood (IronWood/IronAsh/etc.) maybe worthwhile looking into.

Millboard seems to be good but I haven't seen any jobs done in it yet.
Susan Clark thanked MB Design & Drafting
Chris
7 years ago
Our deck is spotted gum which has various colours throughout and it quite pretty. We initially sealed the deck with a water based coating which needed to be recoated every 3 months. This wasn't going to last and so we stripped the deck back to raw and recoated with a good quality oil. We have given it four coats as the timber was dry from the stripping. This beauty of the oil finish is to re-coat we just need to wash the deck down, wait for it to dry and refinish. It looks beautiful now but it did take some work.
Susan Clark thanked Chris
brixnmorta
7 years ago
Hi Susan Have you got the timber grooves facing upwards or downwards ? As the following article says, they're not for aesthetic or non slip reasons. The installer is obliged to reinstall them unless you requested that way.

http://www.build.com.au/should-decking-grooves-face-or-down
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PRO
Vuetrade
7 years ago
last modified: 7 years ago
Just came across this, interested to know how your metal brackets are holding up with the moisture problem in your deck?

You might be interested in these blog posts on our website. Equally as important as the timber you use on decks is the construction methods and quality of the metal brackets used.

Decking around pools (I realise this is not a pool area but similar due to your damp problems)

Timber Decks And Balconies, Using The Right Materials…
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User
7 years ago
Paving or concrete would most probably be your most cost effective and lowest maintenance option long term. A pressure wash will easily deal with the mould and algae from Winter. Uncovered decks like this = maintenance. So close to the ground = more problems. Get your drainage right and concrete/pavers laid properly will be virtually maintenance free forever. There are also sealers around now that reduce staining and also block mould.
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PRO
Concept Products
7 years ago
airflow is certainly a concern. Water gets trapped under and the decking will soak it up. Millboard Decking however is the only board that doesn't have a component of timber fiber. This means that it will not rot/swell etc and wont need airflow.

Also the surface is non porous ensuring that no moss will grow on it which keeps it clean and non slippery.

Millboard Enhanced Grain jarrah · More Info

Millboard Smoked Oak decking · More Info
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