h3 deck frame, ground contact 1 side

[bigbird21]

I have completed my deck frame & started laying composite boards and just realised a 1500mm section & a 1170mm section of outside h3 frame will be touching soil when backfilled. It works out the top of the frame will be level with the ground outside of the fence.

Will it be alright as 1 side is touching ground?

Could I add some h4 against the h3 as a barrier from direct contact to soil?

Looking forward to your opinion.

 

[JacobZ]

Hi @bigbird21,

A warm welcome to the Bunnings Workshop community and thank you for your question.

Attaching some H4 sleepers to the outside of your bearer is a good solution to help protect it. If the width of your decking allows it, make sure to run it over the top of the joint between the H3 bearer and the H4 sleeper to prevent soil from getting in between them. Alternatively, you can attach the sleeper so it sits the height of your decking board above the bearer and your decking butts into it. This will give your deck a nice clean finish and protect that outside edge well.

As your timber is sitting very close to the ground, airflow will be minimal, so any way of preventing moisture from getting inside the bearers is a good idea. 

As an additional measure, I'd suggest coating the bottom third, and outside of your H3 bearer with bitumen membrane and running Protectadeck 45mm x 50m Flexible PVC Joist or CAgroup 50mm x 20m Bearer Protector G-Tape along the top of the bearers. These additional products can help prevent water from getting into the timber and prematurely rotting them.

Let me know what you think.

Jacob

[bigbird21]

Thankyou, I was hoping could add some h4 instead of pulling it up and re-doing the frame.

It's a sloped site so the area from gate approx. 2000mm working right, has a clearance of 30-40mm at base of frame then it gradually increases to a maximum of 140mm (ground to base of frame) over a 5400mm length.

 

For the smaller triangle area  roughly 1170 x 1440 (not yet built) to the left of the gate I am planning to use 70* 45 h3. 

[JacobZ]

Hi @bigbird21,

Ideally, you would create a small retaining wall just outside the fence line so no soil erodes underneath the deck over time but as long as the H4 stops the soil from touching the side or bottom of the H3, it should be ok.

Wherever you can create ground clearance it is certainly worthwhile, so if the triangle area you've mentioned is low, it might be worth excavating some soil, but it's entirely up to you.

If you have any other questions, don't hesitate to ask, I'm happy to help wherever I can. 

I'm excited to see the finished result, so please share some updates once you've completed your deck.

Jacob