We are about to embark on building an outdoor deck over our existing stencil concrete patio.
We are leaning towards using the Ekodeck product and have come up with a deck design for our given space. We want to keep it pretty simple due to having to work around a bay window. (See 1st image….. showing dimensions, placement of breaker boards and orientation of boards, and where bay windows are - hope you can read my diagram).
Now that the deck design is finalised I am planning the substructure and trying to prepare a list of all the materials I require for this part of the job. This next image shows the plan for the substructure - noggins are in place to support breaker /end boards).
After reading though a number of discussions on this forum I have noticed that when using a timber product for the deck that you recommend allowing as much space beneath the deck as possible for air flow etc. In particular I noted you recommended the use of 90x45 H3 Treated Pine and attaching to concrete using Dynabolts and heavy duty zinc plated angle brackets (ensuring timber is not in direct contact with ground).
However as we do not want our deck to sit flush with our brickwork, we were thinking of using the 70x45 instead? The concrete does not pool any water and is currently completely covered with a Vergola / pergola. I understand ekodeck have a minimum ground clearance with adequate drainage of 40mm, so I hope that using the slightly smaller timber would be ok - ie strong enough to support the deck traffic /no sponginess under foot). Do you think this would be ok?
Assuming it’s ok to use the 70x45 H3 treated pine, I was wondering about the carina heavy duty zinc plated angle brackets. Would using the 50x50x40x3.5 be strong enough (rather than the 75x75x40x3.5)?
This may be a silly question (and my husband will probably know the answer, but how many Dynabolts go into the concrete per angle bracket - 1 or 2?
Similarly what screws do you recommend for attaching bracket to the timber joist - am I correct in assuming 2 screws per bracket? Any particular screw you can recommend?
Where the joists attach to the outer frame do I use joist hangers or can these just be screwed in from the outside into the end of each joist (with countersinking so doesn’t affect the way the fascia board sits)?
Finally should I be using Protectadeck PVC Joist system? And if so where do you recommend it is applied - where timber meets brickwork or where screws go into concrete, or both / neither?
I think that about it for now - just wanting to plan for all the materials and costs to start with.
Thank you for joining us and sharing your questions about your Low-level Ekodeck over stencil concrete slab project.
Thank you so much for sharing your decking plans with us. It's great that you've found information and inspiration from the low-level deck projects that have been shared in the community. I recommend using the Treated Pine Outdoor Timber Framing 90 x 45mm if your space allows it. It will save you from having to put too many angle brackets to support it. Using a Treated Pine Outdoor Timber Framing 70 x 45mm can be used but will require extra support.
I suggest using the Dunnings 50 x 100 x 50 x 5mm M12 Galvanised Angle Bracket as it is made for exterior use. One Galvanized Dynabolt is enough to hold the bracket in place. I recommend Galvanized Hex Head Screws to screw the bracket into the timber. I propose using Joist Hangers as they provide greater shear force support to joists. Using Protectadeck 45mm x 25m PVC Joist is highly recommended for both applications. It sounds like a fantastic deck project, we would be keen to see any progress you make while building it.
Here is a link for ideas and inspiration: Top 10 most popular deck projects
If you need more advice or information, please let us know.
Hi @Nat2 full-marks for forward planning!
As was mentioned by @EricL you can use the smaller spec timber, it just means adding more support. No biggie really.
For the extra supports you could even use TuffBlocks.
As was also said, one bolt is normally more than adequate in this sort of situation. Personally I prefer to use screw bolts as I've found you avoid that issue you sometimes encounter with Dynas where they start slipping. You can also put a screw bolt in very close to an edge without risk of cracking as they don't rely on expansion to lock in place.
Thanks Adam and Eric for your advice. Great tip about the screw bolts….. I will be sure to do that especially close to the concrete edges. I will finalise my materials list and get ready for starting to work on it.
This will be an impressive deck when you're done @Nat2 - looking forward to seeing it.
When I install over concrete/brick I use 40x40x3mm aluminium frame as it gives you more room to play with the smaller dimension and you also don't need to allow the airflow you've read about as there are then no timber components in the deck. I've also used composite joists however these must be installed flat/flush on the concrete/bricks as they're not strong enough to bare weight without full support - they flex and snap.
Thanks ProjectPete. That is a good option to consider in our circumstances. I know Ekodeck make their Quickfit kits and clips to suit either timber or steel joists, so it couid be something for me to explore in terms of costs for materials and any additional tools I may need to purchase (such as pop rivet gun to attach clips or different drill bits etc).
We are in the early stages of this project, but I will definitely take photos and post updates as we progress.