How to fix pergola posts and build a deck over brick pavers?

[NadineC]

We’ve just demolished our rotten, dodgy deck. A couple of problems to solve:

- the pergola is in good shape, we want to keep it but the posts are split at the base and 

bolted onto a rotten bearer sitting on half bricks

- we’ve got 280mm to the floor level (top of the sliding door window sill) over solid brick steps I don’t want to have to remove, 440mm over brick pavers for the rest of the deck

- the brick pavers are over steel reinforced concrete so we want to leave those, it also gives us a base level higher than the surrounding path so water won’t flow under the deck

Can I put a bearer 50mm over the brick step and 210mm over the rest of the deck, or am I better off designing a single level structure with joists inside the bearers?

How can I strengthen and secure the pergola posts, as there’s a verandah roof sitting on them?

What’s my best option to fix to the brick pavers- they slope so I might need something I can adjust the height and the angle, or I can build to the existing deck slope. 

Thanks very much

  

 

[JacobZ]

Hi @NadineC,

Thank you for your post and welcome to the Bunnings Workshop community, it is fantastic to have you join us.

It's exciting to have you join us at the beginning of a decking project like this. I am keen to help you in whatever way I can.

I'm struggling to see the overall picture of what you're trying to achieve. Is it possible to get some photos aimed back at the deck area, as well as some photos of how the deck is currently anchored to the ground?

Are you looking to remove all of the existing deck and replace it? Or is your final image where the decking boards have been removed what you are currently working with?

When you ask about whether you can build 50mm over the brick step and 210mm over the rest of the deck, are you referring to the concrete wall on the right of the second image? I have circled this below.

If this is what you are referring to, there is no issue having the deck sit lower to this than the rest of the area.

Unfortunately, I am not confident in the pergola posts being supported how they currently are. Without seeing the way all of the posts are connected, there does not appear to be any kind of bolt down, or concreted attachment to the earth. Without attachment, I would be extremely concerned about uplift, which is the lifting force exerted on roof structures by wind. Without suitable attachment to the ground beneath, it is possible that it can be picked up and thrown by the wind.

My first suggestion is that these pergola posts need to be removed and replaced with a similar sized post that is concreted into the earth or bolted to a suitable footing beneath. This will anchor the pergola down as a completely separate structure to the deck. This can be achieved by propping up the pergola with Acrow Props, cutting out the old posts and replacing them with new ones.

The next problem I see is that bolting the deck to brick pavers means that once again the deck is not connected to a suitable base. Decks are also subject to uplift, and bolting to brick pavers means that you are only connected to an individual paver, which is not heavy enough to counteract uplift.

I would suggest where you want to attach the deck to the pavers, you remove a paver to expose the concrete beneath. You can then use a bolt down anchor such as this Pryda 90mm M10 Bolt Down Post Anchor, attached to the concrete with Ramset 10 x 100mm Galvanised DynaBolt Plus Hex Nut Bolt, with a suitably sized post to support the deck above.

This will ensure the deck is both supported and anchored in place.

Allow me to tag some of our knowledgeable members to see if they have any other thoughts or advice to offer, @Nailbag, @Jewelleryrescue, @Dave-1.

Let me know if you have any further questions and when you get back in touch, I will be happy to offer further advice.

Jacob

[Dave-1]

Afternoon @NadineC

Mmmmmm I can see a few issues with the posts and rails. 

I was going to say the rail between the posts definently needs to go and then I took a closer look at the way the timber is joined to the post... I wouldnt be trusting that at all. 😕 The way the posts are resting on pavers kind of makes me think they used short posts to start with.

When I have notched timbers to slot in a rail I go no further then 1/3 in on the post. (Keeps 2/3rds for structual reasons) It looks like this only has a third of the post left. Some of the joists look like they have long term weathering/rotting sections as well.  (I have gone half way but that was hardwood timber)

From what you have shown us I would be tempted to redo the posts, bearers and joists as well. Otherwise you may put a new looking top down with issues underneath. The posts I would suggest to replace as they will end up being to short as they need to fit into whatever you bolt to the concrete slab.

For the attachment to that concrete slab under the pavers I would definentyly be using something along the lines of what @JacobZ has recomended. I would also support the roof structure soonest with agri-props as they seem to be resting on pavers and ??

The old pergolla that I had when I first moved in to my place "flexed" when I walked on it. Not just because the floorboards were not the greatest but the underlying issues. When I started pulling it up you could really see the timber had rotted and even tho some pieces looked resonable I decided no point on building on bad foundations. This is stage one, there is a stage 2 if you want to look as well. Pool deck stage 1 

Finding a bad state of things dosnt have to mean hair pulling, just means you are fixing a problem now so that hair pulling dosnt happen so soon for next time.

The step height with the joists over it may become a non issue with the redesign of the deck base. Also 50mm clearance I would be happy with. As long as air can circulate and nothing can build up next to it it works. For the stirrups, there are a bunch of different types and it mightbe an idea to wander through the aisles. I stood for hours over weeks trying to nut out how I would go. The post sits within the stirrup but not resting on the base of the stirrup. I left a 20mm air gap so the timber would always stay dry and not rot. This would also work to your advantage of a slopping concrete slab as the stirrup bolted to the concrete and the post can be vertical and then drilled through for the bolts.

Dave

[Nailbag]

Hi @NadineC 

From the photos you have shown I would have to agree with both @JacobZ and @Dave-1 that those rotted timbers need to be replaced. The footings are makeshift being supported on bricks and timber blocks, making them very structuraly unsound especially as they are supporting not only the deck, but the pergola. They also should to be replaced with posts fixed via stirrups to the concrete base or into the ground. Unfortunately if these photos are a sample of the majority of the structure, it would be a more structurally sound long-term investment and time effective to rebuild from scratch, salvaging what materials are still in good condition.  

To make the job easier when replacing the posts you could use an Acrow prop. These can be hired or purchased, depending on how long you need them for. You could do one at a time or could possibly support the entire pergola while you work on the sub-floor. There is a larger range of lengths when you hire them and usually quite cheap.

Regards, Nailbag

[NadineC]

Thanks @JacobZ @Nailbag @Dave-1 

The good news is that the pergola is solid enough while I fix it and rebuild the deck. I agree the posts need to be replaced along with the bearers, joists and deck. In the meantime the pergola is bolted to the brick wall with a wooden beam and are bolted to the existing bearer which is on concreted bricks on the pavers. We’ve had plenty of wind and the roof doesn’t rattle or move at all, it’s also lower than the surrounding roof so sheltered.

I will work out a design using all of your helpful ideas and post it. Cheers

Nadine

[Nailbag]

That is great news @NadineC and glad to hear we are all on the same track with what needs doing on the deck.

Regards, Nailbag