What distance can pavers be from weep holes?

[TimGeo]

I have just completed my deck and about to plan for my next task of building bluestone pavers in a stepping stone style. I planned to have the top level of the pavers at approx 150mm below the F.F.L of the deck which coincidently is the exact level of the bottom of the weep holes of the house as seen in the photo.

I will be using about 100mm thick of concrete pad per paver ontop of a base so I will be moving some of the existing material around to level it out at least so the base is on a somewhat level surface.

I haven't decided what material to back fill between the crushed base and the pavers to fill the gap, but essentially the substrate top surface will be 10 to 20mm below the weep holes.

I may even back fill most of the way with soil, and a layer of stones or pebbles to satisfy any ventilation issues with the weep holes, that way I can at least plant ground cover between pavers and still be freely draining.

I would like to know if this will be ok, and perhaps any tips, I know the minimum should be 50 to 75mm space but I'm taking drainage into consideration 

[MitchellMc]

It's likely a bit difficult to give you a concrete answer there @TimGeo. 

Weep holes serve two main purposes; they allow any moisture in the cavity to drain out and provide ventilation. As long as the weep hole can drain moisture and ventilate the cavity, it operates as intended. If your fill is not above the dampcourse line, then I can't see you introducing any moisture into the brickwork either. Your dampcourse is likely in the mortar line directly below the weep hole. 

The regulation of 150mm clearance to ground level and 75mm to concrete is there to provide a buffer in the case of a torrential downpour. These clearances should be adhered to if you are in a high-intensity rain area. Whether your backfill substrate is considered the ground level, would be up to interpretation. If you're using soil, then it would be. If a flood of water comes through, it will run straight into the weep holes.

You also need to give consideration as to any termite treatments and whether access to the slab is required for them.

Please let me know if you have any questions.

Mitchell

[TimGeo]

Thanks for the input,

as for any kind of torrential downpour, I've neer experienced any flooding on the side or the back of my pathway around the building, i would have to dig a small area near the side to confirm the location of any storm water drainage, as I mentioned with the deck build I found a slotted PVC pipe at 600mm from the building buried in scoria which I would assume runs the length of the wall, past the existing alfresco into a trap ( I will have to open the lid to see if my assumption is correct), which would definately explain the excellent drainage, even when I've left the hose running and there's been pools of water, it's gone within minutes when the tap is turned off.

If we're using the dampcourse line as a reference then as seen in the photo the ground level is currently 75mm below, and the pavers would be 150mm from the deck (in line with the bottom of the mortar), does backfilling up to 65mm depth of a larger diameter pebble (20-60mm) sound like a viable option? 

[MitchellMc · Accepted solution]

The larger the pebble, the better for drainage @TimGeo.  

I can't give you a definitive answer as to whether this is a viable option; you'll have to make the decision on whether this is something you're comfortable with yourself. Given it's against regulations, if there was ever a freak torrential downpour that reached your weeper holes and flooded inside, your insurance would be compromised, and I'd hate for that to happen.

Mitchell

[TimGeo]

Hi Mitch, that's completely understandable,  of course I understand it's a risk, and I'd have to take many things into consideration before going ahead, one thing I have on my side is that I am higher up that my neighbour by 200mm or more on that side of the house, but I'll speak to some people and see what solution I can live with haha

[TimGeo]

So I just wanted to get your opinion.

This is the material that was under the lillydale toppings, it's what I removed from the decking area, I'm not sure what type of base this is but I would like to know if it's possible to re-use this material as my compacted base and lay my concrete pad on?

My brother is a landscaper so he recommended:

20mm paver

20mm mortar

100mm concrete pad

30mm crushed rock

since it appears that I have enough of this to possibly level the whole area and then some, I thought this could be ok to use instead of buying crushed rock and save on the cost of paying for unnecessary material and hiring a bin and removing all this waste.

Would this be stable enough to support the weight of concrete, mortar and pavers? I want to save on cost where I can but I also don't want anything to shift over time.

Thanks!

[MitchellMc]

Hi @TimGeo,

That appears to be something that we call roadbase. It compacts exceptionally well and provides a stable surface for a variety of toppings. I believe using it instead of the 30mm crushed rock would be fine; just make sure to go over it with a compactor.

Please let me know if you have further questions.

Mitchell

[TimGeo]

Hi Mitchell, 

Perfect thanks heaps! Yes I'll be going over with a compactor, thanks for clarifying 👌

[TimGeo]

Hi Mitchell, 

I'm getting close to the point where I will need to level out my road base and compact,

I plan on having 20mm paver, 20mm mortar and about 100mm concrete pad, I have pretty much removed the clay down to 200mm below the top of my pavers, which I thought 60mm of compacted road base would be enough material to support all that weight.

I filled up a small section and whacked it with the flat edge of my rake just to get a visual idea of the height I needed, and I just have some doubts to whether it's enough, I know when I run the plate compactor over it will crush it down even more, which I can top up, but do you think 60mm is OK? Or should I go to 100mm, i can either dig out more material or just make my concrete pad 60mm if need be.

thanks! 

 

[EricL]

Hi @TimGeo 

I believe you can get away with a 60mm concrete pad. Just to give you an idea of how much weight 100mm of concrete can hold. It's strong enough for a standard 4 wheeled vehicle to park over. So 60mm should be enough to hold a fair bit of weight.

I recommend observing the actual height you get after running it over with the compactor. This should give you a better idea of how thick you'll need your concrete pad to be.

If you have any other questions we can help with, please let us know.

Eric