How to build a gravel path and drainage?

[FernyG]

Hi Bunnings Community,

Long-time reader, first time poster, thanks in advance for any advice and apols … my photos got in first and questions are below 😊 👇

 

 

 

 

 

 

My problem

• Previous owners laid pavers and stormwater drainage pipes too high beside my house, plugged up the weepholes in bricks for years and caused rising damp inside lower level (just fixed professionally and quite spendy).
• Problem exacerbated by use of an ag pipe (also previous owners) for part of the stormwater beside the house instead of a PVC pipe, connected into downpipes.

The area

• We are in Queensland - not in a flood zone or any problems in that regard - but it rains a lot and storms can be big. 
• Some water flow comes down from the back garden (terraced) through this area when it rains but does not pool and has always drained off quickly through the pavers. Backyard drainage is fine.
• The side of the house is 11m long and 1.45m wide so not a lot of area to play with.
• Clay type of dirt, high water table after years of rain.

The project (see drawing)

1. Removal of pavers (partially done) 
2. Dig down to bring ground level lower than bricks (currently at least 15cm above the bricks, we're hiring a kanga)
3. Slope the ground away from the house and create fall down to where pipe will join stormwater (there is a nice existing fall once you get past the side of the house towards the front) 
4. Trench and installation of PVC stormwater pipe at correct level (will get plumber for connections) - will use 20mm drainage gravel all around pipe and wrap in geofab 
5. Create a gravel path with 600mm x 600mm paver steps 
6. Plan is weed mat + pins, roadbase or 20mm gravel (100mm deep), compact, sand (50mm? deep), compact, install pavers, decorative gravel (50mm deep).
7. Lift old pavers out front of the house and reuse side pavers, as well as another gravel path. 

Questions - apologies, there are a few  

Materials - There is a LOT of material there now - at least 150mm above the bricks in places so I believe we need to dig out 300mm then put in the base/sand/gravel for 150mm then we're ideally 150mm below the bricks. And how far we dig the trench for the PVC pipe depends on height of stormwater connection (don't know that yet as pavers are not up). 

As pictured, I think what is there now is sand and roadbase (see pictured). We are going to have to dig out so much to dump in a skip, and planned to buy new stuff, but is there a way to reuse? 

The problem is it'll be all mixed up and the material will have grass/weed seeds all through, weeds have been a real problem and want to resolve that as well. Could we maybe do the first 50mm layer old dirt and compact, then weedmat, then 50mm fresh roadbase or gravel? Gravel appeals more for drainage benefits. Then 50mm sand, then 50mm decorative gravel.  

At least then we'll only have to buy half as much roadbase / gravel. Is there a risk the flow from the garden will wash the gravel away if we get a big storm?

Slope

Slope away from house (side): 50mm for first metre I think, then what? The slope away from the house will be towards the raised beds. We had thought about an ag pipe there as well but want to keep it simple.

I'm not clear how we lay the pavers to be flat down the centre if there's a slope?I know the fall to the stormwater connection is minimum 100mm per metre.

Trench 

How far out from house to trench to install the PVC stormwater pipe but still connect to downpipes. The downpipes are new and the plumber said to angle out from the house as much as possible as the old ones were flush and have rotted wood in our cladding.

The trench may not be that much lower than the rest of the ground level depending on fall requirements. If we wrap geofab and surround in gravel does it need to have something to separate it from the 'rest' of the gravel / roadbase for the path? Otherwise it is just sitting all at the same level. But then if we put in a metal separator or something that might trap the water by the house (again) ... sorry I'm not quite sure how to phrase this question. 

Thank you for reading if  you got this far!!   

[FernyG]

@Nailbag - that’s a bloody good idea. Basically all we need is the opportunity for the weepholes to be free to the air but it doesn’t necessarily have to be along the whole wall I suppose does it? I’ll ask my mate. A retaining wall will also take up space in what is already a narrow area. Might be a good way around it. I got those weephole covers today… tomorrow is cleaning off the wall and trying to differentiate between weepholes to clear out, and mortar that has dropped out. The joys. Thanks again, you’ve really given me something to think about! 

[Nailbag]

Morning @FernyG I do have my moments of bright ideas. But I'll will be interested in what your builder mate reckons so please keep us in the loop.

If he agrees. it will be handy to know for future community questions as there are regular posts that involve peepholes in various scenarios.

Nailbag

[FernyG]

Hi @Nailbag @Dave-1 - an update on this. My builder mate has had a detailed look and as our house is a single brick layer, there is no cavity and he says no weepholes would have been included or needed. What I am looking at are holes in the mortar. There are 16 bricks on the inside to floor level..that matches the level the dirt was up to outside the house. If the weepholes were below that they would be lower than the concrete slab floor inside. The bottom of the house was originally likely not designed as a habitable room. Our new plan - redo the mortar with a waterproof additive, waterproof the wall. Get plumber to install an ag pipe carefully next to house to capture all the water coming out of the clay soil (there’s lots!), backfill the wall with road base and gravel on top and grade away from the house so hopefully the water doesn’t get there. Surface water to be caught by 3 x pits but with the gravel / roadbase the water will fall through so I want to make sure I don’t make the clay any wetter. Thanks for all your advice, so much appreciated! 

[FernyG]

@Nailbag - re the weephole covers - I am not sure if it works but did also see that half pvc pipe solution on a reddit thread which said it did the trick. 

[Nailbag]

Sounds great and thanks for the update @FernyG your off and running.

Nailbag

[Nailbag]

Yes I have done the same to @FernyG and also with short cut sleep blocks. I only suggested the downpipes due to the potential depth. Great to hear you don't need anything.

Nailbag