Page 1 of 1

Posted: Tue Aug 19, 2008 2:01 pm
by bluke
Hi

I am about to start on a paving project in a terraced garden. I have excavated a lot of soil from the garden, a deck has been put down and 2 borders on the left and right of the garden have been created using oak sleepers. Now I want to lay Spanish Terracotta tiles (30x30x2.2) on a central path (1m wide x 7 m) and the back area (4x 2m) to create a path and patio. The pictures here show the back patio area.

Image
Image

The first problem I have is soil stability. I discovered an Andersons air raid shelter when I dug down and have removed all protruding pieces of corrugated iron..but the soil now has quite a few soft areas where there are probably cavities and things…I am not sure what to do?

The steps as far as I see it are

1. Level the area (almost complete)
2. Lay some kind of geotextile…like what? Do they make geogrids for gardens? If so who does it? All the companies look industrial?..or should I just put a weed suppressant
3. Lay the hardcore to 15cm depth (I have wickes granular sub-base in bags..hope this is right)
4. Hire a vibrator plate and flatten it…get the fall right too
5. I am a little unsure of the next steps..should I have a thin layer of sand?
Any help or pointers would be appreciated particularly in relation to the soil stabilisation..I get the feeling if I just bulldoze on with the work the patio will sink in the future.

regards
Bluke

Posted: Tue Aug 19, 2008 3:50 pm
by Tony McC
Remove any loose/soft material

Lay a geo-textile such as Terram BuildA, TDP115 or LoTrak

Backfill in layers not exceeding 100mm* depth and consolidate fully with plate compactor or rammer before placing subsequent layers.

* - normally 150-225mm but that assume big heavy plate compactor or roller available

Finish off sub-base at a level approx [thickness of paving] + 40mm

Lay paving on 25-40mm bed of cement bound laying course. See Bedding Materials page.

Posted: Tue Aug 19, 2008 4:12 pm
by bluke
Thanks a lot for this prompt response.

Can I just clarify that when you say remove any soft material do you actually mean dig down into the soft spots?

As the terram looks pretty flexible..If I lay the Terram over the prepared soil then put the aggregate down to 100 mm and compact it, I presume that in the areas where the ground sinks under foot..I will just need to put more aggregate as it pushes down into the cavities?

Will I or should I leave the aggregate layer for a while before continuing with the project to see if their is a really big problem or am I worrying too much?

Posted: Thu Aug 21, 2008 8:10 pm
by Tony McC
Remove the soft spots as far as practical, then compact and lay the geo-sheet. Then build-up your layers.

If you consolidate thoroughly, no need to delay further construction work.