The Brew Cabin

Posted: **Tue Feb 07, 2012 5:15 pm**

I am planning to lay patio in the back garden directly off the back of the house. Already there is a flat, smooth and un-cracked concrete base running the width of the house (5m), 2m into the garden (~10cm high) that I guess is the remnants of a lean too. I plan to pave onto this base, but it doesn't quite go far enough into the back garden, so I would like to extend out by a 1m. Having been bamboozled by this site, my father-in-law and BandQ videos on you tube, I thought I would put a few questions to the Brew...

1. How best to extend out into the garden (which is currently grass), what sub-base etc do I need? How far to dig down etc).

2. I am thinking some kind of bound/mortar mix would be the final layer on this extended area, and I would pave onto that - correct? Is there something pre-mixed I can use?

3. Do I need a layer on top of the current cement base which is there before I can pave on? And how should this best join with the final layer (question 2) on the area I have extended?

4. To lay the slabs, should I use a 5 spot (totally lampooned on this site and recommended by father in law....)?

5. With no experience am I mad to even consider this?

Huge thanks in advance

PS - I plan to use calibrated thickness natual limestone slabs of varing size and shape - like these: http://www.homebase.co.uk/webapp....=735777

Posted: **Tue Feb 07, 2012 6:08 pm**

First of all, after the paving is laid on top of the concrete, how high will it encroach on the Damp proof course? 150mm below is the rule.

Is the concrete sound, solid, no movement, how thick is it?

If it were me id be pulling it up and starting again with and MOT sub-base and 40-50mm sharp sand and cement bedding course.

no the 5 spot method is an absolute no no!

Posted: **Tue Feb 07, 2012 6:29 pm**

How do

1. You need to excavate down 150-200mm depending on how soft the ground is. That will give you approx 100mm for a subbase, 50mm for a bedding mix and then 25mm for your paving material

2. You need to use MOT type 1 for your subbase, You can buy it from Travis Perkins or any good builders merchants. Expect to pay Â£40 ish per ton + VAT

3. If the concrete base is in good condition then you will not need to add anything to it but if it is in bad condition may be worth following DN's advice and ripping out and starting again (assuming you dont want to do this, send a picture so we can take a look )

4. Dont use spots if you want your patio to last for more than six months. Full bed of mortar only

5. Your not mad to consider it but spend a lot of time reading the site first and take your time

6. The limestone slabs are well overpriced. Â£8.99 per 600x300x22mm slab is the equivalent of nearly Â£50 per m2. Daylight robbery for black Indian limestone. We charge Â£18 per m2 for our black limestone and ours has a sawn edge. The stuff homebase are selling has a handcut edge and if you shop around on line you will find it available from as little as Â£12 per metre up to Â£20 per metre. I would never buy natural stone from homebase because they aint got a clue what they are selling.

The black limestone you have chosen is particuarly sensitive to chemicals (i.e the application of certain chemicals for cleaning will completely knacker the stone), probarbly needs sealing and is difficlult to clean. Thats information that homebase wont provide.

Steve

Posted: **Tue Feb 07, 2012 6:33 pm**

realistically better to break the concrete out and start afresh
with a new 100mm type 1 sub base
you need to dig down 150 mm below finished level ,add the 100 mm type 1 then 30 mm of bedding ,finally your flags

you need to mix grit sand and cement for your bedding mix
as specified elsewhere on this site

5 spot pffft! i take it you married the missus for her looks and not daddies technical help
:;):

and it is do-able for a keen ,reasonably fit DIYer,but you must be prepared to listen and learn from the pros

good luck LLL

Posted: **Wed Feb 08, 2012 9:57 am**

jamesb wrote:5. With no experience am I mad to even consider this?

The others have given you some good advice. If you look around on the forums you will see plenty of threads where people with no experience doing great jobs that would put a lot of pros to shame.

The Brew Cabin

Newbie patio advice