Slabs and acco's - Acco drainage

[dan_g_1]

Hi all,

My first post so would just like to say what a great website and forum full of educated and well described information.

In a little pickle of my own which I hope someone could help with? From reading through the website it states that the top of any slabs should be 150mm below DPC, when abutted up to a dwelling.

Just really enquiring could this 150mm become shorter if acco drainage was to be installed around the perimeter of the house?

I ask due to the fact that I am about to lay 45mm thick slabs around the front of my house abutting a wall roughly 5metres long, but there is already a concrete base in front of the house 100mm below DPC by the time I lay my slabs on a wet mix on top of this I am going to be close to DPC. So enquiring whether acco drainage will help my situation?

Another quick question is I am laying my slabs on a wet 6:1 mix so what thickness should my bed be on a) the concrete slab and b)70mm compacted type 1?

Many thanks for your awaited replies

[lutonlagerlout]

building control will allow us to be 1 course /75mm down with an aco installed but sounds like you havent got that
the aco its self needs to sit on 100MM of leanmix so you need to break the concrete out anyway
sorry
LLL

[Pablo]

Hi Dan, Firstly I wouldn't advise paving so close to the Dpc but if you really have to then yes an Acco will give you more protection. Personally I would rip the concrete out and do it properly with a stone base of 100mm . If you're laying over a stone base then the mortar should be approx 40mm deep if its over concrete then you can make it much thinner

[local patios and driveway]

you could also run a 45degree haunch from the acco to the brick as a work around, this makes any rain landing near wall deflect away from dpc

[lutonlagerlout]

you could also run a 45degree haunch from the acco to the brick as a work around, this makes any rain landing near wall deflect away from dpc

Thats a new one on me
if the aco is tight to DPC surely adding a haunch/fillet will add to the bridging of dpc?
or maybe i havent read it right?
LLL ???

[local patios and driveway]

lll i will try and find a drawing it was a work around that i came across online a few years back after researching my options.

this work around was for a finished height of 60mm from dpc to acco. had to move acco 50mm away from wall

[seanandruby]

No disrespect but wouldn't that look shite? An haunch like that would have to be picture perfect as any slight error would draw your eye to it. Best course of action is to rip out the concrete and start afresh. The only way i would use a work around would be if the was no other alternative, ie: high services etc:

[Carberry]

Rip the concrete out or lay some quarry tiles or something on the concrete base instead

[dan_g_1]

Thanks for the prompt responses. I am a bit reluctant to rip out the concrete base as it will mean the patio will be a lot lower than planned, this is bad as i have had new garden walls built at the desired height.. if i lower the patio u will be outside sitting out looking at what would look like a 6ft wall, rather than just a nice knee height decorative wall.

is ther any other way to get around this for example putting a flag on edge up against the house so splashback will hit the flag and run down into the aco, or painting like a bitumen DPC 150mm above the aco?

thanks again Dan

[seanandruby]

try here

[local patios and driveway]

cant find the pictures, it looked really good in the end and of course visible haunching looked spot on as it was me who did it.

[Dave_L]

45mm slabs - can't you go for anything thinner just to give you that bit of extra 'drop'? Or do you already have the paving?

[seanandruby]

cant find the pictures, it looked really good in the end and of course visible haunching looked spot on as it was me who did it.

Good answer :laugh:

[dan_g_1]

45mm slabs - can't you go for anything thinner just to give you that bit of extra 'drop'? Or do you already have the paving?

no i cant dave i have already purchased the paving and have had it delivered.

what i think im going to have to do is shingle up to the wall 150mm then run the aco and then me paving. and just run the risk and see how it goes. if it starts getting slightly damp i may have to add an extra damp at a later date.

thanks for all your ideas and answers will be paving it tomorrow if the sun comes out

has anyone got any thoughts on the rompex paving grout?

thanks dan