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For a tarmac driveway I am trying to find some info on the depth and type of layers that I need. I have done a quick search but I haven't managed to find anything. I know that I will need roughly layer 1 tarmac at 25mm, layer 2 tarmac at 60mm and layer 3 at maybe 200mm.
Does anyone know where the required or recommended depth and type of material for each layer is written down? I need this so I can check what the contractor puts in the written quote matches the building regs or whatever official standard exists to define the driveway foundations.
Cheers
Someone will be along to recommend paving expert in a minute but for now follow these simple steps.
There are NO "recommended" layers as such, site conditions will always dictate the subbase and the longevity of the tarmac.
Get your subbase right and the tarmac could be as little as 40mm base 30mm bitmac.
So as I've said subbase is the key which is your stone layer beneath the first layer of tarmac, I would always place 150mm as a minimum, with terram or similar geotextile beneath the stone if required. So if your contractor is still on soil once removing say 300mm he needs to go deeper and bring back up to level in layers of stone.
There are no definitive regs as such I'm afraid
Building regs don't usually concern themselves much with what goes on outside the building which is why you cant find anything.
Okay cheers. I did wonder if the driveways were done to the same standard as a road although that may be overkill.
Roads aren't covered by building regs either. High-speed roads will be Desigb Manual for Roads and Bridges but this is complete overkill for parking. BS7533 covers things like block pavers but again, this is probably still ott for a driveway. Anyway, as Wrightyson says, it will all depends on what you're building it on, the easiest measurement being a CBR test but there is no way you'll do that for domestic work (most of my non-domestic clients don't bother either).
There is no standard answer but generally people tend to put down 150mm type 1, then approximately 100mm total of tarmac. They can be two different mixes or the same type laid in 2 layers. Layer thickness is also dependant on aggregate size, normally a minimum of 2.5 X the stone size. I.e. 20mm aggregate gets a minimum layer thickness of 50mm.
Thanks, so when the contractor tells me what layers he is proposing I now have a good idea of what he should be offering.
From reading paving expert it seems that a membrane such as TERRAM geotextile will stop the crushed limestone sub base mixing with the sub grade below. Assuming the sub base is compacted correctly and is deep enough, do I definitely need a membrane or is it dependent on the type of ground remaining below the sub base? If it doesn't cost much it may be worth getting it anyway.
You don't need one but again, whether it's a good idea will be site specific. General rule is that if the sub base is compacted properly and and soft spots in the excavation are dealt with for domestic parking it "should" be ok*
Compaction of sub bases is covered in Specific for Highways works series 800. You can find this by Googling Standards for Highways but it's quite a long dry document
*Caveat being without seeing it and having the tests done you probably won't know for sure.
From reading paving expert it seems that a membrane such as TERRAM geotextile
Ahem, I did mention it, but you know everybody loves paving expert! 😂
Best thing to do is come back to this post and tell us what the contractor is proposing, myself and clearly swdan can tell you straight off the bat 8f it's something like.
You do need to question how far he will dig down and whether there would be "extra over" if he has to do so. As a rule of a local contractor he will have a rough idea of local ground conditions for a basic estimate.
I am waiting for a written quote which I should get next week then I can post the specs.
I have been given a rough verbal quote of £70/m2 for 50m^2 which comes to £3500. This is for removing the existing paving slabs, digging down by about a 250-300mm, putting in the hardcore and top two layers of tarmac, adding some drains in front of the house, blue blocks round the edges and taking away the rubbish. He hasn't given me anything in writing yet so I don't know any more details.
Does £70/m2 sound reasonable if he does the job properly as I thought £70/m2 was on the high side? Obviously it is not worth getting someone who is cheap but then does a sub standard job.
No idea regarding the price I'm afraid, I'm a designer not a contractor and generally only deal with large scale developments/local authority roads.
However, I imagine price will somewhat be driven by location.
Don't underestimate the cost of disposing of the old materials from the previous driveway - trade waste disposal licence and landfill tax all add to the cost.
I was told a 16 tonne grab truck would be £180 +VAT=£216 so I didn't think the disposal would be that expensive or does it cost more than this?
Type 1 Mot for sub base at £15 per tonne for 50m2 I estimate I need 22 tonnes which would cost 15x22=£330. So the hardcore and disposal = approx £550. Doers anyone know what the tarmac and labour would cost?
Can't get links to work, but Google Paving Expert. Should tell you all you need to know.
Landfill tax is about £3/ton for "inert" waste, but over £90/ton for anything that is considered "contaminated".