Sub base? - Do i need a sub base?

[islander]

This summer, I'm planning to remove some old mudstone flags from around my house, and lay some new concrete ones in their place. This might sound slightly crazy, but the existing flags are lethal in the wet if you aren't wearing the right type of sole.

What I need to know is whether I need to lay an aggregate sub base - I realise that I'll need to dig out for the bedding layer and the additional flag thickness as a minimum. The sub base page says that a sub base is not necessary for a patio or path, but the FAQ says 75-150mm for BS flags.

Which is appropriate?

[andpartington]

u need a sub base. 100 mm of mot type1 will be fine, if the fags are next to the house wall u might find a layer of concrete which if solid u could lay on to
But first of all I would try washing the flags with a pressure washer to remove the dirt and u might find that stops your problems a lot cheaper and easer than a relay


andy

[islander]

That was quick! Thanks for that, I thought I would need a sub base and I'd planned for 100mm I just needed confirmation really - this is the first time I've planned anything like this.

No concrete apron around the house I'm afraid! It's an 1820 drystone built fisherman's cottage. I've tried cleaning the existing flags, but it's a common problem up here - unless you're wearing rubber soles or doc martins then you skate around on the things when they're wet. I suspect it's down to the surface texture which is extremely fine - not quite a shale but close.

Tony

[andpartington]

Shame they won’t clean up but u should get something for them if you can get them up in one piece that is
just make sure they don’t go in a skip and ask a few different people what they will give u for them. there are often adds in the back of local papers they might even lift them for u

[Suggers]

Can I believe what I'm hearing - they sound fantastic - "looks you up" - blimey - it's the Orkneys - give us a photo - replace with poxy concrete - a shame on you - I'll send a chopper to pick 'em up - let's cover the whole of the UK in concrete and be done with it.
Rant over......
luv Suggers.

[Tony McC]

Are the flags the Caithness Stone that's popular in the far north?

If traction is a problem, one solution is to treat the surface with a sealer that's been doctored with Rhino-Grip. You can choose the type of sealant you prefer, maybe 'invisible', or for the authentic Orcadian look, a high-gloss wet-look, and then add the Rhino Grip to the top coat.

I've no data on just how much diff it makes to the slip resistance, but, from experience, I know it's enough to make you feel helluva lot safer!

[islander]

Hi Suggers, They might sound fantastic, but they really are dangerously slippery in the wet! I've put up with them for 15 years and its getting to the point where I'm concerned about delivery people (especially coal) and postmen slipping and injuring themselves. I really need to do something about it and this winter was the last straw to be honest. I'll have to lift them anyway as I'm putting in some extra drainage so this is definitely the time.

Tony, thanks for that, I'll ask a couple of the local masons if that would work with the flags - a quick look at the website says suitable for porous materials and I'm not sure that these flags qualify. They're similar to Caithness flags (all formed by the same playa lake) but very very fine grained - almost a shale geologically, and irregular shapes and thicknesses.

Some of the flags you see here are lovely - nice course yellow and red sandstones that are perfect in the wet or dry mine aren't unfortunately!

[lutonlagerlout]

i bet the postage would be horrendous,yuppies in hoxton give their eye teeth for this sort of thing!!
always a shame to replace stone with crete,but i have the same problem with yorkstone in my back garden==> lethal when wet,
at the end of the day safety is more important than looks
good luck
LLL

[simple simon]

hello can some 1 help me plz,am after sorting me back garden out to build a dog run n kennels on it due to the dogs have wrecked the grass its all mud now lol,the area am after flagging is 3ft away from path that runs to around my back door, the area is level to the path but id like the area raised up about a step high as i would not like to dig it all out,what would be the3 best way to do it lay hardcore on top the mud with a sand n dry concrete mix then level it with a whacker then lay flags on or what would your advice be as i am attempting it myself as funds are low at the tuime being

[lutonlagerlout]

look here for tips simon
regards LLL

[simple simon]

thanks lagerlout much appreciated now i will carry out the chore in the garden and say goodbye to the mud

[lutonlagerlout]

good luck
LLL