Patio - no geotextile membrane

If it’s bedded with 5pts sharp sand and 1pt cement and the bed is substantial 12mm (average depth). The ground underneath the bed must be prepared appropriately (weeded and defoliated). Finally, pointing the patio with a wet 1pt cement 3pts yellow building sand. (Bricky mix) and the mix is ‘heel driven’ in to the cavities under pressure not swept in and left. It’ll be solid and sound and therefore guaranteed for at least 10 yr.

I’m more than interested what kind of weed can grow through well compacted 100mm mot type 1 and 40/50mm of sharp sand and cement bed. Japanese knotweed? Maybe.

I would ask him why he's not put any down and if he has used any type of weed killer although it is always best to put membrane down.

Yes. Not good! If they aren’t using geotextile weed membrane they shouldn’t be doing the job in the first place. Worrying what the patio area will finish like

Weeds shouldn't be an issue (As mentioned already, not much, if anything, will grow through well compacted type 1 plus the bedding layer) - but the issue is the sub base (type 1) potentially getting intermixed with the soil beneath and causing the base to become unstable. The membrane would ensure the soil and sub-base remain separate permanently. Basically, it's always best to put one down (and doesn't cost much) although it might be OK for a few years at least.

It's common practice to lay the geotextile membrane 1st after dig out and also soak the membrane with a commercial strength weed killer then lay the type 1 waker plate this at the same time of wetting it to compact the base course then lay whatever the customer requires for the finished substrate. You also should always make sure the tradesmen offers a work garentee this way if not happy he or she needs to rectify the issue at his cost.

The weeds are usually growing from the top down in my experience. Those membranes are evil I tell you, they’re evil!!!