sealing block paving

If block paving is laid properly, it is totally waterproof, unless its the new type with bigger joints designed to allow water through.

There are many types of paving sealants on the market, but If you have raising damp through the paving, most of the sealants will either go white or just flake off.

 

DPM

http://www.screwfix.com/p/damp-proo...rch-_-SearchRec-_-Area2&_requestid=261378#_=p

Is the structure timber and just sitting on the paving at present ?

 

I've actually seen some peeps put down a dpm under the block paving, if the area is going to be enclosed..

 

Does the damp only come up at the sides inside?

Mr. HandyAndy - Really

 

Dave I'm thinking the whole paved area is getting damp, not just under the structure, so that DPM would be any good.

 

I did that. I took a brick out all round outside, upped and levelled the floor area, relayed on dpm and sand.

Mr. HandyAndy - Really

 

Whats the best underlay for block paving?
My brother did his with clean 10mm stone chips. Hand screeded with 2m aluminimum screeder and swears by it.

BiO (brother in outlaw) house builder uses a weak sand cement mix and swears by it..

 

If it porous then 10mm or even 6mm chipping, but if it not then compacted sharp sand 50mm thick.

This is for RY.

 

Brother says the sand will soften with rainfall and the fines may even wash away leaving an unlevel surface. Especially with vehicular traffic.
The stone chips on the other hand will never sink and aids drainage.

My Bio is an extremely experienced high end house builder. But I think my brothers method is the best.

Pile driving is often done with solid concrete columns. But another method is drill the pile holes and fill with clean stone.
Because clean stones never sink.

 

As I said, but if the paving isn't the porous type, then its totally waterproof so the sand won't wash away, there are millions of driveways laid this way, using stone chipping is relatively new.

 

If ground is solid under the sand, that compacted sand ain't going nowhere. Wet sand is stiffer than dry.

Mr. HandyAndy - Really

 

With all the will in the world Phil, I fail to see how blocks laid together can be totally waterproof(not like they are glued together with sealant)!

Mr. HandyAndy - Really

 

The sand should be damp when laid, so when compacted its rock hard. Bit like being at the sea side, all the same sand on the beach, but your feet don't sink into the wet stuff like they do on the dry.

 

His paves are 200mm by 200mm decorative pieces. Thought all paves were porous to some extent.

In any case I'm not referring to water ingress through the pave. But rather through the joints.

 

The kiln dried sand in the joint seals when it get wet, it then stays sealed, you must have seen puddles on block paving, especially in retail parks.

 

That's probably after a down pour. Surely water will still be ingressing downwards?

 

I have seen puddles, but I have seen them disappear faster than they would with normal evaporation.

That tells me it has soaked down. Just saying.

Mr. HandyAndy - Really