Block paving safe to pressure wash ?

[John1954]

Can anyone tell me if it is ok to pressure wash block paving. I don't want to undermine the bedding sand, and be left with blocks moving all over the place after. And would I need to brush block paving sand in after the clean,also what is the purpose of this sand.
Thanks

 

[xdave]

If you wash across the blocks, rather than straight down, them you may be ok but afterwards I would not use the area for vehicles until it had dried thoroughly and I had been over it again with the kiln dried binding sand because you will inevitably remove some.

The blocks (including any gaps) and the sand must be completely dry or it will clog up and not fill the gaps properly. The purpose of the sand is to provide friction between the block joints to prevent lateral movement and is where block paved surfaces get all their strength. The best time to do it is at the end of a nice dry hot day. Don't do it in the morning at this time of year as the gaps will be very wet even if the surface of the blocks look dry. I need to clean my drive this year but will wait until the summer.

 

[conny]

I have pressure washed block paving before but as you say, there is a danger that you will wash the 'filling' out and be left with unstable blocks.

If they are fitted tightly together this is greatly reduced. You will have to be careful not to wash between the edges if possible and then let them dry before brushing new fine sand into the joints.

I used to take the opportunity of scraping out any remaining moss/grass that had lodged between the joints and then brushing the sand in. If you have a wacker plate so much the better but as an alternative, to help the sand drop right in and firm up, you can knock the blocks with a heavy rubber mallet.

 

[John1954]

Many Thanks for both replys, I will leave it until the weather improves

 

[ban-all-sheds]

Make sure you show your wife this thread, and this: http://www.pavingexpert.com/refurb_00.htm so that she doesn't think you're just trying to get out of it.

Of course, when you read the 2nd link you may find that the task has grown bigger than you originally thought. Unless you're strapped for cash it might be worth getting quotes from professionals to come and clean/re-sand/seal the paving.

May go against the DIY ethos, but if these guys can do a much better job because of experience and access to better equipment than you, then it probably makes sense.

 

[Bodgeitandleggit]

I would say it is ok to do this from previous experience.... I tried all types of cleaners but had no effect but waited for a hot june day,used a pressure washer resanded it then sealed.... all ok

 

[John1954]

Thanks again for everyone's help

 

[GaryGarden]

Defo no no if you have no membrane under the sand, you may not wash much out on the surface but the sand will run into the hardcore underneath.

Better to use a decent cleaner and the seal it.

Try Algon stinks for a day or 2 but it does a good job

 

[dhutch]

Defo no no if you have no membrane under the sand, you may not wash much out on the surface but the sand will run into the hardcore underneath.

As far as I can see, as long as you don't directly jet down, and re sand it afterwards once dry, there is no harm in pressure washing it. Although using (ideally one of the more eco) drive chemicals afterwards may not be stupid.

Its slow and boring, but have used the patio-washer that came with my Nilfisk washer to good effect and slightly faster and less messy than doing it with a lance if slightly more boring.


Daniel

 

[John1954]

Thanks for that mate, I am getting a quote tomorrow with a professional company, I don't want to make a mess and end up paying a fortune to have it relaid..
Thanks again

 

[deb8z]

I used a pressure washer on mine and after a short period of time they were filthy again,worse than before,they seem to get dirtier quicker!

Mine aren't sealed,are you supposed to seal them with something,this is maybe where I went wrong oops

 

[dhutch]

Sealing is optional, some give a glossy finish which personally I think looks worse than it being dirty. All depends what you want.


Daniel

 

[ban-all-sheds]

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http://www.pavingexpert.com/sealants.htm

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[dhutch]

http://www.pavingexpert.com/sealants.htm

For me the key points there are:
- Sealing cannot be done straight away. Typically a few months is required.
- The site in question are not huge advocates of sealing domestic drives and patios.
- Acrylic sealants can have issues with oils/petrol and short life. Polyurethane sealants don't cost that much more.
- Sealants can help reduce maintenance and weed growth, etc.
- It can be a good option for restoring older drive ways, in conjunction with cleaning (jet washing, etc) and repair where needed.
- You must wait for it to be totally dry; ie summer, and around 14 days after cleaning.


Daniel

 

[ban-all-sheds]

- The site in question are not huge advocates of sealing domestic drives and patios.

IRRC they don't see a great need for it, when looked at in the context of why it's used on filling station forecourts, shopping centres etc.

But if you're happy with the look of a low-gloss seal, and you have particular problems e.g. heavily shaded, leading to moss/algae growth, or trees dropping fruit (or things in trees dropping processed fruit), and you want to make it easier to keep clean, then why not?