Advice for paving over concrete

Hi All, first post. We have an old concrete floor from a garage that has been demolished. The floor is in good nick, with no cracks. We intend to pave it using rough-look pavers, to match the rough side brick wall of the old garage which has been retained and painted. I have been advised to use a morter mix and pave over that- is that the way to go? One other thing is that there is a hole in the middle (an old car-service pit!). I guess I can cut a piece of timber to size and fill it up with the mix?

The pavers we will use are 600 x 600 sandstone - I know that these will be porous so I need to seal them, correct?

Any tips or guides for a first-time paver welcome!

Should come up good, the old style bricks look good with sandstone

Yes, use a 6:1 mortar mix, add another :1 part lime if you want a bit of life in your mortar and it's warm. Get a bottle of Bondcrete (or similar) and add some to the water bucket for the mortar mix, and also add some to a small container mixed with water and get and old paintbrush to slap some on both the paver and the floor- it will help both surfaces adhere better.

Use a runny 3:1 washed sand:off white cement mix for the grouting...it may pay to carefully seal the pavers after laying and it's gone off. Don't get any in the joints or the grout might not stick too well, but the rougher surface of sandstone can be a bugger to sponge excess grout off and the dealer will help it greatly.

As for the hole...it's not one of the ones you step down to work under the car is it? If so probably better to fill it with rock or concrete if its deep!

Thanks for the great advice, plannedL!

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Originally Posted by Planned LScape

Should come up good, the old style bricks look good with sandstone

Yes, use a 6:1 mortar mix, add another :1 part lime if you want a bit of life in your mortar and it's warm. Get a bottle of Bondcrete (or similar) and add some to the water bucket for the mortar mix, and also add some to a small container mixed with water and get and old paintbrush to slap some on both the paver and the floor- it will help both surfaces adhere better.

As for the hole...it's not one of the ones you step down to work under the car is it? If so probably better to fill it with rock or concrete if its deep!

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Yes, that's it- we never used it as the old garage was built for much narrower cars than today! I'm making up a wooden frame and will cover with a cement sheet, which comes up to almost the level of the exisiting concrete. Then mortar over that.

One question- physically, what is the best way to mix small amounts of mortar? Can I do it in the barrow, or should I hire a cement mixer (I have around 25 sqM to pave)?

Pavers have arrived, so almost ready to go.

A cement mixer will do the job very easily - using a 90 /100 ltr builders barrow is also OK but requires a bit more effort. Dont try using one of those barrows they call a garden barrow with the bent handles.

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Originally Posted by Dirty Doogie

A cement mixer will do the job very easily - using a 90 /100 ltr builders barrow is also OK but requires a bit more effort. Dont try using one of those barrows they call a garden barrow with the bent handles.

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Thanks to both for the replies.

Yep- will get a mixer, only 50 bucks a day to hire.

Can I get some advice on how to actually make the mortar? I asked the guy at Mitre10 how much concrete for half a metre of sand and he didn't know! I know the ratio's from your reply above.

As suggested above, I should also use lime? Is it just a matter of putting the required shovelfulls of the dry ingredients in the mixer, adding water (how much) and mixing (how long?). Do I just make up batches, dispense onto the floor, screed and then start laying the pavers? How long is the mortar usable (ie how many sqM can I lay in one go?).

As you see, I am a complete novice, having never done this before.

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Originally Posted by Plunkett

Yes, that's it- we never used it as the old garage was built for much narrower cars than today! I'm making up a wooden frame and will cover with a cement sheet, which comes up to almost the level of the exisiting concrete. Then mortar over that.

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Plunket, two dumb questions.

1. Can you be sure that there is approaite ventlation/circulation/drainage arround the pit cavity? My concern is the timber frame developing rot over time and collapsing.

2. Is the cement sheet cover fully supported or thick enough to carry a substantial load? Concern is that while you may know that a hole is under there and avoid loading it, will subsequent users? A couple of metres of rock and 75mm of concrete as a cap may be a better long term option.

Just my 1c worth.

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Originally Posted by malb

Plunket, two dumb questions.

1. Can you be sure that there is approaite ventlation/circulation/drainage arround the pit cavity? My concern is the timber frame developing rot over time and collapsing.

2. Is the cement sheet cover fully supported or thick enough to carry a substantial load? Concern is that while you may know that a hole is under there and avoid loading it, will subsequent users? A couple of metres of rock and 75mm of concrete as a cap may be a better long term option.

Just my 1c worth.

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Malb- the pit vents to the back, where there is an access door. It's always been very dry down there, and there are wooden shelves that are fine, so should be OK.

I had the same concern. I ended up getting enough timber to fill the gap completely, so it is very strong (I jumped on it!). So I basically have a bed of 4 x 2's covered by the cement sheet.

I would kill for a pit like that. If a man can't have a hoist that is the next best thing.