Estimating materials

16 Aug 2006
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United Kingdom
I need to estimate materials for laying a patio and building various walls. It's been suggested I buy limestone for bedding in the patio slabs and I estimate I'll need one cubic metre for this.

For the foundations - what quantities of what should be used? I'd prefer to use the combined aggregate but I have an eye on cost, would it be cheaper to use a mix of limestone instead of sharp sand? What's recommended - and in what mix?

I estimate the area for foundations for the walls at .60 cu metres

I've estimated the number of bricks I'll need for the walls which total approx 14.5 sq metres, but how do I estimate the amount of mortar needed and what mix is used in mortar? I will also need to grout the slabs once laid and the total area involved is approx 120 sq metres.

Finally, can someone tell me how many wall ties are recommended to use in a double thickness wall?
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Do you want someone to do the job for you aswell lol
Really for all that info either google it or get a BOOK.
Fluffster said:
Do you want someone to do the job for you aswell lol
Really for all that info either google it or get a BOOK.

Thanks Pete. That's really helpful! I was under the impression this was/is the correct place to ask for advice and help. Perhaps it would help you if I pose my questions slowly and in words of one syllable so you won't get so easily confused! As you'll see from my post, the information I've already found (from my DIY book) is provided, the information I do not have is requested.

I was hoping you he-men-muscle-type-builder-know-it-alls would be able to advise a female-first-time-DIYer who's willing to have-a-go but also recognises the need to seek advice and clarification, but I've obviously overestimated your good nature and humanity! As I had some great advice last month on what kind of cement mixer to buy on the Tools section of the forum, I guess you builder types can't be as friendly (or well mannered)!
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I don't know about limestome for footings. I would get a 1 tonne bag of sand/gravel. And 5 bags cement

I would bed slabs on screed sand (if they are uniform thickness) or on mortar dabs (if they are uneven thickness). For grouting, it depends on the joint thickness, but you want screed sand for wide joints (with a bit of cement), or kiln dried/silver sand for very narrow joints. If you lay them on dabs, then make sure you fill under the joints, or the grout will just fall through

Your walls seems to be 14m2 of one brick thick - about 1700 bricks? So you need two 1 tonne bags. And say, 8 bags cement for a 5 and 1 mix

For ties, you need 2 per metre length if wall is less than 1.2m high, and 5 per metre square if higher than 1.2m. If the wall is less than 700mm high, then I would not bother with ties
Thanks for the replies. I tried taking measurements to a builders merchant but they came a bit too close to telling me to take up flower arranging! :evil: Anyway, the job is too big for bulk bag supplies and the savings to be made on loose supplies is too great to loose (I'm a female semi-retired accountant turned DIY'er!).

I've been told sand under patio slabs attracts ants and is expensive anyway. I asked for limestone type-1 and was told 20 mm crushed concrete will do the job, is half the price, and can be used as a combined aggregate for concrete.

Sand - I wanted quotes for soft sand (builders sand) for brick laying mortar; sharp sand for dollops under patio slabs; and silver sand for joint filling (thought builders sand may be too yellow) one has heard of silver sand, and I've been told to use builders sand for all these jobs. Can you confirm? I thought sharp sand would be better for the patio slabs?

For the concrete foundations and 4 x fence posts, I've been told to use the crushed concrete and cement at 1-5. Why no sand?

I've estimated all my materials in cubic metres and need .94 cu mtrs of cement. Can anyone confirm this equates to 60 x 25 kg bags?
Arh, a bean counter. That explains it. lol

You need sand in the concrete mix to act as a binder. Otherwise there are voids which weaken it in this particular use.

Sharp sand alone for spots under slabs may not stick too well, and the slab can become easily detached when leveled or knocked when setting and afterwards. I would use a mix of strong building sand (which is stickier and flexible) or with just a bit of screed sand to toughen it up.

Even if you use a stone or crushed concrete base for the slabs, then you still need a dressing of sand on the top to fill the voids and smooth it off. If you lay spots directly onto stone, then the top pieces of stone will gradually move as the slabs are walked on the pressure passed down to the stone base.

BTW, its not as if all the ants in the vicinity will come and live under your sand base. They will live almost anywhere anyway. Sand does not attract them. Per tonne bulk, its more or less the same as stone.

Stone is inflexible for levelling, and you will end up excavating more then you need to, or building it up more than you need to.

Builders sand is grey or brown when mixed, not yellow.
what area of patio are you laying and what type of slabs are you laying?
Thanks for the replies. If ever you need a bean counter's advice.......:cool:

The total area of the patio is approx 130 sq metres. A lot of this is already loose laid and should only need cosmetic work. 37.5 sq mtrs have had slabs lifted to avoid breakage while heavy construction machinery is used to dig out a further 16 sq metres which used to be a pond. So it's the latter which needs most work and laying with the slabs I already have (some kind of pressed concrete I think).

Woody - thanks for your informative post, I really appreciate it. I haven't come across many ants but don't want to attract them. There are stacks of woodlice so I wouldn't mind attracting something that eats woodlice! :rolleyes: I'll be needing more advice later on when I've got to lay foundations, build walls etc and could do with a project adviser (hint, hint...........I could return the favour by counting your beans :eek: ).

I'm hoping the completion of this project will end in an adequate result. It's a facelift job and won't be stunningly beautiful as I'm not prepared to buy in new slabs or pay for getting rid of the old ones. But it will have soft as well as hard landscaping which I consider essential for the area involved. Whoever designed a patio of 130 sq metres with no planting areas must have been having a serious relationship with his cement mixer!

My costs to date are £650 for earth removal and approx £650 for materials. I estimate a further £100 for finishing touches - trellis, plants, etc and I may be taking on some students during Easter to finish the slab laying, so possibly another £500. The whole job should complete for a bit less than £2K (pretty good for the area involved) and I believe the added investment value to be x3.

I'll try and post some photos to give an idea of what's involved.

If this shows the lower level patio looking south. Slabs have been lifted to allow a digger and dumper to extract earth.


Upper level on left, showing old pond. The area between the pond and the lower level has now been dug out. New walls are needed to line the pond and diagonally to the steps/wall on the lower level.

I'll take another photo soon to show what it looks like since the earth has been dug out.

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