Are bagged ready-mixed mortar and concrete worth the money?
Where a just-add-water bag genuinely earns its premium, where it is an expensive way to buy sand, and the tubbed products that do something loose materials cannot.
- Difficulty
- beginner
- Time
- 8 min
- Read
- 4 min
Short answer
Worth it below about ten bags: small repairs, one-off jobs, working where you cannot store loose materials, and anywhere consistency matters more than cost. Not worth it once the job runs to several barrow loads — you are paying three or four times over for sand you could have delivered. Tubbed ready-to-use mortar is a different product and buys you working time, not convenience.
The premium on a bagged mix is real and so is the value. What decides it is the size of the job and whether you have anywhere to put a bulk bag of sand. A single pointing repair done from a small bag costs a few pounds and takes an hour; the same repair done from separate cement, sand and lime means buying three bags you will not use up.
Step by step
- Work out the volume before you compare prices.Bagged products are sold by weight and used by volume. A standard bag of dry concrete mix yields well under half the volume people expect once compacted. Convert the job to litres or cubic metres first, then count bags.
- Apply the rough threshold.Up to about ten bags, bagged mix wins on convenience and waste. Beyond that, the price gap becomes the dominant factor and loose materials or a delivery win.
- Count storage and transport as part of the cost.A bulk bag of sand needs a place to stand where it will not get rained into and a route to the back garden. A flat, a terrace with no side access or a job you are doing in one evening all push towards bags.
- Value consistency on visible work.Mortar colour is driven by the sand. Bagged mixes are batched consistently, so a repointing patch done over several sessions matches itself. Site-mixed mortar from a heap of sand drifts in colour as the heap dries.
- Do not pay a premium for the wrong product.Postcrete in a slab, concrete mix used as mortar, or a general mortar mix used for a lime wall are all expensive ways to get a poor result. The bag has to be the right material first and convenient second.
- Check the yield printed on the bag.Manufacturers state the approximate finished volume per bag. That figure, not the weight, is what you multiply up.
Tips
- For any repointing job likely to run over more than one day, tubbed ready-to-use mortar removes the whole problem of mixing small quantities repeatedly and matching them.
- Buy one bag more than the calculation says. Running out mid-pour on a slab produces a cold joint that stays visible and is a weak line for ever.
- Bagged products are heavy and awkward. A 25kg bag is a comfortable single lift; a 40kg one is not, and neither is a stack of them carried down a garden.
Alternatives
- Dry bagged concrete mix: Cement and graded aggregate blended in the bag; add water. Consistent, no measuring, no waste. Right for post holes, small bases, a single step, and anything under a few barrow loads.
- Dry bagged mortar mix: Cement and sand, often with an air-entrainer. Good for a small repointing patch, bedding a few bricks, or a coping stone. Colour is consistent between bags, which matters on visible work.
- Postcrete and fast-setting post mixes: Poured dry into a hole with water added on top; sets within minutes. Buys speed on posts and no mixing at all, at a high cost per hole. Worth it for a few posts, poor value for a long fence run.
- Ready-to-use tubbed mortar: Wet mortar with a retarder, usable straight from the tub and staying workable for days once opened. Genuinely useful for repointing spread over several evenings, and available in lime and colour-matched versions. It is not the same material as a cement mortar and it has its own limitations in exposure.
- Loose materials — cement, sand, ballast: Cheapest by a wide margin once you are past a handful of bags, and bulk bags are delivered. You need somewhere to keep them dry, a way to move them, and the discipline to gauge accurately.
- Delivered ready-mixed concrete: A different scale again. Once a pour is measured in cubic metres rather than bags, a truck is both cheaper and better concrete than anything you will hand mix.
Questions people ask
Is bagged concrete mix as strong as mixing my own?
For domestic purposes yes, and often more consistent, because the proportions are right in every bag and the water is the only variable left. The mistakes people make with loose materials are usually in the gauging.
How many bags of concrete mix are in a cubic metre?
It depends on the product and its density, and the yield per bag is printed on the bag. Work from that figure rather than a general rule, and add a margin for compaction and waste.
Can I use ready-to-use tubbed mortar for laying bricks?
Most are sold for pointing and small repairs rather than for structural bricklaying. Read the tub — some are approved for laying and many are not, and using a repair mortar to build a wall is not a good idea.