Dear all, The time has finally come where I've got to get off my a*se and sort the garden out. The first bit of work is to build a low 12.5 metre long retaining/decorative wall for some soil (weed) banking that we've got. It's a new build garden/swamp and nothing else has been done to it apart from turfing the flat bits and putting in extra drainage courtesy of the NHBC. I've googled a bit already but would appreciate any links for hints and tips for mortar/concrete mixes, foundations (if necessary) and other such bits like recommended stone. I'm a real novice at this construction side of things and would appreciate any help and, as mentioned, links to handy sites. Hopefully this doesn't sound like I'm being too lazy but sagely advice from the group would be most appreciated. We have had some landscapers in to do some work in the past but the cost is a bit prohibitive at the moment so I'll just have to bite the bullet and do it myself.
Most builders in England will not think much beyond a 3:1 sand cement mix. But this is far too strong for your needs and cement is a serious consumer of energy and producer of CO2. The mortar's strength and brittlness will mean that it may crack if there is any settlement. To avoid this you may be advised to lay foundations.
An alternative approach is to use a lime based mortar which is weaker and less brittle. Foundations will not be needed, lime requires less energy to produce and reabsorbs from the air the CO2 given off during production as it sets. A 3:1 mix of sand and lime is fine but you could incorporate up to 20% earth in the mix. Dig a hole and use earth from a foot down rather than the topsoil. The resulting mortar will be just as strong and cheaper.
When you buy bagged hydrated lime from a builders' merchant empty the bag into a dustbin full of water. Then use the resulting 'putty' to mix with your aggregate. It will keep forever under water but lime in a bag gradually absorbs CO2 from the air and so is not as good if not used fresh.
Don't worry if it looks as though the mortar is not going hard. It takes weeks and weeks but gradually gets harder and stronger as the lime reacts with the air.
Commenting on the previous post, I ought to add that there was a thread on lime mortar a week or two back, so find it if you want to go that way. I've never heard of using earth in the mix but I can't claim to be an expert. Remember lime putty ( hydated non-hydraulic lime + water ) needs to soak for, well, according to some, weeks as then when mixed with sand it will behave in a 'fatty' way ( which means handles well on a trowel and when you position/adjust stones on it ).
Lime mortar looks nicer ( white ) than cement IMO, but you can get white cement if you wish, I will assume you use cement.
The sand you use also is important. Silver sand gives a light coloured mortar. Sharp sand gives a strong mortar but needs plasticiser added to facilitate good handling. Soft sand gives a weaker mortar but handles well even without plasticiser apparently. Soft sand may be a yellowish colour.
A mix of 1:4 cement/sand by volume works with stone. It's not critical to be honest. You could use a weaker mix. Getting the aount of water in the mix is important: too much and it will be sloppy, too little and it will be stiff and unadjustable.
Get a bricklayer's trowel ( quite big ) so that you can get a decent amount of mortar on it. Stone walls are usually 'battered' slightly ( they are thinner at the top than at the bottom ). With proper stone walls you will have two skins of stones, on either side, with a central mortar and rubble infill, and occasional larger stones that span the width of the wall to hold the two skins together.
If your wall is small and thin you will have to use one skin of stones only. Make sure a single-brick thickness wall ( 4"-5" ) doesn't exceed three feet in height without piers.
You will need to figure out what stone to use. Random quarried stone is too difficult to work with, you need stone with at least one 'fair' face and probably more. Quarries sell walling stone direct sometimes, it will have been selected for fair faces. The style is up to you, but it takes a fair amount of skill and messing about to get close fits between the stones. One cop-out is to fit the main stones as best you can then fill in any gaps where a lot of mortar is showng by pressing in small pieces of stone.
Don't get too perfectionist about filling every single gap between stones with cement: you can fill in a bit when you've finished each course.
Probably easier to work with is quarried slate, as this naturally forms flat and easy-to
-stack pieces. You might need a grinder to square up the ends of some piece. Use a level/long straightedge and your eyeballs as you go along: stone walls are less critical than brick in terms of accuracy.
I'd use some form of foundation on a slender wall, but a thick, low, battered wall is unlikely to be going anywhere and you might get away with just a splash of cement at the base. Leave the mortar to stiffen up a bit before attempting to tidy up the mortar joints, a couple of hours is OK, use a wire brush perhaps.
It may be surprising to many people in Britain but most houses in the world are built with earth rather than cement. Unfortunately our climate means that some weather protection is usually needed for earth buildings so cob houses are traditionally rendered with a layer of lime plaster. Many have survived thus for centuries. Adding some lime to the earth makes the material much stronger and more weather proof.
But back to the earth in the garden wall. Mortar consists of aggregate and a cementing material to stick the aggregate particles together - usually lime or Portland cement. Ideally there should be just enough cement to fill the gaps between the aggregate particles without pushing them apart. This means, roughly, a 3:1 ratio of sand and cement. If the aggregate consists of a range of grain sizes the small bit partially fill the gaps between the large bits so less cement is needed. There is also a larger surface area for the cement to stick to. If the grains tend to be angular in shape they pack together tigtly without slipping past each other. Such is the case with 'sharp' sand. This gives a strong mortar. If a mixture of sharp sand, silt and clay is used, with up to about 25% clay, it can be so strong that the cement may not be needed. This is what earth buildings are made of. For a practical garden wall mortar in rainy England the addition of, say, 10% lime, will to a sharp sand and earth mix will prove satisfactory and cheap.
The advantage of 'soft' sand is more for the bricklayer than the wall. Small, even sized and rounded sand grains will not produce such a strong mortar but it will be more 'workable' as the sand grains can slide over each other easily while the mortar is wet. This allows the brickie to lay zillions of bricks per hour and there will be plenty of strength if he is using Ordinary Portland cement instead of lime. But for the DIY garden wall where speed of build is not critical but cost of materials, appearance, resistance to cracking without resorting to massive foundations, health of the environment and a generally pleasant and interesting experience are the issues, a sharp sand, earth, lime mortar will be excellent.
as the sand grains can slide over each other easily while the mortar is wet!!!! For heavens sake the man wants to build a wall, not take an exam on mud in mortar, well meaning advice but sorry, way off the mark. Firstly, if you are a novice DO NOT attempt to build this wall, its far too much to attempt if you don't know what you are doing. Ask around the local establishment if there are any brickys willing to do cash work, you can do the mixing and loading out whilst the professional does the craft. It won't cost that much and will save you much head scratching and banging of head on not very good garden wall. If you are intent, here is my 10 pence worth, DO put a footing in, 1 ft wide, try and get down to solid base, make concrete 150mm thick, if theres quiet a bit of weight to hold back, put a few pillars in the wall, 1 every 6 ft should do, these can face the rear and be covered by the soil, weed etc. If using brickwork mix at 4 sand, 1 cement. If using sand stone or similar, mix at 6 sand 1 lime 1 cement, although i have walled stone in normal mortar many times. My best advice is get a bricky, why listen to me? House basher (bricklayer) for 17 years, site manager for 5 years, building contractor for 2 years. Hope all goes well.
I wish you'd stop spouting crap about lime mortar.
You like it, that's fine. But you can't sell it on the green angle. Both production processes (for producing cement and lime) use a lot of energy. They also both liberate some co2 from the material being processed. When lime sets, it reabsorbs much of the liberated co2.
However, the amount of co2 produced while making the energy required for the process is far greater than the amounts released/reabsorbed by the material. So the difference in net co2 release between cement and lime production is quite small.
Add to that the fact that you need a lot more lime for the same project, with all the associated transport + storage (energy) costs, and the higher maintenance of lime based construction, and your environmental argument vanishes.
The kilning temperature used to turn limestone, calcium carbonate, to quicklime, calcium oxide, is lower than that used in making Ordinary Portland cement. Thus less energy is required and consequent CO2 emission is lower. The CO2 driven off in the limestone to quicklime reaction is reabsorbed as the lime mortar sets. OPC reabsorbs much less CO2. Dry hydrated lime weighs slightly less than an equivalent volume of OPC so should involve marginally lower transport (energy) costs. Wet lime putty is heavier so that advantage is lost but for a garden wall the extra quality of lime putty hardly justifies its extra cost. Dry bagged lime will do. My suggestion of using a sand / earth / lime mix allows the use of much less lime so the overall cost in cash, energy, CO2 emission and general damage to the environment is reduced.
But hey, let's not get too exited. The planet is not going to be won or lost over a modest garden wall. Remember my first suggestion was a
3:1 sand cement mortar. The rest was just in case someone, perhaps KD, was interested in thinking a little further.
Yes, we still have a few 'cob' walls down here in Devon, and they are essentially mud and whatnot, but I reckon as far as novices go, it might be best to stick to something well-known.
As far as the original poster getting in a brickie, well, that's for him to judge. I built a very passable stone wall a while back, and I had never built anything like that before. I did a bit of research on mortars and walls and just had a go. Being my first attempt I was painfully slow and did everything the hard way. Nevertheless, I got my wall in the end, and I've got a bit of experience now.
Bricklaying/stonework is not easy, it takes a lot of skill to be productive, but if you are prepared to put the effort in then and haven't got ten thumbs then you're in with a chance!
Cheers Andy, I am not aiming high - about two feet in fact ;-) and thankfully I don't have to do this all at once. I can mix batches in small amounts and build slowly. I'll probably be bringing the rocks back to the house in numbers of
10 or less (small car) so it's the only way to go. We've basically got a slope in the middle of the back garden and I want to retain the earth behind a small wall as I work on planting out other tress and shrubs, hence I can build a piece of wall and move along - I hope :O)
Sound exactly like one of the walls I built, a 22" high and 10 foot long retaining wall ( because the garden is on a slope ). I made mine in the shape of an arc centred on a nearby Magnolia tree. Because of that and its thickness, and the fact it was 'battered' I didn't use a substantial foundation, just a bit of mortar under the lowest course of stones.
As it was a retaining wall I made it single-faced: the side that faced the earth was roughly finished with plenty of mortar, and just had the actual stonework giving a nice finish on the visible side. That makes it a lot easier, less than half the work of making a double-faced stone wall.
I topped the wall with a single course of bricks laid on edge just to give a level finish, and also because I'd run out of stone! Small tip, if your stones are quite irregular, lay out a course, or even two courses of stones with no mortar, as a 'dry run', that way you can fit them together more neatly. Takes a bit of time and rearrangement though, and is not as quick as the use-lots-of-mortar-to-fill-the-gaps-and-stick-little-bits-of- stone-in-them-to-make-it-look-better technique!
Hi all, Thanks for all the advice - I'm likely to bottle the masonry option and go for the 'woodblocx' approach which I spotted at B&Q this afternoon while looking for cement and edging. Seems quite attractive and does exactly what I need. If you want to see what I mean then simply go to the .co.uk website (I didn't put the link so people wouldn't think I was spamming or anything). Hopefully after a good 'treatment' the wood will last a while. I'll let you know how I get on if anybody's interested :O)
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.