As a new member to this forum, may I say thanks Tony for producing and maintaining such an excellent, informative and well structured website. A lesson to those web designers who model their sites using bulky code, unnecessary flash and content of little substance. Keep up the good work.
I am about to embark on a small project to build a 6.5x2m flowerbed in an elongated ‘U’ shape where each side is about 0.6m wide and using three/four courses of Bradstone Milldale blocks. Having read your page relating to the construction of walls (http://www.pavingexpert.com/featur03.htm), I am proposing to lay a 150mm deep concrete footing where the wall is to be located.
Questions:
1. Should I still allow 100mm spread either side on the footing for this type of block or can this be reduced and by what amount?
2. You advise the footing to be a minimum of 150mm below the surface to provide frost cover. In this instance it would require at least one course of Milldale to be effectively buried, which is about £140. As these blocks are not cheap, is this still necessary for the footing to be at this depth for this type of wall. If so, any thoughts as to other options to minimise this cost or is it a case of ‘bite the bullet’?
3. Bradstone advise the use of either their adhesive or a 3-4 part building sand/1 cement mortar mix. Have you any other recommended mortar mixes for this type of block?
4. The project includes relaying my patio that was constructed over 20 years ago by the house builder as the 600x600x50mm concrete slabs have sunk over the years. I will be following your excellent advice elsewhere on the site regarding base preparation, laying etc. I am proposing a 1:60 fall to allow water to drain off directly into a 150mm wide gravel strip between the patio and the above mentioned flower bed. The ground appears to be sufficiently porous to allow water to dissipate quickly, but would a gravel barrier of say 150mm deep help?
1 - you could reduce the spread to as little as 25mm for such a dwarf wall.
2 - Use "commons" or concrete bricks or any other cheap but frostproof brick, block or CMU for the below ground construction. For dwarf walls in gardens buyuilt using these expensive decorative blocks, a simple 'model' would be to create the footing 125-130mm below paving level then lay a 100mm block or a brick-on-edge to bring the level up to 12-25mm below paving level (allowing 12mm for the mortar bed), and then start with the fancy stuff. This allows it to look as though the fancy stuff has been use to full depth. What you want to avoid is any of the cheaper bwk being exposed and on view when the paving is in place.
3 - The adhesives work really, really well with these types of walling units, IMO, especially if you're not used to handling mortar and laying bricks/blocks. There's less risk of slopping mortar everywhere and making a mess of the project and the finished effect is much better, to my eyes at least. Somewhere, buried in the bowels of one of the computers, are a pair of piccies showing the diff between walls of this type built using mortared joints and 'glued' joints. I'll see if I can find then over the weekend.
4 - 50-100mm deep for the gravel will probably be ample. If you put it too deep, you just invite every local cat to leave you a present. If it were me, I'd dig a 150-200mm deep trench, fill that to within 25mm of the top with bigger stones, broken bricks, broken flags, etc, and then just dress the top 25mm with the gravel.
Many thanks for the fast reply, which is much appreciated, and I will follow your advice for each of the four points.
A source of cheap 4" concrete blocks is available from a supplier in the village where I live, so I plan to use these in respect of (2) so thanks for the tip on that one. In respect of (3), I am definitely a novice when it comes to brick laying, but am more skilled when laying ceramic floor tiles using specialist adhesive, so I will go with your recommendation. If you can find the photos I would be interested to see them, but don't spoil your weekend looking for them! Fine about the drainage options, you have given me enough ideas to implement (4) and thanks for helping me with this project and potentially saving me a few bob as well!
I can't find the one where the blocks are glued rather than mortared, but this image says it all, for me - you can make out the individual blocks with consummate ease, and the intended appearance of a random stone wall is lost, totally....
I see what you mean Tony and thanks for digging out the photo, it certainly illustrates your point quite well. I will opt for the adhesive approach. All the materials including the 4" concrete blocks have been ordered this morning so it's a case of no more talking about this project, just action from later in the week!! Again, many thanks for the replies and for maintaining your excellent site.
