Source: This article is from the September 2011 issue of Popular Mechanics.
Erecting a sturdy garden shed, building a garage or extending your home can some times be a traumatic exercise, the most pain being felt when the labour bills arrive. (And you thought doctors were well paid.) The good news? It doesn’t have to be that way…
DIY construction The Cheap, Easy Way.
If you’re a budget-conscious DIY type with a building project in mind, then the Stumbelbloc – a locally developed building block produced onsite using reusable plastic moulds – could be your answer.
Invented by Capetonians Andre Esterhuizen and Riedewaan Jacobs, this clever system was originally developed for low-cost construction in rural areas, where transporting materials to remote sites is prohibitively expensive and trained labour scarce. However, the hollow-core Stumbelbloc, with its unique interlocking profile, is by no means restricted to the entry-level market. In fact, it didn’t take long to make its way into leafy suburbia.
A range of blocks has been developed to suit different applications and budgets. All can be made onsite or – if you really don’t feel like sweating over a mortar mix and fiddling with moulds – purchased ready-made. The simplest and cheapest of the range, the “basic-mix” blocks, can be manufactured using only a spade (to mix the cement), trowel and mallet. To make them, you simply fill the moulds (lubricated with old cooking oil) with a mortar mix and leave them to dry under shade for 48 hours. Once removed from their moulds, they need to cure for a further 7 days. The end result: tough, extremely accurate hollow-core blocks that feature male and female indentations, ensuring that they interlock vertically with complete uniformity.
When based on a mortar mix of 6:1, each basic-mix block records an average strength of 4,8 megapascals – a figure significantly higher than the SABS compaction strength conformity requirement of 3,5 MPa. Add small stones (less than 8 mm in size) to the mix, and you can boost their strength even further.
Upping the ante, you get the even tougher “optimal-mix” block. Made from a concrete mix using 13 mm stone, it boasts a formidable compaction strength of 9,2 MPa. Other variants include the “perlite-mix” and “polystyrene/perlite-mix” blocks.
Because perlite (essentially, processed volcanic ash) is to all intents and purposes fireproof, perlite-mix blocks boast excellent thermal properties. They only weigh 6 kg, making them particularly easy to transport as well as handle once onsite. Says Esterhuizen: “We’re currently perfecting our mix to make sure these blocks conform to SABS building standards. We have already achieved strengths of 3,3 MPa and are confident we will attain 3,5 MPa very soon.”
The polystyrene/perlite-mix blocks make knocking up internal walls a breeze, giving conventional drywall building methods a serious run for their money, both in terms of cost and speed of construction. They are also thermally efficient and fireproof.
Instead of using conventional cement mortar, all Stumbelbloc variants are joined – or more correctly, glued – together using Blockgrip (a thin-bed mortar-like product that is both SABS- and NHBRC-approved). Blockgrip sets in three hours, and is applied only to the bottom of each block by simply dipping their bases into the mix, making the construction process at least 10 times quicker and significantly cheaper than conventional methods.
Walls (except where the super-lightweight polystyrene/perlite-mix blocks are used) are load-bearing and can accommodate structures such as roofing or concrete decking immediately. No lintels are required for standard openings such as doors and windows. Instead, a lintel-like equivalent can be made by adding reinforcing steel rods and filling the blocks’ cavities with concrete. Columns, built and subsequently filled with concrete, reportedly cost about 30 per cent less to construct than conventional types.
Building with the Stumbelbloc is a bit like playing with Lego: once a solid, level foundation has been established, accurate construction is a cinch. Esterhuizen elaborates: “A 16 x 2 metre wall can be built from foundations up in about 40 minutes. A small house, including roof, can be constructed from foundation level by four workers in just three days. A 2 m x 2 m soakaway can be constructed, and become fully operational, within 30 minutes. Plus, when working from a firm, level base, building structures such as ponds, boundary walls or simple dwellings require no skill at all.”
Because no messy dagha is used during construction, all the blocks’ cavities remain open and accessible, allowing easy access for piping and electrical conduits, not to mention insulation materials.
Whereas surplus mortar can pose costly disposal headaches at conventional building sites, excess Stumbelbloc mortar can be used for making, well, more blocks. Minimal cutting is required for services access, resulting in virtually no onsite rubble. In fact, a typical day’s construction is said to result in less than one barrowload of waste.
It doesn’t cost a bomb, either. Moulds for full blocks cost about R200 (half-moulds are also available).
If you don’t want to make them yourself, expect to pay R10, R15 and R20 respectively for the optimal-mix, polystyrene/perlite-mix and perlite-mix blocks. For more information, contact Stumbelbloc on 083 228 8036 or visit www.stumbelbloc.com
Build it in a flash
To prove how fast Stumbelbloc construction can be, Andre Esterhuizen recently filmed a small team (comprising one bricklayer, two handymen and four labourers) while they built a 42 m2 cottage from start to finish in a seemingly unbelievable time of just three days. All the brick work was complete in six hours. Only 6 bags of cement were used during construction, and just 0.46 m3 of skim plaster was required to render all the outer walls. And, just two wheelbarrows of rubble were filled during the entire process. To check out how it was done, visit http://www.youtube. com/watch?v=aVCEuJf3LUQ
Ashley Stemmet – Interior designer and DIY writer
Mitre Saw
Splitting his time between his own interior design company and his role as DIY editor for Home magazine, Stemmett’s brief is to create affordable but interesting woodwork projects.
His philosophy: “I prefer projects that look good but don’t cost a lot to make.”
Working mainly with cheap materials such as pine, he uses his mitre saw primarily to cut wood to length.
(Hey, that’s what it’s for.)
Andrew Bain – Company owner and enthusiastic woodworker
Random Orbital Sander
When not busy high-pressure water jetting and spraypainting structures such as roofs or bridges for his company, Hydroblast, Bain indulges his real passion – woodwork.
As he explains it, “I love making sawdust!”.
Without a doubt, his favourite tool is the random orbital sander.
The reason: “Effectively a combined belt- and orbital sander, it’s a super-efficient tool and creates a far superior finish to any other sanding machine I know.”
Heinrich De Jongh – Furniture company owner and woodworker
Festool Domino Handheld Mortising Machine
A former forex trader, De Jongh recently started his own company, Heartwood Furniture, and now does what he likes best – working with his hands.
For him, strong, quality joints are non-negotiable – which is why he swears by his Festool Domino handheld mortising machine.
He explains: “Apart from creating strong, accurate hidden joints, it also features a fantastic dust extraction system that ensures my workshop stays clean.”
Tom Klose – Businessman and hands-on guy
Geared Plierench
Working in his family’s business, Klose Lawnmowers, Klose’s most indispensable tool is a vintage, US-made geared plierench dating back to the 1920s.
Found in a friend’s cellar about 20 years ago, it’s basically a shifting spanner, vice grip and pliers combined, with precise, powerful jaws that can be used for virtually anything, from removing stubborn bolts with damaged heads to pressing roll-pins home.
Says Klose: “I’ve lost count of the number of occasions where this tool has worked and modern, conventional tools have failed.”
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