30 bricks, blocks & stonework Foundations of efficiency
Housebuilders hunting for cost-efficient methods of constructing foundations can overlook established building materials which also offer speed and effectiveness. Cliff Fudge, technical director at H+H explains how lightweight aircrete blocks have been providing practical and financial benefits for decades.
the UK, as it has throughout Europe. There are some parts of the industry however where the material is still seen as representing an unconventional approach. This is a misconception; aircrete has actually been used in the UK since the late 1950s. Despite this longstanding use in
A
construction, there is a belief that high strength materials such as dense aggregates have to be used on foundations could be costing contractors both time and money. In reality, aircrete provides a simplified and cost-effective method of constructing foundations for residential properties. In every test that aircrete has faced as a
foundation material, it has proven itself a resilient building material for masonry foundations in the homebuilding sector, for a multitude of reasons. Aircrete provides a simplified method of constructing foundations. Many builders using traditional materials still construct their foundations using two separate 100mm leaves, laying them with the required cavity onto a strip foundation to support the wall above. This cavity wall is tied together using wall ties and once complete, the cavity is filled with lean mix to shore up the structure. By contrast, a solid aircrete foundation
requires only a single leaf of blocks, and can be laid onto a strip of poured concrete the thickness of the wall. This method also requires no mortar at the perpendicular joints; instead they can be butted against each other. Using foundation blocks of a greater width such as 355mm means the laying rate of
respond online at
www.hbdonline.co.uk
ircrete as it is commonly known has become an increasingly popular choice for housebuilders throughout
aircrete is faster than that of aggregate concrete, enabling contractors to complete jobs in less time but to the same high quality. The weight of an aircrete block is only a
third of the equivalent dense aggregate block, which means they are quicker and safer to transport. Unlike dense aggregate, aircrete can be cut with a hand saw, and because aircrete is so easy to manipulate on site, wastage is also vastly reduced.
“In reality, aircrete provides a simplified and cost-effective method of constructing foundations for residential properties”
The advantages go further than just simplicity
and rate of construction. Independent construction and property consultants Calford Seaden recently published the Foundation Cost Comparison Study, which gave a detailed analysis of the cost of a range of foundation materials. The cost is indicative of a typical three-bedroom semi-detached UK home and results show that a saving of close to 25 per cent for the total build costs of foundations alone. There are several factors that contribute to
the cost effectiveness of aircrete as a foundation material. A fast build speed equals a reduction in labour costs but also the solid construction means fewer materials are needed; materials such as wall ties, lean mix and mortar at the perpendicular ends.
Strength and resilience
Despite aircrete being one of the lightest forms of concrete available for building, aircrete is fully load-bearing and blocks are available in a range of strengths up to 8.7N/mm2
,
which is more than enough for use in buildings up to three storeys. It is a common misconception that the strength required for foundations can actually be less than that required to build the superstructure. The area where strength is needed most is at the lintel bearing where windows and doors are introduced into the wall structure. As the load spreads down the height of the wall, the loading is evenly distributed across the whole length of the wall below the ground floor DPC. Although they remain unseen after a project
is completed, building foundations are continually under attack during the cold winter months in the UK. Problems can occur when inclement weather conditions create
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60