Brick and Block
In modern traditionally built houses the walls are built in two leaves. There is an internal blockwork wall and the external wall built of brick or stone.
These, together with some internal partitions which are also built of blockwork, will support the structure of the house.
Brick and block can be one of the cheapest construction types. Most builders would prefer to build in masonry, so builders tend to price a bit more competitively, and of course a lot of ‘self-builders’ are in the trade, so they have more chance of getting better rates from mates or family in the trade, than they will from a timber frame company.
Modern masonry construction is however slower than a frame construction which can be up with a matter of days.
Timber frame open panel systems, are structurally engineered panels that form the inside load-bearing leaf of the external wall, comprising studs, rails, sheathing on one face and a breather membrane. The open panel system is made from treated softwood timber framing, over which a structural sheet material of either Ply or OSB board is fixed. Depending on the system, U-values ranging from 0.26 down to 0.15 W/m²K, can be achieved.
Are made from studs, rails and insulation, with sheathings and/or linings on the faces of the panel. A vapour barrier is also provided on the warm side of the insulation and a breather membrane on the outer face of the panel. If desired, closed panels may also include fitted windows and internal service zone battens, for ease of installation and construction. U-values from 0.25 right down to 0.10 W/m²K can be achieved. These solutions have been designed to deliver excellent thermal and airtightness properties and are ideal as the basis of a modern energy efficient home.
Insulated Concrete Framework (ICF)
Insulating concrete formwork (ICF) or permanently insulated formwork (PIF) is an insulated in-situ concrete system of building that is quick to construct, providing a practical method of building insulated walls for houses.
ICF is based on hollow lightweight block components that lock together without intermediate bedding materials, such as mortar, to provide a formwork system into which concrete is poured. The block is formed of sheets of insulation materials normally expanded polystyrene tied together with plastic or steel ties, or an integral web of the same insulation.
Once set, it becomes a high strength concrete frame structure with the formwork remaining in place as thermal insulation, with u-values ranging from, 0.3 w/m² k as required by the standard Building Regulations down to 0.11 w/m² k – ideal for zero energy buildings.
Steel Framed Construction
Building in steel has been popular in the USA and South Africa for some time and recently has been the subject of much interest in this country. The steel framework is lightweight, strong, weather resistant and quick to erect. Exterior panels are attached to the steel frame and then rendered. Most of the materials are made to measure prior to delivery on site and thus the house can be made weatherproof very quickly.
Structural Insulated Panels (SIPS)
Structural Insulated Panels (SIPs) provide a cost effective, environmentally friendly and labour saving alternative to traditional timber framing and masonry construction methods.
A typical panel consists of two sheets of oriented strandboard (OSB), which sandwich a thick layer of high quality foam insulation. The core is usually made of expanded polystyrene which is injected between the sheathings under pressure to create an ‘autohesive’ bond. As the foam sets, it bonds chemically with the OSB to create a lightweight, ultra-strong panel, without the need for any internal studwork.
SIPs are quick to erect (typical house erected in 5-7 days including roof), strong and energy-efficient (7 times stronger than timber frame, 3 x stronger than brick and block) making them a fantastic option for self builders – not least because their accurate manufacture helps simplify construction on site, reducing the chance of the project falling behind schedule. Structural insulated panels are usually used in roofs and external walls of buildings but may also be used in floors and internal walls.
The long term benefit of building using SIPs is lower energy bills and reduced energy consumption and CO2 emissions. Their lightweight and factory production reduces transport energy and onsite wastage, therefore reducing the overall carbon footprint.
Making buildings with dirt is an idea that's been around almost as long as man has been on earth The traditional material for English cob was soil (clay-based) mixed with water and straw, sometimes with crushed flint or sand added.
Whilst the cob is simple, it’s incredibly durable, with the oldest standing cob built in the UK dating back to the 1200s.
The technique involves building up thick walls by working in layers, letting each one harden before adding the next. The wall is then plastered with clay or lime, or can be left unfinished.
Cob is simple, cheap, requires few tools other than your hands and is extremely environmentally friendly. The end result dries almost as hard as concrete, making it ideal for structural walls. It’s durable, fire-resistant, has high levels of insulation and malleability, allowing the walls take on any shape you wish. The downside is that the build process can be time-consuming.
Straw Bale Construction
People have built homes using straw, grass, or reed throughout history due to the low cost and ready availability. During the late 1800s on the American plains however, straw bales houses were a matter of necessity; there was no lumber for construction. Now, with the rise in interest in sustainable housing, there's been a revival in straw bale construction.
With straw often being a farm surplus product and very cheap (around 40p a bale, or £1.50 delivered), it's inexpensive, and an easily renewable medium. Properly built, straw bale houses are fire-resistant, waterproof and actually pest free, with super-insulated walls.
Structural Bale Construction. When used to bear load, the bales are placed on top of each other in a stretcher or running bond with long wooden pegs driven through to connect the layers.
Non Structural / Infill System
When used as insulation, the bales infill the walls of a timber frame structure. In both cases the walls are rendered with lime as it’s able to cope with any minor movement in the bales.
You'll need about 300 standard three-wire bales of straw to make a 2,000 sq ft house (186 sq m).
You need to use bales that have a uniform size (about a metre long, half a metre wide), are well secured with two strings, and with very few seed heads. Make sure they're compacted properly and dense - each bale should weight between 16-30 kilos - and dry (and be sure you keep them dry when you're building, for obvious reasons). Even after you've finished the house, you need to be certain the centre of the bales doesn't become wet through either the top or bottom - however, if the outside gets wet, that's fine; it'll dry out naturally.
In theory, at least, a properly constructed straw house, built where there's good drainage, could last for centuries. You should probably use a different material for the roof, however (something more permanent), and build that roof at a steep angle for drainage.
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