6 Construction Systems for Your Self Build Project

Choosing a structural system for your new home is a big decision. Find out the pros and cons of the main options
by Build It
21st June 2020

The method you choose to build your dream home will have implications on practically every level of your project – costs, build speeds, internal layout and energy efficiency are just some of the areas that could be affected.

From the hands-on familiarity of brick-and-block to the ultra-fast build speeds and super-airtightness of structural insulated panels, there’s something to savour in every system.

Local authorities are usually more concerned with the external look of your home rather than the build system at its heart. That’s because, at the end of the day, every new home has to meet Building Regulations – and every system is capable of doing so.

Naturally, if you’re building in an area filled with timber-frame houses, planners and neighbours are more likely to be amenable to a similar build. But unless you opt for a really unusual route (such as an earthship) or your plot lies in a protected area, it’s rare to encounter any problems at planning level with this fundamental decision.

To help make things easier, we’ve put together a guide to each of the major build systems’ pros and cons – and highlighted a few of our favourite alternative routes to boot:

1. Brick and block

Modern masonry is still the most popular build route in the UK, accounting for around 70 per cent of all new homes.

Brick and block consists of an outer brick skin and an inner block skin. These two leaves are held together with wall ties. Internal load-bearing walls are also made of blocks, while timber studwork is used for non-load bearing walls.

In the past, wall cavities were restricted to around 100mm – more than enough to satisfy Building Regulations, but nevertheless a limiting factor on insulation levels.

Recent innovations in wall tie manufacture, however, have led to dramatic improvements. “We regularly deal with brick-and-block constructions involving cavities up to 300mm in width,” says Jamie Hayes, technical officer for insulation manufacturer Celotex.

Brick and breeze block wall

Masonry houses are built entirely on site, beginning with concrete foundations. Work progresses to first-floor level, at which point internal load-bearing walls are constructed and timber floor joists or a pre-cast concrete floor added, before continuing up to the roof.

Build speed: Around 20 weeks for a three-bedroom home (180m2). Site work progresses slower than alternatives such as a timber frame, but lead times for materials are drastically reduced.

Cost: Around £80-100 per m2 for the blockwork, cavity insulation, brick outer wall, lintels, wall ties and cavity closers.

Brick and Block Pros

  • Local tradesmen readily available (hands-on self builders can even get involved themselves)
  • Discrepancies in foundations and levels easily rectified on site
  • Excellent thermal mass helps even out internal temperatures
  • Good acoustic performance is built into the dense materials
  • Can be combined with beam and block floors to enable open-plan layouts and minimise creaking floors

Brick and Block Cons

  • Wet system requires time to dry out, slowing construction
  • Building work cannot proceed in heavy rain or freezing conditions
  • High levels of insulation require thick wall profiles
  • Energy performance of finished house relies on the quality of work by site operatives

Learn more about brick and block

2. Timber frame

Around 25% of all new homes are built using panelised timber frame, many of them by eco-conscious self builders.

In this system, the frame acts as a superstructure, supporting the entire building. So there may be no requirement for internal load-bearing walls, freeing up space for open-plan layouts.

Learn more: How to Build a Timber Frame House

The frame is prefabricated off site, giving you the reassurance of a factory guarantee that the high-quality finished house shell will deliver the performance you’re expecting.

Case Study: Timber Frame Self Build Home

Potton home exterior

Bob and Mandy Williams decided to self build after they couldn’t find a suitable property on the market in the area they wanted to live. After some research, they chose to adapt one of Potton’s timber frame designs into their ideal home.

The couple worked with one of the company’s in-house designers to make extensive modifications to the design they liked, which was then put through planning by the Potton team. Work on site got underway in March 2018; the couple were particularly impressed at just how quickly the timber frame went up on their plot.

Bob and Mandy moved into their new home in December the same year. The finished property features a white rendered exterior and light-filled interiors thanks to large windows and glazed doors. The pale grey composite fenestration and aluminium rainwater goods create a modern look. An air source heat pump works alongside underfloor heating to create a comfortable home, which the pair are delighted with.

Timber framing is a specialist skill, so don’t expect to get too hands-on with this part of the build. Most manufacturers require you to commission them to both fabricate and erect the frame, taking it at least to watertight stage.

Some timber frame suppliers even provide a full turnkey service for your bespoke self build home, where you agree the design and they complete all the works for you. Alternatively, the company may have a list of recommended contractors in your area.

Often, you can either choose from a range of standard designs, which can be tweaked, or ask your timber-frame supplier to work to bespoke plans drawn up by an architect. Design options range from ultra-modern homes clad in swathes of glass to traditional beamed properties.

Build speed: A timber frame home can be erected and made watertight in as little as five days.

Cost: Around £90-120 per m2 for the structural frame.

Timber Frame Pros

  • Speedy on-site construction – standard houses can be complete in 8-12 weeks
  • Ideal for creating open plan internal layouts
  • Cost certainty for completion of the watertight house shell (and possibly beyond)
  • Excellent insulation levels with thinner walls than masonry, with airtightness detailing easy to achieve, too
  • Properly sourced timber is a sustainable resource, and factory-manufacture ensures minimal wastage

Timber Frame Cons

  • Frame fabricated off-site, with typical lead times of 6-8 weeks
  • Foundations must be perfectly level within small tolerances, and you’ll generally have to arrange these through your own groundworks contractors
  • Little room for modification of frame after fabrication, so good planning and a ‘design freeze’ are vital

Learn more about timber frame

3. Insulating Concrete Formwork

If you enjoyed playing with building blocks as a child, then insulated concrete formwork (ICF) could be for you.

Basically, ICFinvolves stacking a series of hollow blocks, which interlock to create a mould that can then be pumped full of ready-mixed concrete for an ultra fast build. The resulting walls are pre-insulated and super airtight.

Common block options include expanded polystyrene (EPS) and bonded wood fibre, while panelled versions are also available.

ICF construction site

Using an experienced ICF installer is the best way to ensure project success. But with a little training, which is often offered by ICF suppliers, self builders can get very hands-on with building work.

The trick to proper construction is getting the first course absolutely plumb, level and square. It’s well worth getting professional assistance at this stage to set the pattern for the rest of the work, as any misalignments tend to get amplified as building progresses.

Case Study: An ICF Self Build

White render house exterior at dusk

When the owners of this contemporary new home struggled to find a property they liked on the market, they decided self building was the best solution to a bigger home that catered for their young family.

After investigating which construction methods would offer a speedy build time and an energy efficient result, the couple decided that insulated concrete formwork (ICF) ticked all the boxes on their brief. They sourced their structural system from ICF Scotland, which supplies Nudura blocks.

Contemporary kitchen

Work started on site in January 2016 and the whole family got hands-on with laying the ICF blocks – one of the benefits of this system. Although they were set back by extreme weather and flooding, plus frustrating delays because of problems concerning getting utilities connected, they were determined to be in the house for Christmas.

Less than a year after they started, they moved into their new home on 23rd December. The result is an energy efficient home that boasts and MVHR system, underfloor heating and triple glazing.

ICF is a quick build system, so even if you employ skilled workers for the duration of the project you should still save on labour costs in comparison to brick-and-block.

Once the concrete pour is set, the structure can then be finished in your choice of cladding. Render, for instance, can be directly applied to the polystyrene blocks.

Build speed: Basic structure can be up in a matter of days.

Cost: Around 5% higher than for a typical brick and block build.

ICF Pros

  • Excellent insulation levels built into structure, and very little construction waste
  • Minimal need for skilled labour
  • Impressive acoustic performance
  • Structural envelope is watertight before cladding, so other trades can start early
  • ICF is cost-effective to waterproof, making it a great choice for projects involving basements

ICF Cons

  • Errors in foundations/early courses costly to remedy
  • Adaptation post concrete pour is difficult and expensive, requiring specialist tools and professional advice
  • Not all follow-on trades have experience with ICF

Learn more about ICF

4. Structural Insulated Panels

Structural insulated panels (SIPs) are very similar to timber frame. They are typically made up of two layers of oriented strandboard (OSB) bonded around an inner core of insulating material.

The precision-engineered panels are prefabricated in a factory, which makes for excellent quality control along with  time and labour cost savings on site.

When used for load-bearing purposes, they’re suitable for building walls, ceilings and floors.

In fact, SIPs panels are so strong that they can be used to create truss-less roofs for liveable loftspace that make best use of available height. We’ve heard of many self builders who’ve combined other build methods with a SIPs roof for this reason.

Sips panels being lowered into place

These SIPs panels are provided by Kingspan

SIPs is also growing in popularity as a wrap-around for green oak frames, combining this system’s airtightness with the charm of internal exposed beamwork.

Whether you choose a full SIPs build or a wrap-around, this system will deliver an exceptionally airtight and highly insulated building envelope. This can make energy-saving standards such as Passivhaus easy to achieve.

As SIPs panels are lightweight they’re quick and easy to crane into place, which will save you time at the construction stage. Experienced teams can erect the structure of a standard SIPs house in as little as three days (or seven to 10 days for an oak frame with SIPs wraparound).

Other timesaving bonuses include pre-cut door and window openings (much like with timber frame).

Closer Look: Stylish New SIPs Home

A large house

Richard and Ros Maudslay worked with the team at [email protected] to create their new dream home. The complex design spreads across two levels, with only one 90° square corner in the whole property. Other interesting architectural features include large spans of glazed walls and a 4.5m overhang created from structural insulated panels.

Off-site precision engineering was the right solution for this ambitious build, but the tight access via rural lanes was a challenge for getting the system delivered to the plot.

However, once there, the [email protected] team quickly assembled the structure, with the home watertight in just over a month. “Seeing the SIPs structure rise from the ground was one of the high points of our project,” says Richard.

Build speed: Can be even faster than conventional timber frame on site, but prefabrication of panels takes around 10 to 12 weeks.

Cost: Can be around 15 per cent more than a standard timber frame up front, but you’ll save on labour costs and heating bills.

SIPs Pros

  • Labour costs reduced due to quick build times
  • Excellent levels of airtightness
  • High levels of insulation built in to the structure
  • Features such as open-plan layouts, vaulted ceilings and habitable lofts easy to achieve

SIPs Cons

  • Extremely precise measurements are required
  • Any alignment issues, especially in foundations, will lead to delays on site
  • Experienced labour is a must, and harder to find than with conventional timber frame

Learn more about SIPs

5. Oak frame

Oak frame is a historic structural system that remains as popular as ever amongst today’s self builders. The characteristic warmth and visual charm of oak works well in both traditional and contemporary builds.

What’s more, many oak frame suppliers now provide a bespoke architectural service, meaning that homeowners can enjoy a seamless design and build process.

Case Study: Contemporary Oak Frame Cottage

This project won the Best Oak Frame Home at the 2018 Build It Awards. The owners wanted to build a house packed with character and wow factor. They were attracted to the warmth and texture of oak framing.

Oak frame home exteriorThey worked alongside design specialists at Border Oak to create internal spaces that have pitched oak roof trusses alongside vast swathes of glazing, creating a rustic, yet contemporary space.

Although this method of construction typically adds roughly 10% to structural costs, you can still build an impressive oak frame home on a range of budgets with carefully considered design.

For the frame to meet modern performance standards, it is usually encapsulated to create a highly efficient thermal envelope. This might be done with SIPs or another pre-insulated panel system.

Oak Frame Pros

  • Many oak frame suppliers have in house designers who can help you create your dream bespoke home.
  • Oak is a natural material, so it’s a sustainable option if it is sourced from environmentally managed forests.
  • Adds wow factor to both traditional and contemporary home designs – usually reflected in the end value.

Oak Frame Cons

  • Oak projects typically cost more than comparative designs in other build systems – but often have a higher resale value.
  • The oak will settle and shrink into place during the drying process and this must be carefully considered in the design phase, especially if you choose to install direct glazing.
  • Most people who build with oak choose to complement the system with high-quality materials such as handmade bricks and roof tiles, which will cost more than standard options.

Learn more about Oak frame

6. Thin joint blockwork

This is a variation on conventional brick-and-block. For self builders, the immediate appeal is that construction speeds are much quicker than standard masonry, assuming you use a contractor experienced with the method.

That’s thanks to the use of quick-drying 3mm mortar lines as opposed to 10mm for traditional masonry (hence the name ‘thin-joint’) and the optional use of oversized aircrete blocks.

Aerated for lightness and to improve their insulating qualities, aircrete blocks are surprisingly strong, and can even be used for foundations.

This system shares many of the advantages of brick-and-block. For example, it’s relatively easy to adapt or extend a thin-joint home.

Labourers should be fairly easy to come by, too, as brickies only need a little retraining to acquaint themselves with the technique. In fact, most trades should find working on a thin-joint home to be a familiar experience.

The use of thin mortar beds allows for greater build accuracy, which means time-saving thin-coat spray plasters or renders can be applied to finish the walls inside and out.

Build speed: A standard design could reach weathertight shell stage in around five to 10 days.

Cost: Likely to come in 5% higher than standard brick-and-block due to increased material costs, although labour savings on large projects may bridge that gap.

Thin Joint Pros

  • Excellent thermal insulation and acoustic performance thanks to aircrete blocks and thin-bed mortar
  • Reduced wastage of building materials
  • Contractors will find the system familiar to work with

Thin Joint Cons

  • Deviations in level or plum cannot be made up in the mortar bed – your contractor may build in conventional masonry up to the damp proof course to even out discrepancies
  • Conventional scaffolding may not be suitable – ‘quick staging’ versions offer more flexibility

Alternative methods

There are other options to the main contenders for your new home, namely systems that use largely natural materials.

Straw bale

  • Popular amongst super eco-conscious self builders who are keen on using natural materials.
    The straw bales can be stacked like bricks to create loadbearing walls or used to infill a structural frame (whether timber, steel or concrete).
  • Straw is an agricultural waste product, which means that building with this method comes with a very low carbon footprint.
  • This is an opportunity to get hands on with building your home.
  • The depth and natural look of the walls adds charm and character.
  • No more at risk of fire and pests than other structural options.

Log building

  • Great way to get that cosy chalet style popular in ski resorts.
  • These designs look particularly fitting in woodland areas.
  • Quick construction as the structure is made in a workshop.
  • Durable and thermally efficient.
  • There are options in terms of the type of wood used.

Cob

  • Lots of people love the historical heritage of this method – building with mud dates back to 8,000BC.
  • Walls are made from mud from clay, water, aggregate and straw, which leaves little carbon footprint and creates an organic aesthetic.
  • Cob is a great option for doing a
  • DIY self build project.
  • Once built, the finished cob structure will require maintenance from homeowners, including an annual lime wash.


Main image: Oakwrights

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