If there is one thing to be said about designing a new home, there are perhaps too many choices available. I mean when you go to buy a new car the choices are limited to alloy type, body colour, seat trim, engine size and saloon or hatchback. You don;t get an option to decide on the metal alloy that will form the exterior shell.
When you have planning permission and are preparing to build your new home, one of the many options available is of course the frame or indeed external structure of your home. Three main types exist here; block-work, timber frame or ICF which we shall consider separately but it should be borne in mind that even though they all have different characteristics and benefits, they will all (as a prerequisite) comply to building regulations in terms of strength, durability, airtightness, insulation and so on.
Blockwork
In Ireland houses were originally built with locally sourced stone and lime. This would have continued right into the 20th century when eventually concrete blocks made from crushed aggregate in a local quarry took over. Though there is a cost to buy the blocks they are far easier to lay that stone and given their regular shape the resulting wall is much easier to control in terms of line and plumb. Blockwork is still the cheapest for of external envelope structure though one of the most complex to work with on site. There are a myriad of moving parts to watch. Cold Bridging especially and junctions and reveals, damp proof courses, tying detail, cavity cleanliness level & plumbness. On top of this there is an ongoing setting out and detailing burden which can be very complex on site depending on the house design. The otter aspect is the trade itself. Blocks have to be delivered by a large truck and lifted onto loading bays for the masons and scaffolding may need to be adjusted to suit. . When you consider these items above blockwork can be a complex and tedious process for the self builder and coupled with the health and safety responsibility of this process and the time it takes to execute, particularly given its sensitivity to wet, windy or sub zero winter weather, it may be a step too far for al but the most seasoned direct labour builder.
Timber Frame
Timber frame construction really took-off in the Irish Market during the early Celtic tiger years. Unfortunately due to the sheer volume of construction in Ireland prevalent at this time meant that this period of Irish construction is not synonymous with quality. However timber frame construction held firm and the quality of the frames and indeed the site detailing by professional builders has increased considerably since then. Key areas to watch here are setting out of the blockwork base (dedwork) and timber frames come factory built so no room for measurement error and because timber is derived from a living tree the timber needs to breath or it will decay. Considerable care on site must be given to the correct ventilation and insulation techniques which are unique to timber. The frame sections will arrive flat pack on an articulated truck and normally they are erected on site using a mobile crane supplied and operated by the timber frame company. Though timber frames will cost a little more than blockwork your house frame will be built considerably faster and with less moving parts to supervise and detail on site as much of this has been thought out already by the timber frame company and manufactured in a controlled factory environment. You will need to have many of your key decisions made early e.g. exact window sizes & kitchen layout as there is little or no room for error or adjustment on site. As regards weather, the main thing to avoid is heavy winds as these will affect crainage.
ICF
ICF or insulated concrete forms are a bespoke frame type that certainly has its use in house frame building. ICF is essentially insulation mounds that contain reinforced concrete in internally. So the concrete in the center becomes the structure and the insulation internally and externally becomes the insulation aspect. Advantages of this approach are that the insulation forms are Lightweight and relatively simple to install. The fixing of the steel is a little more tedious and the concrete is poured using a concrete pump. There is also a significant bracing process required to ensure no movement of the form structure when the concrete is being poured. Though this appears to be a relatively simple process particularly in terms of assembling the insulated forms, once you are tying steel and pumping concrete ther is no room for complacency and this is certainly a specialized trade and best left to the experts. It may however become a subcontract in a direct labour project. The key benefits of this approach are the lightweight aspect of the insulated frames which may suit a site that is difficult to access. The concrete structure will be stronger than block work so could very well double up as a retaining wall (once designed and detailed accordingly but the ICF supplier and your supervising engineer). ICF will likely cost a little more than block work in a standard flat site application but may offer value in a more complex build or site where additional structural strength is required.
So very broadly, blockowk in likely the most cost effective but complex and tedious not execute. Timber frame cost a little more but considerable quicker and will offer many benefits to the direct labour builder as many of the headaches are dealt with by the timber frame company. ICF will also likely cost more but may be of benefit in a hard to reach site or a house requiring additional wall strength in say a retaining situation. ICF is a little more like blockwork in terms of the daily setting-out requirement on site but timber frames come pre-fabricated and merely erected and fixed on site. In truth they all have their benefits and uses but best to evaluate your project in terms of budget, complexity, structure and program to see which approach will work best for your new home
