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There are two very different approaches to housebuilding and these two methods have existed side by side for centuries. The first is to use heavyweight materials like stone, brick or concrete, and to use a team of masons to assemble them into a house. The second is to use lightweight framing materials, traditionally wood, sometimes steel, to build a frame and then to cover it all with some weatherproof cladding: the work is predominantly carpentry.

The Masonry House

The key difference between masonry built homes and timber framed ones is the material used to build the inner, load-bearing walls. The outer, facing walls are not affected: you can use any external walling material with either build method. In fact, it is usually impossible to tell from a visual inspection whether a house is masonry built or timber frame.

However, the way the houses are built is quite different. A masonry house is constructed by bricklayers, building up both internal and external walls, a course at a time. They fix the insulation inside the cavity between the two leafs of the external walls as they go: they may also fix the door frames and the windows as they work up. They stop at first floor level and call the carpenters in to place the floor joists, though sometimes the floor is pre-cast concrete, craned into site. The bricklayers return to build up to roof level and then leave again, whilst the carpenters return to build the roof. If the design includes gable walls, the bricklayers return for a third time to complete the wall building process.

The load-bearing inner skin walls and any load-bearing internal partition walls are constructed in concrete blockwork. Non-load-bearing walls are built either in blockwork, or timber studwork. Services such as wiring and plumbing are fixed to, or chased into, the blockwork and covered by the plasterers.

Masonry Pros
* Easy to design — architects like it
* Readily understood by the building trade
* Materials cheap and readily obtainable
* Forgiving of errors — foundations don’t have to be accurate
* Slightly easier to make alterations and additions
* Inherently good soundproofing and fire resistance
* Traditional hard plastered walls an option if desired

Masonry cons
* Harder to incorporate thermal insulation in external walls
* Awkward cavity details
* Prone to inaccuracy and defects
* More likely to suffer from settlement and shrinkage cracks
* Slow to build and prone to delays from bad weather
* Wet trades create more mess on site and require drying out time

The Timber Framed House

In contrast, a timber framed house is built by carpenters. With the exception of the chimney, all the structural elements above ground level are built using timber. This can all be done on site, in the American way, known as stickbuilding, or the panel building can be carried out off site in a factory, — almost all our timber framed homes are built in factories. This greatly reduces the work of the on-site carpentry team who have to do little more than assemble the panels, a task that typically takes no more than a few days as opposed to the several weeks needed to build a masonry superstructure. The panels often have the windows and doors already in place. Some methods supply fully finished walls and roofs but the typical timber frame house has open panels; a semi-finished state that has to be insulated and cabled on site before the plasterers cover the inner walls with a wall-lining board.

If the house requires a brick or blockwork facing, the bricklayers come in after the timber frame is fully erected. They can work on the outside whilst the finishing trades go on inside and the roofers work overhead.

A typical timber frame wall consists of a framework of timber studs, frequently 90mm deep, boxed over with a sheet of plywood which is itself covered with a layer of waterproof building paper which deflects rainwater away from the frame. The voids between the timber studwork are filled with insulation and on the inside a sheet of polythene known as a vapour control layer is fixed before the whole thing is faced with plasterboard.

Timber Frame Pros
* Prefabricated superstructure erected quickly once on site
* Tends to be built to far tighter tolerances, making fitting out quicker and easier
* Weather delays reduced
* Less shrinkage and settlement
* Inherently good thermal insulation
* Easier to run services through
* Wall cladding is taken off the critical path

Timber Frame cons
* More complex to design — tends to be done by specialists
* Often lengthy lead-in times waiting for kits to be assembled in a factory
* Still not well understood by many Irish builders.
* Needs additional materials for adequate soundproofing
* Can’t have a solid (concrete) first floor
* Requires more accurate foundations
* Finance issues: large sums required upfront by many suppliers

The Main Differences

Virtually all new houses in this country have a foundation built out of concrete and a roof built out of timber, so all homes are to some extent both masonry and timber frame. The question that exercises us here is where to make the switch from one material to the other. Should it be up at the eaves (masonry builds) or down at ground floor level (timber frame)? Over the centuries we have used both methods but in the 19th and 20th centuries, brick and, later, blockwork came to predominate. However, developments in timber frame building methods in Scandinavia and North America have been introduced into Ireland and timber frame has slowly but surely been gaining market share since the 1960s. In Ireland it’s growing at a prodigious rate and in England and Wales timber frame would account for more than the 10% of new homes it already takes if there were more factories up and running to meet the demand.

Builders like several aspects of timber frame. It’s a dry building system, which is erected very quickly (usually in a matter of days) to engineering tolerances, enabling other trades to get on with their work both inside and outside without getting in each others’ way. However, timber frame’s strength – factory built homes – is also arguably its greatest weakness, too, in that the building of the superstructure is taken away from the site crew and into the hands of a specialist sub-contractor, the timber frame company. A good one will make the whole job run smoothly: a bad one will cause far more work and disruption as deadlines are missed and materials fail to materialise. If you choose to work with a timber frame company, do check on their past performance and also their payment terms, as you will in all probability be asked to pay a large amount of the total sum owing before taking delivery of the frame. If you are borrowing to fund the build, you need to let your lenders be aware of this fact.

How Do Costs Compare?
The very fact that both methods are widely used throughout the country indicates that there is little to choose between the methods on cost grounds. If one system were significantly cheaper, it would rapidly predominate.

It used to be held that timber frame was a little bit more expensive but that you tended to claw back the difference by reducing the length of the build — it costs money just to keep a building site up and running. But in recent years we have seen great hikes in labour costs, so the cost differential has all but been eliminated. On the other hand, the strongly growing demand for timber frame has caused a capacity shortage and, consequently, the lead time required to get the frame to site has got longer and longer — in some cases stretching out to 12 or even 16 weeks, so the speed advantage of timber frame is diminished, though the amount of time spent on site is still reduced.

Energy Efficiency

You will be required to meet the same levels of energy efficiency whatever system you use to build your house. However, because its external walling is largely hollow, it is cheaper and easier to build very high insulation levels into a timber frame house. You can pack the insulation into the void between the timber studs, whereas with block walls you have to fit the insulation either side of the blockwork. Usually this is done in the cavity between the inner and outer leaves of the wall but, as insulation requirements have increased, the cavity has got wider and wider. Whilst masonry systems will always be able to cope with the levels of insulation demanded, it is set to become more awkward to achieve.

However, thermal insulation is only part of the picture. An energy efficient building also needs to be well sealed; otherwise the heat will leak away through air gaps and unplanned drafts. Many modern building practices in both masonry and timber frame tend to increase the likelihood of air gaps: it’s particularly common where you use modular materials like plasterboard and beam and block floors where you encounter many joints. One solution is to pay close attention to vapour barriers, a detail often skated over by subcontractors. Another is to use solid concrete floors and wet plastered walls.

Just as timber framed homes can be designed to be very quiet, masonry homes can be designed to be very energy efficient.

What’s soundproofing like in a timber frame house?
Noise transmission between rooms is one of the major reasons self-builders give for choosing masonry construction over timber frame. The perception is that timber frame houses have thin, hollow walls and that you will be able to hear what goes on in every room in the house. The reality is more complex. Dense, heavy materials do absorb sound well: masonry materials will always have this advantage. However, the trend in all forms of housebuilding over the past 50 years has been to use lighter and lighter materials, notably chipboard floors and plasterboard on walls. Consequently, the sound absorption characteristics of the average modern house, whatever the construction, is poorer than it was a century ago.

It’s not difficult to improve on this. There are lots of walling and flooring materials designed to absorb sound. Specifying masonry walls and pre-cast concrete floors is one solution but not the only one: look also at resilient strips and bars, soundcheck boards and acoustic insulation.
Also pay attention to the detailing of your home at the design stage: avoid holes in the ceilings under bedrooms (common with downlighters), build cupboard space into walls, use soft materials like carpet in preference to wood or stone on floors. You can build quiet homes using any construction method: conversely, not all masonry homes are quiet. If you really are concerned about noise levels within your home, pay attention to the issue at the design stage.

External Wall Finishes

As far as external wall claddings are concerned, you can choose any facing material to work with any backing. Brick, stone, timber, tile, render — all can be applied to blockwork and all can be applied to timber framed backgrounds. However, there are significant cost implications, which are sometimes overlooked.

Brick: Often thought of as the natural partner to blockwork (as in ‘brick and block’) but it’s just as easy to lay bricks against a timber frame. Some would argue that it’s even easier because you are usually working with an empty cavity, whereas blockwork cavities have to be packed with insulation, placed in by the bricklayers as the walls go up.

Stone: If the stone to be used can stand up as an independent leaf of a cavity wall — like cropped or reconstituted stone, or is being built up against a backing block to form the outer leaf of a cavity wall, there is nothing to choose between masonry or timber framing. Random stone walling, when built directly against a fully filled cavity will, however, be cheaper to build against masonry, as a backing block will not be required.

Render or harling: Like stone, it’s often set against an outer skin of blockwork, even when the inner skin is built of timber frame. However, there are steel meshes available which can be nailed onto battens around a timber frame which will take a three coat render: this is much quicker than having to build a blockwork wall around the frame though cost-wise there doesn’t appear to be much between them.

Tile, timber and lightweight claddings: There are some significant cost and time savings to be had from placing these against a timber frame background because they can be directly applied to a battened-out frame, whereas with masonry systems they need to be applied to an outer wall. With timber frame, the cost of building a second outer wall is eliminated and the overall wall width is minimised.

Is There a Prejudice Against Timber Frame?
For mortgage purposes and insurance, most lenders and insurers rank timber frame equally with blockwork. As far as resale values are concerned, there appears to be no difference at all between the two systems. However, some individuals have their own preferences, built up from their own experience or things they have heard about either system.

Does the Build System Affect My Internal Wall Finishes?
Yes, but only slightly. If you build with a framing system, then you must cover your walls with a board. If you use blockwork, then you have a choice: you can either use a board, or a wet render and skim finish. Does it make any difference? Cost-wise there is little to choose between them so it largely comes down to preference. Some people prefer the hardness and solidity of a traditional plaster finish but the majority of people don’t even notice how their walls are finished. With boards, you can, in any event, have a traditional wet plaster skim finish: the 3mm thick topcoat can be applied to both plasterboards and cement renders. Additionally, any surface treatments that you might wish to apply to your internal walls, such as ceramic tiles or timber panelling, will sit fine on either wall type.

On ceilings, of course, you have to have a board finish whichever method you choose to build with. The trend here is to not skim the finish but to tape the joints between the boards and to sand and paint over the surface: this eliminates the wet trades altogether and also minimises surface cracking, a common defect in plasterwork in new homes.

Featured in the April 2005 issue of Homebuilding & Renovating magazine. Words: Mark Brinkley.

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