Timber Frame Construction

Timber frame construction has evolved a great deal over recent years. From the days of thin timber used to construct reasonable (but not the warmest or most sound proof of constructions), you can now build a timber frame construction that contains enough insulation to allow you to construct your home without the need for any heating other than that generated naturally!

Timber frame construction has evolved a great deal over recent years. From the days of thin timber used to construct reasonable (but not the warmest or most sound proof of constructions), you can now build a timber frame construction that contains enough insulation to allow you to construct your home without the need for any heating other than that generated naturally!

There are many variations of timber frame construction. You can use a standard timber frame using a 140/145mm stud, space stud or open web stud which is generally 2 sections of separate timber held together with another element for example metal ties, I joist stud which is two sections of solid timber or laminated timber which are again separated but held together with another section of timber usually something like MDF, OSB or a hardboard.

ACJ Group offer a wide range of services and supply a variety of timber frame wall systems with U-Values ranging from 0.14 W/m2K – 0.09 W/m2K and the Therm-u-wall system achieving a U-Value of 0.08W/m2K, one of the most energy efficient closed panel systems on the market, ideal for use in passive house construction. If you would like some more information, please feel free to contact us on 01343 559327.

This lists just a few and due to the possibilities and availability of new methods of timber use, the list will expand for over future years.

One key advantage timber frame has over the traditional building (Brick or Block work construction) is the ability to insulate the centre of the frame (in addition to fixing onto the inside or outside as with traditional construction). This means you can fully utilise insulation in your new build, minimising heat loss and opening up the possibility of your new house paying you back over the years with its energy efficient construction.

Choosing a timber frame

When it comes to deciding which is the best choice of timber frame to go for, the best things to do here are (i) discuss the options with your Architect but probably more importantly (ii) do your research. Due to the ever-evolving types of timber frame, it’s quite possible you will find something that your architect has never have heard of!

Remember not every system will be available in your area and the costs of getting your choice to the site may be uneconomic and there may be an equally good but more cost effective choice. Think about the detailing. The thicker the timber frame the thicker your foundations may need to be. Ask your architect to look into the suitability of your design and consider involving a structural designer involved as it’s often best to leave the detailing and design to the experts.

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Foundations

Two important factors to consider in relation to foundations are site investigation and specification.

Two important factors to consider in relation to foundations are site investigation and specification.

Site Investigation

A site investigation helps determine what sort of work will be required to achieve a good solid load bearing sub-soil, prior to foundation works starting. The foundation is the first most important part of any build as this is the base for supporting the structure in future years. It will also have an overall effect on the quality of the build and the thermal efficiency of the house design. When deciding on the foundations required, you also have to make sure all of the specifications and details you use comply with current regulations and are in line with the local building authority’s guidelines as these will impact on the design and type of build system.

Ideally, you should incorporate a local specialist (e.g. Technician, Engineer or ACJ Group) to oversee the designs and build. Arrange for the site to be properly assessed by a structural engineer who can make recommendations on the appropriate foundations required.

Specification

There are many different types of foundation designs and procedures incorporating different insulated build ups. These designs and systems are dictated by the type of ground you intend to build on and on your house design. Examples include, traditional brick n block methods, standard timber frame or high insulated closed panel construction. The build type and its relation to the ground works will dictate the best solution for creating a sound foundation.

There are a variety of systems currently being used for foundations including pilings, piers and concrete spread footings. The more traditional build method for brick n block and timber frame construction is a solid poured concrete block creating a footing/slab running the area of the load bearing walls required external and internal. Building blocks can then be used to build the external supporting wall head, up to the required area for holding in the house floor design and creating a starting point for the external walls to be built from. This is key to creating a smooth and successful build. Diligence is required to maintain quality and in the setting out of all dimensions, making sure the wall heads are as level and plumb as possible. The internal foundation build can vary and will have a variety of layers building up to the finished floor level.

A common procedure would be to incorporate compacted hard-core, sand blinding, vapour barrier DPM, solid insulation, reinforced concrete slab, floor battens and flooring. If you are incorporating under floor heating, this build-up will replace the battens and flooring resulting in a poured concrete wet mix spread over to form a finished floor to suit supplier’s recommendations.

If you want to build a high insulated low energy home always check the cost implications of the build-up specified and be wary that designs and details can be over engineered and specified so having a set price for the foundation will be key as this is an area that can absorb a lot of the project’s budget. This will also help to cost out the rest of the build and materials required, allowing you to alter any specifications if needed to help achieve the project build within budget.

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Erecting closed panel timber frame

Due to current building regulations and the government pushing for more sustainable homes “Code 6”, construction related companies from timber frame suppliers to on-site manufactures are looking at modern methods of construction. Erecting closed panel timber frame systems can be an attractive option.

Due to current building regulations and the government pushing for more sustainable homes “Code 6”, construction related companies from timber frame suppliers to on-site manufactures are looking at modern methods of construction. Erecting closed panel timber frame systems can be an attractive option.

Timber Frame Systems

There are many timber frame systems available which offer a range of performance levels and they all have their pros and cons. Closed panel construction is a more effective build than standard timber frame methods but it has a higher requirement for accuracy and minimal tolerance in setting out. If you are experienced in timber frame construction then you will know the limits standard timber frames have with regard to site alterations, remedial and making areas fit/work. Some gentle persuasion is normally required however that mindset doesn’t work when it comes to closed panel timber frame houses.

Closed Panel System Construction

Designing closed panel systems becomes more technical and advanced in relation to connection details and introduces a variety of timber shapes, materials and steel ironmongery. Many of these connections and details will be hidden within the timber frame closed panel but they have an important role in the frame’s structural stability and tie in with the rest of the panels erected. It’s likely that the panels will come with an external membrane and internal airtight membrane already in place. This helps keep out the moisture during panel erection but the self-builder is well advised to get the building wind and water tight as soon as possible.

Before you start setting out panels a wall plate will be required. This material will be specified by the supplier along with fixing methods. This will be key to smooth panel erection so setting out all positions tying in with the structural design drawings is important.

When fixing the wall plates ensure you level all areas. This is because the closed panel systems will come square and require a level base which allows the panels to connect close together eliminating any gaps at panel joints.

During panel construction, look closely when setting out panels making sure you can clearly tell the top from the bottom side of the panel. Some will be more obvious than others but always make sure the panels are the right way up. This may sound condescending but some panels might have multiple studs located in areas designed to take high point loads from above. If the panel is upside down the panel may still fit but the structural integrity of the build could be affected in days if not years later.

Once the ground floor panels are in place, creating the first floor deck will be the next before this stage begins. Check to see if a mid floor membrane is required to wrap around the joist deck edge beam as this will help to make the build air tight by connecting the ground floor internal airtight membrane to the first floor around the joist deck. Before first floor panels are fitted, there should be another timber setting out locating plate. This will create the area for your panels to sit on. Once all first floor panels are in place and all fixings applied as per the supplier’s recommendations then the next stage will be the roof. These can be trusses, loose rafters or pre-made roof cassettes. Trusses and loose rafters have more flexibility and can be moved when required if needed, but this has to be approved by the supplier and this may affect the structural stability making the design certificate void.

Roof Cassettes

Roof cassettes are really good for construction as you can create larger room areas and higher void ceilings (as they are insulated). Even though roof cassettes have many positives, they rely on the supporting panel to be as accurate as possible. If the walls are off plumb and not level this can affect all of your cassettes by preventing them from sitting correctly and tying in together. This can also have a significant effect on the build’s air tightness. In short, closed panel systems are a great build method but are less forgiving due to setting out errors and require 100% accuracy.

Closely study your supplier’s designs as there may be many types of ironmongery, connections and air tight materials required which will need to be placed during the erection. Missing their allocated position during the build may not be critical but can make it harder for you to achieve your final goal with the building’s efficiency.

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