Timber or Steel Frame

The most common frame for the standard brick veneer house uses timber.

Steel frames however are becoming much more common. . . . So why should you choose one or the other?

Advantages of Timber

  • Well understood by builders;
  • Cheaper;
  • Easy to adapt or modify during construction or later;
  • Is a sustainable resource;
  • Better sound and heat insulation;
  • Easier to fix fittings into;
  • Lock away carbon.

Advantages of Steel

  • Cannot be attacked by termites or borers; (that doesn’t mean you don’t need termite protection as there will still be plenty of wood in door frames and cupboards etc);
  • Prefabricated frames are lighter than timber;
  • Steel doesn’t have to be treated with chemicals;
  • Doesn’t rot;
  • Doesn’t shrink warp or twist;
  • Doesn’t burn;

NB. Inside a building rust will not be a problem, but just in case most steel frames are galvanised.

All my houses up to now have had timber frames and I have been happy with the result so I would probably continue to use timber if I was getting someone else to erect it.

If I was planning to erect the frame myself I would probably go for steel for the weight saving.

 

To find out more about house frames follow this link: House Construction – The Frame

For similar posts look in the Design Category

 

 

Steel Wall Frames

With a steel frame house a standard wall panel, other than using a different material, is much the same as a Basic Timber Wall Panel.

Once it comes to a panel with openings there are a few differences as the sketch below shows:

Typical differences are:

Diagonal Brace

The diagonal braces are used (instead of a panel of sheet material in the timber frame) to resist sideways forces on the frame.

Lintel

Rather than a solid beam a truss structure is formed to carry loads over the opening.

 

 

Also check the following links:

Brick Veneer

House Construction – The Frame

Timber or Steel Frame

 

Openings in Timber Frame

Openings in a Timber Frame Wall Panel usually mean that the Bracing Straps of the Basic Frame can’t be installed.

The following diagram shows typical panel details.

Bracing Panels

The bracing panels replace the bracing straps to keep the frame square and ensure the panel resists sideways forces. They are a sheet  material that is nailed to the studs top plate, bottom plate, and noggins.

Usually the panels are ply although I have seen other materials such as particle board.

Lintel

The lintel carries loads from above to the studs either side of the opening. The size of the lintel will depend on the width of the opening

Jam Stud

The jam stud in normally the last full height stud before the opening

Secondary Jam Stud

As well as assisting the jam stud to carry the lintel load the Secondary Jam Stud also provides extra stiffness to counteract the fact that there is only one noggin.

Sill Trimmer

This forms a fixing point for a window frame, and also the top fixing point for any Jack Studs.

NB for a small window a Head Trimmer may be used between the lintel and the top of the opening

Jack Stud

The jack stud is a short vertical stud. It can be between:

  • The Bottom Plate and the Sill Trimmer
  • The Lintel and a Head Trimmer

For background information about House Frames see this link: House Construction – The Frame.

Basic Timber Frame Panel

The House Construction-The Frame post explains the background to frame construction.

The drawing below shows a typical standard wall frame

Minimum timber size will be 95mm x 35mm although this may increase for the  following reasons:

  • Additional wall insulation may increase the depth of the frame to 125mm 
  • If the wall requires more structural strength that may increase the timber thickness from 35mm to 45mm.

Studs

Studs are the main structural component as they support the main vertical load of the roof and and upper floors.

Normal spacing is at 450mm centers for external walls and 600mm for internal walls unless specified otherwise for structural reasons.

Top Plate

The top plate fixes the top of the stud in position and acts as a mounting point for the structure above the frame.

A single top plate does not have the strength to carry major loads, such as roof trusses or upper floor beams so these should be fixed directly above the studs. 

To increase the strength, if required, a second timber can be added during erection to make a double top plate. This additional timber is fixed to overlap adjacent frames, junctions, and corners, and increases overall ridgidity

Bottom Plate

The bottom plate holds the frame to the base and fixes the bottom of the stud in position .

It needs to be firmly fixed to the base. If the base is uneven packing needs to be installed under the stud positions to prevent any vertical movement of individual studs.

Noggings

Noggings are the individual short pieces of timber between the studs. They are there to prevent the studs bowing under the load or warping. It is important that they fit exactly into the space.

Maximum spacing between noggons and top and bottom plates is 1350mm. For walls up to 2.74m  high a single noggin meets the standards. Taller rooms and you will need 2.

Diagonal Bracing Strap

The diagonal bracing straps are typically galvanised steel strip which is nailed to each strut. The bracing is the part of the frame that resists any sideways deformation of the frame, such as wind loading.

Although these braces seem insubstantial compared to the struts and plates they are vital to the overall strength. If you find a brace has been cut during construction ask for it to be replaced!

Where there are openings the details in the following link are required: Openings in Timber Frames.

Want to know more?  The following external link is worth a look: Timber Plus Toolbox

House Construction – The Frame

The  Internal Frame is the key structural element in most Brick Veneer House Construction.

In more lightweight structures such as timber cladding and lightweight render it takes on an even more of the structural loads.

The overall frame is composed from a number of individual wall panels, which when fixed to the base, and fastened together, form a rigid box like structure.

Structural Loads

The frame carries several main structural loads:

  • It takes the load of the roof, and any upper floors, down to the foundation.
  • It resists the wind trying to push the whole building over.
  • It provides lateral support for the brick walls.
  • Holds the windows in place.
  • It gives a secure fixing point for the internal wall and ceiling lining boards.
  • In the case of weatherboard or lightweight render construction it supports the outer skin of the building.

Additional Functions

  • Provides a route and fixing points for cables and pipes.
  • Retains insulation.
  • Supports cupboards and shelves.
  • Fixing of building wrap.

 

See also Brick Veneer