Fixing & Applications

Fixing Recommendations:

Setting up: Radially sawn Screen Boards can be fixed wide or narrow face out (NOTE: in most cases, they are fixed narrow face out). Depending on the thickness, Screen Boards can be fixed to rails or supports at centres of up to 1200mm but closer spacings will minimise movement or distortion (ie. 600 to 700mm max. centres would be advisable when fixing 19mm to 25mm thick timber).

Installation: The spacings allowed between seasoned DAR boards will depend on the desired look or function of the screen, however, a minimum spacing of 5mm should be allowed for swelling (NOTE: most privacy or sun screens are spaced at approx. 10mm). Unseasoned screen boards will shrink approximately 7% across their width so this should be considered when designing a screen.

Fixings: Boards can be hand nailed, gun nailed or screw fixed. Fixings should be at least 50mm long for 19mm to 25mm thick boards and at least 65mm long for 30mm to 50mm boards (NOTE: it is advisable to use stainless steel or hot dipped galvanised ring shank nails when fixing boards into treated pine, or twist shank nails for hardwood). Bevelled edge profiles may be “secret nailed” by skewing fasteners through the sloping sides but face fixing will give the best results. Pre-drilling may be required when fixing seasoned boards.

Seasoning & Storage: Some surface checking may occur if timber is exposed to the weather but these non structural cracks are typical in most Australian hardwoods. It is also normal for hardwoods to leach red/brown extractives during heavy rain periods. Extractives tend to be less prominent in lighter species but it is advisable to cover or protect walls and paving until all extractives have leached (can vary depending on rainfall but will generally continue for up to 6 months). Packs should be stored up off the ground and under cover or protected with an additional tarp to prevent swelling. If wetting does occur, allow a min. of 24 hours for timber to dry before fixing.

Suggested Applications

Radially sawn screen boards provide a unique alternative to imported rainforest and treated pine products and have been used in: feature walls, picket fences, balustrades, privacy screens, sun screens & pergolas. For images of Screen Boards visit the screenboards product galleries.

FIXING AND APPLICATION

Transport To Site

Natural edge weatherboards are supplied unseasoned and generally transported to site in log form with the ends uncut. It is not uncommon for logs to break open or boards to split during transport/delivery but Radial Timber Sales generally provides an additional 1 to 2m2 of boards in each log at no cost. If damage occurs, it is recommended that the split boards be put aside and only used as short in-fills around windows and doors.

Setting Up

The ends of each log need to be removed in order to release the boards. This is typically done by cutting in a min. of 350mm from each end of the log with a chainsaw. Once the log ends have been removed, boards spring free from the heart wood or core and have a slight but consistent curve, resulting from natural tensions in the log (see Figure 3). Studs should be spaced at max. 600mm centres.

Installation

Boards are generally installed in sequence by numbering the boards and following the profile of the log (NOTE: overall cover will be reduced if installing the boards in a random pattern). Before fixing the first board, the outer or sapwood edge may have to be cut square in order to remove any natural curvature. Remaining boards can then be fixed by eye (ignoring minor variations in cover) or by scribing the average cover onto weatherboard stops. A minimum board overlap of 30mm is recommended to allow for average shrinkage of up to 7%. First time fixing may take longer than that for conventional square edge boards.

Fixings

Boards can be hand or gun nailed but care should be taken close to ends to avoid splitting (boards may need to be pre-drilled if hand nailing). Typically, 50mm long hot dipped galvanised or stainless steel fixings should be used but it may be necessary to use 65mm nails if boards are thicker than 25mm (NOTE: it is advisable to use twisted shank nails when fixing boards into treated pine). Pre drilling the ends of boards prior to fixing may be required to avoid splitting. A fixing of two nail per board per stud is recommended.

Joining

When joining boards on long runs, the weatherboards should be matched for width and appearance by “book matching” or butt joining the ends of consecutive boards from a log. On long walls, it may be quicker to break up the wall into smaller panels by inserting weatherboard stops (ie. vertical timber sections). Weatherboard stops can also be used at joins on internal and external corners of the building (rough sawn 75x50mm sections and are available from Radial Timber Sales).

Cover

The average cover of weatherboards will vary within a single log or between logs; therefore, achieving the same cover for a whole wall may not be possible. If the effective cover appears to be less than 80mm, it is recommended that these boards be put aside and only used if narrow coverage is a desired effect.

Seasoning And Storage

Some movement may occur during seasoning but boards will generally settle as moisture content in the boards equalise (NOTE: unprotected west facing walls may be subject to extreme temperature changes and therefore, timber is more likely to move). Leaving boards in log form is the recommended way to store timber on site for extended periods of time (ie. logs can be stored for up to 12 months but it is be advisable to cover with a tarp or plastic).

Timber Leaching

It is also normal for hardwoods to leach red/brown extractives (tannins) during heavy rain periods. Extractives tend to be less prominent in lighter species but it is advisable to cover or protect walls and paving until all extractives have leached (can vary depending on rainfall but will generally continue for up to 6 months).The tannin staining can be cleaned with a diluted bleach/water mix.