When you’re setting out to create a sturdy, long-lasting timber project like house cladding or wooden decking, you must ensure you’re setting it up to endure a good many treacherous winters to come.
One of the most common ways that durable timber with high-quality treatment can be let down on this front is if the screws holding it in place are unsuited for the type of wood, unreliable in and of themselves, or even just poorly fitted.
Let’s discuss some of the best ways to avoid these problems when you’re working on an outdoor project you want to stay up for decades to come.
The Dangers of Metal
Before you can \get started on setting up your cladding or decking, you need to consider what screws you’ll be using, and especially what they’re made of. Many poor-quality, mass-produced screws are made from metals that are unsuitable for use with treated timber due to their risk of galvanic corrosion.
While this often occurs because of nails being incorrectly drilled into modern pressure-treated wood, this problem can occur regardless of whether the wood is treated or not. You can minimise the risk of galvanic corrosion in your cladding & decking by avoiding screws that are made of aluminium, electro-plated steel, or brass. Corrosion-resistant materials suitable for use on wood include:
- Stainless steel nails (that are austenitic)
- Silicone bronze (but only for use on shakes and shingles)
- High-performance coated steel
- Hot-dipped galvanized copper.
If the wood you plan to use is western red cedar or Douglas fir, you might need to be more careful, as these species produce acids which corrode particular metals even more than normal. For cladding or decking using these woods, you should only use fixings made from stainless steel, or that have had a specialist coating applied.
Firmly Clad & Fixed In Place
Both cladding and decking use much of the same sorts of screws and nails, but you can’t approach them in the same way when it comes to screwing or nailing; both have their own distinct priorities. Let’s go over some of the important factors with cladding first.
Batten Down The Cladding
When you’re using nails on cladding, you should always use fixing types that have been deemed suitable for exterior use. When cladding boards and battens (the supportive structure of smaller boards laid underneath, to aid in ventilation) meet, you’ll need to fix them in place. Make sure to use two fixings at every such intersection, at quarter points of the board width (i.e, at least 25% of the way in from the edge of the board). If the board is less than 100mm wide, though, you can use just one fixing. No matter how many you use, make sure they’re at least 20mm away from the end of the board itself, to avoid compromising rigidity.
My Secret Fix
Sometimes you might not want to have nails interrupting the visual flow of your cladding. In this case, you should use concealed (or ‘secret’) fixing, a system in which numerous ‘hangers’ hook onto the back of each panel. This holds each panel up individually, removing the issue of nails entirely. When using secret fixing, you should check what kind of timber your clip system is suitable for, and always look for reputable third-party reviews to avoid being sold cut-price clips that won’t keep your timber lifted.
Am I Screwed, Or Did I Nail It?
Whether you should use screws or nails for your cladding depends on whether your cladding uses softwood or hardwood. Always use nails for softwood, and screws for hardwood.
On softwood, ring-shank nails with large-diameter heads (about 2.3mm) are our recommendation. On these nails, the heads should ideally be twice the diameter of the shank. For hardwood, use screws (about 4mm in diameter). Be sure to pre-drill pilot holes if the wood is dense and has the potential to split or, if you can’t, leave a 200mm distance between the hole and the end of the board.
Then it comes to applying the fixings. For nails, any pneumatic fixing gun is fine. For screws, we recommend hand-held impact screw drivers. These are less likely to damage the wood or to leave you with the same ‘coating burn’ that higher-speed power drivers can. In either case, any fixings you insert should end their journey fitting nice and flush with the surface of the board. You should also ensure that the moisture content of your boards is at least 16% or lower, to minimise potential shrinkage that could dislodge the screws or nails from inside the board, undoing your hard work and exposing the cladding to unnecessary problems.
Deck The Floors
Let’s now address some of the necessary factors for fixtures and fittings used in decking. Unlike cladding, which usually has a fairly simple process of ‘attach cladding board to batten’, the process of setting up decking requires the construction of a whole structure in and of itself.
In contrast to the process of fixing some boards to a wall, making a deck requires the building of a mini-structure, and with that comes all the challenges making a timber structure can entail.
Nail Your Deck
When you’re laying down the constituent parts of a deck, your chief concern is making sure it can continue to be dry as possible. While parts of cladding design (especially slanted profiles) can help avoid pooled water, such a problem is impossible to avoid with decking. Make sure any fixings you drill in are good and flush with the surface to avoid corrosion from pooled water.
Keep all your fixings at least 25mm away from the board’s end, and pre-drill all holes to prevent splitting and accommodate for shrinkage, warp and environmental factors. If the board’s hardwood, you should pre-drill every fixing point 2mm more than the screw needs. If the board has grooves, put the fixings at the bottom of the groove.
Where two boards abut together, you should put them over a joist to which an extra batten has been added, for greater structural support. Like with cladding, whenever a board crosses a joist, drill in two fixings at quarter points (25% in from the edge of the board).
Connective Issues
When building your sub-structure, be aware of the specialist fixtures and fittings that aren’t as necessary in cladding. These take the form of pre-formed connectors, specialist pieces that help bolster the joints between different components and aid in mitigating the potential for splitting that can come from a deck made using only nails and screws.
Joist hangers, a common connector, make the connections between joists and beams securer, and are a vital resource in securing the floor of your deck. Post anchors and supports are used to secure the main load-bearing posts of a deck to a concrete footing or solid surface and can also help to keep timber out of direct contact with the ground and thus avoid issues with damp. Post anchors in particular are invaluable if your project will be exposed to heavy or consistent rain, and you can find different types of post anchor that are suitable for whatever kind of terrain the project might be centred in.
A Long Nail Of The Soul
A crucial step in figuring out which nails and screws are applicable to your outdoor project is determining their required length.
Common wisdom says that the fastener length (L) should always be equal to 2.5x the thickness of the board, to properly penetrate the joist or batten beneath. However, this isn’t always so. All a fastener needs to do is secure the board in place and adequately penetrate the structural wood below, and penetration of that full scale isn’t actually required to secure the board to that standard. When you want to calculate how long the nail or screw should be, use the following formula:
LENGTH OF FASTENER (L) = T+PEN+LP
T stands for thickness. Where two boards overlap, add their thicknesses together and use the total for the equation.
PEN means penetration of the threaded fastener into the batten or joist (which should be at least 19mm, or ideally more).
The length of the fastener’s point (LP) should usually be 5mm for screws and 10mm for nails.
If this article has you interested in inquiring about the best fixtures and fittings, then don’t hesitate to reach out to us here at Logie Timber. Many of our staff have a long history of working with some of these fittings specifically, and we provide high-quality service to all clients. If you’d like to join them, call us on 01309 611769; message us on Facebook or Instagram; or drop us an e-mail at info@logietimber.co.uk.
