Fixing Accessories

Screws are better for a deck frame, provided they are structural screws rather than ordinary wood or drywall screws. We recommend galvanised nails or, preferably, screws because that means a corrosion-coated structural screw that will not snap under the sideways (shear) load a hanger carries outdoors. Galvanised square twist or clout nails are perfectly sound, cheaper, and quicker, and are what most carpenters use indoors; the advantage of screws on decking is that they draw the hanger tight to the timber and can be backed out if a joist needs moving. Whichever you use, every pre-cut hole in the hanger must have a fixing in it. 

Yes, carrying load is exactly what a joist hanger is for: it transfers the weight on a joist into the beam or ledger it hangs from. The limit is set by the fixings and the fit rather than the hanger itself. Use the right width so the joist sits snugly, choose a hanger deep enough to support most of the joist’s depth, and fill every hole. A heavy duty joist hanger with all holes filled will carry a 47 x 150mm deck joist and the people standing on it without trouble.

Only where a joist has to finish flush with the beam it meets, rather than sitting on top of it. On a typical ground-level deck the joists rest on bearers or on a ledger strip, and nails or structural screws through the top are all that is needed. Hangers come in when the deck is kept low and the joists butt into the outer frame or a wall ledger at the same level, or when you are joining a new joist into an existing one. Skew-nailing a joist end into a beam is the shortcut people take instead, and it is the reason decks go springy at the edge after a couple of winters. 

The usual alternative is a ledger strip: a length of 47 x 100mm fixed along the bottom of the beam for the joist ends to sit on, so the load is carried directly rather than through a hanger. If the joists can rest on top of the beam, a structural fixing is all you need, and our 125mm to 250mm joist screws driven at an angle make a solid timber-to-timber joint. Angle plate brackets are too small for joists and only suit light rails. Where a joist has to meet the beam flush and there is no room for a ledger, a hanger is still the right choice. 

Leaving fixing holes empty, or filling them with drywall screws. A hanger’s strength assumes a proper nail or structural screw in every hole, so one fixed with three screws out of ten carries a fraction of the load it should. The other frequent faults are a hanger too wide for the joist, which lets it rock and loosen the fixings, and a joist not seated fully on the bottom of the hanger, so the weight hangs on the side fixings instead. Match the width to the joist, push it right home and fix through every hole. 

For most deck frames, choose the heavy duty hanger. It is made for 47 x 100mm and 47 x 150mm joists and carries the weight of a deck. The other three are for lighter or more specific jobs. The 50mm mini hanger is a cheap option for a 47 x 100mm joist or noggin that carries little load. The Jiffy hanger has two long arms that fold over the top of the beam you are fixing to, so it suits joints where you can reach the top of the beam; it comes in 47, 75 and 100mm widths. The Long Leg Jiffy is the same design with longer legs for joists up to 250mm deep, which is usually a floor joist rather than a deck one. 

No. Our black and BZP drywall screws are made for fixing plasterboard to timber and metal studs: they are thin, brittle under load and will rust outdoors, so they should not be used anywhere on a deck. For the boards use our deck screws in 60mm or 75mm.

Use them for rails, never for joists. The angle plate bracket is a small 40 x 40 x 20mm galvanised bracket for fixing a decking handrail to a newel post, where it holds the rail square but carries no floor load. The knee rail strap is a fencing fitting: the rail drops into the slot of a knee rail or birdsmouth post and the strap goes over it and is nailed or screwed down to stop the rail lifting out. A joist hanger is the only one of the three built to carry a joist, so if the timber you are fixing has people walking on it, that is the fitting you need.