How to Fit Herringbone Struts

Fitting Herringbone Struts

Herringbone struts provide extra stiffness to upper floors in houses. Made from either wood or metal, they serve several purposes. They stop a floor from twisting out of shape, damp down vibration and keep the joists uniformly spaced apart from one another. It is important to fit them properly otherwise they will cause the floor to squeak.

Unless you are constructing an entirely new suspended floor it is unlikely that you will have to completely strut out the floor with herringbone. More often than not you will find that there are just one or two struts loose or missing when the floorboards are lifted. For new floors, fitting herringbone struts is a relatively straightforward job which has been made simpler in recent years with the introduction of ready-made metal struts. Herringbone struts should be fitted to joists prior to the installation of floors or ceilings.

How to Fit Herringbone Struts

Suspended timber: 1. Metal joist hanger; 2. Herringbone strut; 3. Outside wall; 4. Concrete block inner wall; 5. Concrete oversite; 6. Wooden joist

Safety Advice

When fitting herringbone struts there will not be any existing flooring in place. To make the job more safe and easy, lay scaffold boards or temporary flooring across the joists to create a working platform.

Wooden Struts

Tools for the Job:

  • tape measure & pencil
  • chalk lines
  • pinch rod
  • sliding bevel
  • mitresaw
  • cordless drill/driver
  • hammer

  1. Measure the length of the joists at each end of the room and divide this into three. Snap a chalk line at both points across the bottom of all the joists.
  2. Make a pinch rod from two thin strips of wood about 15 x 3mm (5/8 x 3/16 in) thick and about 400mm (1ft 4in) long. Use the pinch rod to measure the distance between the top of one joist and bottom of the next joist. Wrap masking tape around the pinch rod to hold it at this setting.
  3. Hold the pinch rod diagonally across a piece of 50 x 25mm (2 x 1 in) timber and transfer the measurement by marking with a pencil at either end. Set a sliding bevel to a shallow angle and use this to mark the same bevel across the face of the timber at both ends of what will be the strut. Ensure the measurements are correct at this stage as this will act as a template for future struts.
  4. After checking for fit, cut the struts using a mitresaw to achieve the bevel — you will need four struts for each joist. Since all bevels are the same, the cut edge of one forms the end cut on the next strut.
  5. Position the struts where the chalk lines cross each joist and skew nail them between the joists, first drilling pilot holes with the aid of a cordless drill. Leave a small gap between each strut to prevent any squeaking as the floor moves.

Tips of the trade

If you have many struts to cut and install it might be cost- and time-effective to hire an electric chop saw. This tool will help you to do the job in half the time.

Tips of the trade

The biggest mistake you can make installing herringbone struts is have them touch at the crossing points. This can cause annoying squeaks to develop once the floor is completed. To avoid this problem use a scrap of ply as a guide to maintain an even gap between struts when fixing them into position.

Metal Struts

Metal struts have now largely taken the place of wooden struts in most new construction. Requiring no cutting, they are faster to fit and can be bought to suit the spacing of floor joists which are typically at 400mm (1 ft 4in) 450mm (1 ft 6in) or 600mm (2ft) centres.

Tools for the Job:

  • hammer
  • chalk line

  1. Set out two chalk lines as described above. Starting at one end of the room, nail through the hole in the top of each strut, using glavanized nails to fix them securely to each joist. Work your way along the length of the room.
  2. Working from the room below bend the struts until they touch the opposite joist. Nail these in position, again with galvanized nails, taking care to maintain a small gap where the struts criss-cross to avoid any possible squeaking.

Tips of the trade

Use a set or long-nosed pliers to hold the nails as you get them started info the joist. This will help to protect fingers from accidental hammer blows.

17. December 2010 by admin
Categories: DIY Home, Flooring | Tags: | Comments Off on How to Fit Herringbone Struts


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