Timber Truss Plates
Exposed-Beam Timber Truss Reinforcement With Custom Timber Plates
Our cabin was built in 1953. The design features a gable roof with an open, vaulted ceiling with exposed, heavy 4″ x 6″ Douglas Fir timber beams. The roof design does not utilize a ridge beam or ridge board. The exposed beam trusses are simply mitered and butt-joined at the top.
Although our cabin has been in service for over 60 years, these ceiling beams make me nervous. I plan to re-roof the cabin soon and decided to reinforce these beams prior to working on the roof.
One easy way to beef up these beams is to add steel timber truss plates at the ridge joint. Not only would steel plates strengthen the beam connections, they would also help prevent progression of the rotation and separation of the beams that I have noticed. Steel plates will also act like mini collar ties between the beams, helping to resist the separation forces of this simple truss design roof.
Our Cabin’s Timber Truss Beams Before Reinforcement
Finding Steel Plates for The Timber Truss Beams
I knew finding off the shelf reinforcement plates for my ceiling beams might be tough. I did find quite a variety of timber plates at several local lumber supply companies, but none had the correct angle I needed for my beams.
My next plan was to have the plates custom made for my project.
After some searching online, I found ShortRun Pro, a metal fabrication company that offers a variety of metal brackets, plates and parts and custom order short-run fabrication services.
The process of ordering the plates from ShortRun Pro was straightforward and reasonably priced – especially considering it was a one-off, custom order. Each 1/4″ thick cold rolled steel plate cost me around $18 plus $50 to ship the order of 20 plates. Not bad. Turn around time was about a month – order time to shipping.
After drawing a rough plate design, ShortRun Pro converted into engineering and CAD drawing and began fabrication. Three weeks later the parts were shipped to my home.
The entire process and the product I received was very impressive and I would highly recommend them for similar projects. They are located in North Carolina and all of their manufacturing is done in the United States.
After receiving the plate, I considered hardware options for mounting the plates.
I really wanted to find some old-fashioned square head bolts and nuts. After some searching online, I found Blacksmith Bolt & Rivet Supply, a supplier of vintage hardware.
I ordered black oxide 1/2″ square head bolts 4 1/2″ long with matching square head bolts and washers. The hardware they sent was awesome! It perfectly matched the old-school black hardware vibe I was looking for.
In addition to the nuts and bolts, I also ordered matching square headed lag bolts to connect the plates for the end beams where I only had access to one side of the beam.
Once I received all the hardware, I washed it to remove any excess manufacturing oil. I then painted the plates to match our ceiling beam color, and after the paint was dry, installed it all.
Install Custom Steel Timber Truss Plates – Preparation
Preparation and Materials
- Level: Basic
- Time: Hours
- Cost: ~$21 per plate (I used 20 plates = $420)
- ~$2.5 per bolt-nut-washer (I used 80 = $200)
Project Big Picture
- Plan plate design
- Order plates.
- Order hardware.
- Drill beams.
- Mount plates.
Materials – Custom Timber Plate Install
|Item||What I used||Cost|
|Custom Steel Timber Plates||$22 / ea|
|Vintage Bolts, Nuts, Washers||$2.5 / set|
|Alkyd Trim Paint||$60 / gal|
Tools – Custom Timber Plate Install
Install Custom Exposed Beam Timber Ceiling Plates – Step by Step
- Organize Materials and Tools.
Order, receive and organize plates. If you decide to have plates made, measure and re-measure your beam angles prior to ordering. It is a very good idea to create a cardboard cutout of your plate plan to ensure it is exactly the right angle and size.
When ordering plates, order 3/16″ thick steel for decorative plates and 1/4″ thick plates for structural plates. Each situation and home is different; consider consulting a structural engineer prior to ordering plates or doing any work on your ceiling framing.
Once you have ordered and recieve your plates, considering cleaning them in mild detergent to remove manufacturing and shipping oils. I planned to paint my timber plates, so I cleaned and dried them thoroughly.
I also washed the hardware to remove excess oils and let it dry.
- Paint or Finish Steel Plates (optional).
The plates I ordered were mild steel and had no finish. We planned to paint them the color of the ceiling beams to which we were mounting them. If you prefer not to paint them, consider sealing, bluing or other process to help prevent the plates from rusting.
Prior to painting the steel plates, we first washed and dried them. If the surface is shiny, also consider lightly sanding them prior to painting.
To paint them, we first applied a primer coat.
After the primer was dry, we added two coats of finish paint. For the finish coat we used the same paint we used for the trim and ceiling timbers – Benjamin Moore Advance waterborne alkyd paint (satin finish).
- Prepare To Install Plates.
Organize your ladders, tools and parts to install the plates. Depending on the height of your ceiling, a decent size step ladder may be enough to get you safely to the beams. I used a 10′ step ladder and my beam peaks are at about 12′.
In addition to standard hand tools, you will need a drill and some drill bits. To greatly simplify the somewhat challenging task of repeatly drilling holes through your beams in a perpendicular and square fashion, I highly recommend the use of a portable drill guide.
Use the drill guide to drill pilot holes starting with a smaller diameter drill bit. Then you can progressively increase the diameter of the holes to match your bolts.
- Mount Plates.
After you have drilled holes through your beams to match the hardware and plate holes, mount the plates. If you are luck enough to have beams and beam joints that are flat, you may be able to simply mount the plates with the final bolts, washers and nuts.
For many of my beam joints, the beams did not meet to form a flush joint. With these misaligned beam joints, I needed to use the plates as a vice to flatten the joint prior to using the final hardware to secure the plates.
This is mainly a problem related to the length of the finish bolts I planned to use. Because I did not want excess bolt on the nuts side of the installed bolt, I selected finish bolts with only a small amount of excess length (~ 3/8″). The beauty of using these “properly” sized bolts is, once installed, they all look the same – the nuts cover all of the excess bolt length, giving a very finished final appearance.
The down side of perfect length bolts is the lack of forgiveness for spread joints requiring longer bolts to get nuts started. Right sized bolts will not be long enough to reach bolts for joints with non-flush beams.
To solve this issue, for spread beam joints, I first installed longer bolts to pull the beams together and flatten the joints. Once the beams were flat, I was able to install the shorter, finish bolts.
- Continue Installation – Use Single Plate With Lag Bolts For End Beams.
Repeat the installation process until all beam plates are installed. For the last (and first) beam of my ceiling, I only have access to one side of the beam. This prevents me from passing bolts through the beam. Instead, I used lag bots to apply a single plate.
- Enjoy Your New Timber Truss Plates.
Ceiling Beam Reinforcement Followup
Regular use flushes the system and add heat to the system.