How to Install Roof Trusses

how to install roof trussesInstalling roof trusses can be a tricky business. One person with lots of experience, building know-how, strength, dexterity and a dose of good luck might could pull off the job, but otherwise, plan on having at least one other helper, preferably more.

As you learn how to install roof trusses, one of the first things you’ll realize is that it is important to get the roof closed and protected against rain and other types of damaging weather as soon as possible. However, you also don’t want to get in such a hurry as to make mistakes that could result in terrible consequences (such as roof truss failure) on down the road from not properly mounting, positioning, and fastening the truss to the house.

Handling and Marking Anchor Points

Another critical part of how to install roof trusses is learning from the very beginning about their strengths, and their weaknesses. The strength in a truss lies in its vertical pressure resistance, not in any horizontal pressure. This means you don’t want to lay the truss on its side against a wall or handle it any other way except from the top or bottom.

For homes higher than one story, you will almost certainly need a crane or levered ropes to get the truss to the top and in the correct position to avoid damaging it.

Mark anchor points every two feet (61 centimeters) to serve as guides as to where to affix the truss to the outside house walls. This important part of how to install roof trusses can save lots of work and help prevent you from having to measure once you’re up in the air, where too much movement could be dangerous.

Measurements taken from the ground are also more likely to be accurate those taken up on top of a roof. Start installation at the end of the roof where the gable will be and continue from there.

Nailing Bracing and Installing Plywood for Fascia and Roof

Most pre-fab roof trusses come with one-by-fours used to separate them and hold the bracing of the truss in place. After you’ve finished anchoring the truss to the outside walls of the house, as part of knowing hot to install roof trusses, you need to know that these should be nailed permanently into place. The manufacturer providing the trusses should have these instructions included with the truss as part of the installation.

Although trusses provide the structure for eaves, you will still need to install the fascia. How to install roof trusses includes knowing this to help close off the roof and prevent rain, hail, or high winds from damaging the roof and house. Plywood roof panels should be installed at right angles to the trusses with joints offset.

Nail plywood-roofing panels every two feet (61 centimeters) between the trusses and use H-clips to attach the panels one to another. And with that you’ve learned some basic knowledge about how to install roof trusses. Remember though, that installing roof trusses, a fundamental part of building your house, needs to be done correctly, so even if it doesn’t seem to make sense, take your time to do it right.

Tips for Installation

1) Since trusses come in various sizes and shapes, you should choose the kind that works best for your project. If your roof has an offset area, you will have to install two perpendicular sets of trusses next to each other. When those are set up, the inner trusses will be a ledge for the rest of the trusses to sit on and be installed.

2) As you start, the goal is to place a truss every two feet on center. Before you can do this however, you need to prepare the roof’s top plate. Place two-inch block spaces along the top so that the inner wall and the top plate are flush, which will then allow for the truss ends and the outer wall to sit flush. The trusses will also be able to be secured to the spacers, which can function as nailer blocks.

3) Reference marks should be made every two feet on center, placed around the edge of the top plate. This shows where each truss’s edge will align – use a clear marking scheme such as an ‘x’, because then each truss can sit directly over an ‘x’ without confusion as to which end of the mark the truss should be placed.

Positioning the Trusses

4) If you’re working with an irregular shape, lift the first alcove truss into place upside-down, using a long brace to turn it over and place it into the right position. When this has been secured to the top plate, it will be in place temporarily – later on, it will need to be secured down permanently. This should be continued for all the rest of the trusses along the alcove.

5) The first main truss can be secured to the back wall of the building, getting it in place on the vertical bracing. When carrying the trusses into the building, they should be held upside-down and then lifted up with a long brace. From here they can be turned up the right way and placed easily on top of each wall.

6) Once each truss is positioned in its place, it should be fastened to the top plate using toe-nailing to hold it together securely. After several trusses have been lifted and placed, they should be temporarily secured together using a horizontal brace. This will ensure that they don’t move, and continue to keep their correct alignment.

After the Trusses Are Placed

7) Following the same steps for the rest of the trusses, the roof construction can then be completed when they’re all in place. Plywood sheathing can be attached to all the gable ends – this should be the same kind of sheathing that was used on the walls earlier in the project.

8) Ladder-design structures can then be rigged up to get the necessary roof overhang over each gable. One should be made for each gable section and then fastened into place.

9) Some of the ends of the trusses will still be exposed at this stage, and 2’ x 4’ boards should be secured to their ends to create a sub-fascia. Then the rest of the roof can be covered in plywood sheathing, starting at one corner and using a chalk line to mark on the wood where the roof trusses are located. This will help to show where the sheathing will need to be secured to the trusses after they’ve been covered.

See Also:

Attic Truss Spans