Timber Frame Joists & Purlins

Timber purlins and joists form the roof and floor framing in timber framed buildings. The old school way to do the joinery is to dovetail them in. Unfortunately, the beautiful dovetail is hidden in the finished building, but its strength and integrity is not. It is a strong joint that lasts over time.

When very heavy loads are involved in a floor or roof system, we use shouldered lap joints. The lap joint allows us to maintain cross sectional area in the girts (main carrying beams).

Give us a call at 802-886-1917 or e-mail to learn how we can help with your post and beam project. Scroll down to learn more about timber framing and post and beam construction.

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Dovetailed Purlins in a Hip Rafter

Here, roof purlins are dovetailed into a heavy timber hip rafter.

Dove Tail Joint in Timber

This joint is strong and beautiful. It is held fast by hardwood wedges that are driving against the angled cut.

Lapped Purlins on Timber Rafter

In order to reduce the amount of wood that is cut out of this top chord, the purlins for the roof system were lapped in and screwed with log hog screws. There is a one inch deep cut in the top of the top chord, and a one inch cut in the bottom of the purlin.

Purlin and Rafter into a Valley

Another View of a Purlin and Rafter into a Valley

Lapped and Shouldered Floor Joist

This joint is used when a girt spans a long distance and every inch of section is critical.


In order to gain an interactive 3D view of some of these joints and connections, download the required specialized applications below. Then click on the icons listed to view the interactive PDF.

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Vermont Timber Works