My chosen trade is stone masonry, but timber framing has been a serious hobby of mine for about ten years now.

Recently, my wife and I decided to design and build a traditional cape cod timber frame house with a central chimney. At first, we thought of doing the frame in wood, but we figure we can bring down costs if we construct only the exterior walls in stone, which we have plenty of on the property, and the roof and floors in timber, which we also have plenty of on the property.

We plan on doing an English style of double-wythe masonry wall, or "cavity" wall. It's a masonry style that is more commonly seen in commercial building construction using brick or block. The difference is that we'll be using natural stone.

Does anyone have suggestions on how to seat the rafters or how to attach girts and girders to the walls? Or, is anyone torn between stone and wood as much as I am!?

Hello,

This double masonry wall construction is standard here in Holland and I built a small house, together with my brick-layer neighbor, like this a while back. If I remember it now at all accurately, the floor joists were supported on masonry piers, wherever there were openings in the outside walls the jams for doors and windows, I completed before hand, and set in place and then we bricked around them as the walls went up so everything fit tight without shimming or any of that. Second story joists were bricked into the walls, extending outside for supporting the rain gutter, level with the underside of the plate and anchored through to the outside with forged eye and pin beam anchors. We clamped the plate with T shaped irons bricked into both walls and passing up the cavity with the threaded end passing through the plate and screwed down tight with washer and nut of 19 mm every meter and a half or so along the length. The roof was what you might call a purlin sort with king posts at the gables, the purlins ending just behind the gables with these forged anchors attached passing through to the outside and pinned there. The rafters there were either bird-mouth jointed to the plate or stub tenoned. Basically the way it has been done since timber frames were outlawed in town back in the 17th century.

Greetings,

Don Wagstaff

Thank you, Don. I didn't think of passing the beams through both the inner and outer walls. I have heard of pre-assembling the headers and sills, but we're using a dense and heavy stone that makes installation very difficult without the use of a crane. We'll probably end up building the jambs in place for this reason. The idea of supporting piers is probably the best suggestion we've had so far. It reminds me of "gunstock" or jowelled posts from colonial frames. Did you build the piers inside or outside of the walls?

In traditional Celtic rubble construction, the English style I've read about calls for 7.5 in. wythes, plus a cavity. That's about 18 in. of wall. How thick did you make your double walls? Did you place insulation inside of them?

Hello,

Crucial to mention regarding the points you bring up: Only outside wall is structural, whether floor joists are supported by piers, ledges, buttresses etc... there is clearance at the end grain to provide free air circulation, all contained within the perimeter walls, the idea of the cavity between the walls is to create a continuous envelope of dead air space encompassing the building, so ideally nothing will bridge that space.

In this case the outside walls were common enough baked brick of the size you might think, the cavity was about two fingers wide and the inside walls were large, dense, compressed clay blocks big enough that after a while I had blood coming out at that bridge of webbing between my thumb and index finger from the stretch - anyway around 25 cm total thickness.

Greetings,

Don Wagstaff