The Standish Farm Restoration

THE GREENHOUSE PHASE ONE - STRUCTURAL REPAIRS

PART ONE - SHORING THE ROOF

I should probably wait until I finish the roof repairs to make any posts about the greenhouse roof, but it takes so long to do anything and there are so many interruptions that I figure I should feed you a little at a time. I've been setting up the restoration of the roof since late winter (remember the post about repairing the adjoining garage roof? Of course you don't; go back a few posts and look). Well, the greenhouse rafters set on the same plate, which I replaced back in March.
So let me refresh your memory.
When I first examined the property in 2012, nine of the greenhouse roof rafters, which hold up the decking that together make the roof structure, had rotted ends. They were no longer in contact with the plate, and so swayed decrepitly towards the ground.

The garage/greenhouse in fall as I began removing some of the junk inside both. I had just built the worktable the same day this was taken. The long timbers in the foreground were the 'joists' in the garage. I've since replaced them with real joists. Not 'joists.'

First view 2012. Note the lower ends of the rotted rafters are not yet below the concrete lintel above the doorway.

Lousy picture taken just after moving in. The rafters ends have sunk over three more inches.

East side of the greenhouse after I had cleared some junk and set my antique heart pine (foreground, middle left) on some boards. I brought this stuff from Little Rock not knowing I would have so much extra from work that what I brought was almost laughable. But not quite.

More greenhouse stuff. Many turnings and legs and arms from chairs and tables fill the boxes. On top of those are pieces of chestnut twelve to twenty inches wide.

I think I'll keep those for reuse.

Beginning to remove the glass (the large panes kept falling out and smashing on the footer), the studs (that don't hold up anything), and the trash. The more trash I removed, the more I marveled at this structure. It looks like it's ready to collapse, but two two-inch iron pipes set in concrete hold up the ridgepole. This sucker ain't goin' anywhere. Plus, it is about twenty by twenty feet and has a forest canopy above it, making it the coolest room on the property. Imagine what it will look like with a slate floor.

The plans for this structure are to use the plethora of colonial 6-lite window sashes I have collected (most are the same size), restore and glaze them, paint them, then install them on three sides of the room. There will be a set inside as well as a set outside, creating an insulated space, more or less. Many of the center sashes will open as casement windows do, on hinges swinging in or out, and the upper and lowers will likely be fixed. The design work continues and completion will be next year. I'll have the roof dried in and finished by winter. This winter will find me restoring the sashes as well as finishing the structural work. I have no need for a greenhouse yet, but by next year, I hope to be growing bonsai starts as well as hanging out there.

Less trash than before, and much of this stuff is useful.

Outside trash pile is still growing. What will burn without contaminating the atmosphere will be burned; the rest will be taken to the transfer station, a nice word for the dump. This pile is three times this size as I write.

First stage or roof rafter repair; build a temporary plate to jack. The 2x blocks are to compensate for the slope of the roof; you want to jack on the level. Otherwise your jacks slip and can fail catastrophically.

Second stage; install something to jack FROM. I chose a 14' 6x6 pressure treated timber set in the damp ground.

As I jack the plate, it comes into contact with the leveling blocks one by one. I jack the lowest rafter first and graduate to the highest. If you look carefully, you'll see that I installed 2x2 pressure treated shims between the plate and the rafters. This will allow me to slip matching 2x8 timbers alongside the rotted rafters (this is called "sistering") without binding. In fact, a 2x2 (actually 1 1/2" x 1 1/2") will allow me to install the sister flat, then roll it into position next to its sister. Very handy when you're dealing with 14 foot 2x8s, I can tell you. Notice that I have a composite 2x4 stiffleg to hold up the roof if the jack fails. It can be added to as the roof level rises. More will be added, and as the roof goes higher, the weight and pressure increases, making the 2x4 too weak. I'll soon switch to 4x4s.

I've removed the stiffleg and installed another jack. The orange jack is a screw jack that can handle about twelve tons; the gray hydraulic job is good for about two.

The jacks must be kept level using shims, or the joint between the jack and the 4x4 will become a hinge that can bend outwards at any time. Constant eyeball monitoring down the timber is absolutely necessary for safety as well as structural integrity. A four-foot level can be used, but eyes and good judgement are far more useful.

Shimming from two directions at once. The lifting is done a little at a time, though taking days to do it is a bit of overkill. This is not a three-story row house, for chrissakes. We are not children here. Constant monitoring of the jacks is essential.

As each leveling block is touched by the plate, it becomes tight and the roof continues to lift. The center (and lowest of the dropped rafters) comes up the most; the outside rafters get less lift to bring them to their original position.

Rafters are now six inches from their dropped position. Someone asked me why the whole roof didn't collapse. The tongue-in-groove decking held it up. T&G decking interlocks and spans the entire twenty-foot roof; it supported the rafters as their ends deteriorated. Only the last two runs of decking are in need of replacement; that's the beauty of wood, especially pine. It is flexible and strong and can be bent back and forth.

Two jacks and a doubled 2x4 stiffleg. Told you the roof would need more support as it gets lifted. As the jacks reach their limit, 2X blocks are added to extend their lifting distance.

The rafters are getting closer to their original position.

Rafters are in their original positions. All leveling blocks are in contact with the plate and each rafter's position is checked against the non-rotted rafters at each end with a straightedge to see where it lines up with the new plate (the green pieces of wood on top of the cinder block wall). The newly lifted rafters must match those on the ends.

Rafters in position with their rotted ends cut off with a reciprocating saw.

"He was level on the level, shaved even ev'ry door..."

-John Prine, Grandpa was a Carpenter

Jacks removed and all stifflegs support the roof. The jacking is done.

It took about four or five hours. Hey, I had to have lunch.

After the jacking, I decided to examine the roof. I knew the valley was badly designed, but I had no idea the flora it supported. All that on the left is poison ivy. Of course.

"I sat on the roof and kicked off the moss.."

Elton Jong and Bernie Taupin, Your Song

I left this moss intact until I replace the shingles with rubberized roll roofing. The pitch is less than 4/12, which means that capillary action will allow water to travel uphill between the shingles and rot the roof. Hey, WAIT! You don't suppose this already happened???!!!!! Actually, it didn't.

A bit of a low spot caused all these problems. A well-defined slope from the front to back would have helped. I intend to define my new slope very well indeed.