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As part of the work, six structural mullions at the French doors are to be replaced. The originals were anchored to the floor slab by two 3/8" steel pins set into the concrete and let into holes drilled into the mullion endgrain. The mullion was not continuous to the roof framing, rather it was interrupted by the transom bar which was semi-continuous over length of the window wall. A short mullion segment was then toe-nailed to the top of the transom bar and extended to the underside of a rafter to which it was toe-nailed. When coupled with the deflection of the ridge ( two 2x6's spanning 28 feet!) the mullions, under lateral loading, hinged at the roof plane, the transom, and the slab, such that the wall bows outward in both plan and section. The roof overhang at this wall is only 12", and due to the slope of the roof and the absence of a gutter, the mullion bases and bottom rails of the windows and doors are soaked at every rainfall or snow melt. The original cypress lower mullions rotted through and were replaced with Douglas Fir in the 1980's which has rotted even faster. About half of the white pine French door bottom rails have been replaced, and all replacements and the originals that remain are rotted through currently.
Roof framing reinforcement and roof framing connection details aside, (they are being addressed) my current puzzle is the mullions. The replacements will extend from slab to roof, that is certain....the existing transom bar will be cut into segments and let into the new framing. Given the shallow eave and water shedding, the mullion and French door bases at Sweeton seem to be more vulnerable to weather and water than those at other Usonian houses which may have: deeper roof overhangs and/or no sheet flow drainage at the window wall. (For these reasons, I'm considering a shallow gutter at this fascia only to direct water to either end of the roof.) Mullion wood endgrain in contact with (often damp) concrete has led to a drinking straw effect. I'm heading toward a galvanized (Likely powder coated) steel mullion "shoe" which will separate the wood from the concrete, and provide a means to anchor the mullion directly to the foundation, rather than the unreinforced floor slab which the rotating point loads have snapped like a cracker. The "shoe" will be an "open back hightop"...the high sides (12" to match the top of the door bottom rails) will shield the wood from rain spatter and the open back will allow the mullion to be slid into place from inside the house once the shoe is set on the foundation. I'll send some pics and sketches to SDR for posting.
The big question is species of wood: Wright chose cypress...it rotted anyway. I'm providing protection, but I don't want to do this again when I'm 70.
Do I consider Ipe? It is hard, it resists rot. Thoughts?
1 Ceiling Cracks from Deflection
2 Window Wall Bowing in Plan and Section -- interior
3 Widening Slab Crack at Length of Window Wall
4 Discontinuous Structural Mullions.
5 Outward Bow of Window Wall
6 Rot Through at Mullion Base
7 East Facade
8 Horizontal Deflection of Mullion Segments
The wood rotting issue at the base of the wood column is attributable to poor maintenance by prior owners. On a lot of these FLW Houses maintenance gets deferred and small problems became major expensive problems. The original design of the wood columns at the base is fine, if built and maintained properly.
Is there space between the concrete and the bottom of the post/mullion, or does the mullion rest directly on the concrete?
I have seen examples of post and beam construction where the wooden post does not actually touch the concrete base, lessening the chance of rot.
Do you have an example of this detail that could be posted? The Sweeton roof framing is bit unique. I'll have SDR post my preliminary framing section which reinforces the mullion to rafter connection...rather than toe nailing the mullion to the underside of the rafter, I'm extending the top of the new mullions to the underside of roof sheathing to allow the existing cut rafter to be sistered and gusseted to the sides of the mullion making a more rigid frame.I would do the continuous vertical plate that usonians typically had.
The mullions are specified to be shellac'd or coated with spar varnish depending on which sheet of the drawings is consulted. The 1980's replacements were painted when epoxy resin patching was done intermittently during the ten years before I bought the house. The resin patches are falling out as the surrounding wood rots from within. The mullions are detailed on the original drawings to be in direct contact with the concrete.
By contrast, the vertical mullions at the front porch of Sweeton are original and in good condition. The portion of roof they support has not sagged causing rotation, and the 3'-6" to 8' deep eaves have kept the mullion bases relatively dry. That said, I believe the east window wall at Sweeton is an entirely different condition that calls into question for me the soundness and durability of the original detail. What may have worked for a flat-roofed or shed roofed house with 3' or 4' eaves and no sheet drainage, is not applicable to an unrestrained gable roof (no collar ties, no ceiling joists, inadequate ridge beam) with 1/3 or 1/4 the eave protection and sheet drainage. I believe endgrain of (topically treated or not) wood, particularly with 3/8" dia. x 1 5/8" deep holes drilled in them should not be in direct contact with concrete on an east facing facade that is subject to weekly, or more, soaking from roof eave spillage that is only 12" away. I'm also suspicious of pointloads at 4' o.c. bearing on an unreinforced 3 1/2" thick slab, that per the drawings, is not turned down at the window wall, thickened at the load points, and has no foundation beneath it....the ever widening slab cracks 6" inboard from the window wall bear that out. Two 3/8" diameter pins set in just a thin, unreinforced slab, let into the end grain of 2x6's at 4' on center is not a secure anchorage for the support of a roof, particularly one subject to lateral loading from wind, snow loads and heavy swinging French doors.
You may also wish to fix the deflecting cantilevered eave extensions at the same time. They can be easily jacked into place and reinforced. I know how to do that also.
If it were me, I would do all of above plus open up the roof from below to fix the eaves structurally, add insulation, conduit, ventilation space above insulation, ridge vent, and soffit vent, etc. Then use a skim coat of plaster on blueboard when the ceiling goes back in place.
Your suggestions are understood and already in motion....I've been planning, analyzing, sketching, dliberating, and detailing all aspects of this for the better part of 3 years. The work will include:
-reinforcement of the roof framing...I enlisted a structural engineer to review my framing schemes and assist in member and connection sizing. Steel flitch plate beams and steel channels will be interwoven to maintain the original roof depth and appearance but to increase load capacity.
-re-roofing all sloped roofs with the originally designed roll roofing, this time with synthetic wood battens and a waterproof membrane underlying all. Working roof venting in was a challenge...ridge was easy as it would appear as another batten, soffits don't want to be violated as they are so visible from the interior and Wright's concept of a continuous uninterrupted plane from interior to fascia needed to be maintained....I'm proposing a top mounted vent to blend with the battens and keep the soffit clear http://www.airvent.com/professional/pro ... ries.shtml
-re-insulation and replacement of the living room and dining area ceiling GWB...always was sand-finished paint on GWB, we'll restore as such.
-removal of existing exterior concrete slab that is dead flat and does not shed roof water adequately. To be replaced with sloped, red tinted concrete of same module with a turn down edge for stability.
-replacement and reframing of the window wall; mullions to be continuous from slab to roof. water and potential for rot issues to be addressed. Original wood to be re-used where possible.
-restoration of window wall French doors and stationary glass. Cracked sheets to be replaced all others reinstalled; rotted doors to be dutchman'd or replaced on case by case basis.
I can relate to some of your problems. I believe picture 6 shows us the various patches on your bottom rails. Do we see 1/4 inch plywood, or worse yet, masonite attached to the bottom rails?
Are the bottoms of the stiles cut off as well?
As you know, this whole window wall will need to opened up which will necessitate erecting a plastic or temporary wall a few feet in to protect the interior from the elements.
The discontinuous mullions do not work...I believe you mentioned you will be replacing them with new wood, which the species has not yet been determined and running them from the concrete pad to the roof. I agree with Paul, Cypress should be installed. As for a finish on all the end grain the West System works like a champ. I will post some picks for you to see. For boat builders it is the glue/epoxy of choice, and for those of us who live with these window walls we can attest that they must function like a wooden boat.
This is a lengthy project, but I know you and Christine will solve it to your satisfaction.
The bottom rails of the French doors and stationary windows were patched, cut, and cobbled in various ways prior to our purchase of the house. Of the three sets of operable doors, one was patched with epoxy resin which is falling out, one was not patched at all (it was operable until two summers ago when the bottom rail sagged while open and was nearly impossible to close..it is too soft to move now), the last pair was patched shut with a sheet of luan plywood screwed to the exterior and sealed with silicone. The stationary panel pairs have both been dutchman'd with stacked 2x6's faced with luan and painted.
None of these repairs was done in a manner approaching adequate craftsmanship or historical authenticity. They will all be undone and repaired using details closely matching the original condition per the drawings. Screens and associated frames per the original drawings will be made for the operable pairs.
A question: The drawings are thin on detail for the underside of the bottom rail of the French doors...from what I could tell, there was no metal strip on the under side to protect the endgrain of the stiles or to provide a positive weather or bug barrier. What was in place or not at Dobkins?
Why cypress, if a better specie is available ? Are the mullions to be painted ? Ipe is great, though very dark. "What Wright did is good enough" doesn't necessarily fly, in my opinion. (I'm still wondering how the roofing/fascia connection was made, without flashing, at Jacobs I -- the only such restoration I'm aware of !)
dtc sends photos of Dobkins; I'll post those next.
Here are DRN's drawings:
Sweeton progress sheet
Proposed mullion base detail (if CMU exists under slab)
Proposed mullion base shoe
Sweeton roof existing framing sketch 2.20.2014
Sweeton roof proposed framing sketch 2.20.2014
I cut out the rot and a couple of inches of sound wood above it.
Glued in new piece/screwed & plugged.
Detail of Dutchman joint.
Bottom rail of mitered window. The joint glued/screwed & plugged.
New stile & bottom rail.
I replaced stops where needed with fresh mahogany & stainless steel brads. All glue "West System".
The house reached its 50th birthday while I was in the middle of it.
They were in very rough shape when we purchased the house back in 1997.
Only one set of doors were operable.
I suspect the mortice and tenons of the doors failed when the house was 30 to 35 years old. Assembled with inferior glues and nails that started to rust a year or so in. Deferred maintenance always takes its toll.